5053

Crossed Cannizzaro reactions can be carried out by using equal molar quantities of two different aldehydes. Often an excess of formaldehyde is used as the aldehyde which is oxidized in such a mixed Cannizzaro reaction. Show the mechanism of this reaction using formaldehyde and any other aldehyde, and indicate what is the practical advantage of this approach.

5234

The sodium ion of the NaBH₄ apparently does not participate in the reduction of a carbonyl group. In hydroxylic solvents (ROH), the proton from the hydroxyl group participates in a mechanism similar to that suggested for the Li ion of LiAlH₄. Draw a picture of the transition state for the NaBH₄ reduction of a carbonyl group.