Synthesis and application of new Schiff base Mn(III) complexes containing crown ether rings as catalysts for oxidation of cyclohexene and cyclooctene by Oxone

Six catalysts MnClL1 MnClL6, containing two crown ether rings, were synthesised and characterised by IR spectroscopy and CHN microanalysis. A combination of Oxone, as oxidant, and these catalysts was used for the oxidation of cyclohexene and cyclooctene. Among the prepared catalysts, MnClL3 and MnClL4 exhibited the best catalytic efficiency. Catalysts MnClL1, MnClL2 and MnClL6 showed a moderate efficiency and MnClL1 showed the lowest efficiency. Comparison of MmclL(1)-MnClL4 and MnClL6 containing crown ether rings with an identical mixture of uncrowned complex MnClL7 [manganese N,N'-bis(salicylidene) ethylenediamine chloride] and crown ether 2 (4'-hydroxybenzo-15-crown-5), revealed a more important role for the crown ether than increasing solubility of Oxone in the organic phase. The effect on reaction times and chemical yields of temperature, pyridine as the axial base, and different alkali metal salts was also investigated.