(A) Reaction of aldehyde and ketones with hydroxylamine gives oximes. The nucleophilicity of nitrogen on hydroxylamine is increased in the presence in oxygen. Methanal reacts with hydroxylamine to give oxime.
(B) Water is added to aldehyde and ketones to form geminal-diol. In a similar reaction alcohols add reversely to aldehyde and ketones to form hemiacetals. (C) Acetone azine can be prepared from acetone and hydrazine. The hydrazone then condense with molecule of acetone to produce azine. (D) A Schiff base is a compound with the general structure containing amine R1R2C=NR′. It is used as catalysts, pigments etc.