Abstract: Substituted imidazoles and leaving groups known from other areas of chemistry have been tested for catalytic efficiency in the peroxyoxalate chemiluminescence (PO-CL) reaction, using bis(2,4,6-trichlorophenyl)oxalate (TCPO) as reagent. Catalytic activity was found for 1,2,4-triazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole and 4,5-dichloroimidazole, while 2-mercaptioimidazole, 2-nitroimidazole, 4-nitroimidazole, benzimidazole, benzotriazole, thiazole, o-benzoic sulfimide, phthalimide, succinimide, 2(1H)-pyridone and 1,2,3-benzotriazine-4(3H)-one yielded no detectable chemiluminescence under the conditions used. None of the tested compounds was more efficient than imidazole in catalyzing the PO-CL reaction. Spectrophotometric measurements of the catalytic breakdown of TCPO showed that an intermediate was formed with almost all catalysts, and that intermediates that were more stable or present at lower concentration led to a reduced catalytic efficiency in the PO-CL reaction of TCPO.

Abstract: Flow injection electrospray mass spectrometry was used to detect the intermediates and products formed during the reaction of chemiluminescent acridinium salts under the conditions necessary for light emission. A stream of aqueous alkaline hydrogen peroxide was mixed with an aqueous solution of N-sulfonylacridinium-9-carboxamide salt immediately prior to entering the ESI-MS interface. The resulting negative-ion mass spectra corresponded to the expected 9-hydroperoxide adduct, the acridone end product normally seen in the chemiluminescent reaction, and unreacted acridinium salt, with no indication of the postulated spirodioxetanone intermediate or competing pseudobase.