A moderate and efficient method for oxidation of ethylbenzene with hydrogen peroxide catalyzed by 8-quinolinolato manganese(III) complexes
摘要:
The oxidation of ethylbenzene with 30% aqueous hydrogen peroxide (H2O2) in an acetone-water medium at 30 degrees C was investigated using hexadentate 8-quinolinolato manganese( Ill) complexes (Q(3)Mn(III)) as catalysts. The results indicated that the Q(3)Mn(III) complexes, with ammonium acetate and acetic acid as additives, selectively catalyzed the side chain oxidation of ethylbenzene at secondary carbon atoms, affording acetophenone as a major product. Among the Q(3)Mn(III) complexes examined, the 5,7-dibrominated Q(3)Mn(III) catalyst was the most active, and provided the ethylbenzene conversion of 26.1% and the oxidation yield of 65% under the optimum conditions. The influence of various parameters on the reaction was checked in detail. Based on the UV-vis spectra, a free radical mechanism for the Q(3)Mn(III) catalytic system was also proposed. (C) 2010 Elsevier B.V. All rights reserved.
A highly efficient method of epoxidation of olefins with hydrogen peroxide catalyzed by changeable hexadentate 8-quinolinolato manganese(III) complexes
Novel hexadentate binding 8-quinolinolato manganese(III) complexes were proposed and conveniently synthesized for the epoxidation of olefins with aqueous hydrogenperoxide in water–acetone media with ammonium acetate and acetic acid as additives. The catalytic efficiencies of the suggested catalysts were found to be obviously superior to the traditional tetradentate salen–MnIIICl, due to their special
提出了新颖的结合六齿酸盐的8-喹啉酮基锰(III)配合物,可方便地在乙酸-乙酸铵和乙酸为添加剂的水-丙酮介质中用过氧化氢水溶液对烯烃进行环氧化。发现所建议的催化剂的催化效率明显优于传统的四齿salen-Mn III Cl,因为它们特殊的六齿结合结构可以通过打开一个轴向MnO键很容易地转化为带有悬垂羟基的五齿结合结构。 UV-vis光谱,原位循环伏安法和石英晶体微量天平表征为反应介质提供了支持。