Oxidation Of Alcohols With Tungsten-based Catalysts

The selective oxidation of alcohols to carbonyl compounds is one of the most important fundamental reactions in organic chemistry both at the laboratory and in industrial level. The oxidation of cyclohexanol,1,4-cyclohexanediol and other alcohols with H2O2 catalyzed by tungsten-based catalysts are studied in this paper.The selective oxidation of cyclohexanol to cyclohexanone was studied systematically, using WO3, Na2WO4·2H2O, Na9[SbW9O33] and the prepared [CTA]9[SbW9O33] as tungsten-based catalysts and H2O2 as oxidant. [CTA]9[SbW9O33] showed the highest catalytic activity. The influence of the amount of substance ratio to the reaction, the temperature and the reaction time were optimized. The conversion of cyclohexanol is 97.4% and the selectivity to cyclohexanone is 99.7%, while the temperature is 80℃, the ratio of H2O2:cyclohexanol:[CTA]9[SbW9O33] is 75:50:0.06(mmol) and the reaction time is 2 h.A series of tungsten-based catalysts were prepared for the oxidation of 1,4-cyclohexanediol. The Na2WO4·2H2O+H7[P(W2O7)6] catalysts were selected as the final catalyst. The conversion of 1,4-cyclohexanediol is 96.9% and the selectivity to 1,4-cyclohexanedione is 99.2% while the temperature is 80℃, the mol ratio of 1,4-cyclohexanediol:Na2WO4·2H2O+H7[P(W2O7)6]:oxalic acid:H2O2 is 100:2:2: 400(mmol) catalyzed by the Na2WO4·2H2O+H7[P(W2O7)6] combined with oxalic acid.In addition, the oxidation of other alcohols with [CTA]9[SbW9O33], TBAB+Na9[SbW9O33], BTAB+Na9[SbW9O33], TDBAC+Na9[SbW9O33] catalysts were also studied, The conversion of the second alcohols and their product selectivities are both high, whereas only the coversion of benzyl alcohol and it's selectivity are high in primary alcohols.