Photolyses of N-nitrosamides in acidic and neutral media.

Photolyses of several N-nitrosamides in acidic and neutral media were studied. The photochemical decomposition of II-nitrosanides was found to involve exclusively nitrogen-nitrogen bond cleavage of the IT-nitrosamide group in contrast to the pyrolytic decomposition which involved cleavage of the acyl nitrogen bond. In acidic media, photolyses of rl-nitrosamides led to the light catalyzed denitrosation of the N-nitrosamides by photo-elimination of the [WOH] group with the formation of alkylidenimides. The alkylidenimides underwent secondary reactions to give the corresponding aldehydes. The photo-elimination products were identified as the 2 ,4-dinitrophenyl-hydrazones of the aldehydes. In neutral media, the primary photolytic process of H-nitrosa.nides was the .formation of nitroso and amide radicals. The amide radical v/as found to abstract intramolecularly a $ hydrogen atom attached to the carbon atom in the S-position^ to give a S-carbon radical. This S-carbon radical then coupled with the nitroso radical to give a C-nitroso compound which either tautomerized to form oxime or dimerized. Alternatively the amide radical underwent elimination of an alpha hydrogen to give the alkylidenimide as an intermediate. if The S-position was numbered in reference to the nitrogen atom of the amide group. For examole , the for vula of & -nitroso-n-hexylformamide would be N=0 0 Ill