Notes15

Question 1

drawbacks of sn1 reactions

Answer 1

1) can form expected products
2) connectivities can change (alkyl/hydride shift)
3) can undergo elimination reactions

Question 2

stabilizes tertiary carbocations

Answer 2

hyperconjugation

Question 3

two major types of sn1 and e1 substrates

Answer 3

1) secondary and tertiary alkyl halides

2) secondary and tertiary alcohols

Question 4

base is like…

Answer 4

a girl looking for a guy. Strong bases are the overly attached gf. Weak base is like a hookup

Question 5

when there is a positive charge on carbon…

Answer 5

neighboring protons become highly acidic

Question 6

saytzeffs rule

Answer 6

in elimination reactions, the product alkene with the most alkyl group connections wins out. MOST STABLE

Question 7

relative stabilities of alkenes measured by

Answer 7

heat of hydrogenation. relationship inverse. the more heat, the greater potential energy stored

Question 8

source of stability in trans

Answer 8

due to no steric effects

Question 9

saytzeffs rule practical usage

Answer 9

count number of non-H bonds attached to vinylic carbon

Question 10

dehydrohalogenation reaction

Answer 10

lose hydrogen and halogen in reaction

Question 11

E2 mechanism

Answer 11

anti H (to halogen) is taken by strong base, electrons left over. New bond releases halogen

Question 12

regioselective

Answer 12

produce one constitutional isomer predominantly

Question 13

favors Zaitsev product

Answer 13

small bases

Question 14

favors Hoffman product

Answer 14

large bases

Question 15

difference between constitutional and structural isomers

Answer 15

isomers - same formula and weight
constitutional - DIFFERENT connectivities
stereoisomers - same connectivities, different3D orientation
diastereomers - cis/trans (sp2)
enantiomers - chirality (sp3)

Question 16

key pattern of elimination reaction

Answer 16

1) break 2 adjacent sigma bonds

2) form new pi bond

Question 17

sn2 stereochemistry

Answer 17

100% inversion

Question 18

sn2 substrate

Answer 18

less steric hinderance. nucleophile needs to get close in

Question 19

sn2 nucleophile

Answer 19

needs strong, small nucleophile

Question 20

sn2 solvent

Answer 20

aprotic polar. (transition state is apolar)

Question 21

sn1 stereochemistry

Answer 21

racemization

Question 22

sn1 substrate

Answer 22

tertiary>2>1 because carbocation stabilization

Question 23

sn1 solvent

Answer 23

polar protic. why? stabilizes leaving group and polar transition states

Question 24

e2 stereochemistry

Answer 24

C-H and C-X bonds must be anti

Question 25

e2 substrate

Answer 25

less steric hindrance the better. for primary need hindered base to prevent reaction with protons

Question 26

e2 base

Answer 26

need strong base

Question 27

e2 solvent

Answer 27

polar protic or aprotic

Question 28

e1 stereochemistry

Answer 28

mixture of E and Z

Question 29

e1 substrate

Answer 29

steric hinderce good. wants a stable carbocation

Question 30

e1 base

Answer 30

generally weak

Question 31

e1 solvent

Answer 31

polar protic

Question 32

e2 clues

Answer 32

1) rate law

2) stereochemisty - anti needed

Question 33

e1 mechanism

Answer 33

1) leaving group leaves and forms carbocation

2) H is removed to form alkene

Question 34

cis isomerism on rings

Answer 34

axial/equatorial if bonds between them are odd

Question 35

charge nucleophiles/bases prefer rxn

Answer 35

prefer “2” reactions

Question 36

sn1 vs sn2 transition states

Answer 36

sn1: two transition states-carbocation and bond formation
sn2: only one transition states

Question 37

molecularity

Answer 37

number of species colliding in the rate determining step

Question 38

factors that influence nucleophilic substitution reactions

Answer 38

1. steric accessiblity
2. stability of sn1 carbocation
3. nature of nucleophile
4. type of solvent used
5. nature of the leaving group

Question 39

secondary carbons… sn1 vs sn2

Answer 39

these are a little tricky, as they can do both. look for resonance stabilized carbocations and other substitution reactions

Question 40

neutral nucleophiles in sn2 rxns

Answer 40

only conjugate base will be attached. lose proton

Question 41

solvolysis

Answer 41

in sn1 rxns, dissociation of organic compounds into ions