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Chapter 10
Multiple Choice Questions:
Topic: Introduction to Alkynes
Section: 10.1
Difficulty Level: Easy
1. For the molecule below, known as 2-pentyne, which of the following describes the
orbital overlap of the C2—C3 sigma bond?
C CCH3CH2CH3
A) sp–sp
B) sp2–sp2
C) sp3–sp3
D) p–p
E) sp3–sp
2. For the molecule below, known as 2,4-hexadiyne, which of the following describes
the orbital overlap of the C3—C4 sigma bond?
H3C C C C C CH3
A) sp–sp
B) sp2–sp2
C) sp3–sp3
D) p–p
E) sp3–sp
3. The sigma bond of an alkyne is formed from the overlap of which orbitals?
A) sp3–sp3
B) p–p
C) sp2–sp2
D) s–s
E) sp–sp
4. What is the hybridization of the carbon atoms numbered 1 and 2 respectively in the
following structure?
CCCCH
H
H12
A) sp3, sp2
B) sp2, sp2
C) sp, sp
D) sp2, sp
E) sp, sp2
5. The C≡C bond of an alkyne is composed of which bond types?
A) three anti-bonds
B) three σ bonds
C) two σ bonds and one π bond
D) one σ bond and two π bonds
E) three π bonds
6. Which of following statements best describes the general reactivity of alkynes?
A) An alkyne reacts as a nucleophile, and is therefore electron rich.
B) An alkyne reacts as a nucleophile, and is therefore electron poor.
C) Alkynes fail to undergo electrophilic addition reactions, unlike alkenes.
D) An alkyne reacts as an electrophile, and is therefore electron rich.
E) An alkyne reacts as an electrophile, and is therefore electron poor.
7. Which of the following statements is true about propyne, H–C≡C–CH3?
A) It contains 3 sigma bonds.
B) It contains three pi bonds.
C) The H–C≡C bond angle is about 109.5°.
D) The C≡C–C bond angle is 180°.
E) All carbon-carbon bonds are of equal length.
8. What is the correct IUPAC name for the molecule shown below?
H2C C C CH2
C
Br
CH3
CH3
H3C
A) 6-Bromo-3-octyne
B) 6-Bromo-6-methyl-3-heptyne
C) 2-Bromo-2-methyl-4-heptyne
D) 6-Bromo-6,6-dimethyl-3-hexyne
E) 2-Bromo-4-octyne
9. What is the correct IUPAC name for the molecule shown below?
C CH
CH2CH3
CH2CH3
CCH3CH2
A) 1,1-Diethyl-2-pentyne
B) 3-(1-Butynyl)pentane
C) 5-Ethyl-3-octyne
D) 3-Ethyl-4-heptyne
E) 5-Ethyl-3-heptyne
10. What is the correct IUPAC name for the molecule shown below?
C CH
CH2CH2CH3
CH2CH3
CHC
H3C
H3C
A) 2-Methyl-5-propyl-3-heptyne
B) 5-Ethyl-2-methyl-3-octyne
C) 1-Isopropyl-3-ethyl-1-hexyne
D) 6-Methyl-3-propyl-4-heptyne
E) 4-Ethyl-7-methyl-5-octyne
11. What is the correct IUPAC name for the molecule shown below?
C
C
H3C
CH3
CH3
H
CCH3C
CH3
A) 2,2,3-Trimethyl-4-hexyne
B) 4-tert-Butyl-2-pentyne
C) 4,5,5-Trimethyl-2-hexyne
D) 4,5,5,5-Tetramethyl-2-pentyne
E) 2,2-Dimethyl-3-(1-propynyl)butane
12. What is the correct IUPAC name for the molecule shown below?
A) 5,6,6-Trimethyl-1-heptyne
B) 5-tert-Tutyl-1-hexyne
C) 2,2,3-Trimethyl-6-heptyne
D) 2,2,3-(3-Butynyl)butane
E) sec-Butyl-tert-butylacetylene
13. What is the correct IUPAC name for the molecule shown below?
Cl
Cl
Cl
A) 1,1,1-Trichloro-4-hexyne
B) 4,4,4-Trichloro-1-butyne
C) 1,1,1-Trichloro-2-butyne
D) 5,5,5-Trichloro-2-pentyne
E) 6,6,6-Trichloro-2-hexyne
14. What is the correct IUPAC name for the molecule shown below?
A) 4,4-Dimethyl-2-pentyne
B) 2,2-Dimethyl-4-heptyne
C) 1-tertButyl-3-heptyne
D) 6,6-Dimethyl-3-heptyne
E) 6,6,6-Trimethyl-3-hexyne
15. What is the correct IUPAC name for the molecule shown below?
A) 4-Ethyl-2-pentyne
B) 2-Ethyl-3-pentyne
C) 3-Methyl-4-hexyne
D) 4-Methyl-2-hexyne
E) sec-Butylpropyne
Difficulty Level: Easy
16. Which of the following is an acceptable structure for hepta-3,6-dien-1-yne?
III III IV V
A) I
B) II
C) III
D) IV
E) V
17. Which of the following is an acceptable structure for 2-hexyne?
I II III IV V
A) I
B) II
C) III
D) IV
E) V
18. Which of the following is an acceptable structure for 3-sec-butyl-1-heptyne?
III III IV V
A) I
B) II
C) III
D) IV
E) V
19. Provide the systematic IUPAC name for BrCH2CH2C≡CCH2CH3.
A) 1-Bromo-3-hexyne
B) 6-Bromo-3-hexyne
C) 1-Bromo-2-hexyne
D) 6-Bromo-4-hexyne
E) 1-Bromo-4-hexyne
20. Provide the systematic IUPAC name for HC≡CCH2CH2CH3.
A) Pentyne
B) 1-Pentyne
C) Butyne
D) 1-Butyne
E) 2-Butyne
21. Provide the systematic IUPAC name for Cl3CCH2CH2CH2C≡CH.
A) 6,6,6-Trichloro-1-hexyne
B) 1,1,1-Trichloro-5-hexyne
C) 5,5,5-Trichloro-1-pentyne
D) 1-Heptyne
E) Trichlorobutylacetylene
22. Provide the systematic IUPAC name for Cl3C(CH2)4C≡CH.
A) 4,4,4-Trichloro-1-butyne
B) 1,1,1-Trichloro-6-heptyne
C) 1,1,1-Trichloro-5-heptyne
D) 6,6,6-Trichloro-1-hexyne
E) 7,7,7-Trichloro-1-heptyne
23. Provide the systematic IUPAC name for (CH3)2CHC≡CCH2C(CH3)3.
A) 1,1,5,5,5-Pentamethyl-2-pentyne
B) 1,1,1,5,5-Pentamethyl-3-pentyne
C) 2,2,6-trimethyl-4-heptyne
D) 2,6,6-trimethyl-3-heptyne
E) tert-butylisopropylacetylene
24. Provide the systematic IUPAC name for the molecule below:
CH3C(CH3)2CH2C≡CCH2CH(CH2CH3)CH3
A) 2,7,7-Trimethyl-5-nonyne
B) 2-Ethyl-7,7-dimethyl-4-octyne
C) 2,2,7-Trimethyl-4-nonyne
D) 7-Ethyl-2,2-trimethyl-4-octyne
E) 6-Undecyne
25. What is the correct IUPAC name for the molecule shown below?
Br
A) 3-Bromo-4-acetylenyl-heptane
B) 3-(1-Bromopropyl)-1-hexyne
C) 3-Bromo-4-propyl-5-hexyne
D) 4-Bromo-3-propyl-1-hexyne
E) 4-Ethynyl-5-bromo-heptane
26. Which of the following is an acceptable structure for (R)-5-bromohept-2-yne.
III III IV V
BrBr
BrBr Br
A) I
B) II
C) III
D) IV
E) V
27. What is the correct IUPAC name for the molecule shown below?
A) (E)-5-methyl-5-hepten-1-yne
B) (Z)-5-methyl-5-hepten-1-yne
C) (E)-3-methyl-2-hepten-6-yne
D) (Z)-3-methyl-2-hepten-6-yne
E) (E)-2-butynyl-2-butene
28. What is the correct IUPAC name for the molecule shown below?
A) (E)-4-isopropyloct-3-en-5-yne
B) (Z)-4-isopropyloct-3-en-5-yne
C) (E)-5-isopropyloct-5-en-3-yne
D) (Z)-5-isopropyloct-5-en-3-yne
E) (E)-4-(2-methylethyl)oct-3-en-5-yne
29. Which structure shown below represents (Z)-3,5-dichloro-3-hexen-1-yne?
Cl
III III IV
Cl
ClCl
Cl
Cl
Cl
Cl
A) I
B) II
C) III
D) IV
E) I and II are both correct
30. Which of the following is an acceptable structure for (2E,4E)-octa-2,4-dien-6-yne?
III III IV V
A) I
B) II
C) III
D) IV
E) V
31. Which of the following is an acceptable structure for octa-3,6-dien-1-yne?
A) HC≡CCH=CHCH=CHCH2CH3
B) CH3CH=CHCH2C≡CC≡CH
C) CH3CH=CHCH2CH=CHC≡CH
D) CH3C≡CCH=CHCH=CHCH3
E) H2C=CHC≡CCH2CH=CHCH3
32. Which of the following is an acceptable structure for 2,5,5-trimethylhept-3-yne
A) (CH3CH2)CH(CH3)C≡CCH2CH(CH3)2
B) (CH3CH2)C(CH3)2C≡CCH(CH3)2
C) (CH3CH2)2C(CH3)C≡CCH2CH3
D) CH3CH2C(CH3)2C≡CC(CH3)3
E) (CH3CH2CH2)CH(CH3)C≡CC(CH3)3
33. What is the correct IUPAC name for the molecule shown below?
Cl
A) (R,Z)-4-chlorohept-5-en-2-yne
B) (S,E)-4-chlorohept-5-en-2-yne
C) (S,E)-4-chlorohept-2-en-5-yne
D) (R,E)-4-chlorohept-5-en-2-yne
E) (R,E)-4-chlorohept-2-en-5-yne
34. What is the correct IUPAC name for diisobutylacetylene?
A) Diisopropylbutyne
B) 2,7-Dimethyl-4-octyne
C) 3,6-Dimethyl-4-octyne
D) 2,5-Diethyl-3-hexyne
E) 2,2,5,5-Tetramethyl-3-hexyne
35. What is the correct systematic IUPAC name for di-sec-butylacetylene?
A) 2-Ethyl-5-methyl-3-heptyne
B) 2,7-Dimethyl-4-octyne
C) 3,6-Dimethyl-4-octyne
D) 2,5-Diethyl-3-hexyne
E) 2,2,5,5-Tetramethyl-3-hexyne
36. Rank the following carbanions, with the weakest base first, then by increasing base
strength.
HC C CH3CH2
III III
H2C CH
A) I < II < III
B) II < III < I
C) III < II < I
D) III < I < II
E) II < I < III
37. Rank the following bases, with the strongest base first, then by decreasing basicity.
HC C CH3CH2OH2N
CH3CH2H2C CH
III III IV V
A) III > I > V > II > IV
B) III > V > IV > I> II
C) V > I > III > II > IV
D) III > IV > II > V > I
E) IV > II > I > III > V
38. Rank the following acids, with the strongest acid first, then by decreasing acidity.
III III IV V
H2O CH3CH3NH3
H2CHC CH
CH2
A) V > I > IV > II > III
B) III > IV > II > I > V
C) V > I > III > II > IV
D) I > IV > V > II > III
E) IV > I > V > II > III
39. Which of the circled hydrogen atoms is the most acidic?
III III IV V
H3C C C H
H2C C
H
H
C H
H
CH3
H3CC H
CH3
CH3
H3CC H
H
H
H
A) I
B) II
C) III
D) IV
E) V
40. Sodium amide (NaNH2, sodamide) reacts with terminal alkynes in the role of the
A) Brønsted acid.
B) Brønsted base.
C) reducing agent.
D) catalyst.
E) electrophile.
41. Which of the bases below would quantitatively deprotonate a terminal alkyne?
A) BuLi
B) NH3
C) NaOH
D) NaOCH2CH3
E) t-BuOK
42. Which of the bases below would result in the greatest deprotonation of the alkyne,
shown in the reaction below?
H3C C C H ?H3C C C
A) NaOCH2CH3 (sodium ethoxide)
B) t-BuONa (sodium tert-butoxide)
C) NaH (sodium hydride)
D) NaHCO3 (sodium bicarbonate)
E) NaOH (sodium hydroxide)
43. Which statement below best explains acetylene’s Ka being greater than ethylene’s?
A) Acetylide anions are resonance stabilized.
B) The 4 electrons of the acetylide anion better stabilize a negative charge.
C) The electronegativity of sp carbons being greater than sp2 carbons.
D) The electronegativity of sp carbons being less than sp2 carbons.
E) Acetylene has only two hydrogen atoms while ethylene has four.
44. Select the best explanation for why methanol, CH3OH, cannot be used as a solvent
for the deprotonation of a terminal alkyne by sodium amide, NaNH2.
A) Sodium amide is not a strong enough base to deprotonate the alkyne.
B) Sodium amide in methanol reduces alkynes to alkenes.
C) Methanol is a poor solvent for dissolving alkynes.
D) Methanol is more acidic than the alkyne, and will be deprotonated instead.
E) Methanol is toxic, and should be avoided when possible.
45. What are the products of the reaction shown below?
CH3OH + CH3C≡C–Na+ → ?
A) CH3C≡CCH3 + Na+OH–
B) CH3C≡CH + CH3O–Na+
C) CH3C≡COCH3 + Na+OH–
D) CH3OC≡CH + Na+CH3–
E) no reaction
46. The major result of treating 1-butyne with 6M aqueous NaOH would be:
A) the production of the sodium acetylide.
B) the production of an alkene.
C) the production of an alkane.
D) the production of an enol.
E) nothing, as the alkyne would not react.
47. Which of the circled hydrogen atoms is the least acidic?
III III IV V
H3C C C H
H2C C
H
H
C H
H
CH3
H3CC H
CH3
CH3
H3CC H
H
H
H
A) I
B) II
C) III
D) IV
E) V
48. Of the species listed below, select those less basic than acetylide?
A) BuLi
B) NaNH2
C) NaOCH3
D) both A and C
E) both B and C
49. For the transformation shown below, select the expected major product.
Br
Br
xs NaNH2
NH3
III III IV V
H
CCCH2
NH2
H2N
A) I
B) II
C) III
D) IV
E) V
50. For the reaction shown below, select the expected major product.
Br
Br KOH
?
Br
Br
O
Br
III III IV V
A) I
B) II
C) III
D) IV
E) V
51. For the reaction sequence below, select the expected major product.
1) Br22) 3 eq. NaNH2/NH3
3) H2O
A) 3-methylhexane
B) 1-bromo-3-methylhexene
C) 2-bromo-3-methylhexene
D) 3-methyl-1-hexyne
E) 3-methyl-2-hexyne
52. Treatment of 2,2-dibromobutane with molten KOH at 200°C would be expected to
produce which of the following:
A) (E)-2-bromo-2-butene
B) (Z)-2-bromo-2-butyne
C) 1,2-butadiene
D) 1-butyne
E) 2-butyne
53. When preparing terminal alkynes by an elimination reaction, sodium amide
(NaNH2) dissolved in liquid ammonia (NH3) is used most frequently. Which of the
following statements offers the best explanation for the above statement?
A) The above statement is false; terminal alkynes are not produced under the
given conditions.
B) Sodium amide deprotonates the terminal alkyne, driving formation of the
alkynide ion.
C) Only sodium amide is a strong enough base to deprotonate a carbon.
D) Terminal alkynes are more stable than the internal alkynes, and are always
the favored product.
E) Steric hindrance favors preparation of the less substituted terminal alkyne.
54. For the reaction shown, select the expected major organic product.
III III IV V
?
H2
Pt
A) I
B) II
C) III
D) IV
E) V
55. For the reaction shown, select the expected major organic product.
Na/NH3
III III IV V
?
A) I
B) II
C) III
D) IV
E) V
56. For the reaction shown, select the expected major organic product.
III III IV V
?
H2
Lindlar's cat.
A) I
B) II
C) III
D) IV
E) V
57. Reduction of 1 mole of (3E,5Z)-3-methylhepta-3,5-dien-1-yne will require how
many moles of hydrogen (H2)?
A) 1
B) 2
C) 3
D) 4
E) 5
58. Select the reagent(s) expected to accomplish the transformation shown below.
C CCH3CH2CH2CH3
?CH3CH2CH2CH2CH3
A) H2, Ni
B) H2, Ni2B
C) Na, NH3(l)
D) A and B
E) B and C
59. Select the best reagent expected to convert 3-heptyne to cis-3-heptene.
A) NaNH2, NH3
B) Na, NH3
C) H2, Lindlar’s catalyst
D) Both A and C
E) Both B and C
60. Which of the reagents below would convert 2-pentyne to trans-2-pentene?
A) NaNH2, NH3
B) Na, NH3
C) H2, Lindlar’s catalyst
D) H2, Pd/C
E) H2O, HgSO4/H2SO4
