Kinetics and mechanism of the denitrosation of a nitrosamine and a trionitrite

Abstract

The work described in this thesis is concerned with the denitrosation of N-methyl-N-nitroeniline (NMNA) and a thionitrite (derived from N-acetyl D,L-penicillamine).The effect of addition of various nucleophiles on the denitrosation reaction of NMNA was examined extensively at three different acidities in the presence of high concentrations of sodium azide to cut out the reverse reaction. The values of k(_1)[H(^+)] (which were obtained from the double reciprocal plots) are constant at any one acidity for different nucleophiles and increase with acidity as expected. The slopes increase as the acidity decreases. The ratio k(_-1)/k(_2) is nearly the same for the same nucleophiles at different acidities, and activity of nucleophiles is found as expected. An was also carried out of the denitrosation of a thionitrite. The general form for the rate of equation was established and the relative reactivity of different nitrite traps measured. Nucleophilic catalysis was observed for the following nucleophiles in increasing order of reactivity H(_2)O < C1 < Br < SC(NH(_2))(_2) < SCN. The reaction mechanism is similar to that proposed for the denitrosation of nitrosamines and also of alkyl nitrites. The thionitrite is approximately 10(^6) less reactive than a corresponding alkyl nitrite; this is probably due to the much smaller basicity of the sulphur protonation site compared with oxygen.