Question

A tertiary amine reacts with hydrogen peroxide to form a tertiary amine oxide.

Tertiary amine oxides undergo a reaction similar to the Hofmann elimination reaction (Section 10.10), called a Cope elimination. In this reaction, a tertiary amine oxide, rather than a quaternary ammonium ion, undergoes elimination. A strong base is not needed for a Cope elimination because the amine oxide acts as its own base.

Does the Cope elimination have an alkene-like transition state or a carbanion-like transition state?

Short answer

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Cope elimination transition state is an alkene-like transition state.

Step-by-step solution

..Cope elimination

In E2 mechanism, there is a single transition state as bond-breaking and bond-making occur simultaneously. Here as bonds are being broken simultaneously double bond formation starts occurring.

Cope elimination transition state

Cope elimination transition state is an alkene-like transition state as here double bond start developing when bonds are being broken because it follows E2 elimination.