Mechanism of the Baudisch reaction was investigated using semicarbazide hydrochloride in lieu of hydroxylamine hydrochloride which is one of the reacting components. It was suggested that pyrocatechol-copper-hydroxylamine complex formed as a reaction intermediate is oxidized to o-benzoquinone-copper complex by hydrogen peroxide and one of the carbonyl groups of o-benzoquinone reacts with hydroxylamine hydrochloride to give ...