Exploratory study of diazoketones as spin traps for nitric oxide†

Abstract

2-Diazocycloheptanone traps nitric oxide to produce a mixture of radicals consisting mainly of the (Z)-iminoxyl radical together with minor amounts of the (E)-iminoxyl radical, a dialkyl aminoxyl and an acyl aminoxyl. Best EPR spectra have been obtained from solutions in tert-butylbenzene which give signals lasting for several hours in the dark. Nitric oxide in aqueous solution could be detected by means of the EPR spectrum obtained on extraction with a tert-butylbenzene solution of the spin trap. Nitric oxide release by isoamyl nitrite has been disclosed with the same spin trap although, under photolytic conditions, the spectrum is dominated by the dialkyl aminoxyl. The main stable product from the reaction of nitric oxide with 2-diazocycloheptanone has been found to be cyclohexanecarboxylic acid. Satisfactory EPR spectra were not obtained from nitric oxide using 5-diazouracil as spin trap in aqueous solution.