Deck 9: Alkynes

Question 1

What is the IUPAC name of the following compound?

A) 5-propyl-3-heptyne
B) 5-isopropyl-3-heptyne
C) 5-ethyl-3-octyne
D) 4-ethyl-5-octyne

Answer 1

5-ethyl-3-octyne

Question 2

Which of the following describes the orbital overlap of the $\mathrm{C}(1)-\mathrm{C}(2)$ sigma bond of 1-butyne, shown below?

A) $\mathrm{sp}-\mathrm{sp}$
B) $\mathrm{sp}^{2}-\mathrm{sp}^{2}$
C) $\mathrm{sp}^{3}-\mathrm{sp}^{3}$
D) $2 \mathrm{p}-2 \mathrm{p}$

Answer 2

$\mathrm{sp}-\mathrm{sp}$

Question 3

Select the best base to quantitatively remove a proton from acetylene.

A) $\mathrm{NaNH}_{2}$
B) $\mathrm{NH}_{3}$
C) $\mathrm{NaOH}$
D) $\mathrm{NaOCH}_{2} \mathrm{CH}_{3}$

Answer 3

$\mathrm{NaNH}_{2}$

Question 4

Predict the major product(s) in the reactions below.

A) 1-nonyne
B) 2-nonyne
C) cis-2-nonene
D) trans-2-nonene

Question 5

Which one of the following alkynes gives a single ketone in the acid-catalyzed hydration of each?

A) 2-decyne
B) 3-decyne
C) 4-decyne
D) 5-decyne

Question 6

Which sequence of reactions works best in synthesizing cis-3-nonene?

A) A
B) B
C) C
D) D

Question 7

Which sequence of reactions below works best in carrying out the following conversion?

A) (1) $\mathrm{HBr}(2)$ excess $\mathrm{NaNH}_{2}$
B) (1) $\mathrm{Br}_{2}$ (2) excess $\mathrm{NaNH}_{2}$
C) (1) $\mathrm{Br}_{2}, \mathrm{H}_{2} \mathrm{O}$ (2) excess $\mathrm{NaNH}_{2}$
D) (1) $\mathrm{H}_{2} \mathrm{O}, \mathrm{H}_{2} \mathrm{SO}_{4}$ (cat.) (2) excess $\mathrm{NaNH}_{2}$

Question 8

Which of the following is the enol intermediate in the acid-catalyzed addition of water to propyne?

A)

B)

C)

D)

Question 9

Identify compound $\mathrm{Y}$ .

A) 2-bromobutane
B) meso-2,3-dibromobutane
C) racemic (2R,3R) and (2S,3S)-2,3-dibromobutane
D) 2,3-dibromo-2-butene

Question 10

What is the major product of the reaction shown below?

A) 1,1-dichlorobutane
B) 2,2-dichlorobutane
C) 1,2-dichlorobutane
D) 1,12,2-tetrachlorobutane

Question 11

Why can't methanol, $\mathrm{CH}_{3} \mathrm{OH}$ , be used as a solvent for sodium amide, $\mathrm{NaNH}_{2}$ ?

A) Sodium amide is nonpolar and methanol is polar.
B) Sodium amide is polar and methanol is nonpolar.
C) Sodium amide does an acid-base reaction with methanol.
D) There would be no ion-dipole attractive forces between the two compounds.

Question 12

Ozonolysis of an alkyne gave the two compounds shown below. What is the IUPAC name of the original alkyne?

$\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}$ and $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCO}_{2} \mathrm{H}$

A) 2,2-dimethyl-3-octyne
B) 2,2-dimethyl-3-heptyne
C) 3,3-dimethyl-4-octyne
D) 6,6-dimethyl-3-heptyne

Question 13

Which of the following ketones cannot be made by the acid-catalyzed hydration of an alkyne?

A)

B)

C)

D)

Question 14

Is the proposed synthesis of cyclohexanone below likely to work? If not, why not?

A) Yes, it would work.
B) No, you would need to start with 1, 2-dibromocyclohexane.
C) No, cyclohexyne will not form.
D) No, the enol of cyclohexanone cannot be formed from cyclohexyne.

Question 15

What major product results from this reaction?

A)

B)

C)

D)