Deck 9: Substitution Reactions of Alkyl Halides

Question 1

Which of the following alkyl halides gives the slowest S_N2 reaction?

A)CH₃CH₂Cl
B)
C)
D)
E)

Answer 1

Question 2

Assuming no other changes, what is the effect of doubling only the concentration of the alkyl halide in the above S_N2 reaction?

A)no change
B)doubles the rate
C)triples the rate
D)quadruples the rate
E)rate is halved

Answer 2

doubles the rate

Question 3

Which of the following S_N2 reactions is the slowest?

A)CH₃CH₂CHBrCH₃ + OH^- → CH₃CH₂CHOHCH₃ + Br^-
B)CH₃CH₂CHBrCH₃ + H₂O → CH₃CH₂CHOHCH₃ + HBr
C)CH₃CH₂CH₂CH₂Br + OH^- → CH₃CH₂CH₂CH₂OH + Br^-
D)CH₃CH₂CH₂CH₂Br + H₂O → CH₃CH₂CH₂CH₂OH + HBr

Answer 3

CH₃CH₂CHBrCH₃ + H₂O → CH₃CH₂CHOHCH₃ + HBr

Question 4

Which of the following is a secondary alkyl halide?

A)CH₃Br
B)(CH₃)₃CBr
C)(CH₃)₂CHBr
D)(CH₃)₂CHCH₂Br

Question 5

Give the mechanism including the transition state.

Question 6

Assuming no other changes, what is the effect of doubling both the alkyl halide and the nucleophile concentrations in the above reaction?

A)no change
B)doubles the rate
C)triples the rate
D)quadruples the rate
E)rate is halved

Question 7

Identify the alkyl halide that reacts the fastest in a S_N2 reaction.

A)2-chloro-2-methylpropane
B)2-chlorobutane
C)1-chlorobutane
D)chloromethane

Question 8

Which of the following are the substitution products of the reaction shown below? CH₃CH₂Br + ^-OH → ?

A)CH₃CH₂BrH⁺ + O^-
B)HOCH₂CH₂Br
C)CH₃CH₂OH + Br^-
D)CH₂ CH₂ + Br^- + H₂O
E)CH₂ CHBr + H₂O

Question 9

Which of the following best describes the carbon-chlorine bond of an alkyl chloride?

A)nonpolar; no dipole
B)polar; δ+ at carbon and δ- at chlorine
C)polar; δ- at carbon and δ+ at chlorine
D)ionic
E)none of the above

Question 10

Give the mechanism including the transition state.

Question 11

Which of the following is not normally considered to be a nucleophile?

A)NH₃
B)NH₂CH₃
C)
D)CH₃CH₂⁺

Question 12

Identify the strongest nucleophile in an S_N2 reaction.

A)isopropoxide ion
B)tert-butoxide ion
C)ethoxide ion
D)tert-pentoxide ion

Question 13

Which of the following S_N2 reactions is the fastest?

A)CH₃CH₂CH₂CH₂Br + OH^- → CH₃CH₂CH₂CH₂OH + Br^-
B)CH₃CH₂CH₂CH₂Br + H₂O → CH₃CH₂CH₂CH₂OH + HBr
C)CH₃CH₂CHBrCH₃ + OH^- → CH₃CH₂CHOHCH₃ + Br^-
D)CH₃CH₂CHBrCH₃ + H₂O → CH₃CH₂CHOHCH₃ + HBr

Question 14

Which of the following S_N2 reactions is the fastest?

A)
B)CH₃CH₂CH₂I + HO^- → CH₃CH₂CH₂OH + I^-
C)
D)CH₃CH₂CH₃Br + HO^- → CH₃CH₂CH₃OH + Br^-
E)CH₃CH₂CH₂I + H₂O → CH₃CH₂CH₂OH + HI

Question 15

Identify the alkyl halide that reacts the fastest in an S_N2 reaction.

A)1-chloropropane
B)1-bromopropane
C)1-fluoropropane
D)1-iodopropane

Question 16

Which of the following is not a nucleophile?

A)"CH₃NH₂"
B)"PH₃"
C)"⁺CH₃"
D)
E)

Question 17

Which of the following does not provide evidence that there are two different mechanisms for nucleophilic substitution?

A)reaction products when CH₃I is used as the substrate
B)reaction products when (CH₃)₃CCH₂I is used as substrate
C)the stereochemistry of nucleophilic substitutions
D)the effect of nucleophile concentration on rate

Question 18

Which of the following S_N2 reactions is the slowest?

A)CH₃CH₂CH₃Br + HO^- → CH₃CH₂CH₃OH + Br^-
B)CH₃CH₂CH₂Cl + HO^- → CH₃CH₂CH₂OH + Cl^-
C)CH₃CH₂CH₂I + HO^- → CH₃CH₂CH₂OH + I^-
D)CH₃CH₂CH₃F + HO^- → CH₃CH₂CH₂OH + F^-
E)

Question 19

What is the nucleophile in the reaction shown below?

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

Question 20

Which of the following compounds will undergo an S_N2 reaction most readily?

A)(CH₃)₃CCH₂I
B)(CH₃)₃CCl
C)(CH₃)₂CHI
D)(CH₃)₂CHCH₂CH₂CH₂Cl
E)(CH₃)₂CHCH₂CH₂CH₂I

Question 21

Provide the structure of the major organic product which results when (S)-2-iodopentane is treated with KCN in DMF.

Question 22

Which of the following is the best nucleophile in water?

A)I^-
B)CH₃SCH₃
C)CH₃OCH₃
D)Cl^-

Question 23

Which of the following species is most reactive in an S_N2 reaction?

A)CH₃CH₂-Cl
B)CH₃CH₂-Br
C)CH₃CH₂-I
D)CH₃CH₂-F
E)CH₃CH₂-OH

Question 24

Provide the structure of the major organic product of the following reaction.

Question 25

Which of the following species is the least nucleophilic?

A)(CH₃)₃CO^-
B)H₂O
C)(CH₃)₃N
D)BF₃
E)CN^-

Question 26

What product results from the S_N2 reaction between (R)-2-chloropentane and hydroxide?

A)(R)-2-pentanol
B)(S)-2-pentanol
C)racemic pentanol
D)1-pentanol
E)3-pentanol

Question 27

Provide the structure of the major organic product in the following reaction.
(CH₃)₃N + CH₃CH₂CH₂I →

Question 28

Which of the following is the strongest nucleophile in an aqueous solution?

A)HO^-
B)F^-
C)Cl^-
D)Br^-
E)I^-

Question 29

Provide the major organic product(s)in the reaction below.

Question 30

Which of the following statements concerning S_N2 reactions of alkyl halides is not correct?

A)The rate of reaction depends on the concentration of the nucleophile.
B)The rate of reaction depends on the concentration of the alkyl halide.
C)The rate of reaction of a particular alkyl bromide depends on the steric accessibility of the carbon of the C-Br bond.
D)All alkyl iodides react more rapidly than all alkyl chlorides.
E)The rate of reaction depends on the relative nucleophilicity of the nucleophile.

Question 31

Draw and describe the transition state in the S_N2 reaction between CH₃I and CH₃CH₂O^-Na⁺.

Question 32

In an S_N2 reaction why does the nucleophile attack the carbon on the side opposite the leaving group?

Question 33

Provide a detailed, stepwise mechanism for the reaction below.
(CH₃)₂CHCH₂CH₂CH₂I + CN^- → (CH₃)₂CHCH₂CH₂CH₂CN + I^-

Question 34

Provide the major organic product(s)in the reaction below.

Question 35

Provide the structure of the major organic product of the following reaction.

Question 36

Provide the major organic product(s)in the reaction below.

Question 37

Provide the structure of the major organic product in the following reaction.

Question 38

Provide the structure of the major organic product of the following reaction.

Question 39

Do all primary alkyl iodides undergo S_N2 reactions with sodium cyanide in DMSO at identical rates? Explain.

Question 40

Which of the following is the best leaving group?

A)HO^-
B)F^-
C)Cl^-
D)Br^-
E)I^-

Question 41

Which of the following correctly describes the relative nucleophilicities of methoxide and tert-butoxide?

A)These alkoxides have essentially the same nucleophilicities since the negative charge in both is localized on an oxygen atom.
B)Methoxide is more nucleophilic because the nucleophilicity of tert-butoxide is diminished by steric effects.
C)tert-Butoxide is more nucleophilic because it contains three methyl groups which increase the charge on its oxygen by donating electron density.
D)tert-Butoxide is more nucleophilic because it is more basic.
E)none of the above

Question 42

A student attempted to prepare 1-chlorobutane by treating 1-butanol with NaCl in acetone. Was the student successful? Explain.

Question 43

Rank the species below in order of leaving group capabilities in S_N2 reactions (worst leaving group to best):
CH₃O^-, H₂O, C₆H₅SO₃^-, H₂N^-.

Question 44

Assuming no other changes, what is the effect of doubling both the concentration of the alkyl halide and the nucleophile in the above reaction?

A)no change
B)doubles the rate
C)triples the rate
D)quadruples the rate
E)rate is halved

Question 45

Which halide reacts most rapidly via an S_N2 mechanism?

A)
B)
C)
D)
E)

Question 46

Identify the alkyl halide that reacts the fastest in an S_N1 reaction.

A)2-chloropropane
B)2-bromopropane
C)2-fluoropropane
D)2-iodopropane

Question 47

Why, in a polar protic solvent, is iodide a better nucleophile than fluoride?

Question 48

In each of the pairs below, which is the best nucleophile in alcoholic solvents?
a. CH₃S^- or CH₃O^{-
b. (CH}₃⁾₂NH or (CH₃⁾₃^{N
c. Cl- or F-
d. SCN- or OCN-}

Question 49

Which halide reacts most rapidly via an S_N2 mechanism?

A)(CH₃)CCH₂CH₂F
B)(CH₃)CCH₂CH₂Cl
C)(CH₃)CCH₂CH₂Br
D)(CH₃)CCH₂CH₂I
E)All primary halides react at the same rate in S_N2.

Question 50

Identify the alkyl halide that reacts the fastest in an S_N1 reaction.

A)2-chloro-2-methylpropane
B)2-chlorobutane
C)1-chlorobutane
D)chloromethane

Question 51

Assuming no other changes, what is the effect of doubling only the concentration of the alkyl halide in the above S_N1 reaction?

A)no change
B)doubles the rate
C)triples the rate
D)quadruples the rate
E)rate is halved

Question 52

Rank the species below in order of increasing nucleophilicity in protic solvents:
CH₃CO₂^- , CH₃S^- , HO^- , H₂O.

Question 53

Provide the major organic product(s)of the reaction shown.

Question 54

Provide the major organic product(s)of the reaction shown.

Question 55

Give the mechanism of the reaction shown below.

Question 56

Assuming no other changes, what is the effect of doubling only the concentration of the nucleophile in the above reaction?

A)no change
B)doubles the rate
C)triples the rate
D)quadruples the rate
E)rate is halve

Question 57

Give the mechanism.

Question 58

Which halide reacts most rapidly via an S_N2 mechanism?

A)
B)
C)
D)
E)

Question 59

Which of the following iodides undergoes S_N2 reaction with cyanide (CN^-)the fastest?

A)1-iodo-3-methylpentane
B)2-iodopentane
C)2-iodo-2-methylpentane
D)3-iodopentane
E)1-iodo-2,2-dimethylpentane

Question 60

Which of the following bromides reacts readily via an S_N2 reaction with NaN₃?

A)C₆H₅Br
B)CH₃CH₂CH=CHBr
C)(C₆H₅)₃CBr
D)(CH₃)₃CCH₂CH₂CH₂Br
E)1-bromo-1-methylcyclohexane

Question 61

Provide the major organic product(s)in the reaction below.

Question 62

S_N1 reactions usually proceed with ________.

A)equal amounts of inversion and retention at the center undergoing substitution
B)slightly more inversion than retention at the center undergoing substitution
C)slightly more retention than inversion at the center undergoing substitution
D)complete inversion at the center undergoing substitution
E)complete retention at the center undergoing substitution

Question 63

Provide the major organic product(s)in the reaction below.

Question 64

Which of the following alkyl halides gives the fastest S_N1 reaction?

A)
B)
C)
D)
E)

Question 65

Which of the compounds below undergoes solvolysis in aqueous ethanol most rapidly?

A)cyclohexyl bromide
B)methyl iodide
C)isopropyl chloride
D)3-chloropentane
E)3-iodo-3-methylpentane

Question 66

Provide the structure of the major organic products which result in the reaction below.

Question 67

Provide the structure of the major organic product of the following reaction.

Question 68

Which of the following factors has no effect on the rate of S_N1 reactions?

A)the nature of the alkyl halide
B)the nature of the leaving group
C)the concentration of the alkyl halide
D)the concentration of the nucleophile
E)the value of the rate constant

Question 69

Provide the major organic products(s)of the reaction shown:.

Question 70

The specific rotation of optically pure (R)-sec-butyl alcohol is -13.52°. An optically pure sample of (R)-sec-butyl bromide was converted into the corresponding sec-butyl alcohol via an S_N2 reaction. What is the specific rotation of the product, assuming 100% yield?

A)-13.52°
B)between 0° and -13.52°
C)between 0° and +13.52°
D)+13.52°
E)zero

Question 71

Which of the following iodides undergoes S_N1 solvolysis in water the fastest?

A)1-iodo-3-methylpentane
B)2-iodopentane
C)2-iodo-2-methylpentane
D)3-iodopentane
E)1-iodo-2,2-dimethylpentane

Question 72

Provide the major organic products(s)of the reaction shown:.

Question 73

Which of the following carbocations is the least stable?

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

Question 74

Which of the following alkyl halides gives the fastest S_N1 reaction?

A)CH₃CH₂CH₂Br
B)
C)
D)CH₃CH₂CH₂I
E)CH₃CH₂CH₂Cl

Question 75

Which of the following carbocations is the most stable?

A)
B)
C)
D)
E)

Question 76

When (S)-2-bromobutane undergoes an S_N2 reaction with CH₃O^-, the product is the compound shown below. What is/are the configuration(s)of the product(s)obtained from this reaction?

A)S only
B)R only
C)a mixture of enantiomers with more R than S
D)a mixture of enantiomers with more S than R
E)equal mixture of R and S

Question 77

Provide the major organic product of the reaction below and a detailed, stepwise mechanism which accounts for its formation.

Question 78

In the S_N1 hydrolysis mechanism of (CH₃)₃CBr, there are ________ elementary steps, ________ distinct transition states, and ________ distinct intermediates.

A)2, 2, 2
B)2, 2, 3
C)2, 3, 2
D)3, 2, 3
E)3, 3, 2

Question 79

Which of the following is the rate law for S_N1 mechanisms?

A)Rate = k[Alkyl Halide] [Nucleophile]
B)Rate = k[Nucleophile]
C)Rate = k[Alkyl Halide]
D)Rate = k[Alkyl Halide] [Nucleophile] + k₂[Alkyl Halide]
E)Rate = k₁[Alkyl Halide] + k₂[Nucleophile]

Question 80

Provide the major organic product(s)of the reaction shown