Deck 8: Alkyl Halides and Elimination Reactions

Question 1

Which of the following statements about the mechanism of an E2 reaction is true?

A) All bonds are broken and formed in multiple steps.
B) The reaction is not concerted.
C) Entropy favors the reactants of an E2 reaction.
D) Entropy favors the products of an E2 reaction.

Answer 1

Entropy favors the products of an E2 reaction.

Question 2

What is the major elimination product obtained from the following reaction?

A) I
B) II
C) III
D) IV

Answer 2

II

Question 3

Which of the following is the most reactive substrate in an E2 reaction? $\mathrm { CH } _ { 3 } \mathrm { Br } \quad \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { Br } \quad \mathrm { CH } _ { 3 } \mathrm { CH } \left( \mathrm { Br } ^ { 2 } \right) \mathrm { CH } _ { 2 } \mathrm { CH } _ { 3 } \quad \left( \mathrm { CH } _ { 3 } \right) _ { 3 } \mathrm { CBr }$
I $\quad\quad\quad\quad\quad\quad\quad$ II $\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad$ III $\quad\quad\quad\quad\quad\quad\quad\quad$ IV

A) I
B) II
C) III
D) IV

Answer 3

IV

Question 4

Which of the following is the least reactive substrate in an E2 reaction?

A) I
B) II
C) III
D) IV

Question 5

What is the major elimination product in the reaction of 1-bromobutane with potassium tert-butoxide in tert-butanol?

A) cis-2-Butene
B) 1-Butene
C) trans-2-Butene
D) Butanol

Question 6

Which of the following is the most reactive substrate in an E1 reaction?

A) I
B) II
C) III
D) IV

Question 7

Which of the following statements about an E1 mechanism is not true?

A) The reaction is fastest with tertiary alkyl halides.
B) A better leaving group makes the reaction rate increase.
C) The reaction follows first-order kinetics.
D) Stronger bases favor the E1 reaction.

Question 8

How many unique $\beta$ carbons are found in the alkyl halide below?

A) 1
B) 2
C) 3
D) 4

Question 9

Which of the following statements about an E1 mechanism is true?

A) The identity of the leaving group affects the rate of reaction.
B) The reaction follows second-order kinetics.
C) The reaction is slowest with tertiary substrates.
D) Polar aprotic solvents favor the E1 mechanism.

Question 10

How many different E2 products can form from the dehydrohalogenation of 2-bromobutane?

A) 1
B) 2
C) 3
D) 4

Question 11

Which of the following statements about an E1 mechanism is not true?

A) It is a two-step process and has the same first step as an S_N1 mechanism.
B) It involves the formation of a carbocation from eliminating a good leaving group.
C) A common competing reaction is rearrangement of a less stable carbocation to a more stable carbocation.
D) The loss of a proton by the carbocation is a slow step.

Question 12

What is the major elimination product obtained from the following reaction?

A) I
B) II
C) III
D) IV

Question 13

Which of the following is the major elimination product of the following reaction?

A) I
B) II
C) III
D) IV

Question 14

Which of the following represents the rate law for an E2 reaction?

A) Rate = k[alkyl halide]
B) Rate = k[alkyl halide][base]
C) Rate = k[alkyl halide]²
D) Rate = k[base]²

Question 15

What is the major product of the following reaction?

A) I
B) II
C) III
D) IV

Question 16

Which of the following statements about the mechanism of an E2 reaction is not true?

A) It is fastest with tertiary halides.
B) It exhibits first-order kinetics.
C) A better leaving group should make a faster reaction.
D) All bonds are broken and formed in a single step.

Question 17

Classify each alkene in vitamin D₃ labeled I, II, III by the number of carbon substituents bonded to the double bond.

A) I = Disubstituted; II = trisubstituted; III = trisubstituted.
B) I = Monosubstituted; II = disubstituted; III = trisubstituted.
C) I = Disubstituted; II = disubstituted; III = trisubstituted.
D) I = Disubstituted; II = trisubstituted; III = disubstituted.

Question 18

How many unique $\beta$ carbons are found in the alkyl halide below?

A) 1
B) 2
C) 3
D) 4

Question 19

What is the major elimination product obtained from the following reaction?

A) I
B) II
C) III
D) IV

Question 20

What is the major elimination product obtained from the following reaction?

A) I
B) II
C) III
D) IV

Question 21

Which of the following is most likely to react as a nucleophile rather than a base? $$\begin{array} { c c c c } \mathrm { KOC } \left( \mathrm { CH } _ { 3 } \right) _ { 3 } & \mathrm { CH } _ { 3 } \mathrm { COO } ^ { - } & \mathrm { DBU } & \mathrm { DBN } \\\text { I } & \text { II } & \text { III } & \text { IV }\end{array}$$

A) I
B) II
C) III
D) IV

Question 22

What is (are) the elimination product(s) of the following reaction?

A) Only I
B) Only II
C) Only III
D) II and III

Question 23

Select the elimination product(s) formed by treating the indicated alkyl halide with a base.

A) Only I
B) Only II
C) Only III
D) I, II and III

Question 24

What is the product of the following reaction?

A) Only I
B) Only II
C) Only III
D) II and III

Question 25

Which of the following is the major E2 product formed from the following alkyl halide?

A) I
B) II
C) III
D) IV

Question 26

Which of the following alkyl halides would afford the indicated product upon reaction with sodium methoxide?

A) I
B) II
C) III
D) IV

Question 27

Which of the following alkyl halides will afford the product below as the major product in an E2 reaction?

A) I
B) II
C) III
D) IV

Question 28

What is (are) the product(s) of the following reaction?

A) I and II
B) II and III
C) I and III
D) I, II and III

Question 29

What is (are) the product(s) of the following reaction?

A) Only I
B) Only II
C) Only III
D) I and II

Question 30

What is the product of the following reaction?

A) I
B) II
C) III
D) IV

Question 31

What is (are) the elimination product(s) of the following reaction?

A) Only I
B) Only II
C) Only III
D) II and III

Question 32

What is the product of the following reaction?

A) I
B) II
C) III
D) IV

Question 33

Which of the following is the dihalide that can be used to prepare the alkyne below?

A) I and II
B) II and III
C) I and III
D) I, II and III

Question 34

What is (are) the product(s) of the following reaction?

A) Only I
B) Only II
C) Only III
D) I and II

Question 35

What is (are) the starting material(s) in the reaction below?

A) Only I
B) Only II
C) Only III
D) II and III

Question 36

Which of the following is most likely to react as a base rather than a nucleophile?

A) I
B) II
C) III
D) IV

Question 37

Which of the labeled protons in the compound below is most readily abstracted under E2 conditions?

A) H_a
B) H_b
C) H_c
D) H_d

Question 38

What is the product of the following reaction?

A) I
B) II
C) III
D) IV

Question 39

Which of the following is the dihalide that can be used to prepare the alkyne below?

A) Only I
B) Only II
C) Only III
D) II and III

Question 40

What is (are) the product(s) of the following reaction?

A) Only I
B) Only II
C) Only III
D) II and III

Question 41

Which of the following alkenes is the most stable?

A) I
B) II
C) III
D) IV

Question 42

What is the most likely mechanism for the reaction below?

A) S_N1
B) S_N2
C) E1
D) E2

Question 43

Consider the following E2 reaction. What rate equation would be observed for this reaction? $$\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { Br } + \stackrel { \oplus \ominus } { \mathrm { KOC } } \left( \mathrm { CH } _ { 2 } \right) _ { 3 } \longrightarrow \mathrm { CH } _ { 3 } \mathrm { CH } = \mathrm { CH } _ { 2 } + \mathrm { KBr } ^ { + }$$

A) Rate = k[CH₃CH₂CH₂Br]
B) Rate = k[CH₃CH₂CH₂Br][KOC(CH₃)₃]
C) Rate = k[CH₃CH₂CH₂Br][KOC(CH₃)₃]²
D) Rate = k[CH₃CH₂CH₂Br]²[KOC(CH₃)₃]

Question 44

Which alkyl halide(s) would give the following alkene as the only product in an elimination reaction?

A) Only I
B) Only II
C) Only III
D) I and II

Question 45

What is the most likely mechanism for the reaction below?

A) S_N1
B) S_N2
C) E1
D) E2