Chapter 20, Problem 28A

Interpretation Introduction

Interpretation:

The definition of alkynes and structural feature that characterizes alkyne should be explained. Also, the general formula of alkynes should be determined.

Concept Introduction:

Alkynes are unsaturated hydrocarbons that contains carbon-carbon triple bond (multiple bond) and hydrogen atoms in the structure.

Explanation of Solution

Alkynes are acyclic unsaturated hydrocarbons containing at least one carbon-carbon triple bond ( $\text{C}\equiv \text{C}$ ). Thus, alkynes are characterized by the presence of carbon-carbon triple bond in the structure.

Structural features of alkynes:

• Alkynes are highly unsaturated hydrocarbons.
• A pair of hydrogen atom should be removed from the alkenes to get alkynes.
• Containing at least one carbon-carbon triple bond ( $\text{C}\equiv \text{C}$) in the structure.

The general molecular formula of alkynes is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$ (where n = number of carbon atoms). For example, acetylene (ethyne) that contains 2 carbon atoms and has general formula ${\text{C}}_2{\text{H}}_{\text{2}}$ .