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Klein, Organic Chemistry 3e Chapter 9 1.

A. B. C. D. E.

For 2-pentyne, which of the following describes the orbital overlap of the C2—C3 sigma bond?

sp–sp sp2–sp2 sp3–sp3 p–p sp3–sp

Answer: A Learning Objective: 9.1 Describe the structure of alkynes and the nature of their chemical function, explaining how alkynes are named Difficulty: Easy

2.

A. B. C. D. E.

For 2,4-hexadiyne, which of the following describes the orbital overlap of the C3— C4 sigma bond?

sp–sp sp2–sp2 sp3–sp3 p–p sp3–sp

Answer: A Learning Objective: 9.1 Describe the structure of alkynes and the nature of their chemical function, explaining how alkynes are named Difficulty: Easy 3. A. B. C. D. E.

The sigma bond of an alkyne is formed from the overlap of which two orbitals? sp3–sp3 p–p sp2–sp2 s–s sp–sp

Answer: E

Learning Objective: 9.1 Describe the structure of alkynes and the nature of their chemical function, explaining how alkynes are named Difficulty: Easy 4.

A. B. C. D. E.

What is the hybridization of the carbon atoms numbered 1 and 2 respectively in the following structure?

sp3, sp2 sp2, sp2 sp, sp sp2, sp sp, sp2

Answer: D Learning Objective: 9.1 Describe the structure of alkynes and the nature of their chemical function, explaining how alkynes are named Difficulty: Easy

5. A. B. C. D. E.

The C≡C bond of an alkyne is composed of which bond types? three anti-bonds three σ bonds two σ bonds and one π bond one σ bond and two π bonds three π bonds

Answer: D Learning Objective: 9.1 Describe the structure of alkynes and the nature of their chemical function, explaining how alkynes are named Difficulty: Easy 6. A. B. C. D. E.

Which of the following statements best describes the general reactivity of alkynes? An alkyne reacts as a nucleophile and is therefore electron rich. An alkyne reacts as a nucleophile and is therefore electron poor. Alkynes fail to undergo electrophilic addition reactions, unlike alkenes. An alkyne reacts as an electrophile and is therefore electron rich. An alkyne reacts as an electrophile and is therefore electron poor.

Answer: A Learning Objective: 9.1 Describe the structure of alkynes and the nature of their chemical function, explaining how alkynes are named Difficulty: Easy 7.

Which of the following statements is true about propyne, H–C≡C–CH 3?

A. B. C. D. E.

It contains a total of three sigma bonds. It contains a total of three pi bonds. The H–C≡C bond angle is about 109.5°. The C≡C–C bond angle is 180°. All carbon-carbon bonds are of equal length.

Answer: D Learning Objective: 9.1 Describe the structure of alkynes and the nature of their chemical function, explaining how alkynes are named Difficulty: Easy 8.

Describe the shape for acetylene.

Answer: linear Learning Objective: 9.1 Describe the structure of alkynes and the nature of their chemical function, explaining how alkynes are named Difficulty: Easy

9.

A. B. C. D. E.

What is the IUPAC name for the molecule shown below?

6-bromo-3-octyne 6-bromo-6-methyl-3-heptyne 2-bromo-2-methyl-4-heptyne 6-bromo-6,6-dimethyl-3-hexyne 2-bromo-4-octyne

Answer: B Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy

10.

A. B. C. D. E.

What is the IUPAC name for the molecule shown below?

1,1-diethyl-2-pentyne 3-(1-butynyl)pentane 5-ethyl-3-octyne 3-ethyl-4-heptyne 5-ethyl-3-heptyne

Answer: E Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy

11.

A. B. C. D. E.

What is the IUPAC name for the molecule shown below?

2-methyl-5-propyl-3-heptyne 5-ethyl-2-methyl-3-octyne 1-isopropyl-3-ethyl-1-hexyne 6-methyl-3-propyl-4-heptyne 4-ethyl-7-methyl-5-octyne

Answer: B Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy

12.

A. B. C.

What is the IUPAC name for the molecule shown below?

2,2,3-trimethyl-4-hexyne 4-tert-butyl-2-pentyne 4,5,5-trimethyl-2-hexyne

D. E.

4,5,5,5-tetramethyl-2-pentyne 2,2-dimethyl-3-(1-propynyl)butane

Answer: C Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy

13.

A. B. C. D. E.

What is the IUPAC name for the molecule shown below?

5,6,6-trimethyl-1-heptyne 5-tert-butyl-1-hexyne 2,2,3-trimethyl-6-heptyne 2,2,3-(3-butynyl)butane sec-butyl-tert-butylacetylene

Answer: A Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy 14.

A. B. C. D. E.

What is the IUPAC name for the molecule shown below?

1,1,1-trichloro-4-hexyne 4,4,4-trichloro-1-butyne 1,1,1-trichloro-2-butyne 5,5,5-trichloro-2-pentyne 6,6,6-trichloro-2-hexyne

Answer: E Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy

15.

A. B. C. D. E.

What is the IUPAC name for the molecule shown below?

4,4-dimethyl-2-pentyne 2,2-dimethyl-4-heptyne 1-tert-butyl-3-heptyne 6,6-dimethyl-3-heptyne 6,6,6-trimethyl-3-hexyne

Answer: D Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy 16.

A. B. C. D. E.

What is the IUPAC name for the molecule shown below?

4-ethyl-2-pentyne 2-ethyl-3-pentyne 3-methyl-4-hexyne 4-methyl-2-hexyne sec-Butylpropyne

Answer: D Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy

17.

Which of the following is a structure for hepta-3,6-dien-1-yne?

A. I B. II C. III D. IV E. V Answer: A Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy 18.

A. B. C. D.

Which of the following is the structure for 2-hexyne?

I II III IV

Answer: C Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy

19.

A.

Which of the following is the structure for 3-sec-butyl-1-heptyne?

I

B. C. D. E.

II III IV V

Answer: B Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy 20. A. B. C. D. E.

Provide the IUPAC name for BrCH2CH2C≡CCH2CH3. 1-bromo-3-hexyne 6-bromo-3-hexyne 1-bromo-2-hexyne 6-bromo-4-hexyne 1-bromo-4-hexyne

Answer: A Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy 21. A. B. C. D. E.

Provide the IUPAC name for HC≡CCH2CH2CH3. pentyne 1-pentyne butyne 1-butyne 2-butyne

Answer: B Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy

22. A. B. C. D. E.

Provide the IUPAC name for Cl3CCH2CH2CH2C≡CH. 6,6,6-trichloro-1-hexyne 1,1,1-trichloro-5-hexyne 5,5,5-trichloro-1-pentyne 1-heptyne trichlorobutylacetylene

Answer: A Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy 23. A. B. C. D. E.

Provide the IUPAC name for Cl3C(CH2)4C≡CH. 4,4,4-trichloro-1-butyne 1,1,1-trichloro-6-heptyne 1,1,1-trichloro-5-heptyne 6,6,6-trichloro-1-hexyne 7,7,7-trichloro-1-heptyne

Answer: E Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Moderate 24. A. B. C. D. E.

Provide the IUPAC name for (CH3)2CHC≡CCH2C(CH3)3. 1,1,5,5,5-pentamethyl-2-pentyne 1,1,1,5,5-pentamethyl-3-pentyne 2,2,6-trimethyl-4-heptyne 2,6,6-trimethyl-3-heptyne tert-butylisopropylacetylene

Answer: D Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Moderate 25.

Provide the systematic IUPAC name for the molecule below:

(CH3)3CCH2C≡CCH2CH(CH3)CH2CH3 A. B. C. D. E.

2,7,7-trimethyl-5-nonyne 2-ethyl-7,7-dimethyl-4-octyne 2,2,7-trimethyl-4-nonyne 7-ethyl-2,2-trimethyl-4-octyne 6-undecyne

Answer: C

Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Moderate 26.

A. B. C. D. E.

What is the IUPAC name for the molecule shown below?

3-bromo-4-acetylenylheptane 3-(1-bromopropyl)-1-hexyne 3-bromo-4-propyl-5-hexyne 4-bromo-3-propyl-1-hexyne 4-ethynyl-5-bromo-heptane

Answer: D Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Moderate 27.

A. B. C. D. E.

Which of the following is the acceptable structure for (R)-5-bromohept-2-yne?

I II III IV V

Answer: E Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Moderate 28.

What is the IUPAC name for the molecule shown below?

A. B. C. D. E.

(E)-5-methyl-5-hepten-1-yne (Z)-5-methyl-5-hepten-1-yne (E)-3-methyl-2-hepten-6-yne (Z)-3-methyl-2-hepten-6-yne (E)-2-butynyl-2-butene

Answer: A Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Moderate

29.

A. B. C. D. E.

What is the IUPAC name for the molecule shown below?

(E)-4-isopropyloct-3-en-5-yne (Z)-4-isopropyloct-3-en-5-yne (E)-5-isopropyloct-5-en-3-yne (Z)-5-isopropyloct-5-en-3-yne (E)-4-(2-methylethyl)oct-3-en-5-yne

Answer: B Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Moderate 30.

A. B. C.

Which structure shown below represents (Z)-3,5-dichloro-3-hexen-1-yne?

I II III

D. E.

IV I and II are both correct

Answer: B Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Moderate

31.

A. B. C. D. E.

Which of the following is the structure for (2E,4E)-octa-2,4-dien-6-yne?

I II III IV V

Answer: D Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Moderate

32.

Which of the following is a 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 Answer: C Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Moderate

33.

Which of the following is the structure for 2,5,5-trimethylhept-3-yne?

A. CH3CH2CH(CH3)C≡CCH2CH(CH3)2 B. CH3CH2C(CH3)2C≡CCH(CH3)2 C. (CH3CH2)2C(CH3)C≡CCH2CH3 D. CH3CH2C(CH3)2C≡CC(CH3)3 E. CH3CH2CH2CH(CH3)C≡CC(CH3)3 Answer: B Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Moderate 34.

A. B. C. D.

What is the IUPAC name for the molecule shown below?

(4R,5Z)-4-chlorohept-5-en-2-yne (4S,5E)-4-chlorohept-5-en-2-yne (2E,4S)-4-chlorohept-2-en-5-yne (2E,4R)-4-chlorohept-2-en-5-yne

Answer: D Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Hard 35. A. B. C. D. E.

What is the IUPAC name for diisobutylacetylene? diisopropylbutyne 2,7-dimethyl-4-octyne 3,6-dimethyl-4-octyne 2,5-diethyl-3-hexyne 2,2,5,5-tetramethyl-3-hexyne

Answer: B Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Hard

36.

What is the IUPAC name for di-sec-butylacetylene?

A. B. C. D. E.

2-ethyl-5-methyl-3-heptyne 2,7-dimethyl-4-octyne 3,6-dimethyl-4-octyne 2,5-diethyl-3-hexyne 2,2,5,5-tetramethyl-3-hexyne

Answer: C Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Hard

37.

Draw all of the constitutionally isomeric alkynes with molecular formula C 5H8.

Answer:

Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy 38.

Provide the IUPAC name for CH3CH(CH3)C(CH3)2C≡CCH(CH3)2.

Answer: 2,5,5,6-tetramethyl-3-heptyne or 2,5,5,6-tetramethylhept-3-yne Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy

39.

Provide the IUPAC name for CH3C≡CC(CH3)2CH(CH2CH3)2.

Answer: 5-ethyl-4,4-dimethyl-2-heptyne or 5-ethyl-4,4-dimethylhept-2-yne Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy 40.

Provide the IUPAC name for CH3CHBrC≡C(CH2)3CH3.

Answer: 2-bromo-3-octyne or 2-bromooct-3-yne

Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy 41.

Provide the IUPAC name for the following compound.

Answer: 4-sec-butyl-2-octyne or 4-sec-butyloct-2-yne Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy

42.

Provide the IUPAC name for the following compound.

Answer: 4,4-dimethylcyclodecyne Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Medium

43.

Provide the IUPAC name for the following compound.

Answer: (S)-2,3,6,6-tetramethyloct-4-yne or (S)-2,3,6,6-tetramethyl-4-octyne Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Hard

44.

Provide the IUPAC name for the following compound:

Answer: (3E,5S)-5-fluoro-2-methylnon-3-en-6-yne or (3E,5S)-5-fluoro-2-methyl-3nonen-6-yne Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Hard 45.

Provide the IUPAC name for the following compound.

Answer: (4R,5S)-4-bromo-5-chloro-3-ethylhex-1-yne or (4R ,5S)-4-bromo-5-chloro3-ethyl-1-hexyne Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy 46.

Draw the line-bond structure for the compound with the IUPAC name 2,5,9trimethyl-2-decen-7-yne.

Answer:

Learning Objective: 9.2 Assign an IUPAC (systematic) name to an alkyne and describe the alkyne as internal or terminal Difficulty: Easy 47.

Rank the following carbanions in order of increasing base strength.

A. B. C. D. E.

I < II < III II < III < I III < II < I III < I < II II < I < III

Answer: A Learning Objective: 9.3 Discuss the reasons for the enhanced acidity of acetylene and terminal alkynes compared to other hydrocarbons Difficulty: Easy 48.

Rank the following carbanions in order of increasing pKa.

A. B. C. D. E.

I < II < III II < III < I III < II < I III < I < II II < I < III

Answer: A Learning Objective: 9.3 Discuss the reasons for the enhanced acidity of acetylene and terminal alkynes compared to other hydrocarbons Difficulty: Easy 49.

Give the hybridization for the carbanion in the acetylide ion.

A. B. C. D. E.

sp sp2 sp3 s2p s2p2

Answer: A

Learning Objective: 9.3 Discuss the reasons for the enhanced acidity of acetylene and terminal alkynes compared to other hydrocarbons Difficulty: Easy 50.

A. B. C. D. E.

Rank the following bases in order of decreasing basicity.

III > I > V > II > IV III > V > IV > I> II V > I > III > II > IV III > IV > II > V > I IV > II > I > III > V

Answer: B Learning Objective: 9.3 Discuss the reasons for the enhanced acidity of acetylene and terminal alkynes compared to other hydrocarbons Difficulty: Easy 51.

A. B. C. D. E.

Rank the following acids in order of decreasing acidity.

V > I > IV > II > III III > IV > II > I > V V > I > III > II > IV I > IV > V > II > III IV > I > V > II > III

Answer: D Learning Objective: 9.3 Discuss the reasons for the enhanced acidity of acetylene and terminal alkynes compared to other hydrocarbons Difficulty: Easy

52.

Which of the circled hydrogen atoms is the most acidic?

A. B. C. D. E.

I II III IV V

Answer: E Learning Objective: 9.3 Discuss the reasons for the enhanced acidity of acetylene and terminal alkynes compared to other hydrocarbons Difficulty: Easy

53. A. B. C. D. E.

Sodium amide (NaNH2, sodamide) reacts with terminal alkynes as a ____. Brønsted acid Brønsted base reducing agent catalyst electrophile

Answer: B Learning Objective: 9.3 Discuss the reasons for the enhanced acidity of acetylene and terminal alkynes compared to other hydrocarbons Difficulty: Easy 54. A. B. C. D. E.

Which of the bases below would quantitatively deprotonate a terminal alkyne? BuLi NH3 NaOH NaOCH2CH3 t-BuOK

Answer: A Learning Objective: 9.3 Discuss the reasons for the enhanced acidity of acetylene and terminal alkynes compared to other hydrocarbons Difficulty: Easy

55.

A. B. C. D. E.

Which of the bases below would result in the most complete deprotonation of the alkyne, shown in the reaction below?

NaOCH2CH3 (sodium ethoxide) t-BuONa (sodium tert-butoxide) NaH (sodium hydride) NaHCO3 (sodium bicarbonate) NaOH (sodium hydroxide)

Answer: C Learning Objective: 9.3 Discuss the reasons for the enhanced acidity of acetylene and terminal alkynes compared to other hydrocarbons Difficulty: Easy 56.

A. B. C. D. E.

Which statement below best explains why the Ka of acetylene is greater than that of ethylene? Acetylide anions are resonance stabilized. The 4  electrons of the acetylide anion better stabilize a negative charge. The electronegativity of sp carbons is greater than that of sp2 carbons. The electronegativity of sp carbons is less than that of sp2 carbons. Acetylene has only two hydrogen atoms while ethylene has four.

Answer: C Learning Objective: 9.3 Discuss the reasons for the enhanced acidity of acetylene and terminal ...