Oxidation of heavy 1- olefins (C12= - C20=) with TBHP using a modified Wacker system

Abstract

The oxidation of heavy olefins (CB12 B¿ CB20B) was carried out using a modified Wacker system with TBHP as oxidant and acetonitrile as solvent at 80ºC. This system allowed the oxidation of 1-octadecene giving rise to 90% conversion with 60% selectivity towards 2-octadecanone after 2 h while the addition of ß-cyclodextrins did not increase the production of 2-octadecanone. The oxidation of a equimolar mixture of n-dodecane + 1-dodecene enhanced markedly the selectivity towards 2-dodecanone yielding 63% instead of 34% in n-paraffin absence after 2 h, likely due to a dilution effect of the n-dodecane which reduces the extent of the isomerisation reactions. The oxidation of a equimolar mixture CB12PB=P + CB16PB=P + CB20PB=P in presence of equimolar amounts of their corresponding n-paraffins gave rise to practically complete conversion and selectivities towards 2-methylketones within 70 ¿ 90%, enhancing with decreasing chain length due to their higher solubility in the biphasic system. The activity of the catalyst dropped after two reaction cycles, indicating its deactivation by formation of palladium clusters. However, it was possible to obtain similar results in terms of activity and selectivity by decreasing the [1-dodecene]/[PdClB2B] ratio to 100, which is expected to increase the catalyst lifetime by decreasing the extent of palladium aggregation. In this regard, the reported system is rather promising for the oxidation of heavy 1-olefins towards methyl ketones.