Metachloroperbenzoesäure

Metachloroperbenzoesäure, often abbreviated as m-CPBA, is an organic compound with the chemical formula ClC₆H₄CO₃H. It is a peroxycarboxylic acid, a class of compounds characterized by the presence of a carboxyl group attached to an oxygen-oxygen single bond. m-CPBA is a white crystalline solid that is relatively stable but can decompose exothermically, especially when impure or heated. It is commonly used in organic synthesis as a mild oxidizing agent.

The primary application of m-CPBA in organic chemistry is its ability to perform epoxidation reactions. It reacts with alkenes to form epoxides, which are three-membered cyclic ethers. This reaction proceeds via a concerted mechanism where the peroxy acid transfers an oxygen atom to the double bond. m-CPBA is also effective for the Baeyer-Villiger oxidation, converting ketones into esters. Furthermore, it can be used to oxidize sulfides to sulfoxides and sulfones, and amines to amine oxides.

m-CPBA is commercially available and is often preferred for its selectivity and ease of handling compared to other peroxy acids. However, due to its oxidizing nature, it should be handled with care. It is typically dissolved in a suitable organic solvent, such as dichloromethane, for reactions. The reaction byproduct is 3-chlorobenzoic acid, which can often be removed by aqueous washes.