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 terminal alkynes has greater s character, stabilizing the negative charge on the conjugate base.

Question 2

What is the major organic product when 1-hexyne is treated with disiamylborane (Sia$_2$BH) followed by H$_2$O$_2$/NaOH?

Accepted Answer

Hexanal

Question 3

Which reagent would you use to selectively reduce an alkyne to a cis-alkene?

Accepted Answer

Lindlar's catalyst

Question 4

A student attempts to synthesize 3-decyne from acetylene using NaNH$_2$ and two alkyl halides. Which sequence of alkyl halides should be used?

Accepted Answer

Ethyl bromide followed by hexyl bromide

Question 5

Which of the following best describes the product of mercuric ion-catalyzed hydration of a terminal alkyne?

Accepted Answer

A methyl ketone via keto-enol tautomerism

Question 6

What is the expected product when 2 moles of HBr are added to 2-butyne?

Accepted Answer

2,2-dibromobutane

Question 7

Which of the following statements about the molecular geometry of acetylene is correct?

Accepted Answer

Acetylene is linear because both carbons are sp-hybridized.

Question 8

Which base is strong enough to deprotonate a terminal alkyne?

Accepted Answer

NaNH$_2$

Question 9

What is the major product when pent-2-yne is treated with warm, basic KMnO$_4$?

Accepted Answer

Two carboxylic acids: acetic acid and propionic acid

Question 10

Which of the following best describes the result of ozonolysis of an internal alkyne?

Accepted Answer

Two carboxylic acids

Question 11

A terminal alkyne reacts with HBr in the presence of peroxides. What is the major product?

Accepted Answer

A vinyl bromide with anti-Markovnikov orientation

Question 12

Which of the following is true about the addition of Cl$_2$ to an alkyne?

Accepted Answer

Two moles of Cl$_2$ can add, forming a tetrahalide.

Question 13

Which of the following is the correct IUPAC name for the compound CH$_3$CH$_2$C≡CCH$_3$?

Accepted Answer

2-pentyne

Question 14

What is the product when an acetylide ion attacks a ketone followed by protonation?

Accepted Answer

A tertiary alcohol

Question 15

Which of the following best describes the bond lengths in acetylene compared to ethene and ethane?

Accepted Answer

The C–C bond in acetylene is shorter than in ethene and ethane.

Question 16

Which of the following functional groups has higher priority than an alkyne in IUPAC nomenclature?

Accepted Answer

Alcohol

Question 17

What is the major product when but-1-yne is treated with HgSO$_4$ and H$_2$SO$_4$?

Accepted Answer

Butan-2-one

Question 18

Which of the following best describes the result of catalytic hydrogenation of an alkyne using Pd/C?

Accepted Answer

The alkyne is completely reduced to an alkane.

Question 19

Which of the following is a correct statement about keto–enol tautomerism in alkynes?

Accepted Answer

The enol and keto forms are structural isomers in equilibrium.

Alkynes: Structure, Properties, Synthesis, and Reactions

Study Guide - Practice Questions