The results of kinetic measurements of the diazotization of aniline in 0.1 mol/l sulphuric acid, were combined with equilibrium data of the dissociation of the anilinium ion, and of nitrosyl-sulphuric acid. The specific rates for the rate-determining reaction, and the quantities AG*, AH* and AS* were calculated. These were compared with the corresponding data for the nitrosation of aniline by nitrosyl chloride. From the values of k', of the activation energy, and of AH?, it was concluded that the diffusion of the reactants is of importance as a rate-determining process.
INTRODUCT'ONA. Hantzsch and M. Schumann(') were the first to measure the velocity of diazotization. They came to the following rate equation, for the diazotization of aniline in dilute acid solutions: d(C6H5Nl)/dt = k,[C6H,NH:] [HN02] (1) Other authors (' ) came to the same conclusion. H. Schmid and G. Muhr (3) found the following rate equation for the diazotization of aniline in dilute sulphuric acid solutions (0.1-0.2 moles/liter): d(C6H5Nl)/dt = k2[C6H5NH:] [HN0212/[H'] (2) (*) In cooperation with A. F. El-Nagaawi. (I) A. HANTZSCH and M. S C~M A N N ,