91Ó°ÊÓ

When cyanohydrins are in basic solutions, the OH loses its proton, and the cyano group is eliminated because the O atom would have a partial negative in the transition state.In basic solutions, a cyanohydrin is converted to the carbonyl compound.

1. In this reaction, the HO^- (base) attacks the OH of the starting material, forming a ketone and eliminating cyanide (C ≡ N) occurs in the first step because it is a weak base. In the second step, the cyanide ion adds up the ß-carbon and forms the following product shown below.
   
   Mechanism of the reaction (a)

b. In this reaction, the HO^-(nucleophile) attacks the OH of the starting material, forming a ketone, and the cyanide (C ≡ N) is eliminated because it is a weak base. In the second step, cyanide ion (CN^-) is again added to the ß-carbon and forms the following product shown below.

Product for the reaction (b)