Q27E - Organic Chemistry (Mcmurry)

Question

Epoxides react with Grignard reagents to yield alcohols. Propose a mechanism.

Step-by-Step Solution

Answer

The mechanism followed as:

Step 1: Reaction of epoxide with Grignard reagent

Epoxide on reaction with Grignard reagent opens as an electrophile on the addition of the alkyl group of the Grignard reagent, and the formation of alcohol occurs.

The hydroxyl group and the alkyl group of the Grignard reagent have trans relations with each other.

Step 2: Reaction of given epoxide with Grignard reagent

The given epoxide reacts with the methyl magnesium bromide to form the intermediate called alkoxide because oxygen has a negative charge, followed by hydrolysis so that the negatively charged oxygen gains the proton, and hydroxyl formation occurs.

Step 3: Mechanism

1. React with methyl magnesium bromide

2. Alkoxide formation

3. Hydrolysis