Bleach and oxidation catalysis by manganese–1,4,7-triazacylononane complexes and hydrogen peroxide

Abstract

The dinuclear manganese compound, [Mn IV 2(μ-O) 3(Me 3tacn) 2](PF 6) 2 ( 1) with Me 3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane, catalyzes a variety of bleaching processes and organic substrate oxidations using hydrogen peroxide as oxidant. Bleaching reactions in aqueous solution include stain bleaching for laundry cleaning, stain and starch removal for machine dishwash cleaning, and wood pulp bleaching. Model substrate conversions indicate that in aqueous and non-aqueous media ( 1) catalyzes both oxygen and electron-transfer reactions. A wide variety of substrates are efficiently converted in non-aqueous media, like alkenes into epoxides and cis-diols, alkanes into their corresponding alcohols and ketones, alcohols into aldehydes and sulfides into sulfoxides and sulfones. Yield and selectivity of reactions frequently depend on the conditions chosen. Dismutation of H 2O 2 can be controlled by using the appropriate solvent (e.g. acetone) or applying an additive, like oxalate or ascorbic acid. Addition of trichloroacetic acid 2,6-dichlorobenzoic acid to ( 1)/H 2O 2 has been shown to give a selective cis-dihydroxylation versus epoxidation (7:1 ratio).