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What are diols and what is the different between vicinal and geminal diols?
Diols are alcohols with two hydroxy groups.
- Geminal diol has the hydroxy groups on the same carbon
- Vicinal diol have hydroxyls on adjacent carbons
How are aldehydes named?
Replace -e of the parent alkane and replace it with -al
How are ketones named?
Replace -e of the alkane with -one
What are the common names for
Methanal
Ethanal
Propan_al_
Propanone
- Formaldehyde
- Acetaldehyde
- Propionaldehyde
- Acetone
What does the suffix -oate indicate?
Ester
What is the order of functional groups from highest to lowest priority
Carboxylic acid
anhydride
ester
amide
aldehyde
ketone
alcohol
alkene or alkyne
alkane
What are three examples of physical properties?
- Melting point
- boiling point
- solubility
How do conformational isomers differ?
differ in rotation around a single bond
What is the difference between the anti and gauche conformation?
Anti: functional groups are 180 degrees apart
gauche: when two largest sub groups are 60 degrees apart
What are the three strains that influence cyclic conformations?
Angle Strain: bond angle differ from normal because of being stretched/compressed
Torsional Strain: ecliped or guache interactions
Nonbonded strain: steric interactions
What is one similarity and two difference between enantiomers and diastereomers?
both are nonsuperimposable
Diastereomers are not mirror images and enantiomers are mirror images
Diastereomers have different chemical and physical properties and enantiomers have the same except for rotation of plane-polarized light
What are the two characteristics of a meso compound?
- chiral centers
- line of symmetry
What is the one difference between E and Z designation? One simularity?
E: highest-priority substituents are on the opposite side of the double bound
Z: on same side of double bond
Both are diastereomers
What are the two difference between Lewis bases and acids?
Lewis Bases are electron donors and are nucleophiles
Lewis Acids are electron aceptors and are electrophiles
What type of bond do Lewis acids and bases form?
coordinated covalent bond: both electrons comes from the same starting atom (lewis base)
What is the difference between base and nucleophile strength?
base strength is based on equilibrium and is a thermodynamic property
nucleophile strength is based on rates of rxn with electrophile so is a kinetic property
What are the four factors that influence nucleophilicity?
- Charge: as electron density increases, nucleophilicty increases
- Electronegativity increases, nucleophilicty decreases
- Steric hinderance: bulkier, nucleophilicty decreases
- Solvent: protic solvents(have H+ attached to an element) can decrease nucleophilicty
What are four factors that impact electrophilicity?
- increase positive charge, increase electrophilicity
- better leaving groups in species without empty orbitals, increases electrophilicity
- acids are strong electrophiles
- Anhydrides> caboxylic acids> esters> amides
What is a heterolytic rxn?
opposite of a coordinate covalent bond
a bond is broken and both electrons are given to one of the two products
How are nucleophiles and leaving groups related?
In substitution rxn, the weaker base (leaving group) is replaced by the stronger bases (nucleophile)
What makes a good leaving group and how?
- Weak bases are good leaving groups (conjugate base of strong acids)
- Have resonance and inductive effects from e- withdrawing groups that delocalize and stabilize negative charge
Why are SN2 stereospecific rxn?
There is an inversion of the relative configuration/ the configuration of the reactant is determined by the configuration of the product
What is one difference between electrophilicity/nucleophilicity and acidity/basicity?
electrophilicity/nucleophilicity: based on rate of rxn so are kinetic properties
acidity/basicity: measure by position of equilibrium so thermodynamic properties
What makes a good rxn site in a redox regent and nucleophiles/electrophiles?
- highest priority functional groups
- For nucleophiles, a good electrophiles is a more oxidized carbons so it has a larger positive charge since electronegative atoms are pulling e- density.
What are 4 strong oxidizing agent? What is one weak oxidizing agent?
- KMnO4, K2CrO7, Cro3, Na2Cr2O7
- PCC
- PCC
What is one strong and one weak reducing agent?
- LiAlH4 (reduce carboxylic acids)
- NaBH4 (reduce aldehydes and ketone)
What is a phenol? What are the three possible arrangments of sustituent groups on phenol?
- hydroxyl groups attached to aromatic rings and the hydroxyl hydrogens are acidic due to resonance with phenol ring
1. ortho: two groups on adjacent carbon
2. meta: two groups separated by a carbon
3. Para: two groups on opposite sides of ring
1.
How can sustituents change the acidity of a phenol?
- electron withdrawing groups increase acidity bc stabalize anion
- electron donating groups decrease acidity
What is another name for vitamin K1 and vitamin K2?
Vitamin K1: phylloquinone
Vitamin K2: menaquinones
Name 3 facts about Ubiquinone?
- Also called coenzyme Q
- Most oxidized form and can be reduced into ubiquinol
- conjugated rings to stablize molecule when carry an e-
What happens when you react an HCN with an aldehyde or a ketone?
Will get a cyanohydrin
What happens when aldehydes and ketons are treated with an excess amount of alcohol?
- will get hemiacetal or hemiketal
- acetla or ketal
What are two reasons hemiketals and hemiacetals are extremely short-lived?
- The -OH group will rapidly become protonates in acidic conditions and is lost in water, which will leave behind a carbocation that will most likely be attacked by an alcohol
- acetals and ketals are more stable because the added group is less likely to be protonated and leave compared to -OH
What is an enol?
carbon-carbon double bond and an alcohol
What are the 3 difference between the thermodynamic and kinetic enolate?
- Kinetic is formed faster and is less stable. Thermodynamic product is formed slower but is more stable
- Kinetic has a double bond to the less substituted alpha-carbon
- Kinetic product is formed by the removal of alpha-hydrogen from less substituted alpha-carbon because it offers less steric hinderance. Thermodynamic product is formed by the removal of alpha-hydrogen from the more substituted alpha-carbon
What is the tautomer of an imine?
Enamines
What is saponification?
mixing fatty acids with lye (sodium or potassium hydroxide)–> get a salt (soap)
-form micelles–> long fatty acids with polar heads
Under what conditions will a carboxylic acids spontaneously decarboxylate (loss of CO2)?
When heated bc of stable cylic intermediate six member ring
Why is there an increased rate of hydroylsis in Beta-lactams?
because they are susceptible to hydrolysis due to high levels of ring strain, which is due to torsional strains and angle strain
What happens in transesterification?
exchange of one esterfying group for another in an ester (requires an alcohol as a nucleophile)
What are the three ways anhydrides can be cleaved?
- addition of ammonia or an amine –> amide and carboxylic acid
- addition of alcohol –> ester and carboxylic acid
- addition of water–> two carboxylic acids
How can cyclic anhydrides form spontaneously?
dicarboyxlic acids when heated
Why should esterification not be carried out in water?
Presence of water would likely revert the esters back into carboxylic acids and alcohol
What are 2 facts about IR spectroscopy?
- measure absorption of infrared light, cause molecular vibrations
- finger print region is between 1500 and 400 cm-1
What are 3 facts about UV spectroscopy data?
- absorbance is plotted against wavelength
- absorbance is caused by electronic transitions between orbitals
- tells use extent of conjugation within a conjugated system with pi or nonbonding e (more conjugated, lower energy of transition, greater wavelength of absorbance).
What are two components of NMR?
- chemicl shift: plotted on x axis and increases left(downfield)
- TMS is used as a standard (0ppm)
What are 4 characteristics of Proton NMR?
- peak height is proportional to number of protons
- deshielding (attach to electronegative groups)/will be downfield
- shielding: smaller ppm
- iif a protons has n protons that are three bonds away, it will be split into n+1 peaks but do not include protons attach to O or N /mag of this splitting is called coupling constant J
Will enantiomers have the same IR spectra?
yes, because they have the same functional groups and will therefore have same absorption freq
What is superheating?
occurs when a liquid is heated to a tempature above its boiling points without vaporization
What is the difference between simple, vacuum, fractional distillation?
- Simple: can be used if boiling points are under 150 and are atleast 25 degrees apart
- vaccum: used if BP over 150 to prevent degradation of product. lower pressure so decrease temp liquid must reach to boil
- should be used if BP are less than 25 degrees apart
How do you calculate Rf value?
Rf=(distance spot moved)/(distance solvent moved)
s
What are 4 traits of Gas Chromatography?
- eluent is a gas
- absorbent is a crushed metal or polymer
- gaseous compounds travel at differnt rates bc they adhere to the absorbent at different degrees
- inject components must be voltatile
What makes a carbon susceptible to nucleophilic attack?
protonate the carbonyl O, after it is attacked by nucleophiles, it will be protonated and leave as water so better leaving group
What is a conjugated system?
has alternating double bonds (alkenes)
What does mass spectrometry looks at?
mass-to-charge ration, remove e through ionization
what is a geometric isomer?
presence of double bond or ring
What will happen when two nucleotide triphosphates are bonding together?
release a small molecule called pyrophosphate, which will be hydrolized into an inorganic phosphate
If a group is attached to a strong nucleophile, will it leave overall structure?
No, large structure will have that group in it
How do you drive the synthesis of an anhydride?
using heat
What charge is the column for cation exchange?
column (stationary phase) is - charge
strong positive charges will elute last
What does aldol condensation look like? Can it be both base and acid catelyzed?
yes but need to have an alpha hydrogen
What does -anhydro mean?
removal of H2O
Is alpha hydrogen next to C=O more or less acidic?
more acidic because conjugate base is resonance stabilized
Are aldehydes more or less electrophilic than ketons?
aldehydes are more electrophilic because less electron donating groups
How does electronegativity impact acidity?
increases acidity becuase e- negative weaken the -OH bond
Where does electrophilic addition occur?
across double bond
Can ethanol act as a nucleophile?
yes
How can you reduce alkynes and alkenes?
H2 gas w/ Pt catalyst
How do electronegative atoms on phenol ring affect nucelophilicity?
contribute to e- density into resonance structure, so make a good nucleophile
How are imines formed?
nucleophilic attack of cabonly carbon with and amine
What synthesis is this? What does it form?
Stretcher Synthesis
amino acids
What synthesis is this? What does it form?
Gabriel Synthesis
Amino acids
What is a retro adol and what can it form?
- two ketones
(acid catalyzed)
How can you form an anhydride?
2 carbonxylic acids with H+ catalyst
What are 3 ways to form an amide?
1) react NH3 with anhydride–> amide + carboxylic acid
2) ester + NH3–> alcohol + amide
3. acyl halide + amine –> amide
What are two ways to breakdown an amide?
- Hydrolysis: H20+ amide + H+ catalyst–> carboxylic acid + NH3
- amide + reducing agent –> amine
What is one way to form an ester?
- transesterification
How do you form an acetal?
Do esters need protecting groups?
No, they are pretty stable
What agent converts carboxylic acids into acyl halides?
SOCl2
Are oxide anions and acyl reactive?
yes
Are bonds that are more polarized easier or harder to break?
easier
is C-N a good leaving group?
yes
What is the difference between a mesylate and a tosylate? what are their two purposes?
- both have sulfer attached to O but tosylate has an aromatic ring attached and ussualy mixed with pyradine because good base
- make -OH a good leaving group
- they can also protect -OH groups from beaing oxidized into ketone or aldehyde
Are peroxides reactive?
very
How does the acidity change with increase substitution of alcohol?
highliy substituted makes it a weak acid but a strong base
What type of formation does phenol favor?
brominated products and use nonpolar solvent to get monosubstitution
What product do you get when you react a carboxylic acid with an ammonia?
ammonium (NH4+)–> acid base reaction
What is the one product of an aldol condensation?
alpha, beta, unsaturated carbonyl
Is the keto form always perferred over the enol form?
yes
What does a cyanohydride look like?
c with triple bond to N
How much s character is from sp3? p character?
25% s and 75% p
What happens when an e absorbs energy from a photon?
moves from HOMO to LUMO
What does IR measure and what molecules will it not detect?
- it measures the way in which the dipole moment of the bond vibrates over time
- if symetrical, like a diatomic molecule with no dipole, no IR
What is the shift of 11.0ppm on H-NMR mean?
carboxylic acid –> down field/deshielded
What do elimation rxn creat? what do they need?
- double bonds
- base catelyzed
How can you remove double bonds?
H2 + Pt (catalytic hydrogenation)
Why cant NH3 be a buffer if it is a weak base?
because it is a gas at room temp/would not use as a buffer for acidic solution
Is -OH a strong nucleophile?
yes
How do addition rxn impact sigma and pi bonds?
increase sigma, decrease pi
What do organic compounds need?
-CH bonds
What is an example of a protic solvent?
DMSO
What does tautamerization need?
need alpha atom to form double bond
Will alcohol protonate?
no
What is an imide?
one acyl group on either side of the nitrogen that ay be attached to an additional R group
What is an enamine?
is the the enol version of imine. double bond between two carbons instead of double bond between N and C (imine)
What are Gringard reactions used for?
used to alkylate a compound with a carbonyl
How might halogenation increase boiling point of an alkane?
Strongest intermolecular force are Lond disperision, but if halogenation, will have dipole-dipole interactions
Do alkanes have cis or trans conformation?
no, can rotate freely
For SN1, where would the most stable carbocation form?
most substitutes carbone with leaving group (halogen)
What is one requirement for a zwitterion?
have to have both positive and negative charges
Is a more stable conjugate base more or less alkaline?
less, have resonance structures to delocalize e density
If two chiral carbons and molecule has symmetry, how many meso compounds?
2
Out of the three, which one is chiral?
- tert-butoxide
- DMSO
- Diethyl tartrate
- Diethyl tartrate
Are cyclic hydrocarbons more or less nonpolar than linear hydrocarbons?
more
What are two rxns involving esters?
hydrolysis: H20 + ester + H+ catalyst–> H3O+ + carboyxlic acid
reduction of ester –> two alcohols
What condition is most ideal for recrystalization?
substance is highly soluble at high temp but insoluble at low temp and ppt forms
When does recrystalization need to be conducted?
if the measured boiling/melting point is extremely different from the expected boiling/melting point
What is the difference between NMR and IR?
IR (Infrared radiation–> low energy radiation) involves absorption of light directly into chemical bonds, a process that occurs at a specific wavelength according to the bond type
NMR triggers a nuclear oscillation at a measurable frequency, use magnetic pulse to displace atomic nuclei
Are all monosaccharides reducing sugars?
yes
How can you drive the forward rxn of an anhydride from two carboxylic acids?
add heat
Do ketones make a compound more or less acidic?
less, bc contribute electron density to conjugate base
What is chromium trioxide ussualy used for?
oxidation rxn
How can a phenol undergo halogenation?
chlorine + H20(Protic solvent)
When is methane active?
in presence of strong base
What is sodium hydride?
strong base
How does protonation affect a rxn?
it makes a compound a better leaving group (ex: protonation of an alcohol makes a better substitutions of -OH)
How do you calculate enantiomeri excess?
Ovserved rotation / specific roation x100
How do you calculate Specific rotation?
obersvered rotation/ (c xL)
c(g/ml)
L(pm)
When is the alpha carbon acidic?
conjugate base is resonance stabilized, inductive effects are able to stabilze negative charge (withdraw electrons)
What is the value of an ionization constant of a weak acid?
close to 0
What conditions favor E1 rxn?
add heat
Do ethanols protonate?
yes, they are acidic
How can you form an acetal from a hemiacital?
acid conditions
What is pyridine?
weak base
What is a good buffer?
pka+/- 1
What is SOCL2 used for?
convert carboxylic acids into acyl halids
What condition do you get monosubstitution of an aromatic ring?
aprotic solvent
is crystal formation exothermic or endothermic?
endothermic
How do you know which carbon will be attacked by nucleophile?
most substituted, good leaving group
What is acetylation?
attachement of R=O
What is a gringard reagent?
RMgBr, will alklylnate
What happens to absolute configuration when the lowest priority group is facing me?
Have to revserse the configurations
What does a dashed line mean in lewis structure?
they are pointing into the paper/ away from you
What are two sources of saturation?
rings and multiple bounds
How does pH impact nucleophilicity?
increase –> increase pH to deprotonate and increase negative charge
What is the trend of nucleophilicity in periodic table?
Nucleophilicity increases going down due to greater size and polarizability
Does a strong nucleophile impact the kinetics or thermodynamics of a rxn?
kinetics
What is the difference between L and D configuration?
L is S configuration and D is R. These are the absolute configurations at C5 in sugars
How does acidity change down a periodic table?
increases bc increasing radii, more likely to dissociate, also more stable at delocalizing charge
How does acidity change with increase Zeef charge?
increases
What type of base is ammonia (NH3)?
weak base
What is an example of a non-reducing sugar?
sucrose because does not contain a free carbonyl ketone or aldehyde
Which has a better leaving group, acyl chloride or acyl iodide?
acyl iodide bc larger and delocalize charge better
What is transesterification?
conversion of one ester into another using an alcohol, The –OH acts as a nucleophile and attacks the ester’s carbonyl carbon, replacing the previous R group on the ester with its own
What happens when you put an ester in water?
hydrolyze ester and get carboxylic acid and alcohol
Are carboxylic acids more acidic than phenols?
yes
What are configuarational isomers?
structural isomers and are just bonded in a different way (isopentane, pentane)
WHat does a high pKb mean?
a weak base
Are tertiary alcohols less or more acidic than primary?
less, bc electron donating
Is acetal formation reversible?
yes and can have acid catalyzed to recover aldehyde and ketone
How to make an ester?
alcohol and carboxylic acid
What can break a cyclic ketal?
acidic conditions
What are three examples of polar protic solvents?
ethanol, ammonia, H2O
