Effects of Surfactants on the Oxidative Deamination of Amines by Coenzyme PQQ

Abstract

The effects of surfactants on the oxidative deamination of amines by coenzyme PQQ (1) were studied. The cationic micelle provides a good environment for the oxidation, and enhancement of the rate in the oxidation of cyclohexylamine (more hydrophobic substrate) is much greater than that in the oxidation of benzylamine. Amphoteric (13), (14), nonionic (15), and anionic surfactants (16) are not effective. The rate of the oxidation is remarkably retarded using the cationic surfactants (7) and (8) having shorter lipophilic groups, and bulky N-substituents of the surfactants (10), (11), and (12) are also undesirable for the reaction. As a counter anion, bromide ion is better than chloride ion. Furthermore, hydrophobic PQQ-models (3) and (5) do not have as high reactivities as PQQ. The oxidation is thus considered to proceed in the electrostatic layer of the micellar surface.