Deck 6: Alkyl Halides: Nucleophilic Substitution and Elimination

Question 1

The flame retardant below has been found to be an androgen agonist and may have a contribution to an increasing rate of occurrence of prostate cancer (J. Med. Chem. 2006, 7366). What is the correct term that describes the relative position of the bromides in this structure?

A) geminal
B) vinyl
C) vicinal
D) aryl

Answer 1

vicinal

Question 2

Which of the following is a primary alkyl halide?

A) methyl bromide
B) isopropyl bromide
C) t-butyl iodide
D) cyclohexyl bromide
E) isobutyl chloride

Answer 2

isobutyl chloride

Question 3

Provide an acceptable name for the compound shown below.

Answer 3

4-bromo-1,1-dimethylcyclohexane

Question 4

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

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

Question 5

Which of the following is a geminal dihalide?

A) cis-1,2-dibromocyclopentane
B) 3,3-dichloropentane
C) trans-1,4-diiodocyclohexane
D) isobutyl chloride
E) 1,3-dibromoheptane

Question 6

Provide an acceptable name for the compound shown below.

Question 7

Which of the following is a vicinal dihalide?

A) cis-1,2-dibromocyclopentane
B) 3,3-dichloropentane
C) trans-1,4-diiodocyclohexane
D) isobutyl chloride
E) 1,3-dibromoheptane

Question 8

What is the IUPAC name of the compound shown below?

A) (1S,3S)-1,3-dichloro-1-ethyl-3-methylcyclopentane
B) (1R,3S)-1,3-dichloro-1-methyl-3-ethylcyclopentane
C) (1R,4S)-1,4-dichloro-1-ethyl-4-methylcyclopentane
D) (1R,3S)-1,3-dichloro-1-ethyl-3-methylcyclopentane
E) (1S,3R)-1,3-dichloro-3-ethyl-1-methylcyclopentane

Question 9

Provide the structure of isopropyl iodide.

Question 10

Which of the following is classified as a vinylic halide?

A) CH₃CH - CHOH
B) CH₃ - CH-CHCl
C) CH₃CH-CHCH₂Cl
D) CH₃CH₂CH₂CH₂Br
E) BrCH₂CH-CH₂

Question 11

Which of the following is a tertiary halide?

A) ClCH₂CH₂C(CH₃)₃
B) ClCH₂CH₂CH(CH₃)₂
C) (CH₃)₂CClCH₂CH₃
D) (CH₃)₃CCHClCH₃
E) ClCH₂C(CH₃)CH₂CH₃

Question 12

Provide an acceptable name for CHCl₃.

Question 13

Provide the structure of 1-bromo-3-methylhexane.

Question 14

Provide the name of the bromoalkane shown below.

Question 15

Draw the structure of cis-1,3-dichlorocyclopentane.

Question 16

What is the IUPAC name of the compound shown below?

A) (2R,3S,4S)-2-chloro-3,4-dibromo-3-methylhexane
B) (2R,3S,4S)-3,4-dibromo-2-chloro-3-methylhexane
C) (3S,4S,5S)-3,4-dibromo-5-chloro-4-methylhexane
D) (2R,3R,4S)-3,4-dibromo-2-chloro-3-methylhexane
E) (2R,3S,4R)-3,4-dibromo-2-chloro-3-methylhexane

Question 17

Which of the following is a secondary alkyl halide?

A) methyl bromide
B) isopropyl chloride
C) t-butyl iodide
D) propyl bromide
E) isobutyl chloride

Question 18

Provide an acceptable name for CH₃CH₂CH₂C(CH₃)₂I.

Question 19

Which of the following is a secondary halide?

A) ClCH₂CH₂C(CH₃)₃
B) ClCH₂CH₂CH(CH₃)₂
C) (CH₃)₂CClCH₂CH₃
D) (CH₃)₃CCHClCH₃
E) ClCH₂C(CH₃)CH₂CH₃

Question 20

What general classification is given to the molecule below?

A) primary chloride
B) secondary chloride
C) tertiary chloride
D) vinyl chloride
E) benzyl chloride

Question 21

The following structure is a proteasome inhibitor that may find application in treating cervical cancer (J. Med. Chem. $\textbf{ 2011 }$ , 449). The halides in this structure may be classified as ________ and ________.

A) vicinal & vinyl
B) vicinal & aryl
C) vinyl & aryl
D) vinyl & geminal

Question 22

Draw the structures of the two major products formed in the following reaction. Indicate which of the two structures would be predicted to predominate under thermodynamic condition and explain why.

Question 23

Arrange the following alkyl halides in order of increasing boiling point:
CH₃CH₂Br, CH₃CH₂CH₂Br, (CH₃)₂CHBr, CH₃CH₂F.

Question 24

Name the haloalkane shown. Be sure to include the appropriate R or S description if needed.

Question 25

The term CFC is an abbreviation for ________.

Question 26

When 2,2-dimethylbutane is subjected to free-radical chlorination, ________ distinct monochlorinated products are possible and ________ of these contain asymmetric carbon atoms.

A) 4, 2
B) 5, 0
C) 3, 0
D) 5, 2
E) 4, 0

Question 27

Among the following alkyl halides, choose the one with the lowest boiling point.

A) t-butyl chloride
B) n-butyl chloride
C) t-butyl bromide
D) n-butyl iodide
E) t-butyl iodide

Question 28

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

Question 29

Consider the reaction of (CH₃)₃CO^- with iodomethane. Will the reaction rate increase, decrease, or remain the same if the concentration of iodomethane is increased? Explain.

Question 30

Although F is more electronegative than Cl, the C-Cl bond has a larger dipole moment than the C-F bond. Explain.

Question 31

Provide the major organic product of the reaction below.

Question 32

When water is shaken with dichloromethane, a two-phase system results. Which compound forms the upper phase? Explain.

Question 33

Provide a detailed, stepwise mechanism for the reaction below.
(CH₃)₂CHCH₂CH₂CH₂I + CN^- → (CH₃)₂CHCH₂CH₂CH₂CH₂CN + I^-

Question 34

Which of the following best describes DDT?

A) a chlorocarbon used to decaffeinate coffee beans
B) a polybrominated organic compound used as a herbicide
C) a Freon used as a foaming agent
D) a mixed alkyl halide used as an anesthetic
E) a polychlorinated organic compound used as an insecticide

Question 35

Name the haloalkane shown. Be sure to include the appropriate R or S description if needed.

Question 36

Show how the following reaction might be constructed using an S_N2 reaction by drawing structures for the starting materials.

Question 37

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

Question 38

Draw two reasonable resonance structures and the hybrid of the intermediate formed in the following reaction.

Question 39

What type of intermediate is present in the S_N2 reaction of cyanide with bromoethane?

A) carbocation
B) free radical
C) carbene
D) carbanion
E) This reaction has no intermediate.

Question 40

Which of the following alkyl halides has the smallest molecular dipole moment?

A) CH₃F
B) CH₃Cl
C) CH₂I₂
D) CH₂Cl₂
E) CF₄

Question 41

Which of the following factors is favorable for nucleophilicity but not basicity?

A) highly polarizable
B) low electronegativity
C) negatively charged
D) sterically hindered

Question 42

Do all primary iodides react with N₃^- at the same rate via the S_N2 mechanism? Explain.

Question 43

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

Question 44

Provide the structure of the major organic product that results when the reagents below are combined, and name the mechanism through which this reaction is proceeding.
CH₃C=C:^-Na⁺ + CH₃CH₂CH₂I

Question 45

List the following alkyl halides in order of their increasing reactivity as substrates in S_N2 reactions: 2-chlorobutane, 2-iodobutane, and 1-iodobutane.

Question 46

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

Question 47

Arrange the following species in order of increasing nucleophilicity:
CH₃CH₂S^-, CH₃CH₂O^-, (CH₃)₃CO^-, (CH₃)₃COH.

Question 48

List the following bromides in order of their increasing reactivity as substrates in S_N2 reactions: PhBr, PhCH₂Br, and PhCH(CH₃)Br.

Question 49

Which of the following compounds is the most nucleophilic?

A) CH₃SH
B) CH₃OH
C) H₂O
D) CH₃CO₂H
E) BF₃

Question 50

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

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

Question 51

Which of the following species is the least nucleophilic?

A) H₂O
B) BF₃
C) (CH₃)₃N
D) CH₃O^-
E) CN^-

Question 52

Which halide is a better nucleophile, iodide or fluoride? Explain.

Question 53

What type of solvent is best for S_N2 reactions which employ anionic nucleophiles: polar, protic solvents; polar, aprotic solvents; or nonpolar solvents? Explain.

Question 54

Which of the following alkyl chlorides will undergo S_N2 reaction most readily?

A) 1-chloro-4-methylpentane
B) 2-chloro-4-methylpentane
C) 2-chloro-3-methylpentane
D) 3-chloro-2-methylpentane
E) 2-chloro-2-methylpentane

Question 55

Arrange the following substrates in order of their increasing SN2 reactivity with NaCN:
bromoethane, 1-chloro-3,3-dimethylpentane, 1-chloro-2,2-dimethylpentane, and 2-bromo-2-methylpentane.

Question 56

Name one factor that is favorable for nucleophilicity but not for basicity.

Question 57

Which is more nucleophilic, t-butoxide or ethoxide? Explain.

Question 58

Which of the following solvents could be described as polar and protic?

A) ethanol
B) acetonitrile
C) dimethylformamide
D) acetone
E) 18-crown-6

Question 59

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

Question 60

Which of the following alkyl chlorides would undergo substitution most rapidly when treated with or Provide the structure of the substitution product.

Question 61

List the following bromides in order of their increasing reactivity as substrates in S_N1 reactions: 2-chlorobutane, 2-iodobutane, and 1-iodobutane.

Question 62

Draw the highest energy transition state in the solvolysis of (CH₃)₃CI in CH₃OH.

Question 63

Show the best way to prepare CH₃OCH(CH₃)₂ by an S_N2 reaction.

Question 64

Arrange the following compounds in order of increasing reactivity toward ethanol solvolysis:
t-butyl bromide, t-butyl iodide, isopropyl chloride, methyl iodide.

Question 65

Which of the following statements describe a favorable attribute of a leaving group? (More than one answer is possible.)

A) The leaving group should be highly polarizable.
B) The lower the electronegativity of the leaving group the better.
C) Good leaving groups need to have low steric hindrance.
D) The departed leaving group should have low basicity.

Question 66

Which of the following alkyl halides reacts most rapidly via an S_N2 reaction with NaCN?

A) 1-iodohexane
B) 1-fluorohexane
C) (R)-2-bromohexane
D) iodocyclohexane
E) 1-iodo-1-methylcyclohexane

Question 67

Provide the major organic product of the reaction below.

Question 68

List the following bromides in order of their increasing reactivity as substrates in S_N1 reactions: PhBr, PhCH₂Br, and PhCH(CH₃)Br.

Question 69

Complete the following S_N2 reaction by providing structures for the necessary starting materials.

Question 70

List the following bromides in order of their increasing reactivity as substrates in S_N1 reactions: 1-iodo-1-ethylcyclopentane, chlorocyclopentane, and iodocyclopentane.

Question 71

S_N2 reactions take place with ________ of stereochemistry at the center undergoing substitution.

Question 72

List the following compounds in order of increasing reactivity in an S_N1 reaction.
CH₃Br, CH₃CH₂CH₂I, (CH₃)₃CI, CH₃CHBrCH₃, CH₃CHICH₃

Question 73

Provide the major organic product of the reaction below.

Question 74

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

Question 75

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

Question 76

Which of the following alkyl bromides undergoes solvolysis in aqueous methanol most rapidly?

A) PhCHBrCH₃
B) (CH₃)₂CHCH₂CH₂Br
C) (CH₃)₂CHCH₂CHBrCH₃
D) CH₃CH₂CH₂CH₂Br
E) PhBr

Question 77

Which of the following alkyl halides reacts most rapidly via an S_N1 solvolysis reaction in hot methanol?

A) 1-iodohexane
B) 1-fluorohexane
C) (R)-2-bromohexane
D) iodocyclohexane
E) 1-iodo-1-methylcyclohexane

Question 78

Provide the major organic product of the reaction below.

Question 79

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 80

Rank the following molecules in order of increasing relative rate of S_N1 solvolysis with methanol and heat (slowest to fastest reacting).

A) 3 < 2 < 4 < 5 < 1
B) 2 < 3 < 4 < 1 < 5
C) 5 < 4 < 3 < 2 < 1
D) 2 < 3 < 4 < 5 < 1
E) 1 < 2 < 5 < 4 < 3