Mechanochemically Induced Anion Exchange in Aminoazobenzene Salts

minoazobenzene sulfate salt reacts with the crystals of KBr in solid-state under high pressure yield-ing corresponding bromide salt. The reactant and product differ also in the position of protonation, amino group, and azo group, respectively. Since protonation of azo-group destroys the coplanarity of two benzene rings and diminishes -conjugation, the product differs from the reactant also in color, from orange to violet. Hence, the reaction is the example of the piezochromic effect. This solid-state process is studied by kinetic measurements, and the structures of the compounds were analyzed by X-ray chrystallography