Jelle Brinksma

Homogeneous cis-dihydroxylation and epoxidation of olefins with high H2O2 efficiency by mixed manganese/activated carbonyl catalyst system

Abstract The use of [Mn2O3(tmtacn)2](PF6)2 (tmtacn=1,4,7-trimethyl-1,4,7-triazacyclononane) in combination with glyoxylic acid methylester methyl hemiacetal (GMHA) results in a highly active and hydrogen peroxide efficient catalyst for the epoxidation of olefins as well as the first homogeneous catalytic cis-dihydroxylation system with H2O2 and with turnover numbers up to 420.

New ligands for manganese catalysed selective oxidation of sulfides to sulfoxides with hydrogen peroxide

Abstract In situ prepared manganese complexes with ligands 1 – 5 have been used in the catalytic oxidation of sulfides to sulfoxides using hydrogen peroxide at 0°C in acetone. Using ligand 4 , methyl phenyl sulfoxide is obtained in 55% yield and turnover numbers up to 250, while the formation of sulfone is almost suppressed.

New manganese catalysts for alcohol oxidation

Abstract The in situ prepared manganese complexes based on ligands 1 – 6 have been used in the catalytic oxidation of alcohols to aldehydes or ketones. Highly active and selective catalysts were found with excellent turnover numbers (up to 900) using aqueous hydrogen peroxide as oxidant at ambient temperatures. EPR spectroscopy and electrospray mass spectrometry has indicated that dinuclear species may be involved in the catalytic oxidations. Comparing the rate of oxidation of benzyl-d 7 alcohol with that of benzyl alcohol by the different catalysts yielded isotope effects ( k H / k D ) of 2.2–4.3. Although the exact nature of the oxidising species has not been elucidated, these results indicate that hydroxyl radicals are not involved in these processes.

The dinuclear manganese complex Mn2O(OAc)2(TPTN) as a catalyst for epoxidations with hydrogen peroxide

In acetone and at ambient temperature, the dinuclear manganese complex of TPTN is able to catalyse the oxidation of several alkenes to the corresponding epoxides with high turnovers numbers (up to 900) using H2O2 as oxidant.