Proton Transfer in Solid State: Mechanochemical Reactions of Imidazole with Metallic Oxides

Mechanochemical reactions of crystalline imidazole with 23 metallic oxides have been studied by milling in a mortar and in ball mill vibrators of low and high mechanical intensity. The reactions were monitored by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. ZnO, HgO, Ag2O, and Cu2O react rather readily in the mortar, forming the corresponding imidazolates but CdO, Ga2O3, and In2O3 require intense mechanical milling to transform. CuO and NiO do not react immediately but turn bluish after a few months of aging. The oxides of Mg(II), Ca(II), Be(II), Al(III), Fe(II), Co(II), Co(III), Pb(II), Eu(III), Ce(III), Bi(III), Ti (IV), Zr(IV), and Sn(IV) are inert to imidazole even on strong milling for several hours.