Identification of hydrogen peroxide as the autoxidation product of N-phenyl-2-propyl-3,5-diethyl-1,2-dihydropyridine

Abstract

Recently, dihydropyridines have been used as autoxidizable materials in novel air-activated adhesives. The dihydropyridines react with air to produce peroxide species, which are capable of initiating free radical polymerization of methacrylates. It is proposed that N-phenyl-2-propyl-3,5-diethyl-1,2-dihydropyridine undergoes autoxidation in the presence of glacial acetic acid, yielding a pyridinium ion and an unknown peroxide product. Employing a variety of analytical techniques, including polarography, spectrophotometry and an enzyme-based biosensor, it has been shown conclusively that hydrogen peroxide is generated in the autoxidation of this dihydropyridine. An aqueous extraction procedure was utilized to remove the hydrogen peroxide from an organic matrix and also to eliminate any interference from the dihydropyridine in the analysis procedure.