By F. P. GINTZ, D. R. GODDARD, and (in part) M. J. COLLIS.Nitryl chloride, in various solvents a t room temperature and below, chlorinates (rather than nitrates) toluene, mand p-xylene, and mesitylene, although not benzene. The extent of chlorination was measured and the products isolated.With polar solvents, in which nitryl chloride forms yellow solutions, the chlorinating agent is probably free chlorine produced by the reaction of nitryl chloride with traces of water. With the less polar solvents, i n which nitryl chloride forms colourless solutions, it is probably the nitryl chloride molecule itself.The kinetics of chlorination in nitromethane-ether were studied by dilatometric and chemical techniques. With the aromatic compound in excess, the reaction velocity was of the first order. The rate increased markedly with increase in the reactivity of the hydrocarbon and with increase in the polarity of the solvent. These facts are consistent with a mechanism involving a bimolecular attack by a chlorine molecule on the aromatic compound.THE formula of nitryl chloride, NO,Cl, suggests that it could either nitrate or chlorinate aromatic compounds. Gillespie and Millen predicted the following series of nitrating agents of increasing power, on the basis that the efficiency of X*NO, depends on the electron affinity of X: EtO-NO, < HO*NO, < AcO-NO, < NO,*NO, < Cl*NO, < H,O+*NO, < NO,+. The order is also that of the increasing strength of the acid HX.They expected, therefore, that nitryl chloride should be a very reactive nitrating agent, even more powerful than dinitrogen pentoxide. Similarly, chlorinating agents could be arranged in order of reactivity, the efficiency of the agent Y*Cl increasing with the electron * Part I, preceding paper.
