THE BASE-CATALYZED DECOMPOSITION OF NITRAMIDE - MECHANISM OF THE 2ND REACTION PATHWAY

Rates of decomposition of nitramide via a new base-catalyzed reaction pathway, in which the nitronate anion is the reactive species, were measured in aqueous buffer solutions of six monofunctional alcohol, RO-, and two bifunctional gem-diol monoanions, R2C(OH)O-. The monofunctional anion give a good Bronsted relation with the slope beta = 0.44 +/- 0.02, from which the bifunctional anions deviate in a direction that makes them more reactive than predicted. This suggests that the latter are acting as bifunctional acid-base catalysts which donate and remove protons through a cyclic transition state; this hypothesis is supported by differences in entropies of activation for the two kinds of catalyst. Other bases of different charge type show systematic deviations from the Bronsted relation based on the monofunctional anions; these deviations are consistent with electrostatic interactions in the transition state, and a rationalization is offered explaining why these effects are present here but absent in nitramide decomposition by the traditional pathway.