The effect of boric acid on the dehydration step in the formation of oxime from salicylaldehyde

Abstract

Boric acid accelerates notably the reaction rate of oxime formation from salicylaldehyde. The kinetic results and the UV spectroscopic analysis, which demonstrate no complex formation between salicylaldehyde and boric acid, suggest that the effect of boric acid is on the transition state of the dehydration step of the reaction via its complexation with the neutral addition intermediate formed by a rapid equilibrium between salicylaldehyde and hydroxylamine. The mechanism proposed is different from that previously suggested.