ALKYNE

Brown Organic Chemistry 6e Test Bank 1

CHAPTER 7—ALKYNES

MULTIPLE CHOICE

1. Approximately how long is a carbon-carbon triple bond of an alkyne?

a. 110 pm

b. 121 pm

c. 135 pm

d. 156 pm

ANS: B

2. What is the approximate CCC bond angle in propyne?

a. 90

b. 109

c. 120

d. 180

ANS: D

3. How many alkynes are there with the molecular formula C6H10?

a. 4

b. 5

c. 6

d. 7

ANS: D

4. How many terminal alkynes are there with the molecular formula C7H12?

a. 5

b. 7

c. 8

d. 9

ANS: C

5. Which atomic orbitals overlap to form the carbon-carbon triple bond of an alkyne?

a. 2s + 2s; sp + sp; 2p + 2p

b. sp + sp; sp + sp; 2p + 2p

c. sp + sp; 2p + 2p; 2p + 2p

d. sp2 + sp

2; sp + sp; 2p + 2p

ANS: C

6. Which atomic orbitals overlap to form the carbon-carbon single bond of 1-propyne?

a. 2s + sp

b. sp + sp2

c. sp + sp3

d. sp2 + sp

3

ANS: C


7. What is the smallest cycloalkyne that is stable at room temperature?

a. cyclohexyne

b. cyclononyne

c. cyclododecyne

d. cycloeicosyne

ANS: B

8. What is the IUPAC name of the following compound?

CH3CH2CH2CCCH(CH3)2

a. 1-isopropyl-1-pentyne

b. 2-methyl-3-heptyne

c. 6-methyl-4-heptyne

d. isopropyl propyl ethyne

ANS: B


(CH3)2CHCH2CCCH(CH3)2

a. 2,6-dimethyl-3-heptyne

b. 2,6-dimethyl-4-heptyne

c. 1,1,5,5-tetramethyl-2-pentyne

d. 4-nonyne

ANS: A


a. 3,4-dimethyl-1-hexen-5-yne

b. 4-ethynyl-2-vinylbutane

c. 3-methyl-4-vinyl-1-pentyne

d. 4-ethynyl-3-methyl-1-pentyne

ANS: A

11. What is the IUPAC name of the following compound

a. vinylcyclohexane

b. allylcyclohexane

c. ethynylcyclohexane

d. acetylcyclohexane


ANS: C


a. (R)-4-methyl-2-hexyne

b. (S)-4-methyl-2-hexyne

c. (R)-3-methyl-4-hexyne

d. (S)-3-methyl-4-hexyne

ANS: B

13. What is the IUPAC name for the following compound?

a. (R)-3-methyl-1-penten-4-yne

b. (S)-3-methyl-1-penten-4-yne

c. (R)-4-methyl-4-penten-1-yne

d. (S)-4-methyl-4-penten-1-yne

ANS: A

14. Which of the following is the strongest acid?

a. propane

b. cyclopropane

c. propene

d. propyne

ANS: D

15. Which of the following has the lowest pKa?

a. butane

b. 1-butene

c. 1-butyne

d. 2-butyne

ANS: C


16. What is the correct assignment of the acid, base, conjugate acid and conjugate base in the following

equilibrium?

a. 1 = acid; 2 = base; 3 = conjugate acid; 4 = conjugate base

b. 1 = acid; 2 = base; 3 = conjugate base; 4 = conjugate acid

c. 1 = base; 2 = acid; 3 = conjugate acid; 4 = conjugate base

d. 1 = base; 2 = acid; 3 = conjugate base; 4 = conjugate acid

ANS: B

17. What is the major organic product obtained from the following reaction?

a. cyclohexyne

b. 1,3-cyclohexadiene

c. cyclohexene

d. 1,2-diaminocyclohexane

ANS: B


a. (E) 2-butene

b. (Z) 2-butene

c. 2-butyne

d. 1-butyne

ANS: C

19. Which sequence of reactions can be used to convert 1-pentene to 1-pentyne

a. Treatment with HBr; followed by treatment with NaOH

b. Treatment with Br2; followed by treatment with NaNH2

c. Treatment with Br2; followed by treatment with H2SO4

d. Treatment with Br2, H2O; followed by treatment with NaOH

ANS: B

20. Which sequence of reactions can be used to convert (Z) 2-pentene to 2-pentyne

a. Treatment with Br2; followed by treatment with NaNH2

b. Treatment with Br2, H2O; followed by treatment with NaOH

c. Treatment with Br2; followed by treatment with H2SO4

d. Treatment with HBr; followed by treatment with NaOH


ANS: A


a. 2-methyl-3-hexene

b. 2-methyl-3-heptyne

c. 2-bromo-3-methylbutane

d. 2-methyl-2-butene

ANS: B


a. 1-methyl-4-nonyne

b. 2-methyl-4-nonyne

c. 2-methyl-3-nonyne

d. 3-methyl-4-nonyne

ANS: D


a. (E) 1,2-dibromobutene

b. (Z) 1,2-dibromobutene

c. (E) 2,3-dibromobutene

d. (Z) 2,3-dibromobutene

ANS: C


a. (E) 3,4-dibromohexene

b. (Z) 3,4-dibromohexene

c. (E) 2,3-dibromohexene

d. (Z) 2,3-dibromobutene

ANS: A



a. 2,3-dibromobutane

b. 2,2,3,3-tetrabromobutane

c. 2,3-dibromobutene

d. 2,2-dibromobutane

ANS: B


a. 3,4-dibromohexane

b. 3,3-dibromohexane

c. (Z) 3,4-dibromohexene

d. 3,3,4,4-tetrabromohexane

ANS: D


a. 2,3-dibromobutane

b. 2,2,3,3-tetrabromobutane

c. 2,3-dibromobutene

d. 2,2-dibromobutane

ANS: D


a. 3,4-dibromohexane

b. 3,3-dibromohexane

c. (E) 3,4-dibromohexene

d. 3,3,4,4-tetrabromohexane

ANS: B



a. butanal

b. cis-2-butene

c. 2-butanol

d. butanone

ANS: A


a. 2-hexanone

b. hexanal

c. 2-hexanol

d. cis-2-hexene

ANS: B


a. butanal

b. cis-2-butene

c. 2-butanol

d. butanone

ANS: A


a. 2-hexanone

b. hexanal

c. 2-hexanol

d. cis-2-hexene

ANS: B



a. 1 b. 2 c. 3 d. 4

ANS: A


a. 1 b. 2 c. 3 d. 4

ANS: D



a. 1 b. 2 c. 3 d. 4

ANS: D



a. 1 b. 2 c. 3 d. 4

ANS: B

38. What type of intermediate s formed in the Hg2

catalyzed hydration of an alkyne??

a. an alcohol

b. an enol

c. a 1,2-diene

d. an epoxide

ANS: B


a. 1 b. 2 c. 3 d. 4

ANS: C



a. 1 b. 2 c. 3 d. 4

ANS: D


a. butane

b. 1-butene

c. cis-2-butene

d. trans-2-butene

ANS: D


a. 1 b. 2 c. 3 d. 4

ANS: B



a. butane

b. 1-butene

c. cis-2-butene

d. trans-2-butene

ANS: C


a. 1 b. 2 c. 3 d. 4

ANS: A


a. butane

b. 1-butene

c. cis-2-butene

d. trans-2-butene

ANS: C



a. 1 b. 2 c. 3 d. 4

ANS: A

47. What is the best choice of reagent(s) to perform the following transformation?

a. 1 mole of Br2

b. 2 moles of Br2

c. 1 mole of HBr

d. 2 moles of HBr

ANS: D


a. 1 mole of Br2

b. 2 moles of Br2

c. 1 mole of HBr

d. 2 moles of HBr

ANS: A



a. H2O; H2SO4

b. 1. 3 moles of NaNH2; 2. H3O+

c. KMnO4, NaOH, H2O

d. Zn

ANS: B


a. H2/Pt

b. H2/Lindlar catalyst

c. Na/NH3

d. BH3; followed by H2O2, NaOH

ANS: C


a. H2/Pt

b. H2/Lindlar catalyst

c. Na/NH3


ANS: B


a. H2/Lindlar catalyst

b. Na/NH3

c. (sia)2BH; followed by H2O2, NaOH



ANS: C



b. Na/NH3

c. (sia)2BH; followed by H2O2, NaOH


ANS: D

54. What is the major organic product obtained from the following series of reactions?

a. 1 b. 2 c. 3 d. 4

ANS: A


a. propanal, CH3CH2CHO

b. 1-propanol, CH3CH2CH2OH

c. butanal, CH3CH2CH2CHO

d. butanone, CH3COCH2CH3


ANS: D


a. (E)-5-phenyl-2-pentene

b. 6-phenyl-1-hexene

c. (Z)-6-phenyl-2-hexene

d. (E)-6-methyl-3-heptene

ANS: C


a. (Z)-2-heptene

b. (Z)-1,5-heptene

c. 1-heptene

d. heptane

ANS: D


a. (Z)-2-heptene

b. (E)-2-heptene

c. 1-heptene

d. heptane

ANS: B

59. Which of the following reagents react with 2-butyne to form (Z)-2-butene

1. H2/Lindlar catalyst

2. (sia)2BH followed by CH3COOH

3. Na/NH3

a. only 1

b. only 2

c. only 3

d. only 1 and 2

ANS: D


60. Which of the following reagents react with 2-butyne to form butane


b. H2/Pd

c. (sia)2BH followed by CH3COOH

d. Na/NH3

ANS: B

PROBLEM

1. What is IUPAC name of the following compound?

ANS:

(R)-4-chloro-2-pentyne


ANS:

(S)-2-chloro-3-hexyne


ANS:

1,5-heptadiyne


ANS:

2,5-octadiyne



ANS:


ANS:


ANS:


ANS:



ANS:


ANS:


ANS:


ANS:


ANS:



ANS:


ANS:

16. Outline how one might achieve the following transformation, showing reagents and the isolated

intermediates in the synthesitc scheme.

ANS:




ANS:


intermediates in the synthetic scheme.

ANS:




ANS:


intermediates in the synthetic scheme.

ANS:

ALKYNE

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