Nitrosation of aniline by N2O4

Kinetics of nitrosation of aniline by N2O4 in donor non-aqueous solvents, e.g. acetonitrile, ethylacetate and a 1:1 v/v mixture of both, have been studied. The reaction is first-order with respect to N2O4 and zero-order with respect to aniline in each of the donor solvents added. The average observed order of k values is ethylacetate (7.195 × 10–3) > acetonitrile (4.773 × 10–3) > 1.1 v/v acetonitrile + ethylacetate mixture (3.216 × 10–3 s–1).The variation of k values in the different solvents is interpreted in terms of solvation ability of the solvents. Conductivity measurements and u.v. studies of N2O4 solutions are reported. Both the initial and integral rate methods show that the rate-determining step is the one which involves the formation of the nitrosating agent, NO+, from N2O4. Accordingly a mechanism of nitrosation is proposed.