Q52E - Organic Chemistry (Mcmurry)

Question

1-Octen-3-ol, a potent mosquito attractant commonly used in mosquito traps, can be prepared in two steps from hexanal, ${\mathbf{CH}}_3{\mathbf{CH}}_2{\mathbf{CH}}_2{\mathbf{CH}}_2{\mathbf{CH}}_2\mathbf{CHO}$ . The first step is an acetylide-addition reaction like that described in Problem 9-50. What is the structure of the product from the first step, and how can it be converted into 1-octen-3-ol?

Step-by-Step Solution

Answer

Step 1: Addition of acetylide anion

The structure of acetylide anion is ${}^{-}\mathbf{C}\equiv \mathbf{CH}$.

When this acetylide anion is added to the carbonyl group then $\mathrm{C}=\mathrm{O}\to \mathrm{C}-\mathrm{OH}$. The Carbonyl group gives a nucleophilic addition reaction. The acetylide anion adds to the carbonyl group.

Step 2: Mechanism of reaction

Hexanal is reacted with acetylide anion to give alkyne intermediate. Which on further reaction with 1 equivalent of ${\mathrm{H}}_2$gives 1-Octen-3-ol.

Mechanism of reaction