Electrochemical and Spectrometric Study of Reactivity of Orthophthalaldehyde with Hydroxylamine: Mechanistic Considerations

Abstract Orthophthalaldehyde ( o ‐phthalaldehyde, OPA) is a broadly used biologically, synthetically and analytically significant compound. Its properties are connected with its reactivity towards nucleophiles, namely amines in aqueous – mostly basic – solutions. Since the reaction mechanisms of OPA and amine condensation are complicated, strongly depending on the amine structure and, therefore, a systematic study of this kind of reaction is presented. Structure activity relationships based on amine structure and their application in reaction optimization are reported. The present paper deals with reaction of OPA with hydroxylamine which is monitored electrochemically and spectrometrically. The mechanism was formulated on the basis of detailed analysis of electrochemical behavior, of the interception of the intermediate (phthalaldehyde mono‐oxime) and of the isolation and identification of the main product (1 H ‐2,3‐benzoxazin‐1‐ol).