The oxidations of a series of 21 alkylaromatic compounds by trans-[Ru(VI)(L)(O)(2)](2+) (L = 1,12-dimethyl-3,4:9,10-dibenzo-1,12-diaza-5,8-dioxacyclopentadecane) have been studied in CH(3)CN. Toluene is oxidized to benzaldehyde and a small amount of benzyl alcohol. 9,10-Dihydroanthracene is oxidized to anthracene and anthraquinone. Other substrates give oxygenated products. The kinetics of the reactions were monitored by UV-vis spectrophotometry, and the rate law is: -d[Ru(VI)]/dt = k(2)[Ru(VI)][ArCH(3)]. The kinetic isotope effects for the oxidation of toluene/d(8)-toluene and fluorene/d(10)-fluorene are 15 and 10.5, respectively. A plot of Delta H(++) versus Delta S(++) is linear, suggesting a common mechanism for all the substrates. In the oxidation of para-substituted toluenes, a linear correlation between log k(2) and sigma(0) values is observed, consistent with a benzyl radical intermediate. A linear correlation between Delta G(++) and Delta H(0) (the difference between the strength of the bond being broken and that being formed in a H-atom transfer step) is also found, which strongly supports a hydrogen atom transfer mechanism for the oxidation of these substrates by trans-[Ru(VI)(L)(O)(2)](2+). The slope of (0.61 +/- 0.06) is in reasonable agreement with the theoretical slope of 0.5 predicted by Marcus theory.

A silica gel-immobilized [(Me(3)tacn)Ru(III)(CF(3)COO)(2)(H(2)O)]CF(3)CO(2) complex (1-SiO(2), Me(3)tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane) was prepared by simple impregnation, and the catalyst was characterized by powdered X-ray diffraction, nitrogen adsorption/desorption, Raman, and diffuse reflectance UV-vis spectroscopies. The supported Ru catalyst can effect facile oxidation of alcohols by tert-butyl hydroperoxide (TBHP). Primary and secondary benzyl, allylic, and propargylic alcohols were transformed to their corresponding aldehydes and ketones in excellent yields; no oxidation of the C=C and Ctbd1;C bonds was observed for the allylic and propargylic alcohol oxidations. Likewise alkene epoxidation by TBHP can be achieved by 1-SiO(2); cycloalkenes such as norbornene and cyclooctene were oxidized to their exo-epoxides exclusively in excellent yields (>95%). The 1-SiO(2) catalyst can be recycled and reused for consecutive alcohol and alkene oxidations without significant loss of catalytic activity and selectivity; over 9000 turnovers have been attained for the oxidation of 1-phenyl-1-propanol to 1-phenyl-1-propanone. 4-Substituted phenols were oxidized by the "1 + TBHP" protocol to give exclusively ruthenium-catecholate complexes, which were characterized by UV-vis and ESI-MS spectroscopies. No (tert-butyldioxy)cyclohexadienone and other radical coupling/overoxidation products were produced using the "1 + TBHP" protocol. The formation of ruthenium-catecholate is proposed to proceed via ortho-hydroxylation of phenol.

A simple and green method that uses [Ru(Me3tacn)Cl3] (1; Me3tacn = N,N',N''-trimethyl-1,4,7-triazacyclononane) as catalyst, aqueous H2O2 as the terminal oxidant, and Al2O3 and NaCl as additives is effective in the cis-dihydroxylation of alkenes in aqueous tert-butanol. Unfunctionalized alkenes, including cycloalkenes, aliphatic alkenes, and styrenes (14 examples) were selectively oxidized to their corresponding cis-diols in good to excellent yield (70-96%) based on substrate conversions of up to 100%. The preparation of cis-1,2-cycloheptanediol (119 g, 91% yield) and cis-1,2-cyclooctanediol (128 g, 92% yield) from cycloheptene and cyclooctene, respectively, on the 1-mol scale can be achieved by scaling up the reaction without modification. Results from Hammett correlation studies on the competitive oxidation of para-substituted styrenes (rho = -0.97, R = 0.988) and the detection of the cycloadduct [(Me3tacn)ClRuHO2(C8H14)]+ by ESI-MS for the 1-catalyzed oxidation of cyclooctene to cis-1,2-cyclooctanediol are similar to those of the stoichiometric oxidation of alkenes by cis-[(Me3tacn)(CF3CO2)Ru(VI)O2]+ through [3+2] cycloaddition (W.-P. Yip, W.-Y. Yu, N. Zhu, C.-M. Che, J. Am. Chem. Soc. 2005, 127, 14239).