Reaction of Phthalaldehyde with Aminoethanol under Different Conditions: Products and Mechanisms of Their Formation

Analysis of amino acids and very efficient disinfection procedures are based on the reaction of phthalaldehyde (OPA) with primary amines. In this contribution, aminoethanol (=kolamin) as a nitrogen-containing nucleophile was used for the investigation of its reaction mechanism with OPA performed in basic aqueous buffered media (pH 9.5), where an influence of hydration or solvation is expected, and in anhydrous acetonitrile. Depending on the detailed reaction conditions, seven products were isolated and their structures determined by NMR, mass spectrometry, and X-ray structure analysis. Reaction mechanisms are proposed, which involve hydride transfers to OPA (Cannizzaro-type reaction).