Nitrosation, diazotisation, and deamination. Part XII. The kinetics of N-nitrosation of N-methylaniline

Abstract

The rate and kinetic form of the N-nitrosation of N-methylaniline with nitrous acid in aqueous perchloric acid (0·002–6·5M) are similar to those observed for the diazotisation of aniline over the same range of acidity. At acidities below about 1M, the nitrosation of the free amine by nitrous anhydride provides the most important reaction path but, as the acidity is increased, this is supplanted by a strongly acid-catalysed mechanism which we attribute to the attack of a positive nitrosating agent on the protonated amine. The similarity of the nitrosation results with the diazotisation results shows that N-nitrosation is the rate-determining stage of diazotisation over the whole of this range of acidity.