Catalytic activity of SBA-15 supported CuO for selective oxidation of veratryl alcohol to veratraldehyde

Abstract

Selective oxidation of veratryl alcohol (VAlc) to veratraldehyde (VAld) under mild conditions using heterogeneous catalysts is advantageous for industrial applications. In the present study, newly developed SBA-15 supported copper oxide catalyst designated as CuO(5,10,15 wt.%)/SBA-15 was examined for the selective oxidation of VAlc to VAld using tert-butyl hydroperoxide (TBHP) as an oxidant between 40 and 100 °C. CuO(10 wt.%)/SBA-15 showed high conversion (82.5%) compared to others by forming VAld with 100% selectivity. We examined its selective oxidising power using a substrate possessing both the primary and secondary alcoholic functions, namely propylene glycol (PG). In this substrate, only the secondary alcoholic group was oxidized to hydroxyacetone (HA). It suggests preferential adsorption of the primary alcoholic group of PG on the catalyst surface close to the adsorbed TBHP, thus leaving only the secondary alcoholic group positionally favourable for oxidation. In addition, the catalyst effectively oxidized 2-butanol to 2-butanone. So, the catalyst is verified active against both primary and secondary alcohols, but when both of them are present on the adjacent carbons of the same compound, only the secondary alcoholic function is oxidized. So, the present catalyst could have tremendous applications for selective oxidation in organic synthesis.