Exam 2 Flashcards
Lectures 15-27 (79 cards)
1
Q
SN1
A
- loss of a leaving group
- nucleophilic attack
- proton transfer if nucleophile is neutral
- stepwise
- nucleophile
2
Q
nucleophilic attack
A
lone pair on nucleophile to carbocation
3
Q
SN1 proton transfer
A
lone pair on nucleophile to hydrogen, bond of hydrogen to lone pair
4
Q
E1
A
- loss of a leaving group
- proton transfer
5
Q
E1 proton transfer
A
lone pair on nucleophile to beta hydrogen, bond of that to bond of carbocation (forming alkene)
6
Q
is more or less subsituted more stable
A
more substituted
7
Q
Hofmann product favored
A
bulky base
less subsituted
mneumonic: home buyers lose
8
Q
Zaitsev product favored
A
small base
more subsituted
zebras smell mud
9
Q
A
10
Q
what product do good leaving groups favor
A
zaitsev
11
Q
primary alcohols
A
sn2
12
Q
how to tell if it’s sn1, sn2, e1, or e2 given starting and ending molecule
A
- will be sn1 or sn2 if the carbon skeleton is the same and the leaving group was replaced by the nucleophile
- will be e1 or e2 if there’s an alkene
13
Q
SN1 and SN2
A
subsitution
14
Q
E1 and E2
A
elimination
15
Q
addition rxns favored by higher or lower temps
elimination rxns favored by enthalpy or entropy
A
low temps
entropy
ALOE
16
Q
elimination rxns favored by enthalpy or entropy
A
entropy
17
Q
enthalpy
A
heat energy exchange between rxn and surroundings
18
Q
homolytic cleavage
A
1 electron to each atom
19
Q
heterolyte
A
2 electrons to one atom
20
Q
BDE is also ____
A
change in enthalpy
21
Q
bonds broken vs bonds formed more stable in exo and endothermix rxn
A
exothermic - bonds formed
endothermic - bonds broken
22
Q
change in enthalpy formula
A
(BDE bonds broken)-(BDE bonds formed)
23
Q
entropy
A
molecular disorder
24
Q
what’s the entropy when mol product>mol reactant
A
positive
25
what's the entropy when a cyclic molecule becomes acyclic
positive
26
gibb's free energy
△G=△H-T△S
27
△G<0
spontaneous and exergonic
28
△G>0
nonspontaneous and endergonic
29
△G on a graph
line between reactants and products
30
activation energy on a graph
line between reactants and peak
31
does △G<0 facor products or reactants
products
32
kinetically favored
lower activation energy
33
thermodynamically favored
higher change in free energy
34
tertiary carbocation
tertiary: C+ attached to 3 other Cs
35
is tertiary or primary carbocation the most stable
tertiary
36
when will rearrangment occur
when secondary or primary can turn into tertiary or when primary can turn into tertiary or when tertiary without resonanced can turn into teritary with resonance
37
when will the nucleophilic attack be reversible
when there's a good leaving group
pka is less than 10 units
38
alpha carbon
carbon attached directly to halogen
39
tertiary alkyl halide
alpha carbon connected to 3 other carbons
40
is primary or tertiary alkyl halide the most stable
primary
41
SN2 rxn inversion
if the leaving group is in the page, the nucleophile that replaces it will be out of the page and vice versa
* every substituent at the C gets inverted stereochem, not just the leaving group
42
backside attack rule
nucleophile attacks from side opposite leaving group
43
what type of nucleophile and solvent do you need for an SN2 rxn
strong nucleophileb
polar aprotic solvent
* aprotic: don't H-bond
44
antiperiplanar
hydrogen atom and the leaving group are almost coplanar ex. 178 degrees
45
what condition needs to happen for an E2 rxn to occur
* H and leaving group are coplanar or periplanar, and anti
* on a chair confirmation, the H and L.G must be axial
* on a cyclohexane, the H and L.G. must be 1 wedged and 1 dashed
46
stereospecificity
stereoselectivity
1 stereoisomer as product
2 stereoisomers as product
| poet
47
protic solvents
water, methanol, ethanol, ammonia, acetic acid
48
aprotic solvents
acetone, DMF, DMSO
THF, acetonitrile, HMA
49
what conditions for alcohols to undergo substitution and elimination
strongly acidic
50
primary alcohol mechanism
sn2
51
secondary and tertiary alcohol mechanism
sn1
52
alcohols with H2SO4
e1
53
alcohols treated with Ts
strap Ts group to O of OH
54
how to do sn1, sn2, and e2 with alcohols
same as normal except do protonation beforehand
55
e1/e2 reactions don't forget...
base can go to the hydrogens on methyl
56
remember
* check for rearrangement for addition, E1, and SN1
57
synthesis
* Br on cut off end
* Na to balance out the -1 charge
58
SN1
**racemic** so one going into the page and one coming out
* 50/50 but actually more of the inversion product
59
mechanisms for protic solvents
SN1 and E1
60
mechanisms for aprotic solvents
SN2 and E2
61
solvolysis
when the nucleophile is also a base
62
E1 and E2 favors which product
trans, not cis
63
if there's a tie for the number of susbtituents...
check for hydrogen next to methyl
63
naming alkyl halides order
1. chircal center number and orientation (for all)
2. alphabetical order
64
remember
alkenes don't have wedges or dashes, they are all coplanar
65
picking a mechanism for alcohols
primary, secondary, tertiary takes priority over the base/nucleophile used
* primary = sn2
* secondary and tertiary = sn1
66
tosylate
OTS
* group leaving group
67
mesylate
OMs
68
triflate
OTf
69
naming alkenes are the same as naming alkyl halides except...
70
addition rxn
addition of 2 groups, 1 on each side of the alkene. in the process, the pi bond is broken
71
elimination rxns favor
higher temperatures
entropy
72
addition rxns favor
lower temperatures
enthalpy
73
markovnikov
* hydrogen atom gets added to carbon already with more hydrogen atoms
* halogen gets added to more subsituted carbon
74
antimarkovnikov
* happens in ROOR (peroxide)
* hydrogen atom gets added to tghe carbon with less hydrogen atoms
* halogen gets added to less substitued carbon
75
when to use E/Z vs R/S
use E/Z when there's no cyclo___
use R/S when it's cyclo___
76
synthesis picking nucleophile and electrophile
small electrophile (alkyl halide)
bulky base/nucleophile
* put alkyl halide with bigger piece (I think)
77
don't forget when naming
to specify stereochemistry for naming when there's a chiral center
78
mistakes when doing 2025 quizzes
* when it asks for product, pick the one that is either more or less subsituted depending on the base and the trans one over the cis one
* don't forget stereochemistry
* if tie between length of parent chain, pick path with the most substituents
* alphabetical order
* for sn1 last step, H gets revmoved, not other thing
* resonance
* adjacent C, not alpha C
* for sn1 and e1, write the whole mechanism because there could be rearrangement
* reminder:
sn1 - racemic (so write both for major)
e1- just write the more or less subsituted one depending on if it's a small or bulky base
sn2 - inversion
e2 - rules for antiperplanar
