Question

Question: What steps are needed to prepare phenylacetylene, ${\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{5}}\mathbf{C}\mathbf{\equiv }\mathbf{CH}$, from each compound:

$$\begin{gathered} a.{\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CHBr}}_{\mathbf{2}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}} \\ \mathbf{b}\mathbf{.}\mathbf{}\mathbf{}{\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{CHBrCH}}_{\mathbf{3}} \\ \mathbf{c}\mathbf{.}\mathbf{}\mathbf{}{\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{OH}}_{\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}} \end{gathered}$$

Short answer

Answer

Step-by-step solution

Step-by-Step SolutionStep 1: Preparation of alkynes from alkyl halides

The alkynes can be prepared by the elimination reactions by using a strong base. A strong reaction with an alkyl halide is able to abstract two equivalents of hydrogen halide to produce the alkynes.

The two successive E2 elimination reactions take place in order to produce the alkynes from the vicinal or geminal dihalides.

The preparation of the given compounds

1. The phenylacetylene can be prepared by using the compound a in the following way:

b. The phenylacetylene can be prepared by using the compound b by the following reaction

c. The phenylacetylene can be prepared by using the compound c by the following