Deck 12: Organohalides: Nucleophilic Substitutions and Eliminations

Question 1

Consider the pair of reactions below to answer the following question(s).
a. or
b.
Refer to instructions. If the alkyl halide in each of these reactions was an alkyl chloride instead of the bromide,

A) the reaction rate would decrease.
B) a better leaving group would be involved.
C) a polar aprotic solvent would be needed.
D) ΔG^‡ would be decreased.

Answer 1

the reaction rate would decrease.

Question 2

For each question, draw a structure corresponding to the given name.
Draw:
trans-1-sec-butyl-3-chlorocyclohexane

Answer 2

Question 3

For each question, draw a structure corresponding to the given name.
Draw:
3-iodoprop-1-ene

Answer 3

Question 4

For each question, provide structures for the reactants, intermediates, or products, as indicated. Draw the structures in the boxes provided.
Complete the following reaction sequence by drawing the structure of the products in the boxes provided.

Question 5

Provide a IUPAC name for each of the following alkyl halides.
Name:

Question 6

For each question, provide structures for the reactants, intermediates, or products, as indicated. Draw the structures in the boxes provided.
Draw the structure of the product of the following reaction.

Question 7

For each question, provide structures for the reactants, intermediates, or products, as indicated. Draw the structures in the boxes provided.
If the pK_a of methane is 60 and that of ethene is 44, predict if the following reaction occurs and if so write the formula for the product.

Question 8

Circle the correct response in each set below.
Refer to instructions. The best leaving group in an elimination reaction.

Question 9

Circle the correct response in each set below.
Refer to instructions. The least reactive compound in an S_N1 reaction.

Question 10

For each question, provide structures for the reactants, intermediates, or products, as indicated. Draw the structures in the boxes provided.
Draw:

Question 11

Consider the pair of reactions below to answer the following question(s).
a. or
b.
Refer to instructions. The alkyl bromide starting materials in these reactions are classified as:

A) 3°
B) 2°
C) 1°
D) 4°

Question 12

Provide a IUPAC name for each of the following alkyl halides.
Name:

Question 13

Consider the pair of reactions below to answer the following question(s).
a. or
b.
Consider the reactions above.
a)Which reaction would be predicted to be faster?
b)Classify the reactions as S_N1 or S_N2.
c)Explain your answers to the questions above.

Question 14

Consider the pair of reactions below to answer the following question(s).
a. or
b.
Refer to instructions. Which of the following statements is false?

A) The kinetics of these reactions are second-order
B) The kinetics of these reactions are first-order in the nucleophile
C) The rate law would be of the form R = k[alkyl halide]²
D) The kinetics of these reactions are first-order in alkyl halide

Question 15

For each question, provide structures for the reactants, intermediates, or products, as indicated. Draw the structures in the boxes provided.
Draw:

Question 16

Circle the correct response in each set below.
Refer to instructions. The best nucleophile in a substitution reaction at a primary carbon.

Question 17

Circle the correct response in each set below.
Refer to instructions. The least reactive compound in an S_N2 reaction. Explain your choice.

Question 18

For each question, provide structures for the reactants, intermediates, or products, as indicated. Draw the structures in the boxes provided.
Draw:

Question 19

For each question, provide structures for the reactants, intermediates, or products, as indicated. Draw the structures in the boxes provided.
Which of the following would produce a mixture of products when treated under appropriate conditions with N-bromosuccinimide?

A) oct-4-ene
B) hept-1-ene
C) 4,4-dimethylcyclopentene
D) 4,5-dimethylcyclohexene
E) all of these produce a mixture of products

Question 20

Provide a IUPAC name for each of the following alkyl halides.
Name:
The solvents: CCl₄ and CH₂Cl₂

Question 21

Consider the reaction below to answer the following question(s).
Refer to instructions. Compound B is the:

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

Question 22

Which of the following statements about an S_N2 reaction is true?

A) the reaction occurs in two steps
B) rate = k[RX]
C) stabilization of R⁺ is important
D) the reaction causes racemization
E) the reaction is favored by aprotic solvents

Question 23

Consider the pair of reactions below to answer the following question(s).
a. or
b.
Refer to instructions. The nucleophile in these reactions is:

A) K⁺
B) alkyl group
C) Br−
D) I−

Question 24

Consider the reaction below to answer the following question(s).
Refer to instructions. Compound C is the:

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

Question 25

Which conditions favor an efficient (fast, high yield) S_N2 reaction between an appropriate alkyl halide and a nucleophile with a charge?

A) high concentration of a strong nucleophile, polar protic solvent
B) high concentration of a weak nucleophile, nonpolar solvent
C) low concentration of a strong nucleophile, polar aprotic solvent
D) low concentration of a weak nucleophile, nonpolar solvent
E) high concentration of a strong nucleophile, polar aprotic solvent

Question 26

Consider the reaction below to answer the following question.
Refer to instructions. The mechanism for this reaction is:

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

Question 27

The bromination of an alkene using N-bromosuccinimde involves

A) the formation of a free radical.
B) a chain reaction mechanism.
C) a resonance stabilized intermediate.
D) maintaining the double bond in the alkene.
E) all of these

Question 28

What is the preferred stereochemistry of the E2 elimination?

A) inversion
B) retention
C) antiperiplanar
D) synperiplanar
E) gauche

Question 29

Consider the reaction below to answer the following question(s).
Refer to instructions. Draw a Newman projection of the reactive conformation of the starting material.

Question 30

What is the IUPAC name of the following compound?

A) (R)-2-bromo-2-vinylpentane
B) (S)-2-bromo-2-vinylpentane
C) (S)-3-bromo-3-propylbut-1-ene
D) (R)-3-bromo-3-methylhex-1-ene

Question 31

Consider the pair of reactions below to answer the following question(s).
a. or
b.
Refer to instructions. The solvent in these reactions is:

A) nonpolar aprotic
B) polar aprotic
C) polar protic
D) nonpolar protic

Question 32

Consider the pair of reactions below to answer the following question(s).
a. or
b.
Refer to instructions. The mechanism for these reactions is:

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

Question 33

Consider the reaction below to answer the following question(s).
Refer to instructions. The mechanism of this reaction is:

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

Question 34

Which is most reactive in an S_N1 reaction? Explain your choice.
a.

b.
CH₃I
c.

d.

e.

Question 35

Which of the following statements about an S_N2 reaction is true?

A) There are two transition states.
B) There is one energy maximum.
C) The transition state can be isolated and studied.
D) For a carbon electrophile in the transition state, the hybridization of an sp³ carbon remains unchanged.
E) The reaction rate does not depend on the concentration of the electrophile.

Question 36

Consider the reaction below to answer the following question(s).
Refer to instructions. Write the product that results from the indicated electron flow in the reaction, showing any resulting stereochemistry

Question 37

Which of the following statements about an S_N1 reaction is true?

A) the reaction occurs in one-step
B) there is no effect on reaction rate by nucleophile
C) primary alkyl halides react faster than secondary alkyl halides
D) the reaction proceeds with inversion of stereochemistry
E) the reaction is favored by aprotic solvents

Question 38

What is the rate law for the E2 reaction of an alkyl halide (RX) with sodium ethoxide (NaOEt) in ethanol solvent (EtOH)?

A) rate = k[RX]
B) rate = k[RX]²
C) rate = k[RX][Na⁺]
D) rate = k[RX][OEt−]
E) rate = k[OEt−]

Question 39

Which mechanism is favored by the reaction of a secondary alkyl bromide with potassium t-butoxide?

A) S_N1
B) S_N2
C) E1
D) E1_CB
E) E2

Question 40

Which mechanism is favored by the reaction of a tertiary alkyl chloride with ethanol?

A) S_N1
B) S_N2
C) E1
D) E1_CB
E) E2

Question 41

Which of the following represents the transition state of the S_N2 reaction between methyl iodide and ammonia?

A)

B)

C)

D)

Question 42

Upon treatment with base, the following isotopically labeled compound gives rise to a major and a minor elimination product. Draw their structures and label each as major or minor.

Question 43

Predict the product of the following reaction: