QOI 0809 E1 E2
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Which of the following are the elimination products of the reaction shown below?
CH3 CH2Br + - OH → ?
A) CH3 CH2Br+H + O-
1)
B) HOCH2 CH2 Br
C) CH3 CH2OH + BrD) CH2 CH2 + Br- + H2 O
E) CH2 CHBr + H2 O
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
2) Draw the alkene product which results when 1-bromopentane is heated in acetone
containing NaOH. Give a detailed, step-by-step mechanism for the production of this
compound.
2)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
3) Which of the following compounds undergoes E2 reactions with the fastest rate?
A)
B) CH3 CH2CH2 Cl
C) CH3 CH2CH2 I
D)
E) CH3 CH2CH2 Br
1
3)
4) Which of the following bases gives the highest anti-Zaitsev product in E2 reactions when reacted
with 2-bromo-2, 3-dimethylbutane?
A)
B)
C)
D)
E)
2
4)
5) What is the major product of the following E2 reaction?
5)
A)
B) CH3 CH2CHCH2
C)
D)
E)
6) How many distinct alkene products are possible when the alkyl iodide below undergoes E2
elimination?
A) 1
B) 2
C) 3
D) 4
E) 5
7) Which of the alkyl chlorides listed below undergoes dehydrohalogenation in the presence of a
strong base to give 2-pentene as the only alkene product?
A) 1-chloropentane
B) 2-chloropentane
C) 3-chloropentane
D) 1-chloro-2-methylbutane
E) 1-chloro-3-methylbutane
3
6)
7)
8) When 2-bromo-3-methyl-1-phenylbutane is treated with sodium methoxide, why is the major
product 3-methyl-1-phenyl-1-butene?
A) SN2 predominates over E2.
B) E1 predominates over E2.
C) The bulkiness of the methoxide results in the less substituted alkene.
D) The newly formed double bond in this compound is conjugated with the phenyl ring.
E) The less substituted alkene is always more stable than the more substituted alkene.
8)
9) What is the major organic product of the following reaction?
9)
A) 2,3-dimethyl-1-hexene
B) 2,3-dimethyl-2-hexene
C) 2-isopropyl-1-pentene
D) (Z)-2,3-dimethyl-3-hexene
E) (E)-2,3-dimethyl-3-hexene
10) What is the major organic product of the following reaction?
10)
A) 2,3-dimethyl-1-hexene
B) 2,3-dimethyl-2-hexene
C) 2-isopropyl-1-pentene
D) (Z)-2,3-dimethyl-3-hexene
E) (E)-2,3-dimethyl-3-hexene
11) Which of the following halides is most reactive in an E2 reaction with sodium methoxide?
A) (CH3 )3CCH2I
B) (CH3 )2CHCHICH3
C) (CH3 )2CHCH2 Br
D) (CH3 )2CHCH2 Cl
E) (CH3 )2CHCH2 CH2 Cl
11)
12) Which of the following halides is least reactive in an E2 reaction with sodium methoxide?
A) (CH3 )3CCH2I
B) (CH3 )2CHCHICH3
C) (CH3 )2CHCH2 Br
D) (CH3 )2CHCH2 Cl
E) (CH3 )2CHCH2 CH2 Cl
12)
4
13) Which of the following statements is true concerning the E2 reactions of alkyl fluorides?
A) Alkyl fluorides react more readily in E2 reactions than do alkyl iodides.
B) The transition state of this E2 reaction resembles a carbanion rather than an alkene.
C) The C-F bond is the weakest carbon-halogen bond so SN2 will always predominate over E2
in the reactions of alkyl fluorides.
D) Alkyl fluorides react to form the most stable carbocation intermediate.
E) Alkyl fluorides cannot adopt the proper stereochemical alignment for an E2 reaction to occur.
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
14) When 1-iodo-1-methylcyclohexane is treated with NaOCH2 CH3 , the more highly
substituted alkene product predominates. When KOC(CH3 )3 is used instead, the less
highly substituted alkene product predominates. Offer an explanation.
14)
15) Provide the structure of the major organic product which results when
2-bromo-2-methylbutane is treated with sodium ethoxide.
15)
16) Draw all likely alkene products in the following reaction and circle the product you expect
to predominate.
16)
17) Draw all likely alkene products in the following reaction and circle the product you expect
to predominate.
17)
18) Draw all likely alkene products in the following reaction and circle the product you expect
to predominate.
18)
5
13)
19) Supply the missing alkyl halide reactant in the elimination reactions shown below.
19)
20) Provide the structure of the major organic product of the following reaction.
20)
21) Provide the structure of the major organic product of the following reaction.
21)
6
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
22) Which of the following alkyl halides undergoes E1 reactions with the fastest rate?
A)
22)
B)
C)
D)
E) CH3 I
23) Which of the following alkyl halides forms the most stable carbocation when it undergoes an E1
reaction?
A) I
B) II
C) III
D) IV
E) V
24) Which of the following statements correctly describe(s) E1 reactions of alkyl halides (RX)?
I. Rate = k[base]
II. Rate = k[base][RX]
III. Rate = k[RX]
IV. The reactions occur in two distinct steps.
V. Rearrangements are sometimes seen.
A) II and IV
B) III and V
C) I, IV, and V
D) I only
E) III, IV, and V
7
23)
24)
25) Consider the following experimental data for the rate of the reaction given below:
Experiment #1
1
2
3
[Alkyl Halide]
0.01
0.02
0.01
[Base]
0.01
0.01
0.02
25)
Rate
1
2
1
What is the mechanism for the reaction?
A) first order, SN1
B) first order, SN2
C) first order, E1
D) first order, E2
E) none of the above
26) Which of the following correctly reflects relative stabilities of carbocations?
A) 3° allylic > 2° > 1° benzylic
B) methyl > 2° benzylic > 3°
C) 3° benzylic > vinyl > 1°
D) 2° allylic > 2° > vinyl
E) 1° benzylic > 3° > 3° allylic
26)
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
27) When 1-bromo-2, 2-dimethylcyclopentane is heated in ethanol, one of the products which
results is shown below. Provide a detailed, stepwise mechanism for the production of this
compound, and give the name of the mechanism by which it is produced.
27)
28) List the following compounds in order of increasing reactivity in an E1 elimination.
28)
CH3 CH2CHBrCH3, CH3 CH2CH2 CH2 Br, (CH3 )3CBr
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
29) Dehydrohalogenation of 2-bromobutane in the presence of a strong base proceeds via which of the
following mechanistic pathways?
A) SN1
B) SN2
C) E1
D) E2
E) none of the above
8
29)
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
30) Provide the structure of the major organic product in the following reaction.
30)
31) Why is the E1 not a likely mechanism when 1-chloropentane is heated in ethanol?
31)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
32) Which of the following is least likely to be found in the product mixture which results when
2-iodopentane reacts with sodium ethoxide in ethanol?
A) 1-ethoxypentane
B) 2-ethoxypentane
C) (Z)-2-pentene
D) (E)-2-pentene
E) 1-pentene
32)
33) What is the major product which results when (2R,3S)-2-chloro-3-phenylbutane is treated with
sodium methoxide in methanol?
A) (E)-2-phenyl-2-butene
B) (Z)-2-phenyl-2-butene
C) (S)-3-phenyl-1-butene
D) (R)-3-phenyl-1-butene
E) (R)-2-methoxy-2-phenylbutane
33)
34) Why is the alkyl halide below not capable of undergoing an E2 reaction upon treatment with
sodium ethoxide?
34)
A) Br- is too poor a leaving group.
B) The substrate is too hindered.
C) Too much angle strain would be present in the alkene product.
D) Sodium ethoxide is a poor base to use in E2 reactions.
E) The C-H and C-Br bonds which need to break cannot achieve an anti-periplanar orientation.
9
35) Which of the compounds shown below is/are the product(s) of this reaction:
35)
A) I only
B) II only
C) I and II are of equal yield.
D) I is major, II is minor.
E) I is minor, II is major.
36) Which of the following compounds is/are the products of this reaction:
36)
A) I only
B) II only
C) I and II are of equal yield.
D) I is major, II is minor.
E) I is minor, II is major.
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
37) Provide the structure of the major organic product which results in the following reaction.
10
37)
38) Provide the structure of the major organic product which results in the following reaction.
38)
39) Which diastereomer of 1-bromo-4-t-butylcyclohexane, the cis or the trans, undergoes
elimination more rapidly when treated with sodium ethoxide? Explain your answer.
39)
40) Provide the structure of the major organic product which results in the following reaction.
40)
41) Provide the structure of the major elimination product which results when the alkyl
bromide below is heated in ethanol.
41)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
42) A primary kinetic isotope effect could most likely be observed in which of the following
mechanisms?
A) SN1 and SN2
B) SN2
C) E1 and SN1
D) E2
E) E1
11
42)
43) What is the major product of the following reaction?
43)
A) CH2 CHCH2 CH3
B) CH3 CHCHCH3
C)
D) CH3 CH2CH2 CH2 OCH2 CH3
E)
44) What is the major product of the following reaction?
A) CH2 CHCH2 CH3
B) CH3 CHCHCH3
C)
D) CH3 CH2CH2 CH2 OCH2 CH3
E)
12
44)
45) What is the major product of the following reaction?
A) I
B) II
C) III
45)
D) IV
E) V
46) What is/are the product(s) of the following reaction?
46)
A)
B) CH2 CH2
C)
D) A and B
E) A and C
47) Predict the two most likely mechanisms for the reaction of 2-iodohexane with sodium ethoxide.
A) SN2 and SN1
B) E1 and E2
C) SN2 and E2
D) E1 and SN1
E) E2 and SN1
13
47)
48) Predict the two most likely mechanisms which occur when 2-iodohexane is heated in ethanol.
A) SN2 and SN1
B) E1 and E2
C) SN2 and E2
D) E1 and SN1
E) E2 and SN1
48)
49) What is/are the product(s) of the following reaction?
49)
A)
B) CH2 CH2
C)
D) A and B
E) A and C
50) What mechanism predominates in the reaction below?
A) SN2
B) SN1 without rearrangement
C) SN1 with rearrangement
D) E2
E) E1
14
50)
51) What mechanism predominates in the reaction below?
51)
A) SN2
B) SN1 without rearrangement
C) SN1 with rearrangement
D) E2
E) E1
52) What mechanism predominates in the reaction below?
52)
A) SN2
B) SN1 without rearrangement
C) SN1 with rearrangement
D) E2
E) E1
53) Which of the following is least likely to be found in the product mixture which results when the
alkyl iodide below is heated in water?
A) I
B) II
C) III
D) IV
E) V
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
54) Which base, ammonia (NH3 ) or triethylamine [(CH3CH2 )3 N], would be a better choice for
use in converting 1-chlorohexane to 1-hexene? Explain briefly.
15
54)
53)
55) Provide the structure of the major organic product of the following reaction.
55)
56) Can primary alkyl halides react by SN2, SN1, E2, and E1 mechanisms? Are any of these
mechanisms prohibited? What conditions favor a particular mechanism?
56)
57) What reaction mechanism predominates when 1-bromo-1-propylcyclopentane is treated
with sodium methoxide in methanol?
57)
58) What reaction mechanism predominates when 1-bromo-1-propylcyclopentane is heated
in ethanol?
58)
59) Provide the major organic product(s) in the reaction below.
59)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
60) Starting with 2-butene, which of the following is the best method for preparing 2-butyne?
A) HBr; H2 /Ni; Zn/H+
60)
B) HBr; Zn/H+ ; H2 /Ni
C) Br2 /CCl4 ; Zn/H+ ; H2 /Ni
D) Br2 /CCl4 ; 2NaNH2
E) HBr; NaNH2
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
61) Which of the following alkyl chlorides would undergo substitution most rapidly when
treated with NaCCH: chloroethane, 2-chloropropane, or 1-chloro-2, 2-dimethylpropane?
Provide the structure of the substitution product.
61)
62) Show the best way to prepare CH3 OCH(CH3 )2 by an SN2 reaction.
62)
16
63) Write the structures for the products of the following SN2 reactions.
63)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
64) What is the major product of the following reaction?
64)
A) CH2  CHCH2CH  CH2
B)
C) CH2  CHCH  CHCH3
D)
E) CH2  CHCH2CH2 CH2 OH
65) Which sequence of reagents works best to convert 3-hexene to 3-hexyne?
A) 1. HCl 2. NaNH2
B) 1. BH3·THF 2. HO-, H2O2 3. NaNH2
C) 1. NaNH2 2. HI 3. H3O+
D) 1. Br2, CH2Cl2 2. NaNH2 (excess)
E) 1. Cl2, CH2Cl2 2. NaCN (excess)
65)
66) Which sequence of reagents works best to convert 1-bromobutane to hexane?
A) 1. NaOCH3, CH3OH 2. NaCN 3. Na, NH3
B) 1. NaC≡CH 2. H2 (excess), Pd/C
C) 1. CH3CH2OH, delta 2. H2 (excess), Pd/C
D) 1. NaCN 3. BH3*THF 4. HO-, H2O2
E) 1. NaC≡CCH2CH3 2. Na, NH3
66)
17
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
67) Provide the major organic product(s) in the reaction below.
67)
68) Provide the major organic product(s) in the reaction below.
68)
18
Answer Key
Testname: UNTITLED1
1) D
ID: oc5b 9-1
Diff: 0
Skill:
2)
ID: oc5b 9-2
Diff: 0
Skill:
3) D
ID: oc5b 9-3
Diff: 0
Skill:
4) E
ID: oc5b 9-4
Diff: 0
Skill:
5) C
ID: oc5b 9-5
Diff: 0
Skill:
6) E
ID: oc5b 9-6
Diff: 0
Skill:
7) C
ID: oc5b 9-7
Diff: 0
Skill:
8) D
ID: oc5b 9-8
Diff: 0
Skill:
9) B
ID: oc5b 9-9
Diff: 0
Skill:
10) C
ID: oc5b 9-10
Diff: 0
Skill:
11) B
ID: oc5b 9-11
Diff: 0
Skill:
12) A
ID: oc5b 9-12
Diff: 0
Skill:
19
Answer Key
Testname: UNTITLED1
13) B
ID: oc5b 9-13
Diff: 0
Skill:
14) The unhindered ethoxide produces the more stable alkene product (ie, the more highly substituted alkene possible).
When the bulky t-butoxide is used, the most accessible hydrogen is removed. This results in the least highly
substituted alkene possible.
ID: oc5b 9-14
Diff: 0
Skill:
15)
ID: oc5b 9-15
Diff: 0
Skill:
16)
ID: oc5b 9-16
Diff: 0
Skill:
17)
ID: oc5b 9-17
Diff: 0
Skill:
20
Answer Key
Testname: UNTITLED1
18)
ID: oc5b 9-18
Diff: 0
Skill:
19) a) bromomethylcyclohexane
b) CH3 CH2CHBrCH2CH3
c) CH3 CH2CH(CH3 )CH2 Br
ID: oc5b 9-19
Diff: 0
Skill:
20)
ID: oc5b 9-20
Diff: 0
Skill:
21)
ID: oc5b 9-21
Diff: 0
Skill:
22) D
ID: oc5b 9-22
Diff: 0
Skill:
21
Answer Key
Testname: UNTITLED1
23) D
ID: oc5b 9-23
Diff: 0
Skill:
24) E
ID: oc5b 9-24
Diff: 0
Skill:
25) C
ID: oc5b 9-25
Diff: 0
Skill:
26) D
ID: oc5b 9-26
Diff: 0
Skill:
27)
ID: oc5b 9-27
Diff: 0
Skill:
28) CH3 (CH2)3 Br < CH3 CH2CHBrCH3 < (CH3 )3CBr
ID: oc5b 9-28
Diff: 0
Skill:
29) D
ID: oc5b 9-29
Diff: 0
Skill:
22
Answer Key
Testname: UNTITLED1
30)
ID: oc5b 9-30
Diff: 0
Skill:
31) Primary halides cannot undergo E1 reactions because of the difficulty encountered in forming primary carbocations.
ID: oc5b 9-31
Diff: 0
Skill:
32) A
ID: oc5b 9-32
Diff: 0
Skill:
33) B
ID: oc5b 9-33
Diff: 0
Skill:
34) E
ID: oc5b 9-34
Diff: 0
Skill:
35) A
ID: oc5b 9-35
Diff: 0
Skill:
36) E
ID: oc5b 9-36
Diff: 0
Skill:
37)
ID: oc5b 9-37
Diff: 0
Skill:
38)
ID: oc5b 9-38
Diff: 0
Skill:
23
Answer Key
Testname: UNTITLED1
39) The cis isomer reacts more quickly. An axial orientation of the C-Br bond is required for E2 in six-membered ring
systems. In order for this to occur in the trans isomer, the bulky t-butyl group must also assume an axial orientation;
this requires substantial energy of activation.
ID: oc5b 9-39
Diff: 0
Skill:
40)
ID: oc5b 9-40
Diff: 0
Skill:
41)
ID: oc5b 9-41
Diff: 0
Skill:
42) D
ID: oc5b 9-42
Diff: 0
Skill:
43) B
ID: oc5b 9-43
Diff: 0
Skill:
44) C
ID: oc5b 9-44
Diff: 0
Skill:
45) E
ID: oc5b 9-45
Diff: 0
Skill:
46) C
ID: oc5b 9-46
Diff: 0
Skill:
47) C
ID: oc5b 9-47
Diff: 0
Skill:
24
Answer Key
Testname: UNTITLED1
48) D
ID: oc5b 9-48
Diff: 0
Skill:
49) D
ID: oc5b 9-49
Diff: 0
Skill:
50) A
ID: oc5b 9-50
Diff: 0
Skill:
51) C
ID: oc5b 9-51
Diff: 0
Skill:
52) D
ID: oc5b 9-52
Diff: 0
Skill:
53) D
ID: oc5b 9-53
Diff: 0
Skill:
54) Triethylamine. Amines can serve as both nucleophiles and as bases in reactions with alkyl halides. Increasing the steric
bulk about the nitrogen diminishes the nucleophilicity while allowing the amine to continue to function effectively as a
base.
ID: oc5b 9-54
Diff: 0
Skill:
55)
ID: oc5b 9-55
Diff: 0
Skill:
56) Only SN2 and E2 pathways are available to primary halides. SN1 and E1 cannot occur due to the instability of primary
carbocations. SN2 will typically predominate over E2 unless there is steric hindrance in the alkyl halide or
nucleophile/base.
ID: oc5b 9-56
Diff: 0
Skill:
57) E2
ID: oc5b 9-57
Diff: 0
Skill:
25
Answer Key
Testname: UNTITLED1
58) SN1
ID: oc5b 9-58
Diff: 0
Skill:
59)
ID: oc5b 9-59
Diff: 0
Skill:
60) D
ID: oc5b 9-60
Diff: 0
Skill:
61) Chloroethane reacts most rapidly; CH3 CH2 CCH is produced.
ID: oc5b 9-61
Diff: 0
Skill:
62) CH3 I + NaOCH(CH3 )2
ID: oc5b 9-62
Diff: 0
Skill:
63) a)
b)
c)
3-cyclopentyl-1-propyne
2-iodo-4-methylpentane
1-methoxypropane
ID: oc5b 9-63
Diff: 0
Skill:
64) C
ID: oc5b 9-64
Diff: 0
Skill:
65) D
ID: oc5b 9-65
Diff: 0
Skill:
66) B
ID: oc5b 9-66
Diff: 0
Skill:
67)
ID: oc5b 9-67
Diff: 0
Skill:
26
Answer Key
Testname: UNTITLED1
68)
ID: oc5b 9-68
Diff: 0
Skill:
27