Exam 3

Question 1

concerted reaction

Answer 1

happens in one step
E2 and SN2
1 hump on energy diagram

Question 2

stepwise reaction

Answer 2

proceeds through intermediates
E1 and SN1
energy diagram:
-# of humps=# of steps
-# of valleys=# of intermediates
-highest energy=rate-determining step

Question 3

nucleophile

Answer 3

an ion/compound capable of donating electrons

Question 4

electrophile

Answer 4

ions/compounds poor in electron density-can be attacked by nucleophiles-target for electrons

Question 5

nucleophilicity

Answer 5

measure of how quickly a nucleophile will attack an electrophile

Question 6

basicity

Answer 6

measure of the position of equilibrium for an acid-base reaction

Question 7

carbocation

Answer 7

target for electrons (alkyl groups stabilize carbocations)

Question 8

nucleophilic attack

Answer 8

characterized by a nucleophile attacking an electrophile

Question 9

nucleophiles are electron rich…(best to least)

Answer 9

negative charge
lone pair
pi bond

Question 10

carbocation stability

Answer 10

the number of carbon neighbors the empty p-orbital, immediate neighbors one bond away
most stable=tertiary (3) carbocation
secondary (2) carbocation
primary (1) carbocation
methyl carbocation

Question 11

nucleophilic attack

Answer 11

characterized by a nucleophile attack an electrophile

Question 12

proton transfer

Answer 12

a base will remove a proton from (deprotonate) an acid

Question 13

loss of a leaving group

Answer 13

leaving group is partially or completely removed

Question 14

rearrangement

Answer 14

characterized by a change in the location of the electron deficient center (C+)

Question 15

substitution

Answer 15

replace an atom (or group) with another Sn1 and Sn2 are common

Question 16

elimination

Answer 16

two atoms are lost to form an alkene

opposite of addition

Question 17

addition

Answer 17

add new atoms to an alkene

opposite of elimination

Question 18

Sn2

Answer 18

substitution
nucleophile, a good source of electrons is present
concerted, bimolecular, concentrations of both the nucleophile and substrate impact the rate of rxn
one step with two arrows
primary or secondary
inversion occurs

Question 19

Sn1

Answer 19

substitution
nucleophile
rate dependent on the substrate and its ability to form a carbocation stepwise with intermediates
two steps with one arrow
secondary or tertiary
racemization occurs

Question 20

trans or cis isomers

Answer 20

trans

Question 21

how do nucleophiles affect Sn2 reactions

Answer 21

strong nucleophiles speed up Sn2

weak nucleophiles slow down Sn2

Question 22

in Sn1 reactions the solvent…

Answer 22

helps to stabilizee the leaving group and carbocation formation
acts as the source of electrons to attack the carbocation

Question 23

protic solvent

Answer 23

a solvent that has a proton connected to an electronegative atom

Question 24

aprotic solvent

Answer 24

a solvent that does not have a proton on an electronegative atom

Question 25

most stable to least stable carbon neighbor formations

Answer 25

tetra-substituted tri-substituted di-substituted (trans, cis, geminal) mono-substituted

Question 26

naming alkenes

Answer 26

1. The C=C is the key functional group. We must include C=C in the parent chain. Number through the C=C. 2. Number from the end of the molecule that gives the C=C the lowest number. Substituents are numbered after that. 3. Use E/Z to describe the stereochemistry. Elimination reaction source of electrons (neg charge, lone pair, pi bond)

Question 27

Sn1 and E1 always do...

Answer 27

proton transfer

Question 28

E2 process

Answer 28

a base removes a proton, causing the simulation expulsion of a leaving group (one step=no intermediates) Zaitsev's product and Hoffmann product

Question 29

zaitzev's product

Answer 29

more-substituted

Question 30

hoffmanns product

Answer 30

less-substituted

Question 31

regiochemistry

Answer 31

where the reaction takes place

Question 32

antiperiplanar

Answer 32

H and leaving group opposite on Newman projection

Question 33

E1 process

Answer 33

two steps where the leaving group leaves, forming a carbocation, and then a proton transfer occurs

Question 34

when can E2 occur on chairs

Answer 34

when the leaving group is axial | bulky bases always perform E2 but do not follow Zaitsev's rule

Question 35

primary substrate

Answer 35

never Sn1 Sn2 E2-LDA and t-BuO- (these do not follow Zatizev's Rule)

Question 36

secondary substrate

Answer 36

Sn1/E1-H2O, CH3OH, CH2CH3OH Sn2-Na+-SH, DMSO, DMF, acetone E2-LDA, t-BuO- (these do not follow Zatizev's Rule) or E2-Na+-OH, H2O

Question 37

tertiary substrate

Answer 37

never Sn2 SN1/E1-H2O, CH3OH, CH2CH3OH E2-LDA, t-BuO- (these do not follow Zatizev's Rule) or E2-Na+-OH, H2O

Question 38

nucleophile (only) reagents

Answer 38

Cl-, Br-, I-, HS-, H2S, RS-, RSH

Question 39

base (only) reagents

Answer 39

H:-, tBuO

Question 40

strong nuc and strong base reagents

Answer 40

HO-, MeO-, EtO-, tBuO

Question 41

weak nuc, weak base reagents

Answer 41

H2O, MeOH, EtOH

Question 42

primary nucleophile

Answer 42

Sn2

Question 43

secondary nucleophile

Answer 43

Sn2

Question 44

tertiary nucleophile

Answer 44

Sn1

Question 45

primary base

Answer 45

E2

Question 46

secondary base

Answer 46

E2

Question 47

tertiary base

Answer 47

E2

Question 48

primary strong nuc/strong base

Answer 48

E2 (minor) and Sn2 (major)

Question 49

secondary strong nuc/strong base

Answer 49

E2 (major) and Sn2 (minor)

Question 50

tertiary strong nuc/strong base

Answer 50

E2

Question 51

primary weak nuc/weak base

Answer 51

Sn2 and E2

Question 52

secondary weak nuc/weak base

Answer 52

Sn2, Sn1, E1, and E2

Question 53

tertiary weak nuc/weak base

Answer 53

Sn1 and E1

Question 54

endothermic

Answer 54

products higher than the reactants

Question 55

exothermic

Answer 55

reactants higher than the products