Highly efficient oxidation of alcohols by the system 'hydrogen peroxide-[lmn(o)3mnl](pf6)2 (l = 1,4,7-trimethyl-1,4,7-triazacyclononane)-oxalic acid'

摘要

The dinuclear manganese(IV) complex [LMn(O)3MnL](PF6)2 (1, L = 1,4,7-trimethyl-1,4,7-triazacyclononane) catalyzes the extremely efficient oxidation of alcohols with hydrogen peroxide at room temperature. Oxalic acid is an obligatory co-catalyst. The oxidation of isopropanol, for example, yields acetone with turnover numbers up to 40000 after 5-10 h in the absence of a solvent. 2-Cyanoethanol was oxidized by this system with somewhat lower efficiency (conversion 70%). The catalytically active cation from salt 1 was obtained in an insoluble form containing a heteropoly anion [Mn2O3(TMTACN)2]2[SiW12O40]. Oxidation of 2-cyanoethanol using this heterogenized catalyst and oxalic acid gave the oxo-products with the 54% total yield.