THERMAL DECOMPOSITION OF ORGANOGERMANIUM PEROXIDES AND HYDROPEROXIDES

The thermal decomposition reactions of a number of organogermanium peroxides and hydroperoxides were studied to gain information about the mechanism of the cleavage of the peroxidic link when bound to germanium. Bis(triphenylgermyl) peroxide thermally decomposed with first-order kinetics (Ea = 33.7 kcal/mol) in hexadecane in the absence of oxygen at 190-210° yielded phenol, diphenylgermanium oxide, triphenylgermanol, but no oxygen. The migratory aptitudes of the phenyl and the p-trifluoromethylphenyl groups in the decomposition of bis(diphenyl-p-trifluoromethylphenylgermyl) peroxide were about equal, consistent with a free-radical mechanism. The thermal decomposition of triphenylgermyl hydroperoxide (1.0 mmol) in o-dichlorobenzene produced oxygen (0.17 mmol), water (0.35 mmol), and triphenylgermanol (0.93 mmol) as the major products, and phenol (0.06 mmol) and diphenylgermanium oxide (0.07 mmol) as the minor products. The effect of solvents, radical initiators, radical inhibitors, and ultraviolet light were consistent with a radical mechanism producing these products. The products of the thermal decomposition of triphenylgermyl hydroperoxides in which one of the phenyl groups was substituted in the para position gave a migratory aptitude series (p-CH3OC6H4 1.98; p-CF3-C6H4, 1.36; C6H5, 1.00) consistent with a radical mechanism for the formation of phenols in this reaction. Triphenylgermyl hydroperoxide decomposed in o-dichlorobenzene at 150-170° in an initially oxygen-free system with zero-order kinetics at 0.01 M concentration (Ea = 35 kcal/mol) but followed no simple order at higher concentrations. The thermal decomposition of tricyclohexylgermyl hydroperoxide (1.0 mmol) produced cyclohexene (0.56 mmol), cyclohexanol (0.06 mmol), tricyclohexylgermanol (0.29 mmol), and dicyclohexylgermanium oxide (0.18 mmol). © 1969, American Chemical Society. All rights reserved.