Chem and Orgo Flashcards
Why are cycloalkanes unlikely to have derivatives?
For a molecule to have derivatives, it must be able to react in a way to create the derivatives— can’t be non-reactive
True or false: organic solvents are ideal for hydrogen bonding
FALSE: can’t H bond with organic solvents— think of all the CH bonds!
Which is the proper pairing of amino acid configurations?
- S/R and D/L
- S/D and L/R
- S/L and D/R
S/L and D/R
S enantiomer goes with L rotation
R enantiomer goes with D rotation
If a molecule has 3 chiral centers, how many stereoisomers does it have?
2 stereoisomers for each chiral center
So 3 chiral centers = 2^3 stereoisomers
What are the necessary characteristics of stereoisomers?
Stereoisomers must have 4 different substituents, no double bonds
What is the difference between nucleophiles and electrophiles?
Nucleophiles have a charge or a lone pair, they donate electrons to electrophiles, which are electron deficient
What is the name of a hemiacetal ring that has its aldehyde oxidized to carboxylic acid during the time it is in its open-chain conformation?
Aldonic acids
Oxidized aloses
Why are monosaccarides with a hemiacetal ring considered reducing sugars?
When the hemiacetal ring is in its open chain form as it switches between alpha/beta configurations, the aldehyde can be oxidized to carboxylic acid (oxidized aldose)
Aldoses can be oxidized, so they are considered reducing agents
So any monosaccharide with a hemiacetal ring is a reducing sugar
What is tautomerization?
Rearrangement of binds in a compound
Usually by moving a hydrogen and forming a double bond
What is the difference in deoxyribonucleic acid and ribonucleic acid and how can you tell the difference from their names alone?
Deoxyribonucleic acid has a hydrogen instead of a hydroxide
(Ribonucelic acid has a hydroxyl in this position)
Deoxy sugars contain a hydrogen that replaces a hydroxyl group
What reaction do hexokinase and glucokinase (the analogous enzyme in the liver and pancreatic beta cells) catalyze?
Phosphorylation of glucose in glycolysis
Hemiacetals/hemiketals react with alcohols to form acetals/ketals under what condition?
Under acidic conditions, hemiacetals/hemiketals react with alcohols to form acetals/ketals
True or false: anomeric carbons of cyclic sugars can react with any hydroxyl group of any other sugar molecule, regardless of alpha or beta configuration
TRUE: formation of an alpha or beta glycosidic linkage is nonspecific
What is the technical name for sucrose?
Glucose-alpha-1,2-fructose
What is maltose a disaccharide of?
2 glucose molecules
Glucose-alpha-1,4-glucose
What is the difference between estérification and glycoside formation?
Estérification: hydroxyl group + carboxylic acid or derivative
glycoside formation: alcohol group + hemiacetal/ketal on sugar to form alkoxy group
What is the metabolic value in carbohydrates being oxidized?
Carbohydrates reduce other molecules
Aerobic metabolism requires reduced electron carriers
What is the effect of lowering the temperature in gas chromatography?
GC is for 2 liquids with significant changes in BP
lower temperature = longer retention time = more resolution between peaks
How does polarity affect boiling point?
More polar = higher BP
What does mass spectrometry measure?
Mass to charge ratio
What happens when an electron absorbs energy?
Electron absorbs energy, becomes excited, releases light and relaxes to ground state
The Henderson-Hasselbalch equation states that for every 1 unit difference between pKa and pH…
For every 1 unit change between pKa and pH, ratio of acid/base or base/acid changes by a factor of 10 (for every 2 units, factor of 100, and so on)
When the pH > pKa …
More base than acid
Why does CO2 buildup in the blood cause acidosis?
CO2 buildup —> right shift of equilibrium, favoring products —> acidosis
How does decreasing salt concentration affect hydrophobic chromatography?
Hydrophobic chromatography relies on high salt concentrations to strengthen hydrophobic interactions
Decrease causes protein to dissociate from column
What is the range of visible spectrum wavelength?
390-700nm
Violet- 390nm
Red- 700nm
Which has higher boiling points, trans or cis stereoisomers?
Trans has higher BP
cis generally more compact, trans generally linear—> pack tighter
What is sucrose made of?
Glucose (6 membered) + fructose (5 membered)
Mannose And glucose are…
Epimers
What are different about dideoxyriboses ?
Deoxyribose = no 3’ hydroxyl
So
Dideoxyribose = no 2’ or 3’ hydroxyl
What is the equation for work function? Which electrons does it refer too?
E = hf0 where E is the work function, h is Planck’s constant, f0 is threshold frequency
Minimum energy needed to remove valence electrons
What happens to the excess energy when the energy added is greater than the work function?
Excess energy is transferred to kinetic energy of ejected electron
A metal with a work function of 500J is struck by a photon of 500J. The electron will:
The work function = the energy
So the electron will be free from its attraction to the nucleus
But it will not move because it lacks excess energy to be converted to KE
An atom undergoes radioactive decay, resulting in the atomic mass number being reduced by 4 and the atomic number being reduced by 2. What kind of decay is this?
Alpha decay- loss of one He nucleus, which has mass number of 4 and atomic number of 2
An atom undergoes radioactive decay which changes a neutron into a proton with ejection of an electron. What type of decay is this?
Beta decay- neutron chantes to proton, electron ejected
Which type of decay does not change the number of nucleons?
Gamma emission- byproduct of other types of decay. No change in number of nucleons
True or false: binding orbitals are higher in energy than antibonding orbitals
FALSE: antibonding orbitals are higher in energy than bonding orbitals
“Out of phase” electrons that are “repulsive”
Is energy released or required to form a bond?
Energy is always released when a bond is formed
ATP->ADP releases energy because the bonds formed in making ADP releases more energy than what is required to break ATP bonds
When nitrate loses an oxygen it becomes what?
Nitrate: NO3-
Nitrite: NO2-
Name the following:
- ClO3-
- ClO4-
- ClO2-
- ClO-
Hypochlorite: ClO-
Chlorite: ClO2-
Chlorate: ClO3-
Perchlorate: ClO4-
When balancing a chemical reaction, which atoms should you balance first?
Balancing reaction:
- Balance carbons
- Balance hydrogens
- Balance oxygens
Then do the other atoms
Which requires more oxygen to combust, propane (C3H8) or propanol (C3H8O)?
Quick trip for finding high species requires most oxygen to combust:
Add 1 for each C, subtract 0.5 for each O
Propane: (3x1) - (0x0.5) = 3
Propanol: (3x1) - (1x0.5) = 2.5
Propane requires more energy to combust
How does increasing pressure affect a reaction at equilibrium?
Increasing pressure causes shift in reaction towards side with fewer moles of gas
What are the axis of a first order reaction graph?
ln[A] vs time
Linear with a slope of -k
A rate order graph shows 1/[A] vs time that is linear with a slope of k. What order reaction is this?
Second order reaction
What is the structure of acetone?
CH3(C=O)CH3
Has ketone group
What does combustion produce?
Combustion —> CO2 + H2O
What is the best way to tell if molecules exhibit similar properties?
Do they contain atoms from the same periodic groups?
Which groups on the periodic table easily replace Hydrogen in a single replacement reaction?
Groups 1&2 easily replace hydrogen in single replacement
Hydrogen gas always produced
According to the activity series, can fluoride replace bromine in a single replacement?
Yes: for halide to replace another halide, it must be above it on periodic table (more electronegative)
What does HCO3 dissociate into?
HCO3 -> CO2 + H2O
What gas does the reaction between CaBr2 and F2 produce?
CaBr2 + F2 -> CaF2 + Br(g)
Fluorine is more electronegative than Bromine so it can replace it
What gas will the reaction between CaSO3 and HCl produce?
CaSO3 + HCl -> H2SO3 + CaCl
H2SO3 dissociates into SO2(g) and H+
What gas will H2CO3 produce?
H2CO3 -> CO2(g) + H2O
What gas will H2SO2 produce?
H2SO2 -> SO2(g) + H2O
What gas will NH4OH produce?
NH4OH -> NH3(g) + H2O
What gas is produced in a reaction with sulfide?
Sulfide produces H2S(g) in reaction
Which of the following is a stronger nucleophile?
OH- or H2O
OH- is a stronger nucleophile than H2O —> negatively charged nucleophile is always stronger than its neutral component
Which is the stronger nucleophile?
NH3 or H2O
NH3 is a stronger nucleophile than H2O —> N vs O, nucleophilicity decreases L->R on periodic table
As size and polarizability increase down the periodic table, nucleophilicity…
Nucleophilicity increases down the periodic table as size and polarizability increase
Will bronsted lowry or Lewis acid-base reaction occur faster?
Bronsted Lowry occurs faster than Lewis
Bronsted Lowry: acid is H+ donor
Lewis: acid accepts e- pair
Which is likely to form coordinate covalent bond with nickel?
BF3
PH3
NH4+
PH3
Coordination covalent bond between transition metal with positive oxidation state and atom with lone pair
How do radius and ionization energy predict electronegativity?
Small radius and large ionization energy —> high electronegativity
True or false: covalent bonds can conduct electricity in solution
TRUE: some covalent bonds can conduct electricity in solution (HCl)
What is the only thing that changes the value of Keq?
TEMPERATURE
What is likely to cause each of the following:
Changing colors in a flame test
Changing colors in solution chemistry
Flame test = photon emission
Solution chemistry = partially filled d orbitals of transition metals
You make a solution by adding 200mL of 0.8M Fe2(SO4)3 to 2L water. How many moles of sulfate ions are present?
M = mol/L (0.8)(0.2L) = 0.16mol of Fe2(SO4)3
There are 3 moles of SO4 in this compound, so 0.16 x 3 = 4.8x10^-1
How many more neutrons are there than electrons in 54Fe+? (Fe atomic number is 26)
54-26= 28 neutrons
Fe+ also has a 1+ charge
So 3 more neutrons than electrons
How does lowering the temperature affect gas chromatography?
GC- for 2 liquids with big differences in BP
Lower temp = longer retention time = more resolution between peaks
How does polarity affect boiling point?
More polar = higher BP
What does mass spectrometry measure?
Charge-to-mass ratios
What happens when an electron is excited by absorption of energy?
Electron releases photon (light), relaxes to original energy state
If the pH > pKa what is the ratio of acid to base
pH > pKa = more base than acid
Complete this sentence:
According to Henderson-Hasselbalch, for every 1 unit difference between pKa and pH….
For every 1 unit difference between pKa and pH, ratio of acid/base changes by a factor of 10
For every 2 units, factor of 100… so on…
What effect does buildup of CO2 in the blood have?
CO2 buildup in blood causes acidosis
Shifts bicarbonate buffer equation right (CO2 is a reactant)
CO2 + H2O -> H2CO3 -> H + HCO3
How will decreasing the salt concentration of the eluent affect hydrophobic chromatography?
Hydrophobic chromatography- relies on high [salt] to strengthen hydrophobic interactions
Decreased [salt] causes proteins to dissociate (weaker interactions)
What is the range of visible spectrum?
390-700nm
Violet is lowest, red is highest
Do cis or trans isomers have higher BP?
Trans isomers have higher BP
trans are generally more linear, cis do not pack as tightly
What is sucrose made of And what numbered rings are these?
Sucrose = glucose (6 membered) + fructose (5 membered)
In size exclusion chromatography, which molecules elute first?
Large molecules elute first in size exclusion chromatography
As arteries narrow, how is velocity of blood flow affected?
Q=AV
narrower artery (smaller area due to smaller radius) increases velocity
Given that deoxyribose has no 3’ hydroxyl, what can you infer about dideoxyribose?
Dideoxyribose - no 2’ or 3’ hydroxyl
What Is a black body radiator?
Black body radiators absorb all energy and emit 100% of energy as electromagnetic radiation
Which type of calorimeter provides content pressure and which type provides constant volume?
Coffee cup- open to atmosphere, so constant pressure. Allows for PV work
Bomb calorimeter- sealed, so constant volume. Does not give enthalpy but measures change in interval energy
What is the difference between an isolated and closed system?
Isolated system- no exchange with environment
Closed system- only energy exchange with environment (deltaE = q + w)
A high heat of combustion is associated with stable or unstable molecules?
Unstable molecule = high heat of combustion (going from unstable to stable molecule, heat released)
What is the fundamental thermodynamic equation?
deltaG = deltaH - TdeltaS
What are Arrhenius acids and bases?
acid- produces H+
Base- produces OH-
How is a bronsted Lowry acid different than a Lewis acid?
Bronsted Lowry- acids donate protons (H+), bases accept protons
Lewis- acids accept electrons, bases donate electrons
In the ionization of water, how does adding a base affect the equilibrium of the ionization of water?
Adding either an acid or base shifts the equilibrium for ionization of water to the left
H2O + H2O <> H3O+ + OH-
What are the strong acids?
HI, HBr, HCl, HNO3, HClO4, HClO3, H2SO4, H3O+
Why is HF not a good acid?
F is too small- cannot spread charge, conjugate base would be unstable
Where is the half equivalent point in a titration curve?
Half equivalence point- middle of nearly horizontal section
[HA] = [A-]
After Crossfit, your body maintains homeostasis by which of these?
Conduction
Convention
Radiation
Conduction- direct contact
Radiation- heat release
Not convection (heat rises)
Which of these has the larger negative heat of combustion?
HF (bond energy= 600kJ/mol)
F2 (bond energy= 150kJ/mol)
Unstable species = larger negative heat of combustion (going from unstable to stable molecule)
F2 (small bond energy) has larger negative heat of combustion
Which of these must increase entropy of a system?
Pressure or volume
Volume
Pressure does not increase entropy (disorder). Think about how increasing pressure of gas creates solid (less disorder)
0.001kg mass increases temp from 250K to 275K when 1000J is applied. What is specific heat capacity?
Q = mc(delta)T
1000J = (0.001kg)c(275-250K)
c = 4x10^4 J/kg•K
Heat source of 50Watts of power submerged in bucket of 1kg water. How long will it take to raise temp of water by 5 C? (Water specific heat = 4.18 kJ/kg•C)
50 watts = 50 J/s
Q = mc(delta)T
Q = (1)(4.18)(5) ~ 20 kJ
20kJ = 20,000J x (1 s/ 50J) x (1min/60s)
~7 minutes
A rxn known to have very high activation energy can also have which of the following:
Fast reaction rate
deltaG < 0
very large Keq
Can have all of these
High temp can induce fast reaction rate
deltaG can be < 0 if temp and entropy increase is high enough
Keq can be large- can produce a lot of products at equilibrium, just takes more energy to get there
Which of these has the lowest Ka? HClO4 HClO3 HClO2 HClO
Low Ka = least acidic
HClO is least acidic- conjugate base not as stable (less resonance because less oxygen atoms)
What are the strong bases?
Group IA hydroxides (NaOH, KOH, etc) NH2- H- Ca(OH)2 Sr(OH)2 Ba(OH)2 Na2O CaO
Which 2 atoms in the first 3 rows of the periodic table are stable with 6 valence e (but can have up to 8)?
Boron (B) and beryllium (Be)
How many oxygens go with each of these naming conventions? “Per- -ate” “-ate” “-ite” “Hypo- -ite”
“Per- -ate” —> 4 O
“-ate” —> 3 O
“-ite” —> 2 O
“Hypo- -ite” —> 1 O
Also: “ate” = “-ic acid”
“ite” = “-ous acid”
(There are some exceptions)
How do you know something is a nucleophile?
Lone pair, negative charge, double or triple bond
How do you know something is an electrophile?
Atom attached to strong electron withdrawing group, positive charge, carbocation
What’s a carbonyl group, how does it effect reactivity of nearby groups?
Carbonyl: C=O
Strong electron withdrawing group because O is very electronegative, so C has a partial positive charge
Could reduce the nucelophilicity of nearby group
Is oxygen electron donating or withdrawing?
O IS ELECTRON WITHDRAWING
If something is a good leaving group, is it a good nucleophile?
NO. too stable on its own
In general you can think of nucleophiles as bases, except in this situation:
If it’s really bulky, it can be a base but not a nucleophile
Match:
Carbocation/ carbanion
Electrophile/ nucleophile
Carbocation = electrophile Carbanion = nucleophile
So alkyl groups donate or withdraw electrons?
Alkyl groups are electron donating, due to dipole moments!
Decarboxylation always forms what as a leaving group?
CO2 is always leaving group of decarboxylation. What’s left behind always has a negative charge on the C (nucleophile), can be reacted with further
When giving priority in R/S convention, what should you do when the bonded atom has a double bond after it (if comparing it in a tie)?
Count the atom bonded via double bond twice (C=O is like 2 O’s, C=C is like 2 C’s, so C=O would be higher priority)
A leaving groups leaves what behind? deprotonation leaves what behind?
Leaving group —> carbocation
Deprotonation (H) —> carbanion
Describe the general structure of an amine
Lone pairs on top of N, bonded to something below
What’s the formula for glucose?
C6H12O6
What’s the charge of sulfate ion?
-2
Which of these is not a coordinate covalent bond?
Cu(NH3)4^2+
Co(CH4)4^2+
Ni(PBr3)4^2+
Co(CH4)4^2+ is NOT a coordinate covalent bond because CH4 doesn’t have a lone pair
What explains the reactivity of metals in water going down a period?
Decreasing ionization energy (easier to be IONIZED)
If a question says calcium reacts with water, is it solid or aqueous?
SOLID. Otherwise it would say aqueous calcium
What’s the structure of acetone?
CH3-C=O-CH3
What should you do when asked what species requires the most oxygen to combust?
+1 for each C, -0.5 for each O
The largest number will require the most O2 to combust
What is Avogadro’s number?
6x10^23
Which increases yield:
Increasing temperature
Removing product
REMOVING PRODUCT
temperature affects rate, not yield
What’s the energy of a photon?
E = hf
What happens in beta decay?
Neutron is changed into a proton, an electron is lost
How many lone pairs does chlorate have?
ClO3-
One lone pair
What is the VESPR geometry of SF4?
4 substituents, 1 lone pair
See-saw
What is the VESPR geometry of BeF3?
3 substituents, 2 lone pairs
T shaped
If Br and Cl are cis and adjacent on a cyclohexane, what will the cyclohexane lowest energy conformation be?
Br is larger so it will be equatorial, Cl will be axial (they can’t both be equatorial when they are cis and adjacent)
What is the formula of nitrate?
NO3-
No lone pairs on nitrogen
When you abstract a proton from a hydrocarbon, what is left behind?
Carbanion
What is the formula and structure of nitrite?
NO2-
One O is double bonded, the other is single bonded and has negative charge
N has no formal charge, 1 lone pair
How many lone pairs are on chlorite?
ClO2-
One O is double bonded the other carries a negative charge
Cl has 2 lone pairs
Carboxyl group is removed from carbon chain and CO2 is produced. What is this process and what type of intermediate is formed?
Decarboxylation (-COOH is removed)
Carbanion (negative charge)
For a greater overlap of p orbitals in a double bond, the atoms should be:
Smaller
Larger
Smaller- able to get closer to each other
What is the s character of sp, sp2, and sp3 hybridizations?
Sp- 50% s character
Sp2- 33% s character
Sp3- 25% s character
When enantiomers react with a chiral molecule, how many products are produced?
2 different substances are produced, 1 for each enantiomer
NaBH4 will reduce aldehydes to what kind of alcohol
Primary
NaBH4 will reduce ketones to what kind of alcohol
Secondary
Creates chiral carbon- 1 H, 1 OH, 1 methyl, 1 R group
Which has a lone pair, ammonium or ammonia?
Ammonia has lone pair (NH3)
How does separation of charge factor into resonance contribution?
Least separation of charge = major contributor of resonance
Are alkenes nucleophilic or electrophile?
Alkenes are electron dense, and so nucleophilic
Are electrophile electron withdrawing or donating, and what charge will they have?
Positive charge = electron withdrawing
When distinguishing between a nucleophile and a base, what should you consider?
Size- bulky molecule will act as a base
what do Grignard reactants do?
Reduce carbonyl to alcohol while adding R group- lengthen C chain
Reduction of carbonyl via LiAlH4 would add which to carbonyl carbon?
Methyl group
Hydrogen
Hydrogen
What does the Witting reaction do?
Carbonyl is replaced with alkene
Jones reagents are good for what?
Strong oxidizing agents
What is more basic OR- or OH-?
OR- is more basic because carbon chain (R) is weakly electron donating (to O, giving partial negative) while H is neutral
What mass of cyanide in the bloodstream corresponds to a lethal blood cyanide level for a person whose total blood volume is 4.8L, if 115uM is lethal? (Molar mass of cyanide is 26g/mol)
(115x10^-6mol/L)(4.8L)(26g/mol)
= 0.014g or 14mg
You’re halfway submerged under water (you’re 80kg and weigh 784N). If your density is the same as water, what’s your apparent weight?
You’re the same density as water, so just divide your weight in half for half submerged —> 392N
What’s the empirical formula of the conjugate acid of the anion in strontium acetate, Sr(CH3COO)2?
The anion is acetate, the conjugate acid of acetate is acetic acid —> C2H4O2 (extra H)
Reduce this to find empirical formula- CH2O
How does length of an extended conjugated double bond system affect its light absorption?
Longer conjugated double bond system, longer the wavelength of visible light that will be absorbed (so lower frequency light)
An inhibitor is found to bind enzyme only after substrate is bound. What kind is it?
Uncompetitive inhibitor
An inhibitor is found to bind either bound or unbound enzyme equally. What kind is it?
Non competitive inhibitor
What does Km represent?
Affinity of enzyme for its substrate
Substrate concentration that will produce initial velocity 1/2 Vmax
What kind of inhibitor is best for continuous inhibition?
Noncompetitive- inhibitor will reduce reaction velocity at any substrate concentration (binds allosteric site)
(Competitive inhibitors can be overcome at high substrate concentration)
What is the oxidation state of manganese in MnO2?
Oxygen has -2 oxidation state, so to balance out both oxygens, Mn must have oxidation state +4
(Manganese (IV) oxide)
Acetoacetic acid can be used as fuel in starvation except in: Heart Liver Brain Muscles
Liver
Acetoacetic acid is ketone body, and liver lacks enzyme to convert ketone bodies to ATP (because liver produces ketone bodies when blood glucose is low)
Rate of substrate turnover was measured for an enzyme with Vmax of 2uMs^-1 and Km of 15uM. What is the initial velocity when substrate concentration is 5uM?
Need MM equation:
V0 = (Vmax*[S]) / (Km + [S])
V0 = (2*5)/(15+5) = 0.5uM^-1
True or false: antibonding orbitals are lowest in energy
FALSE: antibonding orbitals are highest in energy and decrease molecular stability (whether partially or completely filled)
To be aromatic, molecule must adhere to 2 things:
Must be planar, and follow 4n+2 rule
(Cis or trans orientation of bonds is irrelevant)
4n+2 rule: count number of pi electrons. 4n+2 will equal number of pi electrons. If you solve for n, it must be a whole number (then it is aromatic)
How does 4n+2 rule work?
Count number of pi electrons
4n+2 = number of pi electrons
Solve for n, it must be a whole number
(Pi electrons: electrons with pi bonds, or lone pairs within p orbitals)
How do you calculate power in constant velocity situations?
P = force x velocity
How do Archimedes principle and Bernoulli effect differ in their relation to fluids?
Archimedes principle relates to static fluids
Bernoulli effect relates to dynamic fluids (like effect of fluid speed on pressure)
What is the energy of photons at wavelength 584nm?
E = hc/I
E = (6.6x10^-34 x 3x10^8) / (584x10^-9) = 3.4x10^-19J
What charge will the intermediates of aldol addition and condensation reactions have?
Aldol addition and condensation reactions proceed under basic conditions by abstraction of the acidic alpha carbon hydrogen
Intermediates will have negative charges (so you will NOT have a carbocation)
Aldol addition: ketone enolate (nucleophile) and aldehyde (electrophile) produce aldol (C-C bond formed)
(Enolate: organic anions from deprotonation of carbonyl compounds)
Which will have greater p orbital overlap:
C=O
N=O
N=O
Smaller atom will be able to get closer
Atom size decreases left to right because of electronegativity
What’s the structure and VESPR geometry of sulfur dioxide?
SO2 has S double bonded to both O, and a lone pair (doesn’t follow octet)
Bent shape
True or false: tetra-substituted alkenes are the least stable and therefore most reactive
FALSE: tetra substituted alkenes are the MOST stable (low heat of combustion), but ARE more reactive as nucleophiles
Which is an electrophile:
CH2CH2
HCl
Alkenes are NOT electrophiles but HCl is a GREAT electrophile
Which is the most basic substituent:
Cl
OH
OR
OR- carbon is more electron donating than hydrogen
Cl is a weak base because it is the conjugate base of a strong acid (so it’s stable)
Which is stronger- sigma bond or pi bond?
Sigma bond
Higher electron density (head-to-head overlap is closer together)
HOWEVER a double bond (a pi bond plus a sigma bond) is stronger together than a single bond
What type of bond is most reactive?
Triple bonds (because pi bond is more reactive than sigma bond)
Reactivity has to do with tendency of third bond (a pi bond) to react
What are the possible VESPR shapes of sp2 hybridization?
Trigonal planar or or bent (1 lone pair)
What are the possible VESPR shapes of sp3 hybridization?
Tetrahedral
Trigonal pyramidal (1 lone pair)
Bent (2 lone pairs)
How is iron bonded in the heme unit of hemoglobin?
Coordinate covalent bond
Which atoms are stable with 6 valence e?
Boron and beryllium
Which atoms on the periodic table can accept more than 8 electrons?
Third period or higher
PCl5, SF6, (PO4)3-, (SO4)2-
What is an aryl functional group?
Benzene ring as functional group
What is a hydrazine functional group?
NH2-NH2
What is a vinyl functional group?
-CH=CH2
What is an imine functional group?
R1R2-C=N-R3
N has a lone pair
What is an acyl functional group?
R(C=O)-
What is a sulphone functional group?
S double bonded to 2 O’s, and single bonded to 2 R groups
What is a hemiacetal?
What is an acetal?
Hemiacetal: Alcohol and ether attached to the same carbon
Acetal: 2 ethers attached to same carbon
What is a hemiketal?
What is a ketal?
Hemiketal: An alcohol and an ether attached the same carbon, along with 2 other carbons
Ketal: 2 ethers attached to same carbon, along with 2 other carbons
Dextrorotary rotates light in which direction?
Clockwise, +
Levorotary rotates light in which direction?
CCW, (-)
In E/Z convention, which is same side and which is opposite side to have higher priority substituents?
Z = same side (cis)
E = opposite side (trans)
In anomers, if the anomeric OH/OR group and the CH2OH group are on the same side, it is…
Beta
n anomers, if the anomeric OH/OR group and the CH2OH group are on different side, it is…
Alpha
Bases abstract (fill in the blank)
Nucleophiles attack (fill in the blank)
Bases abstract protons (hydrogens)
Nucleophiles attack carbons (or other central atoms)
Basicity is a function of ___
Nucelophilicity is a function of ___
Basicity —> thermodynamics (compares stability of reacted and unreacted base)
Nucelophilicity —> kinetics (rate at which it reacts with electrophile)
Which substitution reaction will create racemic mixture?
SN1
Which reactions prefer polar protic solvents?
E1, SN1
True or false: combustion of an alkane is radical and exothermic
TRUE. Has high energy of activation
Alkane reacted with H2 in presence of metal catalyst gives what?
Syn addition (H bonds added on same side)
Are alkenes nucleophiles?
Yes. Pi electrons in double bond will attack electrophiles (leave behind carbocation)
What is the formula of benzene?
C6H5
How can alcohols act as both nucleophiles and Lewis acid?
Nucleophile- lone pair acts as Lewis base
Lewis acid- when oxidized to carbonyl group, oxygen accepts pairs of electrons from the OH bond as proton is abstracted
How does substitution affect alcohol acidity?
Less substituted alcohols are more acidic
Tertiary alcohols are destabilized by induction
Oxidation of secondary alcohols form:
Ketones
Can tertiary alcohols be oxidized?
No
Primary alcohols can be oxidized to ___ which is further easily oxidized to ___
Primary alcohol -> aldehyde -> carboxylic acid
What are the Jones, Collins, PCC, PDC, O3, CrO4, and KMnO4 reagents used for?
Oxidation
What can NaBH4 reduce?
What can LiAlH4 or H2/pressure reduce?
NaBH4- aldehydes and ketones
LiAlH4 or H2/pressure- aldehydes, ketones, carboxylic acids, esters (stronger reagent)
LiAlH4 produces 2 equivalent of H-, NaBH4 only produces 1
When Vic-diol is combined with hot acid (Pinacol Rearrangement), what do you get?
Ketone or aldehyde
“Vic”= adjacent (2 adjacent hydroxyl groups)
Carbons with functional groups must be tri- or tetra- substituted
—> tri = aldehyde
—> tetra = ketone
What is forming tosylates and mesylates good for?
They make great leaving groups
Formation of a tosylate/mesylate is what kind of reaction?
SN2
Alcohol attacks tosyl/mesyl halide (kicks off halide)
Is dehydration of an alcohol an equilibrium reaction?
Yes
In dehydration of an alcohol (equilibrium reaction), what conditions favor alkene and what conditions factor alcohol?
Alkene- hot, concentrated acid
Alcohol- cold, dilute acid
Protonation of alcohol with extension or carbon chain is what kind of reaction?
What reagent does it use?
Grignard synthesis
RMgX (usually RMgBr)
What are ethers and how reactive are they?
R-O-R
NOT reactive
EXCELLENT solvent
Do alkenes donate or withdraw electrons?
Alkenes are weakly electron withdrawing
Electron donating groups increase or decrease basicity?
Increase
Carbocations are always formed on most stable carbocation except when? (Tertiary > secondary > primary)
When peroxides are present
Which will give the greatest heat of combustion?
- molecule with least negative heat of combustion
- highest bond energy
molecule with least negative heat of combustion or smallest bond energy = least stable = highest heat of combustion
Compare the difference in acid/base strength when making a buffer and when titrating
Buffer- weak acid/weak base or strong acid/ strong base
Titration- weak acid/strong base or weak base/strong acid
What does Ksp describe?
Equilibrium constant specific for solubility
What type of molecule is palmitoleic acid?
Fatty acid. Hydrophobic carbon chain and acidic group
What does an IR peak at 3200-3500 represent?
Carboxylic acid OH
What does an IR peak at 1700-1750 represent?
Carbonyl (C=O)
What does an IR peak at 1580-1610 represent?
Conjugated C=C (like in benzene)
In the context of binding affinities, what does a high Ka represent?
High affinity binding (Ka > 1)
What is e- configuration of Zn2+ (atomic # is 30)?
1s2 2s2 2p6 3s2 3p6 4s2 3d10
Or
1s2 2s2 2p6 3s2 3p6 4s0 3d10
1s2 2s2 2p6 3s2 3p6 4s0 3d10
4s subshell has highest principle quantum number so it empties first
How many electrons can be held in the 3rd shell of an atom?
Max number of electrons allowed in a shell = 2n^2
So if n=3 …. 18 electrons
In the 4th subshell of an atom, how many electrons can there be?
Max number of electrons in a subshell = 4l+2
So in 4th subshell, l=4
So… 18 electrons
Which elements in the periodic table can only have paired electrons in their ground state?
Elements on the end of a block (s, p, d, f block)
What is the equation for angular momentum?
L = mvr
What two equations combine to give that for the energy of a photon?
E = hf
c = f x wavelength
…
E = hc/wavelength
Is the energy difference greater between the 3 and 4th shells or the 1 and 2nd shells?
Difference in energy is function of:
[1/ni^2 - 1/nf^2]
So there’s a greater energy difference between 1 and 2 shells
(1/1 - 1/4) vs (1/9 - 1/16)
For n=3, what are the possible quantum numbers?
n = 3 l = 0,1,2 ml = -2,-1,0,1,2 ms = +/-1/2
How does the n+l rule help you decide competitive energies of subshells?
The lower the sum of n and l value, the lower the energy
When determining electron configuration of cations, where do you remove electrons from?
Remove electrons from subshells with highest n value first
What does Hund’s rule say?
In given subshell, orbitals are filled to give max number of half filled orbitals with parallel spins
(Like avoiding sitting next to someone on a bus)
Which will be attracted to a magnet?
Paramagnetic or diamagnetic
Paramagnetic- has unpaired electrons
For each block (s,p,d,f), where will the valence electrons be?
s block- only highest s subshell (Group I And II) p block- highest s and p subshells (Group 13-18) d block- highest s and d subshells (Transition) f block- highest s and f subshells (Lanthanides and actinide)
Which will travel farther in TLC, CO2 or methanol?
CO2- least polar compounds travel further, have larger Rf
TLC has nonpolar solvent, capillary action will pull eluent up—> more soluble eluent will travel farther
Which would have highest Rf value on TLC- benzyl ester, methanol, or cyclopentanol?
Rf- distance travelled by solute/ distance travelled by nonpolar solvent
Benzyl ester (other two are polar alcohols)
Nonpolar solvent in TLC, capillary action pulls eluent up the plate- nonpolar travel farther—> larger Rf value
You’re making an artificial bone matrix. Phosphate (PO4^3-) works great, but ClO4- doesn’t work well. What’s different about these two that could cause this?
Different charges
ClO4- (perchlorate) has one negative charge
PO4^3- (phosphate) has 3 negative charges
What type of interaction is likely to be important for complex formation in antigen binding?
Hydrogen bonding!
An electron moves from the 4th to 2nd shell. Describe what happens
Energy is released
Shells farther from the nucleus will have lower ionization energies. To move to a shell closer to the nucleus (one with higher ionization energy, more stable), energy is released
Which peak is more likely for an amide hydrogen in NMR? 2 or 8
8 —> amide hydrogen would be highly deshielded by electronegative nitrogen
Deshielded = downstream (higher number)
Diethylamine is a weak base. What are the odds it will be protonated?
Not likely, weak bases not readily protonated
Describe the conditions needed for hydrolysis of amides?
Acidic or basic, but acidic easier
Basic amide hydrolysis requires strong base/heat
What does acidic hydrolysis of amides give you? What’s the reverse of this reaction?
Amides + H3O+/heat —> carboxylic acid + amine (R-NH-R)
Reverse is condensation reaction:
Carboxylic acid + amine —> amide + water
For acid-base equilibrium at constant temperature, which value is constant- pKa or [weak acid]
pKa
Acid-base equilibrium constant is Ka
What is ammonia
NH3
Has a lone pair
Weak base
Compare Lewis and bronsted bases
Lewis bases must have lone pair of electrons to donate to Lewis acid
Bronsted bases accept protons
“Forms a pi bond” =
Double bond formed
What does molecular mass relate to freezing point?
Inverse
Increase molecule mass, decrease freezing point
If CH3COONa is added to cytosol, will it become acidic or basic?
Basic
Acetate ion is a proton acceptor (conjugate base of a weak acid is itself a weak base)
What is the oxidation state of hydrogen with a metal?
What is the oxidation state of oxygen in peroxides?
Hydrogen with metal: -1
Oxygen in peroxide’s: -1
Assign oxidation state to each atom in
(NH4)2SO4
N: -3
H: +1
S: +6
O: -2
Assign oxidation state to each atom in
FeCO3
Fe: +2
C: +4
O: -2
What does a positive electric potential mean?
Species really wants to be reduced- wants electrons
Negative E*- less likely to gain electrons than hydrogen ions (Hydrogen Half-Cell is standard comparison)
True or false: a species with a negative electric potential cannot be spontaneously reduced
FALSE: can be spontaneously reduced if paired with another species with more negative electric potential
To find the cell potential (E*cell), the sum of electric potentials for two half reactions, you must reverse…
… the half reaction of the species with the lowest reduction potential and take the negative of its E value (this is the oxidation potential)
DON’T USE STOICHIOMETRY. moles don’t matter here
Compare a galvanic cell to an electrolytic cell
Galvanic- (+) cathode/ (-) anode, cell potential is always positive, can be created using any two metals (current spontaneously generated)
Electrolytic- external voltage applies to galvanic cell which forces electrons to flow in opposite direction (-) cathode/ (+) anode, cell potential is always negative, lower reduction potential species is reduced. Sum of external voltage and negative cell potential must be positive
Both- REDUCTION AT CATHODE, oxidation at anode
What is the purpose of the salt bridge in galvanic cells?
Neutralizes charge buildup; allows electron flow to continue
How does the electric potential compare for a concentration cell compared to a galvanic cell?
Electric potential of concentration cell is always 0
Always positive for galvanic cell, negative for electrolytic cell
Which has (+) which has (-) electric potential, galvanic cell and electrolytic cell
Galvanic is positive. My GALS are always POSITIVE
Electrolytic is negative. ELECTRONS are NEGATIVE
How do you find free energy change of a redox reaction?
deltaG* = -nFE*
Where n is number of moles of electrons transferred in redox rxn
F is faradays constant (the charge on one mole of electrons- 6x10^23 x 1.6x10^-19 = 9.6x10^4)
E* is electric potential
So positive electric potential = negative free energy change = spontaneous
What is the ideal gas law and give the constant in both Latm/molK and J/mol*K
PV=nRT
R = 0.08 Latm/molK or
8.3J/mol*K
What are the 2 major ideal gas law assumptions?
Gas molecules have no volume and no intermolecular forces
What are the ideal gas law STP conditions?
P = 1 atm V = 22.4 L n = 1 mole R = 0.08L*atm/mol*K or 8.3J/mol*K T = 273 K (0* C)
What is the combined gas law and why is it helpful?
P1V1/T1 = P2V2/T2
Helpful because R is constant, can be used when given same number of moles of gas
How do intermolecular forces affect real gases compared to ideal gases?
Decreases pressure
PV/nRT < 1
Due to intermolecular forces assumption—> at low temperature, pressure is decreased
How does molecular volume of real gases affect gases as compared to ideal gases?
Increased molecular volume increases volume in real gases
PV/nRT > 1
Ar high pressure, molecules are pushed close together and their actual size begins to matter- becomes comparable to the distance between them
Gas -> solid is
Deposition
What is supercritical fluid
On a phase diagram, occurs past the critical point- liquid and gas phase merge. No heat of vaporization at critical point.
True or false: different phases of substance have same heat capacities
FALSE: can be seen by differing slopes on heating curve
What do the horizontal sections of a heating curve represent?
Phase change. All energy goes towards phase change, so no change in heat
Will horizontal segment be longer on a heating curve for melting or evaporation?
Evaporation- only some intermolecular forces broken in melting, all broken in evaporation to form gas
How does temperature affect vapor pressure and how does this relate to boiling?
Increase temp, increase Vp
Liquid boils when Vp = Patm
Must increase temp to cause boiling
How does addition of nonvolatile compared to volatile substance affect vapor pressure?
Addition of anything decreases Vp
More intermolecular forces to be broken
Solubility of a gas in a liquid is directly proportional to…
… partial pressure of that gas over that liquid
True or false: polar and non polar gases do not readily form homogenous mixtures
FALSE- no intermolecular forces (ideally) in gas so it doesn’t matter
Which side (receiving or giving water) will have higher osmotic pressure?
RECEIVING water has HIGHER osmotic pressure
What is osmotic pressure formula
Osmotic pressure = iMRT
i is # of ions formes in solution (van’t hoff)
M is molarity
Which can scatter light, true solutions or colloids?
colloids- solvents with very small un dissolved particles
What is a hydrate
Inorganic compound in water in which water molecules are permanently bound into crystalline structure
Compare molarity and molality
Molarity = mol/L Molality = mol/kg
What is the only thing that can change Ksp (solubility constant)
Temperature (same as with Keq, Ka, Kb)
All compounds containing these are soluble:
those containing:
Nitrate (NO3)
ammonium (NH4+)
GroupIA metals
All compounds containing the following are insoluble (unless paired with something from always soluble list- ammonium, nitrate, group 1A)
Those containing: Carbonate (CO3^-2) Phosphate (PO4^-3) Silver Mercury Lead
Dihydroxylation of alkenes with cold, dilute KMnO4 to give…
Vicinal diols
How do atomic radii and ionic radii compare between metals and nonmetals?
Metals- large atomic radius, small ionic radius
Nonmetals- small atomic radius, large ionic radius.
What does effective nuclear charge (Zeff) measure and what’s its trend in the periodic table?
Electrostatic attraction- measure of net positive charge experienced by valence electrons
Increases left to right
More or less constant in a group because of increased electron shielding down a group (from increased principal quantum number- valence electrons are increasingly separated from nucleus by more energy shells)
How does Zeff affect atomic radius?
Zeff increases left to right
So atomic radius decreases left to right
Atomic radius also increases down a group (larger principal quantum number n)
Compare ionization energy to electron affinity to electronegativity
Ionization energy- energy required to remove electron
Electron affinity- energy dissipates when an electron is gained (opposite concept of ionization energy)
Electronegativity- attractive force an atom exerts on electron in a chemical bond
What 5 electrons above the 3rd period violate the octet rule?
Hydrogen (2) Helium (2) Lithium (2) Beryllium (4) Boron (6)
What type of bonding makes crystal lattice?
Ionic
Compare melting/ boiling points of covalent and ionic compounds
Much higher for ionic- strong bonding
Formal chargers (over/underestimate) effect of electronegativity difference, while oxidation number (over/underestimates) effect of electronegativity difference
Formal charger- underestimate
Oxidation number- overestimate
A Lewis stud it’s with (more/less) separation of charge is more stable
LESS
Why do large molecules have greater dispersion forces?
Larger = more polarizable
What are 3 types of reactions that involve coordinate covalent bonds (one atom donates all the electrons)?
Nucleophile- electrophile
Lewis acid-base
Complexation
A 2N solution of acid contains a concentration of H ions equal to ___ moles per liter
2
Normality often used for hydrogen ion concentration
Normality always assumes rxn goes to completion
How can you use normality to find molarity?
Normality / n = molarity
Where n is number of whatever you’re looking for (protons, ion, electrons, etc)
Memory trick for -ite vs -ate stoichometry
The lITEst anions have fewest oxygen
The heaviest anions ATE the most oxygens
Ex: nitrite = NO2-, nitrate = NO3-
What’s the formula for acetate
C2H3O2-
What the formula for permanganate
MnO4-
Why do oxyanions of transition metals make really good oxidizing agents?
Have high oxidation numbers on the metal, so tend to gain electrons to lower this
Ex- MnO4- (permanganate), CrO4^2- (chromate)
How do you find the number of electrons transferred in a redox reaction?
Number of e- transferred =
Oxidation # of product - oxidation # of reactant
When do you use R = 0.082 Latm/molK and when do you use R = 8.314 J/mol*K?
R = 0.082Latm/molK is basically in units of volumepressure/moltemperature —> use for PV=nRT
R = 8.314 J/mol*K includes a unit for energy —> deltaG = RTlnK (energy)
What does NAG SAG PMS tell you about solubility?
Nitrates (NO3-)
Acetate (CH3OO- or C2H3O2-)
Group 1
Sulfates (SO4^2-, except when paired with Ca2+, Sr2+, Ba2+, Ag+, Pb2+)
Ammonium (NH4+)
Group 17
NOT SOLUBLE:
Pb (lead)
Mg (Mercury)
Si (silver, Ag2+)
Is carbonate soluble?
CO3^2- is NOT soluble except when paired with group 1 or ammonium
Phosphates (PO4^3-) follow same rule
How do the diffusion rates compare for two gases, A and B, if B has a molecular weight twice that of A?
Rates of velocities of gas diffusion is proportional to the inverse of the ratio of the square roots of the molar masses
VA = sqrt(B MW)
—- —————-
VB = sqrt (A MW)
À will travel faster (small mw)
How does increasing temperature affect molarity?
All solutions expand in volume when heated
Molarity will increase with temperature
Which of the following is least soluble in water? K2SO4 (NH4)2CO3 PbNO3 CaSO4
Ammonium and nitrate are always soluble
Sulfate (SO4^2-) is usually soluble except when with Ca2+, Ba2+, Sr2+, Hg2+, Pb2+, Ag2+
Evaporation occurs when:
- KE of molecule exceeds bond energy
- KE of molecule exceeds intermolecular forces
KE of molecule exceeds intermolecular forces
What kind of bonds are detected by IR
Dipole bonds
Dipolar bonds oscillate at specific vibrational frequency- determined by strength of bond and molecular weight
How does strength of bond and molecular weight affect IR?
stronger bond and higher mw = higher frequency
Roughly follows Hooke’s law, F=km where strength is like k, mw is like m
Give IR absorbance for Carbonyl Saturated alkane Amine Amide Nitrile
Carbonyl, C=O: 1700 sharp, deep
Saturated alkane: 2800 sharp, deep
Amine, NH: 3300 broad, shallow
Amide, NH: 3300 broad, deep
Nitrile, C[triple]N: 2250 sharp, deep
How does conjugation affect UV spec?
More conjugation = farther to the right on absorption scale- at a higher wavelength
Which bonds will appear on UV spec?
Double and triple absorb strongly (triple more than double)
Single bonds will not
Electrons absorb energy from radiation and excite to next energy level- absorption is measured
What is the base peak in MS?
Most common fragment, usually most stable
To register on NMR, atom must have …
Odd atomic number or odd mass number
These atoms have nuclear spin, which creates magnetic field
(Same for MRI, basically NMR on human body)
How can you tell how many neighbors an atom has from NMR?
n + 1 sub peaks, where n is number of non-equivalent hydrogen neighbors
Number of hydrogens presented by that peak is # of sub peaks - 1
Where will very shielded hydrogens be on NMR?
Upfield = shielded
Downfield = Deshielded
How can addition of acid or base improve separation during extraction?
Gives molecules charge- more soluble in aqueous layer
Where will polar and nonpolar products be found in extraction layers?
Nonpolar layer is less dense than water- on top
Polar products are in bottom
Why is it bad to use a solvent with a high boiling point in separation? (Extraction)
Difficult to evaporate off the solvent to obtain the product
Why is vacuum distillation helpful?
Vacuum drives pressure down to meet vapor pressure
Liquids boil when P = Patm
Lowers boiling point- good for substances with high boiling points
What’s the first substance out in chromatography
NONPOLAR
If Rf = 0.9, is the substance polar or nonpolar?
Nonpolar
Number close to 1 means polarity of component is similar to solvent (which is usually nonpolar)
Describe recrystallization process
Product dissolved in minimum amount of hot solvent
Solution cooled slow as possible- if temp is dropped just below melting point of product, crystals will form and impurities will remain in solution
Why are carbonyle good electrophiles
Partial positive on carbon
Are hydrogens on alpha carbons of carbonyls acidic or basic
ACIDIC
Due to resonance stabilization (alpha carbon is that on carbon adjacent to carbonyl carbon) of conjugate base
When 2 carbonyls separated by single carbon, the hydrogens on middle carbon are VERY acidic (partial positive of carbonyl carbons)
How do substituent groups affect reactivity of a carbonyl with a nucleophile
Donating groups decrease reactivity (less partial positive)
Withdrawing groups increase reactivity (less electron dense- most partial positive)
Bulky groups decrease reactivity (steric hinderance)
What’s the formula of formaldehyde
HCHO
Acetaldehyde
CH3CHO
Benzaldehyde
C6H5CHO
Acetone
CH3COCH3
Aldehydes/ ketones are H bond donors or receivers?
Recipients only
What does “-oxo” mean in nomenclature?
Ketone or aldehyde
Aldehydes and ketone are nucleophiles or electrophiles?
Electrophiles- carbonyl carbon with positive charge is attached by nucleophile
Aldehydes/ketones undergo nucleophilic (substitution/addition)
Carboxylic acid/ amides/ esters/ anhydrides undergo nucleophilic (substitution/ addition)
Aldehydes/ketones undergo nucleophilic addition
Carboxylic acid/ amides/ esters/ anhydrides undergo nucleophilic substitution (need a leaving group to undergo substitution)
Aldehydes/ketones leaving group would be a strong base- BAD leaving group
Explain how aldehydes and ketones function as Lewis acids
Accept electrons when a base abstracts an alpha hydrogen (on carbon adjacent to carbonyl carbon)
Explain basic concept of keto-enol tautomerization
Alpha hydrogen adjacent to aldehyde/ketone becomes bonded to carbonyl oxygen
Double bond is switched from C=O to bond between carbonyl carbon and alpha carbon
Which is more stable, keto or enol tautomer
Keto- sum of bond energies is greater (C=O in keto vs C=C in enol)
Compare acetals/ketals to hemiacetal/ketals
Acetals/ketals: 2 -OR groups
Hemiacetal/ketals: 1 -OR group And 1 -OH group
What acts as nucleophile in formation of acetals/ketals? What’s the leaving group?
Alcohol is nucleophile- attacks carbonyl carbon, pushes pi e- from C=O to oxygen
Negatively charged O is protonated, original alcohol deprotonated to form ether
Alcohol protonated again to form leaving group - water
Deprotonation of second alcohol gives another ether, yielding either acetal (from aldehyde) or ketal (from ketone)
How can you protect ketones/ aldehydes from reaction with nucleophile or base? How can you return them to original form?
Conversion to acetal (aldehyde) or ketal (ketone) using alcohol (diols best)
Acidic conditions reverses this
In halogénation of aldehyde or ketone, a base abstracts an alpha hydrogen, leaving…
CarbANION
carbanion attacks diatomic halogen
Aldol condensation
Condensation of aldehyde or ketone with another aldehyde or ketone
- Base abstracts alpha H
- carbANION attacks any carbonyl carbon
- Oxygen protonated—> alcohol
What should there always be in the product of aldol condensation?
One carbon in between carbonyl carbon and carbon bearing hydroxyl group (C=O and C-OH)
What is alpha-beta unsaturated carbonyl?
Aldehyde or ketone with double bond between alpha and beta carbons
Electrophile- carbonyl is electron withdrawing (partial positive)
Formic acid
HCOOH
basically carboxyl acid with a hydrogen group
Acetic acid
CH3COOH
carboxylic acid with methyl group
Benzoic acid
C6H5COOH
Carboxylic acid on benzene ring
Can carboxyl acids hydrogen bond
Yes! Twice! To form dimers. Though dimers actually don’t have a net dipole despite being very polar, so slightly soluble in nonpolar substances (as a dimers only)
RCOOH + H2O —>
RCOOH2+ + Nu:-
—> RCONu + H2O
Decarboxylation requires what catalyst
Loss of CO2 from beta-keto carboxylic acid
Leaves behind resonance stabilized carbANION
BASE catalyst
Carboxylate ion usually retakes hydrogen from base to from keto-enol tautomer
What reaction is this, and finish the products:
RCOOH + ROH —>
What type of catalyst does it need?
Estérification (alcohol And carboxylic acid)
RCOOH + ROH —> RCOOR + H2O
Forms ester
Requires ACID catalyst (because hydroxyl must become water to be good leaving group)
What 3 reagents readily produce acid chlorides when added to carboxylic acids?
PCl3
PCl5
SOCl2
Why doesn’t addition of chloride ion to carboxylic acid produce acid chloride?
Cl- is more stable than -OH, so makes better leaving group
What is most and least reactive carboxylic acid derivative?
Acid chloride- most reactive (Cl- is really good leaving group, Cl is strongly withdrawing and makes partial positive on carbonyl strong)
Amides- least reactive/most stable (NH2 is strong base and so BAD leaving group)
RC(=O)Cl + RCO2 —>
Acid chloride
Anhydride
RC(=O)OC(=O)R
RC(=O)Cl + NH3 —>
RC(=O)NH2
Amide
RC(=O)Cl + H2O —>
RCOOH
carboxylic acid
RC(=O)Cl + ROH —>
RCOR
ester
What does acid chloride and R2CuLi give you
Ketone
How is anhydride related to ester
Anhydride is ester where -R group is carbonyl
R-C(=O)-O-C(=O)-R
Anhydrides are nucleophiles or electrophile
GREAT electrophiles
2 carbonyl carbons are highly reactive to nucleophile because leaving group is resonance stabilized carboxylate ion
Amide vs amine
Amide:
R-C(=O)-NH-R
Amine:
R-NH2
What’s the hybridization like for nitrogen in amide?
N in amide donates electrons via resonance- closer to Sp2 because of partial double bond character
Which is more basic amides or amines?
Amines more basic
Amides N has less electron density because of partial double bond character and partial positive of carbonyl
What is Hofmann degradation?
How does Hofmann degradation shorten the length of the carbon chain?
Primary amides react in strong, basic solutions of Cl2 or Br2 to form primary amines
Mechanism includes decarboxylation- shortens chain
Allows you to add amine to a tertiary carbon
Esters are H bond donors or receivers?
Recipients only
What is saponification and what does it give
Hydrolysis of ester gives alcohol and salt of carboxylic acid
- Hydroxide ion attacks carbonyl carbon
- Electrons go up to oxygen but fall back down and kick off -OR
- Either -OR or hydroxide ion abstracts carboxylic acid hydrogen—> carboxylic ion, which Na+ or K+ associates with (soap)
What is acetoacetic ester synthesis
Use Beta keto ester to make ketone
Beta keto ester:
-C(=O)-CH2-C(=O)-O-
Hot acid causes loss of COOR group to get ketone
What are bodily examples of inorganic esters?
Triphosphate- ATP, GTP, UTP
Diphosphate- FADH2, NADH
monophosphate- FMN, DNA, RNA
Ammonia vs ammonium- which is nucleophile; which is electrophile
Ammonium- electrophile
Ammonia- nucleophile
Imine structure
R-C(=NR)-R/H
In synthesis of alkyl amine, ammonia acts as nucleophile, attacking alkyl halide via what kind of reaction?
SN2
Kicks or halide, halide ion acts as base and abstracts H
NH3 + CH3Br —> NH2CH3 + HBr
What’s Gabriel synthesis for
Formation of primary amine from primary alkyl halide, but avoids side reactions of alkyl amine synthesis
Hydrazine
NH2-NH2
Name 3 common reducing agents
LiAlH4
NaBH4
H2/ catalyst with pressure
Amides can reduce to primary amine with only one reducing agent- which one
LiAlH4
Addition of primary amine to carbonyl gives ___
Secondary amines give ___
Tertiary amines give ___
Primary amine —> imine
Imine: R-C(=NR)-R
Secondary amine —> enamine
Enamine: R2C=C(-NR2)R
Tertiary amine do not react (steric hinderance, will be a base not a nucleophile)
Which atom is exception to trend of ionization energy increasing up and to the right
Oxygen. Repulsion from additional electron in already half filled 2p orbital
Ionization energy: N>O>C
Pi bond is overlap of what
Side to side overlap of 2 p orbitals
What bond is sp2 overlapped with p orbital
What about sp2 to sp2 overlap
Both sigma bonds
NaNO3 is acid or base?
Base
How to solve Fischer projection
All groups on right are below plane, all groups on left are above plane
Hydroxyl group on next-to-last carbon will be nucleophile that attacks the aldehyde carbonyl during ring closing
Start with linear projection, so If the answers are Fischer projections try each one
Na2S + 2AgNO3 -> Ag2S + 2NaNO3
Given 0.5 mol each of your reactants, how much of excess reagent will be leftover (in mol)?
0.5 mol of each, but AgNO3 is used at twice the rate
So Na2S will be excess, and only half will be used, so 0.25 mol will be left
Au2S3 + 3H2 -> 2Au + 3H2S
Given 2 mol Au2S and 5 mol H2, what is limiting reagent
1:3 molar ratio
So you would need 6 mol H2 to react with 2 mol Au2S, but you only have 5, so H2 is limiting reagent
What are the shapes of SF4 and BrF3?
SF4- 4 groups + 1 lone pair = see-saw (2 groups act as base of seesaw, 2 groups make the board, lone pair on top)
BrF3- 3 groups + 2 lone pairs = T shaped (2 lone pairs push groups done to make a T)
Does nitrate have 3 formal charges or a lone pair on nitrogen?
3 formal charges
NO3-, N has NO lone pairs
Formal charge of nitrite
NO2-
One O is negative the other is double bonded. N has 3 bonds, no formal charge (0)
Shape and hybridization of chlorite
ClO2-, one O is negative the other is double bonded
Cl has 2 lone pairs, 2 bonded O
Gives sp3 (2 groups) and bent shape
Decarboxylation leaves behind a…
CARBANION
Epimers
Differ at only one chirality center
Meso compounds
Opposite R/S at all pairs of chiral carbons across plane of symmetry but groups must be in SAME stereochemical configuration (same side of plane)
SO2 structure
1 lone pairs + 2 double bonded O
Which is most effectively resolved via reaction with chiral reactant?
Diastereomers
Epimers
Enantiomers
Enantiomers
2 different substances produced for each enantiomer
Which has higher heat of combustion:
Monosubstituted alkene
Tetrasubstituted alkene
Monosubstituted alkene
Less stable molecule has higher heat of combustion (more reactive, more energy)
Why is alpha H on acetaldehyde more acidic than that on acetone?
Carbonyl C in acetaldehyde (more acidic alpha H) is stronger e- withdrawing group than carbonyl C in acetone
This makes the carbanion more stable in acetaldehyde (stronger partial positive pulling electrons)
Which of these will donate electrons via hyperconjugation when attached to benzene ring?
-NH2, -SH, -NO2, -CHCH2, -NH3
Molecules with negative charges donate electrons. Species that donates electrons via hyperconjugation will have positive formal charge after attachment.
WILL: -NH2, -SH
WILL NOT: -NO2, -CHCH2 (alkene- electron withdrawing), -NH3 —> these will all have positive formal charges
Give increasing order of basicity for
NH3
N(CH3)3
NH2COOH
Having e- withdrawing groups decreases basicity, e- donating groups increase basicity
NH2COOH < NH3 < N(CH3)3
Which reacts more readily with strong base?
Amine
Aldehyde
Aldehyde- relatively acidic alpha H
Amine with abstracted H is a strong base itself- so amine is weak acid that doesn’t want to give up H
N,N-dimethylamine reacts with chlorocyclohexane how
Dimethylamine is bulky, acts as a base in E2
Single step rxn to abstract H from chlorocyclohexane
Bulky base will be E2 or SN2?
E2
SN2 requires strong nucleophile for back side attack (bulky bases can’t be strong nucleophile because steric hinderance)
A C=O group turns into C with an OH group and an CH3 group by which reagent? Reduction with LiAlH4 in methanol Wittig reaction Grignard synthesis Jones reagent
Grignard- reduces carbonyl to alcohol while adding R group to lengthen chain
LiAlH4 would add H, not methyl (not lengthen chain)
Wittig- replace carbonyl with alkene
Jones- strong oxidizing agent
Wittig rxn
Replaces carbonyl with alkene
Jones Reagent
Strong oxidizer
An increase in pressure causes equilibrium system to move in what direction?
Increase in pressure associated with increase in partial pressures of each gas
System moves towards side with fewer moles of gas
Why does temperature affect equilibrium
Temperature changes Keq, so Q (reaction quotient) is no longer the same as Keq
Which form faster, kinetic or thermodynamic products
Kinetic
But thermodynamic products are more stable (more negative deltaG)
How does isothermal process affect first law of thermodynamics
First law: deltaU = Q - W
Temperature and internal energy are directly proportional, so U is constant
So Q = W aka heat added to system equals work done by system
Hyperbolic curve on PV
How does adiabatic process affect first law of thermodynamics
First law: deltaU = Q - W
Adiabatic- no heat exchange between system and environment
Q = O
So deltaU = -W
Hyperbolic on PV
How does isobaric process affect first law of thermodynamics
Does not affect first law
(deltaU = Q - W)
But will be a flat line on PV curve
How does isochoric process affect first law of thermodynamics
First law: deltaU = Q - W
Isochoric = isovolumetric
Gas doesn’t expand or compress (no change in volume) so no work is performed
deltaU = Q
Vertical line on PV
Compare standard conditions to STP and when to use them
Standard: 25C (298K), 1 atm, 1M
Used for kinetics, equilibrium, thermodynamics
STP: 0C (273K), 1 atm
For ideal gases
In evaporation, what is the heat source
Endothermic process
Liquid is the heat source, so liquid temp actually decreases
But obviously liquid receives thermal energy itself from another source
What is a cold finger used for
Sublimation
To purify product that is heated under reduced pressure. Pure product is more volatile than impurities
Why does the critical point happen
Liquid heated in closed system decreases in density
Density of vapor above increases
Liquid/ gas densities become equal so there is no distinction between phases
Heat of vaporization = 0
State function vs process function
State function- path independent, but may be dependent on each other
Process function- define the path (Q and W)
Bomb calorimeter vs coffee cup calorimeter
Coffee cup- constant pressure (Patm)
Bomb- constant volume
Hess’s law
Enthalpy changes of reactions are additive
What kind of reaction is glycolysis
Combustion
C6H12O6 + 6O2 -> 6CO2 + 6H2O
How to find heat of reaction?
deltaHrxn = bonds broken - bonds formed
Breaking bonds is endothermic, forming bonds is exothermic
Second law of thermodynamics
Energy spontaneously disperses (increase in entropy)
deltaG is negative, but is also endothermic. The reaction is
Spontaneous
Free energy change is irrespective of enthalpy
What does rate of reaction depend on
Activation energy
Not free energy change. Spontaneous reactions can be fast or slow
Describe the products that form from a reaction as time goes on using terms kinetic and thermodynamic
Major product at first will be the one that forms quicker- kinetic product (under kinetic control)
Given enough time, thermodynamic (more stable) product dominates- under thermodynamic control. Lower free energy value
What device should you use to measure heat capacity of a liquid?
Heat transfer- use calorimeter
Reaction coordinates can tell you what:
Endothermic/ exothermic
Endergonic/ exergonic
Both
Endo/exothermic
Endergonic/ exergonic describe free energy and cannot be determined by reaction coordinate
Which phase change is associated with largest decrease in entropy
Deposition
Solid-> gas
Tautomerization is basically what
Movement of proton (H+) and its electrons (e- in a double bond)
What does tautomerization with an acid give you? With a base?
Acid: carbonyl attacks acid proton, then conjugate base of acid attacks alpha H —> get an enol (R-C(OH)=C-R)
Base: base attacks alpha H and double bond is moved from carbonyl to C=C (concerted to avoid 5 bonds on carbon) —> get an enolate (R-C(O)=C-R). Enolate becomes protonated at oxygen—> get an enol
ALWAYS deprotonate alpha H
Only common sugar if ketone form
Fructose
Can get glucose from fructose via keto-enol tautomerization
How does water (or weak acid) contribute to acetal/ketal formation? What about alcohol? (Both are used)
Water (or weak acid) carries H from one O to the other O
Alcohol causes addition of R group (need 2 equivalents of alcohol to get both R groups). Alcohol attacks carbonyl carbon (partial positive charge because of e- withdrawing carbonyl group)
How can you make a carbonyl more reactive
Protonate it! Might see H+ added into reaction
RC(=OH+)R is more reactive
Which carbon of a glucose Fischer projection is reversed
Carbon 3
Glucose:
CHO
H———OH
OH——-H
H———OH
H———OH
CH2OHWhat carbon is reversed in the Fischer projection of mannose and what’s its relation to glucose
Epimers
Carbon 2 reversed instead of carbon 3 (glucose)
Remember: Mannose, Mountain, one above glucose switched carbon
Lactose and its bond
Glucose + galactose (both 6 membered)
Beta-1,4-glycosidic bond
Sucrose and its bond
Glucose (6C) + fructose (5C)
Alpha-1,2-glycosidic bond
Bonds in starch. What starch is linear? Which is branched?
Glucose monomers
Alpha-1,4-glycosidic bonds
Linear- amylose
Branched- amylopectin
Bonds in starch vs cellulose
Both made of glucose polymers
Starch- alpha-1,4
Cellulose- beta-1,4
Explain the basicity of amines based on substituents
NH3 < 3* < 1* < 2*
Tertiary is too bulky
SN1 takes 3* bases not because it is preferred but because 3* bases CANNOT do SN2 (requires backside attack)
Where can nucleophiles attack an alpha-beta unsaturated carbonyl and why do we even care about them?
:Nuc attacks either at carbonyl carbon or beta carbon- 2 away (depends where the positive charge ends up in resonance structure)
Double bond is always between alpha and beta carbons
Alpha-beta unsaturated carbonyls make good reactive species
What type of addiction happens when :Nuc attacks carbonyl carbon of alpha-beta unsaturated carbonyl? What if it attacks beta carbon?
Attacks beta carbon —> 1,2 addition
Attacks carbonyl carbon —> 1,4 addition
Either way, H adds to O and :Nuc adds to C
What will happen if you react an alpha-beta unsaturated carbonyl with each of these, and what type of addition will it likely be?
- Grignard
- NaBH4
- LiAlH4
Grignard- lengthens chain with R group (RMgBr, ether 2) H3O+)
NaBH4 or LiAlH4- add H
These usually all occur via 1,2 addition
When will you see electrophilic addition?
Something with electrons (double/ triple bond) adds to something else
Ex, C=C adds to H2O to make C(OH)-C(H)
What’s an imine, what’s an enamine, and what kind of amine will give you each
Primary amine attacks carbonyl, gives you imine (like replacing O in carbonyl with N-R)
Secondary amine attacks carbonyl, gives you enamine (add N-R where O was in carbonyl, but put double bond between carbonyl C and alpha C)
Secondary amines have an R group instead of a second H group, so no H to be deprotonated to from double bond. Tertiary amines have no H at all to be deprotonated, so won’t react
Rules for Fischer projections:
- Only ___ C go on chain
- Designate first dash/wedge as L/R, then ___
- For cyclic compounds, ___
Only chiral C on chain (non chiral go on end)
Designate first wedge/dash as L/R, then reverse each carbon
For cyclic, all up on one side/ all down on other side (break the cyclic molecule). Last R group goes in direction the end molecule (on the top or bottom of Fischer) was pointed in the cycle
How will being given hyperbaric oxygen affect blood oxygen levels?
Higher blood oxygen because of increased solubility because of increased partial pressure
At high pressure, how does gas volume deviate from ideal? What about at low temperature?
Both High pressure and low temperature- volume is less than ideal due to significant intermolecular forces
As gas approaches condensation pressure/ temperature
What is density of neon gas at STP if molar mass of neon is 20.2g?
- 2g / 22.4L = 0.9
22. 4 L is STP volume
How to relate density to PV = nRT
P = (density)RT
——————
M
M is molar mass
What is the most important factor in deciding boiling point
Intermolecular forces- H bonding
Alkene + cold/dilute H3O+
Alcohol
Rearrangement may occur to produce more stable carbocation via methyl shift
What bond should always be present in the product of Grignard reactions
Will always be a new bond between the carbonyl C and the C next to the Mg
What will happen if tert-butyl MgCl is reacted with aldehyde
MgCl can attack carbonyl of aldehyde and cause addition. Carbonyl becomes an oxygen
This is example of Grignard reaction
Primary alcohol + 2 equivalents of oxidizing agent
Carboxylic acid
Secondary alcohol + 2 equivalents of oxidizing agent
Ketone
No other H to be oxidized if it’s secondary
Carboxylic acid + LiAlH4
Primary alcohol
LiAlH4 is strong reducing agent
What is the first step of pinacol rearrangement of vic-diol?
Vic-diol: alcohols on adjacent carbons
First step: spontaneous dissociation of one protonated alcohol.
Then followed by methyl shift- other alcohols H is abstracted and carbonyl forms (final product)
Sort by increasing acidity: Alcohols Water Aldehydes Carboxylic acid
Aldehydes < alcohols < water < carboxylic acid
Waters conjugate base is more stable then alcohols
Which is more reactive, imine or carbonyl?
Imine is basically carbonyl with NH/NR instead of O
Carbonyl is more reactive because C=O is more polar than C=N
Describe the decarboxylation that occurs during base-catalyzed decarboxylation of beta-keto acid
Beta-keto acid: ketone on the beta carbon of a carboxylic acid (2 C away)
Base abstracts H on beta-keto acid and the electrons collapse down to form a double bond to the C. The bond between the carbonyl carbon and alpha carbon is broken —> decarboxylation
This leaves carbanion on alpha carbon that is stabilized by resonance onto neighboring ketone. This will be protonated in solution. Final product- ketone and CO2
What contributes more to alpha H acidity?
resonance
Induction
Resonance
Induction helps but not as important
Can enamines tautomerize? If so how?
Yes, into imines
Enamine: double bond on C=C, not amine group
Imine: double bond between C=N
React NH4+ with imine- nitrogen attacks H in ammonium, and C=N gives electrons to N while NH3 pulls H from methyl group, causing double bond to form between C=C
How do enols tautomerize
Keto (electrophilic) + water -> water protonates C=O
so double bond shifts down to C=C to remove positive charge on O
-> now you have enol (nucleophilic)
Which of these can be used to protect carbonyl from reduction?
Tosyl chloride
CH3MgBr
HOCH2CH2OH
HOCH2CH2OH (diol)- can react with carbonyls to form cyclic structures that can be easily reversed by acid
Tosyl chloride is electrophile and so is carbonyl- won’t react
Grignard reduces carbonyl to alcohol, not easily reversed
Which of these can be used to protect alcohol from oxidation?
Tosyl chloride
CH3MgBr
HOCH2CH2OH
Tosyl chloride (electrophile)- commonly used to protect alcohols and other nucleophiles
Alcohol attacks tosyl chloride
The first step in the aldol condensation of 2-butanone is abstraction of hydrogen from which carbon?
2-butanone: ketone on carbon 2 (4 carbons total)
The hydrogen will be abstracted from C1- there are not R groups (only H)
C3 has weakly donating R groups (CH2) so the carbanion will be unstable
Aldol condensation: condensation of one aldehyde or ketone with another.
What 3 reagents are best for producing high yield of acyl chloride, given a carboxylic acid?
Acyl (acid) chloride: -COCl
PCl3, PCl5, SOCl2 (strong halide reagents)
Imine-substituted benzene is reacted with LiAlH4. What’s the intermediate and final product?
Imine: RC(=NH/R)R
LiAlH4: strong reducing agent
Hydride ion produced by LiAlH4 attacks partial positive carbon and kicks double bond (of C=N) onto nitrogen—> intermediate is nitrogen anion. Final product is primary benzyl amine (becomes protonated)
Carbonyl (electrophile) and H2S (nucleophile) react. What will happen
Sulfur will attack carbonyl carbon. Double bond will push electrons up to oxygen. Oxyanion will be protonated to create water, which will leave.
The product is a thioketone- R2C=S
How will hydrazine react with carbonyl?
Hydrazine (nucleophile) attacks carbonyl (electrophile) and causes addition of hydrazine to carbonyl carbon
You have a cyclic compound with an alkene and a carbonyl group. A strong reducing agent would reduce both- how can you protect the carbonyl?
Transform ketone into acetal. Acid work up will return acetal to ketone
Acetal: two -OR groups on same carbon, that carbon being attached to another R group and an H (ketal would be 2 more R groups)
2,2-dichloropentane (a gem halide) is reacted with excess methanol. What do you get?
Excess alcohol would give 2 -OR groups—> an acetal
Ar3CBr reacts with water to form an alcohol by which mechanism?
SN1/2
E1/2
Tertiary, sterically hindered
Groups that induce induction—> stable carbocation
Br (leaving group) will leave first, then nucleophile will add to carbocation—> SN1
Ester —> alcohol and acid salt is what reaction?
Saponification. Basic hydrolysis of ester
Soluble in acid but not base- what is it?
Amine
Soluble in base but not acid?
Carboxylic acid
Which cannot be reduced to primary amine with NaBH4? RNO2 R2C=NH RCONH2 RC=N
RCONH2 (amide) can only be reduced to primary amine by LiAlH4
Nitro groups (RNO2), nitriles, and imines (R2C=NH) can be reduced to primary amines by all common reducing agents
Do you always need a base catalyst for decarboxylation?
No, if you have a carbonyl double bond that can act as a nucleophile, it can abstract H from neighboring carboxylic acid to form enol
Enol: double bond on C=C (carbonyl C and alpha C)
Reminder: decarboxylation forms keto-enol tautomer and CO2
Keto-enol
Vs
Acetal- ketal
Keto: has C=O
Enol: has C-OH
(Enolate: has C=C below O-, between carbonyl and alpha C)
Ketal: 2 -OR groups, 2 R groups
Acetal: 2 -OR groups, 1 R group, 1 H
2-Oxobutanoic acid structure
2-hydroxybutanoic acid structure
CH3-CH2-CO-CO-OH
(Ketone next to carboxylic acid)
Oxo = ketone
For hydroxybutanoic acid: replace ketone group with hydroxyl
Which molecule will undergo base-catalyze decarboxylation to form ketone and CO2?
4-oxybutanoic acid
3-hydroxybutanoic acid
3-oxybutanoic acid
3-oxybutanoic acid will
In order to undergo decarboxylation, must be resonance to stabilize carbanion- ketone must be in beta position
Which of these could react with a strong acid? Amine Acid chloride Ammonium Amide
Amine (RNH2)- nucleophile
Acid chloride and ammonium are both electrophiles
Amides (RCONHR) won’t react with anything at carbonyl carbon and H on amide N are not acidic
Reminder: Lewis acids are electrophiles, Lewis bases are nucleophiles
Amides are to amines what esters are to ____
Amide (RCONHR) are to amines (RNH2) what esters (RCOOR) to alcohols (ROH)
Why are columns packed in fractional distillation
Causes condensation of component with higher boiling point by increasing surface area for condensation
Distillation separates by ___
Boiling point
Compare the structures of phenol, aniline, benzoic acid, and toluene
Phenol: benzene + OH
Aniline: benzene + amine (NH2)
These can H bond
Benzoic acid: benzene + carboxylic acid
Toluene: benzene + methyl
T/F: H-NMR works by increasing strength of external magnetic field
FALSE. Strength of magnetic field is not varied, but frequency of external electromagnetic radiation (usually radio) is.
H-NMR absorbances created by nuclear energy transition- transition of nucleus from with the field to against it
Basic principle of UV? Of IR?
UV- electron excitement
IR- intramolecular vibrations
Why must you have an odd mass number for NMR?
NMR depends on nuclear spin which is zeroed out if there is an even number of protons+neutrons
How does IR spectrum of amides compare to amines?
Amines are very shallow (3300-3000 region)
Amides are deep, not a smooth bottom like alcohol (3700-3500). Amides also have carbonyl at 1700
Acid anhydride + amine
Acid anhydride: RC(O)OC(O)R
Acid anhydride + amine —> amide (RC(O)NHR)
Alkene + HgOAc2/NaBH4 —>
Alcohol
Acid chloride + H2O —>
Carboxylic acid
Acid chloride + R’OH
Ester (RCOOR)
Acid chloride + R’CO2
Acid anhydride
Acid chloride + H-
Alcohol
Acid chloride + R2CuLi
Ketone
Cl replaced by R group
Acid chloride + NH3
Amide
Cl replaced by NH2
How does MS work?
External magnetic field gradually increases so all species fragments (of different mass to charge ratios) hit detector
In MS, which species will hit detector last- lowest or highest charge to mass ratio?
Highest mass/charge ratio will hit last- heaviest will have slowest acceleration
Which is more reactive, carbonyl carbon of ketone or ester?
Ketone- ester has resonance that creates double bond with carbonyl carbon between C=OR, so the oxygen donates electrons to carbonyl carbon, making it less electrophilic
What is the normality of 2M H2SO4?
Find the gram equivalent weight of H3PO4 (mw = 98g/mol)
GEW = (g/mol) x (mol polyvalent/ # of equivalents)
Phosphoric acid is triprotic acid
GEW = (98)(1 mol/ 3 H+ equivalents) =
33g/ H+ equivalent
What kind of polyprotic acid is K2CO3? What mass of K2CO3 must be added to 0.4L water to create a 1N solution (mw = 138g)?
K2CO3 -> 2K+ + CO3^2-
CO3^2- + 2H2O -> H2CO3 + 2OH-
K2CO3 is dibasic
0.4L x (1 equivalent H2O/ 1 L H2O)
x (1 mol K2CO3/ 2 equivalents H+)
x (138g/mol)
= 27.6 g
What’s true for a buffer solution with a pH of 6.5 if the concentration of the acid and the conjugate bases are both tripled? I. Buffering capacity is now 3x II. Buffering capacity is now 6x III. pH will change IV. pH will not change
Buffering capacity is 3x, and pH will stay same
pH = pKa + log([A-]/[HA])
Ratio is same, so pH is same
Buffering capacity is 3x because there are more molecules of H3O+ to neutralize OH-. Not 6x increase because conjugate base doesn’t contain H3O+ ions
H2SO4 + 2NaHCO3 ->
Na2SO4 + 2CO2 + 2H2O
This reaction will: Lower Ka of H2SO4? Prevent blood alkalosis? Raise [H+]? Act as buffer
Act as buffer- neutralizes H2SO4 by bicarbonate (NaHCO3 dissociates)
HCl + H2NC(CH2OH)3 ->
H3N + C(CH2OH)3 + Cl-
What role does H2NC(CH2OH)3 play?
Lewis acid
Arrhenius base
Bronsted Lowry base
Bronsted Lowry base: accepts H ion (note Cl- ion)
Lewis acid: donates electron pair
Arrhenius base: increases [OH-]
Equation for Ka? If you know molarity and the Ka, how can you find the pH?
Ka = [H+][A-]/ [HA]
Ka = x^2 / (molarity - x)
“-x” can be considered negligible
Solve.
Which part of titration curve for diprotic acid corresponds to optimal buffering capacity?
Half equivalence point- point of neutralization. pH = pKa
Acyl halide + primary alcohol
Ester
Acyl halide is carbonyl with halide (like ketone where one R group is halide)
C of acyl halide is electrophile. Alcohol (:Nuc) attacks/ pushes electrons onto O. Double bond reformed by kicking off halide (good leaving group). O from alcohol loses protons, so left with an ester (like a ketone where one R group is OR)
Chelation
Central cation bound to same ligand in multiple places
How to solve dilution problems?
(MV)1 = (MV)2
IV stock solution contains 90g NaCl per 10 L of water. How would you find mole fraction and percent composition of mass of NaCl?
Mole fraction:
Find mol of NaCl, divide by mole of (NaCl + water)
Water would be 1000g (density = 1g/mL)
Percent composition by mass:
Divide 90g NaCl by (90+1000) total grams
Ion product is analogous to what
Ion product (IP) is analogous to reaction quotient (Q)
What is the change in vapor pressure when 2 mol glyceraldehyde is added to 0.18 L of water at 100*C?
P = XP* where X is mole fraction of solvent and P* is vapor pressure in pure state
Density of water at 100*C = 1g/mol, pressure will be 1 atm (because it’s at boiling point)
0.18L = 180g -> /18 = 10 mol water
Mole fraction of water = 10/12(total) ~ 0.8
P = (0.8)(1 atm) = 0.83 atm
Change in P = 1 - 0.83 = 0.17 atm
What would the Ksp formula be for the dissolution of Fe(OH)3, and if the molar solubility of Fe(OH)3 is 4x10^-10mol/L, how would you find Ksp value?
Fe(OH)3 -> Fe + 3OH
Ksp = [Fe][OH]^3
Ksp = (x)(3x)^3
You would plug in 4x10^-10mol/L for x
The first step in aldol condensation of 2-butanone is abstraction of hydrogen from carbon __
Carbon 1
An R group will weakly donate electrons on carbon 3, making an unstable carbanion
No such R group on C1
How will a hydrazine react with a carbonyl
Hydrazine is nucleophile
Carbonyl is electrophile
Nucleophilic addition to carbonyl C
2,2-dichloropentane + excess methanol
Acetal
Alcohol adds via SN2, would add with its R group (carbon chain)- this would give an acetal (2 -OR groups)
If a, b, and c having similar boiling points are put through GC, the one that elutes first will: Be least polar Be most polar Have highest MW Have lowest MW
Be least polar
MW has little to do with rate at which gas passes through stationary phase first
MW only affects elution order to the degree it alters boiling point
If magnetic field strength is gradually increased during MS, which fragment of CH3Br will register last at detector? CH3* Br* CH2Br* H3Br*
Fragments that hit last will have highest mass/charge ratio-> heaviest will hit last
CH2Br* will hit last
(Also H3Br* could not be a fragment because this would require 2 different fragments being recombined somehow)
Which is more reactive, carbonyl C of ketones or esters?
Ketones
More likely to be attacked by a nucleophile!
Describe pinacol rearrangement of a Vic-diol
Spontaneous dissociation of one protonated alcohol
Methyl shift
Other alcohols H is abstracted-> carbonyl forms
How will H2S react with a carbonyl
H2S is a nucleophile
Sulfur will attack carbonyl C
Oxyanion will be protonated to create water (leaves)
Thioketone (R2C=S) formed
Which can undergo base-catalyzed decarboxylation to form ketone and CO2 gas?
4-oxobutanoic acid
2-oxobutanoic acid
3-oxobutanoic acid
3-oxobutanoic acid
4 carbon chain with carboxylic acid on the end, and carbonyl on C3
To do decarboxylation, must be resonance to stabilize carbanion
Ketone must be in beta position
Anhydride + amine
Amide- NH bonded to carbonyl
(Anhydride- 2 ketones with oxygen in the middle)
Amide nitrogen attacks one carbonyl C. Double bond goes up to O then lone pairs fall back down and know off middle O of anhydride. Left with amide
Alkene + HgOAc2/NaBH4
Alcohol
Acid chloride + KOH
Carboxylic acid
OH group attacks carbonyl C
Double bond goes up to O, lone pairs fall back down and Cl is knocked off
The OH group is still attached and double bond is back on carbonyl C, so get carboxylic acid
alpha keto acid
ketone on carbon in alpha position relative to carboxyl group
which will produce carbon ether? tert-butanol and an acid ethyl alcohol and ethyl tosylate ethyl alcohol and ethylamine tert-butanol and tert-butyl chloride
tert-butanol + acid will eliminate alcohol, but no good nucleophile to form ether
ethyl alcohol + ethyl tosylate- CORRECT, ethanol is nucleophile, ethyl tosylate is leaving group
ethyl alcohol + ethylamine is 2 nucleophiles, no leaving group
tert-butanol + tert-butyl Cl is sterically hindered and tert-butyl Cl is poor electrophile
s orbital will completely fill before d orbital unless
unless you can create 5 degenerate orbitals in 3d (4s1 3d5)
oxidation of primary alcohol
carboxylic acid
given a reaction with a rate constant of 6.5x10^-8 s^-1 and an initial concentration of 2M, what is the rate of the reaction?
s^-1 = first order,
so 2 x (6.5x10^-8) = 1.3x10^-7 is reaction rate
in the combustion of methane, which could increase reaction rate?
catalyst
increase in pressure
open reaction vessel to atmosphere
open reaction vessel to atmosphere- combustion gives water and CO2 gas, so opening to atmosphere allows CO2 gas product to be lost–> pushes reaction forward
which bond will absorb longest wavelength? cyclohexane or benzene
benzene- conjugated system is more stable -> less energy -> longer wavelength
mitochondria are most similar to which type of electrochemical cell
concentration cell
proton gradient drives charge conduction
which two electrochemical cells are spontaenous
Galvanic aka voltaic concentration cell (special type of galvanic cell)
electrolytic cell is nonspontaneous
for all electrochemical cells, what is true for:
current
movement of electrons
location of reduction
current runs from cathode to anode
electrons flow from anode to cathode
reduction occurs at the cathode (RED CAT)
how does emf related to free energy change for electrochemical cell
always opposite spontaneous cell (galvanic) has positive emf nonspontaneous cell (electrolytic) has negative emf
emf is voltage of cell- positive emf means the cell is able to release energy
as the spontaneous reaction proceeds in a galvanic cell, the movement of electrons results in what type of energy change
electrical potential –> kinetic energy
plating, aka galvanization
precipitation process onto cathode itself in galvanic cell. cations of salt bridge flow into solution on cathode side to balance out charge of ions left in solution when cations are reduced and precipitate onto the electrode
how do the half reactions in galvanic and electrolytic cells vary
half reactions must occur in separate compartments in galvanic cells
do not need to be separated in electrolytic cells because the reaction is nonspontaneous- must provide an external source to force the reaction anways
you have an electrochemical cell with a negative emf and half reactions occurring in the same compartment. is the free energy change negative or positive
positive- this is an electrolytic cell
how is Faraday constant derived, and what can it be rounded to
F is charge carried by a mole of electrons
charge of electron x mole of electrons
1.6x10^-19 x 6.02x10^23 ~ 10^5 C/mol e-
in what type of electrochemical cell are the electrodes chemically identical
concentration cell
therefore have same reduction potential
so current is function of concentration gradient
a rechargeable battery acts as both a galvanic cell and electrolytic cell. when it is recharging, what is it functioning as?
electrolytic cell- external power source reverses electroplating process and concentrates acid solution. reverses cell potential (Emf)
in all electrochemical cells, the cathode and anode attract what, respectively
cathode attracts cations
anode attracts anion
for galvanic cells, the electrode with the more (negative/positive) reduction potential is at the cathode
galvanic cell- electrode with more positive reduction potential is at cathode
reduction occurs at the cathode
Fe3+ + 3e- > Fe has Ecell = -0.036V
(I3)- + 2e- > 3I- has Ecell = +0.534V
What is the Emf of the reaction driven by an electrolytic cell?
in electrolytic cell, species with lower reduction potential is forced to be reduced by external power source
Ecell = Ecathode - Eanode
reduction always occurs at cathode
Ecell = -0.036 - 0.534 = -0.57V
(electrolytic cells have negative Emf because Emf is opposite sign of free energy, which is positive for nonspontaenous reaction)
when will logarithm be positive, negative, and 0?
log(>1) is positive
log(<1) is negative
log(1) = 0
same goes for ln
Zn2+ + 2e- > Zn has Ered = -0.7V
Ag+ + e- > Ag has Ered = +0.3V
What is emf of:
Zn2+ + 2Ag > 2Ag+ + Zn
zinc is reduced
Emf = Ecathode - Eanode
reduction always occurs at cathode
Emf = -0.7 - 0.3 = -1V
which of these is more likely to be found in a salt bridge of a galvanic cell: NH4NO3 or SO3
NH4NO3
salt bridges contain inert electrolytes, ionic compounds are strong electrolytes
SO3 is covalently bonded- will not dissociate in solution
what are the only three types of molecular geometry that can have 4 groups?
bent (two groups, two lone pairs)
tetrahedral (4 groups)
trigonal pyramidal (3 groups, 1 lone pair)
why does SN2 prefer polar aprotic solvent
SN2 prefers unhindered, strong nucleophile
polar protic solvent creates strong H bonds that stabilize nucleophile, inhibit substitution
so SN2 prefers polar aprotic
ether
R-O-R
Formation of rust is an oxidation process. Considering this, which would have highest reduction potential?
old rusted nail
stainless steel pan
polyurethane pipe
polyurethane pipe
if rusting is oxidation process, than the thing least likely to rust will have highest reduction potential (least likely to be oxidized)
this option doesn’t even have metal in it- unlikely to rust
you're performing a redox titration. you put a copper electrode into a solution of CuSO4. For new copper to form on the electrode: Cu(s) must be oxidized Cu(s) must be reduced Cu2+ must be oxidized Cu2+ must be reduced
Cu2+ must be reduced
ions in solution must be reduced to Cu(s)
a 45L sealed reaction vessel contains methane that is combusted as:
CH4 + 2O2 > 2H2O + CO2
If there are 3 moles of gas total and vessel is 0*C, what is partial pressure of CO2?
PV=nRT
compared to STP, volume is 2x and moles is 3x
P will be 3/2 or 1.5x –> 1.5atm total
2 H2O for every 1 CO2, so partial pressure of CO2 will be a third of total… 0.5atm
which is the most soluble?
FeCl3, Ksp = 1x10^-12
FeCl2, Ksp = 1x10^-3
Fe(NO2)3, Ksp = 1x10^-3
to compare solubility, take power of Ksp and divide by number of ions formed
- 12/4 = -3
- 3/3 = -1
- 3/4 = -0.75 –> Fe(NO2)3 is most soluble because this is the least negative
which does not change with temperature: molarity or molality
molality (mol/kg)- mass doesn’t change with temperature
solutions expand with temperature- affects molarity
which is least soluble in water: K2SO4 (NH4)2CO3 PbNO3 CaSO4
CaSO4
ammonium and nitrate always soluble
SO4 not soluble with group 1 elements
given 220g of CaCl2 (MW 110g/mol) at room temperature, dissolved in water to produce 1L of solution, how would you set up the equation to solve for osmotic pressure?
osmotic pressure = iMRT i = 3 M = 220/110 R = 0.08 T = 298 osmotic pressure = (3)(220)(0.08)(298)/(110)
for two buffer systems, one with pKa of 6.8 and another pKa of 9.1, what will be predominant species (acid or base) at pH of 8?
pH > pKa, [HA] more base
pKa of 9.1 in pH of 8–> more acid
diamagnetic vs paramagnetic
diamagnetic- all electrons paired, won’t interact with magnetic field
paramagnetic- unpaired electrons, will interact with magnetic field
gabriel synthesis
make primary amines with potassium phthalimide (protected form of ammonia) to prevent multiple alkylations (prevented by steric hinderance of phthalimide)–> follows SN2
strecker synthesis
uses potassium cyanide and an aldehyde to make amino acids
all amino acids are L except __
all amino acids are S except __
glycine is not chiral, so neither L or D (or S or R)
L amino acids- H with dashed line (behind plane)
cysteine- only R amino acids
what extraction could cause an amine and a phenol to enter the aqueous layer consecutively?
NaOH then H2SO4
NaHCO3 then HCl
H2SO4 then NaOH
H2SO4 then NaOH
amines are weak bases- need strong acid (H2SO4) to be protonated
phenols are weak acids- need strong base (NaOH) to be deprotonated
what is the purpose of boiling chips in vacuum fractional distillation?
boiling chips create air bubbles that break surface tension of liquid being heated- prevent superheating and bumping
if red litmus paper is dipped in Na2CO3 aqueous solution, what color will it be?
(CO3)^2- + H2O -> HCO3- + OH-
red litmus paper will turn blue in a base
what gas forms when HCl reacts with (CO3)^2-
CO2
atomic radius periodic trend
atomic radius decreases from left to right
because effective nuclear charge increases from left to right, drawing in outermost electrons
when NaNO2- reacts with water, what is formed
NO2- + H2O -> NO3 + OH-
NaNO2 is basic
alpha/beta prefixes of monosaccharides apply to which carbon?
C1
carbon with -OR
common name of methanal? Ethanal? Propanal?
methanal = formaldehyde ethanal = acetaldehyde propanal = propionaldehyde (-al = aldehydes)
common name for 2-propanone
acetone (-one = ketone)
common name for methanoic acid? ethanoic acid?
methanoic acid = formic acid
ethanoic acid = acetic acid
(carboxylic acids)
ester
carboxylic acid derivative
hydroxyl replaced with alkoxy
amide
carboxylic acid derivative
hydroxyl replaced by amino group
angle strain vs torsional strain
angle- bond angles deviate from ideal
torsional- eclipsed or gauche
configurational isomers
same molecular formula
type of stereoisomer, but requires breaking/ reforming bonds (enantiomers, diastereomers)
dextrorotatory is CW or CCW?
dextrorotatory = CW, or (+) levorotatory = CCW, or (-)
what is used to protect alcohols and other nucleophiles? What protects carbonyls?
tosyl/methyl chlorides protect alcohols and other nucleophiles (nucleophile attacks it)
diols protect carbonyls
can atoms have an even mass number and be detected with NMR?
NO. must have odd mass number or else nuclear spin is zeroed out
amides can only be reduced to primary amine by what
LiAlH4 is only one strong enough
amide is carboxylic acid derivative with amine group instead of hydroxy group
why is second ionization of Na an exception to the rule that ionization energy increases linearly from first, second, third, onward?
first ionization energy of Na gives noble gas electron configuration
which one is sp2 hybridized, benzene or cyclohexane?
benzene
sp2 = 3 bond regions (double bond, single C bond, H bond)
sp3 = 4 bonds (4 single bonds as in carbons of cyclohexane)
bond regions can be lone pairs or bond to another atom
proteins fold spontaneously despite unfavorable entropy of folding because:
- enthalpy of H bonds
- enthalpy of electrostatic attractions
- entropy of hydrophobic effect
all of these are true!
which can affect yield: temp or enzyme
temperature can affect yield by changing Keq!!
enzymes only affect rate!
what percent s character is sp2
33%
sp = s+p
sp2 = s+p+p –> 1/3 is s
sp3 = s+p+p+p
how to count degrees of unsaturation?
double bond counts as one
whole ring counts as one
triple bond counts as 2
oxidation states found by giving bonding electrons to…
given this, what are oxidation states of hydroxyl radical
give bonding electrons to most electronegative atom
hydroxyl: O starts with 6 valence e, gains all bonding e- so it ends up with 7–> -1 oxidation number
H began with 1 and now has 0–> +1
basic reaction begins with __
acidic reaction begins with __
basic- deprotonation (abstract alpha H- most acidic H)
acidic- protonation
which will precipitate:
KOH and HNO3
Ba(OH)2 and HCl
Ba(OH)2 and H2SO4
Ba(OH)2 and H2SO4–> Ba2+ and SO4^2- will be insoluble
conjugation =
delocalized valence electrons
metals exist in nature as ___, so ___ is used to recover pure metals
exist as cations, reduction used to purify metals (reduction of copper cation Cu2+ to produce solid Cu)
what is physiological temp, room temp, and freezing point of water in celsius and kelvin
physiological- 37C, 310K
room- 25C, 298K
freezing water- 0*C, 273K
nucleophilicity trend on periodic table
nucleophilicity increases going down periodic table due to greater size and polarizability
use of crown ethers
increase solubility of inorganic compounds into organic solvents
the more __the carbon, the higher priority it is
higher oxidation = higher priority
the highest priority group will determine the suffix
what does prefix “n-“ mean?
normal, as in straight chain alkane
if the alcohol is not the highest priority group, then it will have what prefix?
hydroxy-
hydrates
geminal diol (on same carbon)- these spontaneously dehydrate to lose water, producing carbonyl (C=O)
what is isopropyl alcohol
2-propanol
what is other name for ethanol
ethyl alcohol
what are formaldehyde, acetaldehyde, and propionaldehyde?
aldehydes
formaldehyde = methanal
acetaldehyde = ethanal (an acetyl group with just an H attached, in other words!)
propionaldehyde = propanal
what is an acetyl group
CH3CO- (carbonyl with methyl on one side)
what is acetone
2-propanone (ketone)
what is highest priority functional group tested on MCAT
carboxylic acid
what are formic acid, acetic acid, and propionic acid?
carboxylic acids
formic acid = methanoic acid
acetic acid = ethanoic acid (an acetyl group with a hydroxyl attached, in other words)
propionic acid = propanoic acid
esters or ethers are carboxylic acid derivatives?
esters!! hydroxyl group replaced with alkoxy group (-OR, where R is hydrocarbon)
how are anhydrides formed?
two carboxylic acids, one water removed
many anhydrides are cyclic because of intramolecular dehydration
quantum number: n represents shell, l represents __, ml represents ___?
n = shell l = subshell ml = orbital
is it possible to break only one of the bonds in a double bond?
yes- that’s how you get a single bond from a double bond
double bonds stronger than single bonds, but pi bond weaker than sigma bond. you just break the pi bond to get the single bond
pi bonds are formed by which orbitals?
two p orbitals
Be only has 2 valence e-. What is the hybridization of Be in BeH2?
sp (bonded to just the two H)
match:
Lewis acid/ base
nucleophile/ electrophile
lewis acid = electrophile
lewis base = nucleophile (unless it’s too bulky)
what kind of covalent bond is formed between lewis acids and bases?
coordinate covalent bond- lewis base is source of all electrons
which of these has a strong conjugate base:
alkane
alcohol
water
alkane- very weak acid, so strong conjugate base
alcohol and water are fairly strong acids, so weaker conjugate bases
bond strength and acidity trends on periodic table? (hint- they’re related)
bond strength decreases down periodic table, so acidity increases
acidity- right and down is increase (HCl would be bottom right)
basicity- up and left is increasing
why are hydrogens of enols particularly acidic
enol form of carbonyl-containing carbanions is stabilized by resonance, so their H are acidic and easily lost
(enol has hydroxyl group and C=C on alpha C)
main functional groups that act as bases?
amides and amines
how to identify nucleophiles?
carbon, hydrogen, oxygen, or nitrogen with a minus sign or lone pair (CHON-)
why do protic solvents hinder nucleophilicity?
protic solvents protonate nucleophile or H bond to it
how does solvent affect nucleophilicty trend?
polar protic solvents, nucleophilicity increases down periodic table (normal trend)
polar aprotic solvents, nucleophilicity increases UP periodic table (opposite)- relates directly to basicity
HO-, RO-, CN-, N3-, NH3 and amine groups are all examples of good ___
nucleophiles
what reaction (substitution) gives racemic mixture? which uses backside attack? which requires strong nucleophile?
SN1- planar intermediate gives racemic mixture
SN2- backside attack, requires strong nucleophile, inversion of stereochemistry
molecules with high electron affinity and high oxidation states make good oxidizers/reducers?
good oxidizers. oxidation is increase number of bonds to O or other heteroatoms (atoms not C or H)
which oxidizing agent can be used to stop oxidation halfway at aldehyde?
PCC
CrO3, potassium/sodium dichromate, KMnO4, H2O2, O3 (Followed by H2O2), Pb(OAc)4 are all used for what?
oxidation
name 3 reagents you can use to get carboxylic acid from aldehyde
H2CrO4
KMnO4
H2O2
(oxidizers)
what will O3, followed by H2O2 or KMnO4/heat/H3O+ do to alkene? what about alkyne?
alkene- make carboxylic acid and ketone (split the double bond into two molecules)
alkyne- 2 carboxylic acids
what will OsO4 or KMnO4/HO- give you from alkene?
vicinal diol
NaH, CaH2, LiAlH4, and NaBH4 make good what?
reducing agents- they produce H- ion
which are more reactive towards nucleophiles, aldehydes or ketones?
aldehydes generally because less steric hinderance
aldehyde + 2eq alcohol (or diol) gives? what about if it where ketone?
aldehyde gets you acetal
ketone gets you ketal
(done to protect group)
if reaction involves acid or base, first step is __
if reaction involves nucleophile, first step is __
acid/base- first step is protonate/deprotonate
nucleophile- attacks electrophile and forms bond
acidic workup is often used to do what?
remove protecting groups
1-hexanol is treated with PCC, what do you get
hexanal (PCC, oxidizer, stops at aldehyde)
what is molar concentration of Na+(aq) in a solution prepared by mixing 10mL of 0.01M NaHCO3 (aq) with 10mL 0.01M Na2CO3(aq)?
1 equivalent of NaHCO3 gives 1 eq of Na+, so Na+ molar concentration is also 0.01mol/L
but 1 equivalent of Na2CO3 gives 2 eq of Na+, so Na+ molar concentration is also 0.02mol/L
equal volumes of both solutions, so resulting molar concentration will be average
(0.01 + 0.02) / 2 = 0.015mol/L of Na+(aq)
oxidation number of aluminum in Na[Al(OH)4]?
Na is +1, (OH)4 is -4, so Al is +3
which phenol is the best acid, an ortho, meta, or para phenol? (assume both groups are e- withdrawing)
hydroxyl H of phenols are acidic due to resonance of phenol ring
ortho= groups on adjacent carbons
meta= groups with one C in between
para= opposite side of ring
ortho will be most acidic because less separation of charge
what is more acidic, phenol or methanol?
phenols because resonance with aromatic ring
aldehydes are rapidly hydrated to form ___, which are easily oxidized to ___
aldehydes hydrated to form gem diols, oxidized to carboxylic acids
why can’t tertiary alcohols be oxidiized?
they’re already as oxidized as can be! (without breaking a bond)
same reason alkyl chain can’t be reduced!
what is Jones reagent
CrO3, strong oxidizer
two ways mesylates/tosylates can be used with alcohols
make better leaving group
protecting groups
what’s the structure of mesylate
Sulfur with 2 double bonded O, 1 negative charged O, 1 methyl group
quinones serve as electron acceptors in ETC, making them resonance-stabilized ___
electrophiles
ubiquinone is e- carrier of complex I, II, and III
what is needed to convert cyclic acetal to carbonyl and dialcohol?
acidic workup- deprotection (alcohol was used as protecting group)
what is the molecular geometry of nitrogen in peptide bonds?
trigonal planar (not trigonal pyramidal) because of partial double bond character from neighboring carbonyl
what is Keq a ratio of
rate constant of forward/reverse rxns
K(f)/K(r)
all the common amino acids are primary secondary tertiary amines?
primary amines
what’s a good general rule of thumb to determine if a compound is basic or acidic, using the formula AOm(OH)n where A is central atom?
if A (central atom) is alkali or alkaline earth metal, compound is basic if A is nonmetal, compound is acidic
also:
if electronegativity difference between A and O is large, A-O bond breaks and OH- is released
if electronegativity of A is large, the O-H bond breaks and releases H+
which common disaccharide is NOT a reducing sugar?
sucrose- lacks hemiacetal group necessary to undergo mutarotation (ring opening)
intermediate of ring opening is aldehyde
principle quantum number measures:
shape of electron cloud
radial size of electron cloud
number of valence electrons that orbit a nucleus
radial size of electron cloud- principle quantum number most closely associated with potential energy of the electron, which is proportional to the square of the distance of 2 oppositely charged particles
according to Archimedes’ principle, the ratio of the density of an object to the density of the fluid it is submerged in is equal to ratio of…
equal to ratio of weight of object in air to difference of submerged weight and weight in air:
object density / fluid density =
weight/ (weight - submerged weight)
what does Rf represent in TLC?
ratio of distance travelled by analyte/ distance travelled by solvent
what type of orbital of central atom is involved in bonding in octahedral compounds
d^2sp^3
how would common ion effect affect satruated solution
would caused decreased solubility of saturated compound, shifting equation left
which is not possible by nucleophilic rxn? carboxylic acid--> ester ester --> carboxylic acid anhydride --> amide ester --> anhydride
ester–> anhydride cannot happen
higher reactivity can form derivative of lower reactivity, but not other way around through nucleophilic rxn
anhydride > esters and carboxylic acids > amides
how do electron-withdrawing groups affect acidity and stability?
electron-withdrawing groups increase acidity and therefore decrease stability !!
what makes carbocations stable
more alkyl substituents! electron donating, which stabilizes positive charge! (stable = nonreactive)
how can a carbonyl be a nucleophile and an electrophile?
carbonyl is nucleophile in condensation rxn
carbonyl is electrophile in nucleophilic addition
what is the geometry of the intermediate when a nucleophile (such as an amide) attacks a carbonyl?
tetrahedral- pi bond is broken and the pi electrons pushed onto oxygen
if a good leaving group is present, the carbonyl will reform (but only if there’s a good leaving group)
cyanide is:
acidic
nucelophile
both! triple bond/ electronegative N makes it acidic
deprotonation makes it nucleophilic
when nitrogen-containing derivative reacts with aldehyde or ketone, what reaction happens and what do you get?
nucleophilic substitution, you get an imine
when the alpha H is removed from aldehyde/ketone, what type of intermediate is formed?
enolate intermediate (negative charge on O, double bond between C=C below), which is resonance stabilized now follow up with acid (protonate) and you have an enol
are alpha H more acidic in ketones or aldehydes
aldehydes, because extra alkyl group of ketone is destabilizing (e- donating) for carbanion
(remember, in carbocations alkyl groups are stabilizing, but here deprotonation gives carbanion, so negative charge will destabilize)
given a ketone with 2 different alkyl groups, which alpha hydrogen will be removed first?
alpha H of less substituted alpha C will be removed first because of less steric hinderance (kinetic product), but this is not as stable. favored by rapid, irreversible, low temp, sterically hindered base rxns
eventually thermodynamic product will win out (more substituted alpha C). favored by high temp, slow rate, reversible, weaker bases
where is the double bond in in enamine vs imine
imine: N=C
enamine: C=C
what is an aldol (hint: it’s in the name)
contains ALDehyde and alcohOL
aldol condensation: combining 2 ketones/aldehydes because one acts as electrophile (in keto form) while other acts as nucleophile (in enolate form after deprotonation by base)
when benzaldehyde is reacted with acetone, which will act as nucleophile
acetone will be nucleophile after addition of strong base (enolate ion), because benzaldehyde doesn’t have an alpha proton to be abstracted
(benzene ring with aldehyde group)
when ethanal is reacted with base, then acid, what do you get
ethanal + base = aldol (deprotonates), then acid stops the reaction –> get 3-hydroxybutanal
you’re combining 2 ethanals in aldol condensation
what kind of bond connects dimers
H bonding
which of these are e- donating groups? -NO2 halides -NH2 -OCH3
- NH2 and -OCH3 are e-donating
- NO2 and halides are e-withdrawing
which cannot be oxidized to carboxylic acids: primary secondary tertiary alcohols?
secondary and tertiary alcohols cannot be oxidized to carboxylic acids because they already have at least 2 bonds to other carbons
esters are a combination of ___ and ____ and are formed under ___ conditions
carboxylic acid + ether in acidic conditions
(O of carboxylic acid is protonated, enhances polarity of bond and makes carbonyl susceptible to nucleophilic attack)
condensation rxn- water is leaving group
under what condition do carboxylic acids spontaneously decarboxylate
heat
what is the leaving group in reaction between carboxylic acid and amide?
water
