Question

Treatment of an $\alpha ,\beta$-unsaturated ketone with basic aqueous hydrogen peroxide yields an epoxy ketone. The reaction is specific to unsaturated ketones; isolated alkene double bonds do not react. Propose a mechanism.

Short answer

Epoxidation of alpha and beta-unsaturated ketone is carried out by various reagents like hydrogen peroxide under very strong basic conditions.

Strong bases NaOH, KOH & K₂CO₃ are used.

Peroxide generally attacks the carbon-carbon double bond and epoxide form.

Step-by-step solution

Epoxidation of alpha, beta-unsaturated ketones

Epoxidation of alpha and beta-unsaturated ketone is carried out by various reagents like hydrogen peroxide under very strong basic conditions.

Strong bases NaOH, KOH & K₂CO₃ are used.

Peroxide generally attacks the carbon-carbon double bond and epoxide form.

Mechanism of the given reaction

In the given reaction first acidic hydrogen of hydrogen peroxide is abstract by the base and we get an anion O-O-H

In the next step, the anion form is attacked on the carbon-carbon double bond and we get epoxide on the $\alpha ,\beta$unsaturated double bond as shown in the mechanism.