The reaction can be extended to aldehydes with catalysis in the presence of ;the reaction mechanism is essentially the same. These compounds areimportant in the synthesis of . The addition is also possible with ; for instance is a reagent in the .
The cyanide ion serves three different purposes in the course ofthis reaction. It acts as a , facilitates protonabstraction, and is also the in the final step. Thebenzoin condensation is in effect a and not acondensation because a small molecule like water is not released inthis reaction. For this reason the reaction is also called abenzoin addition. In this reaction, the twoaldehydes serve different purposes; one aldehyde donates a protonand one aldehyde accepts a proton. 4-Dimethylaminobenzaldehyde isan efficient proton donor while benzaldehyde is both a protonacceptor and donor. In this way it is possible to synthesise mixedbenzoins, i.e. products with different groups on each half of theproduct.
The benzoin condensation is a reaction ..