Question 1

Which of the following statements best explains why terminal alkynes are more acidic than alkenes and alkanes?

Accepted Answer

The sp hybridized carbon in alkynes stabilizes the negative charge on the conjugate base due to higher s character.

Question 2

What is the correct IUPAC name for the following compound: a seven-carbon chain with a triple bond between carbons 3 and 4, a methyl group on carbon 2, and a bromo group on carbon 6?

Accepted Answer

6-bromo-2-methyl-3-heptyne

Question 3

Which of the following bases is strong enough to deprotonate a terminal alkyne?

Accepted Answer

Amide ion ($$\mathrm{NH_2$^-})$$

Question 4

Which product is formed when 1-hexyne is treated with excess bromine ($$\mathrm{Br_2$}) in $$dichloromethane?

Accepted Answer

A tetrabromoalkane

Question 5

What is the major product when 2-butyne is subjected to catalytic hydrogenation using Lindlar’s catalyst?

Accepted Answer

cis-2-butene

Question 6

Which of the following statements about the addition of hydrogen halides to alkynes is correct?

Accepted Answer

In the presence of peroxides, the addition can follow anti-Markovnikov selectivity.

Question 7

Which reagent would you use to convert a terminal alkyne into a methyl ketone via hydration?

Accepted Answer

$$\mathrm{$$HgSO_4$$}$$, $$\mathrm{H_2SO_4}$$, $$\mathrm{H_2O}$$

Question 8

Which of the following best describes the geometry around the carbon atoms in an alkyne?

Accepted Answer

Linear

Question 9

What is the product of the reaction between a terminal alkyne and formaldehyde followed by aqueous workup?

Accepted Answer

A primary alcohol

Question 10

Which of the following statements about the oxidative cleavage of alkynes with potassium permanganate ($$\mathrm{$$KMnO_4$$}) is $$correct?

Accepted Answer

Terminal alkynes yield a carboxylic acid and formic acid.

Question 11

Which of the following best explains why alkynes undergo nucleophilic addition reactions more readily than alkenes?

Accepted Answer

Alkynes have a higher electron density in their $$\pi$$ bonds.

Question 12

Which of the following is a correct statement about the reaction of acetylide ions with alkyl halides?

Accepted Answer

Acetylide ions react best with methyl or primary alkyl halides.

Question 13

Which of the following is the correct order of acidity (from most acidic to least acidic) for the following types of hydrogens: alkyne, alkene, alkane?

Accepted Answer

Alkyne \u003e Alkene \u003e Alkane

Question 14

What is the product of the reaction of 1-hexyne with $$\mathrm{$$NaNH_2$$}$$ followed by $$\mathrm{CH_3I}$$?

Accepted Answer

1-heptyne

Question 15

Which of the following reagents would you use to selectively reduce an alkyne to a trans-alkene?

Accepted Answer

$$\mathrm{Na} in$$ $$\mathrm{NH_3$} ($$liquid ammonia)

Question 16

Which of the following best describes the product of hydroboration-oxidation of a terminal alkyne using $$\mathrm{(Sia)_2BH}$$ followed by $$\mathrm{H_2O_2}$$ and $$\mathrm{NaOH}$$?

Accepted Answer

An aldehyde

Question 17

Which of the following statements about the bond energies of carbon-carbon bonds is correct?

Accepted Answer

A C-C triple bond is stronger than a double bond, but not three times as strong as a single bond.

Alkynes: Structure, Properties, and Reactions

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