The action of light on solid humulene nitrosite, C15H24N2O3. Characterization of reaction products, e.p.r. studies and reaction mechanisms

Abstract

Humulene nitrosite (1) exhibits needle and platelet crystalline forms. Photolysis of compound (1) with red light generates N₂, NO, NO₂, dinitrohumulene (2), 1,4,4-trimethyl-8-methylene-9-nitrocycloundeca-1,5-diene (3), isomers (4) and (5) of compound (3) and, in the case of the platelets, caryophyllene derivatives. Several nitroxide radicals are also generated, and changes in their e.p.r. spectra have been monitored as a function of irradiation time. These spectra have been analysed to yield spin-Hamiltonian parameters, and they give information about the molecular structures of the nitroxides and about their formation and decay in the solid. The combination of chemical and spectroscopic evidence enables some of the steps involved in the solid photolysis reaction to be unravelled.