KINETIC, ISOTOPIC, AND N-15 NMR-STUDY OF N-HYDROXYBENZENESULFONAMIDE DECOMPOSITION - AN HNO SOURCE REACTION

Decomposition of N-hydroxybenzenesulfonamide (C6H5SO2NHOH) in alkaline solution to yield N2O and sulfinate (C6H5SO2-) is first order in C6H5SO2NHO-, with rate constant = 2.44 (+/-O.23) x 10(-4) s-1 at 25-degrees-C, DELTA-H(double-dagger) = 94.1 kJ mol-1, and DELTA-S(double-dagger) = 6.64 J K-1 mol-1. The reaction occurs via reversible release of HNO (and/or its conjugate NO-), followed by rapid dimerization of the intermediate to form N2O. It is shown by N-15 tracer methods that this species and the NO- intermediate formed in trioxodinitrate decomposition are capable of codimerization, showing them to be in the same (singlet) electronic state. Protonation of C6H5SO2NHO- brings about a N-15 NMR shift of -28.6 ppm. The free acid and its basic anion exhibit identical, large NOEF values (-4.16), showing that the dissociable hydrogen in C6H5SO2NHOH is bound to oxygen rather than to nitrogen, despite contrary literature reports.