Hydrolysis and chemiluminescence of diazaquinones

Abstract

1. The hydrolysis of 6-dimethylamino-1,4-dihydrophthalazine-1,4-dione at pH 6-13 leads to four principal products: 4-dimethylaminophthalhydrazide, 4-dimethylaminophthalic acid, and 4- and 5-dimethylamino-2-formylbenzoic acids, with various ratios of the products depending on the pH. 2. Proof has been obtained for the formation, in the hydrolysis process, of a relatively long-lived (from milliseconds to seconds) intermediate, for which the acyldiazene structure has been proposed (a mixture of two isomers of 4- and 5-dimethylamino-2-carboxybenzoyldiazenes). 3. In alkaline media, the acyldiazene chemiluminesces in the presence of O2 and is probably responsible for the chemiluminescence of the diazaquinone in the presence of OH− and O2. 4. The formation of the hydrazide in the process of diazaquinone hydrolysis takes place because of reduction of the diazaquinone by the acyldiazene. 5. In the presence of H2O2 acyldiazene does not show chemiluminescence. Chemiluminescence of diazaquinone under the influence of alkaline H2O2 is connected with a direct reaction: diazaxinone + HO2−; here part of the diazaquinone is reduced to hydrazide.