Application of Schiff Base Mn(III) Complexes Grafted to Crown Ether Rings as Catalysts for Oxidation of Benzyl Alcohol Derivatives by Oxone

A combination of crowned Schiff base manganese(II) catalysts 1 or 2 and Oxone, as oxidantin CHCl3 was used for the oxidation of various benzyl alcohol derivatives to correspondingaldehydes and ketones. the prepared catalysts in this research showed better efficiency incomparison of the identical crown free catalysts. Furthermore, Among the prepared catalysts,catalysts 1, containing pyridine ring, showed excellent catalytic efficiency. we think the presenceof crown rings bonded to these complexes would not only increase the solubility of theoxidant (KHSO5) in the organic phase, but also may facilitate bringing the KHSO5 into thevicinity of the manganese [1], leading to faster oxidation of manganese (III) to oxo manganese(V) which is a better oxidant than KHSO5 [2]. The addition of pyridine improved thechemical yields of all the reactions catalyzed by catalyst 2, but the reaction times of catalyst 1remained nearly constant. It is concluded that the additional N atom on the bridge groups ofcatalyst 1 itself might play the role of axial base, therefore, the presence of pyridine as an externalaxial base only slightly improves corresponding reaction times in this case [3].