Orgo 1/2 Flashcards
which are stronger? sigma or pi?
sigma bonds
define hybridized orbitals
combination of multiple types of orbitals at an intermediate energy levels
what shape is ammonium
tetrahedral
which of these is is a polar bond and why
A. C-C
B. C=C
C. C-O
D. C-H
C. C-O
it is the carbon bonded to a oxygen
true or false: breaking bonds requires energy
true
atoms usually want 8 electrons. what are the 4 exceptions to this rule?
H, He= they have S orbital so they only want 2
Boron and beryllium = want 6
in resonance, stable structures are _________ together/apart
closer together
define constitutional isomers
compounds that have the same chemical formula but have different atom to atom connectivity
think: constitution is written the same but connects to ppl differently
define diastereomers
2 compounds have different absolute stereochemistry at 1+, but not all stereocenters
is E2 a slow or fast reaction
what is formed/not formed
fast: no carbocation is formed, but alkene is formed
is SN1 a slow or fast reaction
what is the resulting formations
slow: carbocation is formed, 1 functional group is swapped for another
if boiling point is increased, what happened to the polarity
it increases
what is the most stable carbocation
primary
secondary
tertiary
quaternary
tertiary
quaternary is not a real thing
which of theses is not an oxidizing agent
LiAlH4
O3
Cr2O7
KMnO4
LiAlH4
the rest have Os
what do you think when you see a vic-diol functional group?
a ring with neighboring attachments (different point but right next to each other)
think: in spanish neighbors is vecin
what do you think when you see a gem-diol functional group?
a ring with 2 attachments on the same point
think: the ring looks like a ring with a gem
when a pi bond is present a _______ bond is also present
sigma
in terms of strength, rotation, stability, and reactiveness, describe the difference between sigma bonds and pi bonds
sigma: stronger, allow rotation, more stable, and less reactive
pi: weaker, prevent rotation, less stable, more reactive
what is hybridization
bonded atoms will create hybridized orbitals that are at an intermediate energy level
how does energy come into play when it comes to forming and breaking bonds
when a bond is broken, energy is required
when a bond is formed, energy is released
more stable molecules have a (greater/smaller) heat of combustion
less stable molecules have a (smaller/greater) heat of combustion
more stable: smaller heat of combustion
less stable: greater heat of combustion
what is the octet rule
atoms in the first two rows have a propensity to gain/lose electrons to fill a valence shell of 8
what are the three rules of stability, in order of importance
the most stable structure
1. allows the most atoms to have a full octet
2. has the fewest amount of formal charges
3. if there are charges, has them closer together
what is an isomer
two or more molecules with the same molecular formula but different bonding patterns
conformational isomer
compounds that only differ due to rotation about a single bond
not true isomer!
structural isomer
compounds that differ in bond to bond connectivity
stereoisomer
compounds that differ only only in 3D arrangement of their atoms
what is a stereocenter
any carbon that has 4 different groups bonded to it
what is the definition of chiral
any molecule with one or more stereocenters
enantiomers
2 compounds with different absolute configuration at every stereocenter
(mirror images)
dextrorotatory vs levorotatory
D: when compounds rotate light clockwise(think to write a D you need to draw clockwise)
L: when compounds rotate light counterclockwise
what is more stable: cis or trans
cis
what is a meso compound
molecules containing 2+ chiral centers containing a plane of symmetry
this symmetry cancels out any optical activity
how many steps do E1/E2 have?
Sn1/Sn2?
E1: 2
E2: 1
SN1: 2
SN2: 1
what is a carbonyl functional group
any carbon double bonded to an oxygen
what is the purpose of extraction
separates aqueous and organic layers
if you are given 2 benzene rings to extract, where will the benzene rings end up and why?
in the organic layer: 2 benzene rings are 2 hexagons(with lines in the middle) connected by 1 line
they have no polar properties because it is all bonded by C-H bonds. so it would end up in the organic layer
in extraction, what kind of molecules would go to organic?
what would do to aqueous?
polar and hydrophilic would do aqueous
nonpolar and hydrophobic would go to organic
what does distillation do
separates compounds based on boiling points
what determines boiling points? how does that work in terms of stronger and weaker?
INTERmolecular forces
lower intermolecular forces means lower boiling points
for example, if you were given a benzene ring and a water molecule, which would have the higher boiling point
since boiling point is based on intermolecular forces, figure out which one has more/stronger
benzene: VanderWaals (also has hydrophobic interactions bc of the C-H bonds)
water: VanderWaals, hydrogen bonding, Dipole-Dipole
this would mean that water would have the higher boiling point
what is chromatography?
what are 2 common approaches
using molecular interactions to separate compounds
1. gas chromatography
2. liquid chromatography
what are the 2 phases in chromatography and what are their characteristics
stationary: doesn’t move, nonpolar
mobile: passes through stationary, polar
what happens if a polar molecule is put in to gas chromatography
since it is polar, it would travel more closely with the polar mobile phase
this means it elutes more quickly in gas chromatography
what are the two kinds of spectroscopy?
IR and HNMR
what is the known as the ‘fingerprint’ region in IR spectroscopy?
500-1000
what is the range for C=O in IR spectroscopy
sharp or broad?
1650-1800
sharp/narrow
what is the range for C triple bonded to N or C triple bonded to C in IR spectroscopy?
sharp or broad?
2100-2260 sharp/narrow
what is the range for C-H in IR spectroscopy?
sharp or broad?
2850-3100 sharp
what is the range for O-H in IR spectroscopy?
sharp or broad?
3200-3400 broad
what is the range for alkyne C-H in IR spectroscopy?
sharp or broad?
3300 sharp
what is the range for N-H in IR spectroscopy?
sharp or broad?
3300-3500 sharp
what does UV spectroscopy do?
shows absorbance due to double or triple bonds and conjugated systems
the higher the nm, the greater degree of conjugation
in NMR spectroscopy, what is the ppm for H and C
1H: 0-12ppm
13C: 0.220ppm
in extraction, how can the separation be improved?
add acid/base to add/remove charge
repeat process multiple times
in extraction, how can the separation be messed up?
vigorous mixing
solvents that will react with the solute
solvents with high boiling point
what happens during vacuum filtration
air is sucked out of the bottom flask to increase filtration rate
what happens in recrystallization
impure product is dissolved into solvent, the solution is heated to melt the product, then is cooled and more pure solvent is solidified
what is an amine
any organic molecule with a basic nitrogen atom
what are the characteristics of amines? how do they act
they act as bases (function of thermodynamics) or nucleophiles (function of kinetics)
what is a formal charge
valance minus electrons surrounding atoms
how many valence electrons in C
4
how many valence electrons in N
5
how many valence electrons in O
6
how many valence electrons in F
7
alkane
/\/
alkene
/\/
alkyne
\///
alcohol
OH
/\/
ketone
…O
||
/\/\
ether
/\/O\/
what is the difference between R and S when it comes to stereochemistry
R is clockwise (the way you write it)
S is counterclockwise
enantiomers
2 compounds with different absolute configuration at every stereocenter
absolute stereochemistry
at any chiral carbon, if the priority of the groups proceeds clockwise the absolute stereochemistry is R. if the priority proceeds counterclockwise, the absolute stereochemistry is S
what are the qualities of a base?
does it accept or reject protons?
is it electron dense or not?
what kind of charge does it have?
the stronger the base, does the product become more stable or less?
accept protons
electron dense
negatively charged
strongest base forms the most stable product
what are the qualities of nucleophiles?
what does it attack?
is it electron dense or not?
what kind of charge does it have?
how does the speed come into play?
attacks electrophiles
electron dense
negatively charged
strongest nucleophile attacks the fastest
what qualities does an electrophile have?
charge?
electron dense?
positively charged
electron poor
compare and contrast E1/E2
steps
speed
carbocation formation
product stereochem
favored by
E1:
2 steps
slow speed
yes to carbocation formation
planar product stereochem
favored by weak bases
E2:
1 step
fast speed
no to carbocation formation
planar product stereochem
favored by strong bases
compare and contrast Sn1/Sn2
steps
speed
carbocation formation
product stereochem
favored by
Sn1:
2 steps
slow speed
yes to carbocation formation
racemic mixture product stereochem
favored by weak nucleophile
Sn2:
1 step
fast speed
no carbocation formation
inversion product stereochem
favored by strong nucleophile
what are radicals
they are dangerous and can cause DNA damage
are alkenes nucleo or electro philes?
why?
nucleophiles
electrons in a pi bond attack electrophile, leaving a carbocation (electrophile), which is then attacked by the nucleophile
the more substituents an alkene has, the (more/less) stable it is
more stable
alkynes have how many bonds?
triple
what defines an alcohol
-OH functional group
what is a benzene
hexagon, with the 3 lines inside it
boiling point (increases/decreases) with (increased/decreased) molecular weight and (increases/decreases) with more branching
boiling point increases with increased molecular weight and decreases with more branching
hydrogen bonding donors and acceptor
anything with an -OH or -NH can be a hydrogen bond donor
anything with an -O,-N,-F is hydrogen bond acceptor
alcohols have (higher/lower) melting & boiling points and (higher/lower) stability due to the presence of hydrogen bonds
alcohols have higher melting & boiling points and higher stability
are alcohols more or less acidic than water
less acidic than water
what are some oxidizing agents
O3, Cr2O7, CrO4, KmnO4, Jones reagent, Collins reagent, PCC, PDC
what are the reducing agents (classify weak and strong)
weak: NaBH4
strong: LiAlH4, H2/Pressure
why are grignard synthesis important?
important because they allow us to add carbons to a chain
how does polarity and electronegativity go together?
larger the difference in electronegativity, the more polar a bond
which is more polar?
C-O
C-F
C-O is less polar
C-F is more polar
what does a compound have to do to be considered an acid, in terms of a charge
either a partial or full positive charge
what does a compound have to do to be considered an base or nucleophile, in terms of a charge
either a partial or a full negative charge
how does charge relate to electronegativity
more electronegative: partial negative charge
less electronegative: partial positive charge
how does charge relate to the withdrawing/donating of electrons?
full/partial positive: withdraw
full/partial negative: donate
H donates or withdraws electrons?
alkanes donates or withdraws electrons?
alkenes donates or withdraws electrons?
H does neither
alkanes donate
alkenes withdraw
the (more/less) the conjugate base, the (stronger/weaker) the acid
the more stable the conjugate base, the stronger the acid
how does acidity and basicity relate to electron withdrawing/donating groups
withdrawing: increase compounds acidity
donating: increase compounds basicity
do electron donating/withdrawing groups affect the stability of a compound?
yes
carbocations are more or less stable with more substituents?
more
are cyclic ethers highly reactive? if so why?
yes, due to their extreme ring strain
what is an ether
oxygen bonded to 2 are groups
The stereochemical designators α and β distinguish between
epimers at anomeric carbon atom
the a/B distinguish between molecules with multiple chiral centers
these molecules differ only in the configuration of the site, anomeric carbon atom
which is more chiral
alpha or beta carbons
alpha
are carbonyl carbons achrial or chiral?
achiral
what do you do when asked to find out how many stereoisomers a “compound” has?
count the chiral centers = n
2^n
when finding discrete signals on a proton NMR spectrum, what do you do
look at the compound given to you, then find the carbons. if the carbons are the same, they count as 1 kind of carbons; if they are different then they act as different one
which of these is the least reactive?
ethanol
diethyl ether
dichloromethane
acetone
diethyl ether
hydrophobic interaction chromatography relies one high or low salt concentrations
high salt concentrations
