A study of the reaction mechanism of 3-nitro-4-R-furoxans formation by nitrosation of dipotassium salts of 1-hydroxyimino-2,2-dinitro-1-R-ethanes.

The mechanism proposed earlier for explanation of the furoxan ring formation in the nitrosation of dipotassium salts of 1-hydroxyimino-2,2-dinitro-1-R-ethanes with NaNO/AcOH was confirmed experimentally by determining the ionization constants of the dinitromethyl and oxime fragments in the starting dipotassium salt and by examining H, C, N, and N NMR and mass spectra of isomeric 3(4)-nitro-4(3)-R-furoxans with the N(5) and N(2) ring atoms, respectively, and 3,4-diarylfuroxan with both N-labeled ring atoms. A comparative analysis of the IR and Raman spectra of the N-labeled furoxan derivatives obtained and their unlabeled analogs allowed refinement of the literature data on interpretation of the vibrational spectra of furoxan derivatives. [ABSTRACT FROM AUTHOR]