Reduction of ruthenium(IV) to ruthenium(III) in aqueous-alcoholic solutions of hydrochloric acid under microwave radiation

摘要

The behavior of a kinetically inert form of ruthenium(IV), the #mu#-oxo-bis-[pentachlororuthenate(IV)] ion [Ru_2OCl_(10)]~(4-), was studied in aqueous-alcoholic solutions of hydrochloric acid under microwave radiation and upon heating of solutions.The conditions were selected for the quantitative reduction of ruthenium(IV) to ruthenium(III) with alcohols in 0.6-10 M HCl solutions in a microwave field. The maximum time it takes to reduce ruthenium(IV) under microwave radiation (30 milt) was all order of magnitude shorter than that under heating the solutions in a boiling water bath. Regardless of the type of an alcohol, most rapid reduction of ruthenium(IV) was observed at the boundaries of the studied range of hydrochloric acid concentrations. Itwas found that, under microwave radiation, thermal effects were the driving force of the process in a 0.6 M HCl solution at 98 deg C, whereas, in 8-10 M HCl solutions, the contributions of nonthermal and thermal effects were comparable. It was shown that the enhancement of the reducibility of saturated monoatomic C_1-C_4 alcohols with an increase in the number of carbon atoms was also due to specific features of microwave radiation.