Comments on: m-CPBA (meta-chloroperoxybenzoic acid)

By: James Ashenhurst

James Ashenhurst — Wed, 20 May 2026 00:24:35 +0000

In reply to X.O..

There’s free rotation about the bond, so it can be drawn in many different ways and is still equivalent.

Like drawing a stick figure of a person with an arm up instead of arm down. Still the same person, it’s just that the arm can move.

By: X.O.

X.O. — Tue, 19 May 2026 10:54:43 +0000

Hi! Different database shows different 3D structures of m-CPBA, especially for the position of the hydrogen interested. Is that really flexible, or it should be close to the carboxyl group?

By: James Ashenhurst

James Ashenhurst — Tue, 31 Oct 2023 03:18:52 +0000

In reply to Xiaobing. Well, after one epoxidation of the diene you'll still have an alkene. It won't be as reactive as the diene, but it is still capable of undergoing epoxidation.

By: James Ashenhurst

James Ashenhurst — Tue, 31 Oct 2023 03:18:00 +0000

In reply to Jessica Reel. Yes - it will, sorry, I should have put that in there!

By: Jessica Reel

Jessica Reel — Mon, 30 Oct 2023 22:56:15 +0000

For the epoxidation of the cis alkene, would product (B) also form as a mixture of enantiomers? Thank you for a wonderful site.

By: Xiaobing

Xiaobing — Sun, 29 Oct 2023 01:40:54 +0000

for 1,3-cyclohexadiene reacts with peroxyacetic acid to form epoxide, there is very small amount of diepoxide formed (further epoxidation of monoepoxide). What’s the reason for that?

By: James Ashenhurst

James Ashenhurst — Thu, 24 Aug 2023 01:01:26 +0000

In reply to nafiz. mCPBA is the electrophile in this reaction and the alkene is the nucleophile. In the transition state, the C-C pi bond is breaking and there are partial positive charges on the alkenyl carbons. So groups bonded to the alkenyl group that help to stabilize the positive charges will lead to a more stable (lower energy) transition state, accelerating the reaction.

By: nafiz

nafiz — Wed, 23 Aug 2023 08:03:59 +0000

electron donating group increase the rate of epoxidation of an alkene with perbenzoic acid. explain

By: James Ashenhurst

James Ashenhurst — Fri, 02 Dec 2022 03:33:20 +0000

In reply to Sisira. It depends! I once used mCPBA in a reaction which had a diene and two ketones. The diene was electron poor (connected to an ester) and only one of the ketones was really accessible. So it did a Baeyer-Villiger!

By: James Ashenhurst

James Ashenhurst — Fri, 02 Dec 2022 03:32:02 +0000

In reply to Lohi. Just quench with bisulfite to get rid of the oxidant, acidify and extract. You can run columns on carboxylic acids if you acidify your eluent.