Chapter 27, Problem 51E

Interpretation Introduction

Interpretation:

The method to synthesized $\left(E\right)\text{-}$ and $\left(Z\right)\text{-hept-3-ene}$ from the acetylene should be determined.

Concept introduction:

Alkyne can be reduced to cis-alkenes by the use of Lindlar’s catalyst and alkyne can be reduced to trans-alkenes by the use of ${\text{Na/NH}}_{\text{3}}$ reagent.

Lindlar’s catalyst is a common reducing catalyst used to reduce internal carbon-carbon triple bond to give a cis-alkene. The general reduction reaction is as follows:

Sodium metal in liquid ammonia reduces internal carbon-carbon triple bond to give trans-alkene. The general reduction reaction of internal alkynes is as follows: