Abstract
Oxidation of cyclohexene by cheap and environmentally friendly oxidants, namely H
2
O
2
and CO
2
has been catalyzed by Co
1.5
PW
12
O
40
. It has been found that the main products of the oxidation are 2-cyclohexen-l-one (enone), 2-cyclohexen-l-ol (enol) and 1, 2-cyclohexanediol (diol) with the enone as the major product. Oxidation by CO
2
along with H
2
O
2
remarkably increased the conversion compared to that by CO
2
and H
2
O
2
separately. This might be due to the fact that CO
2
increases the percarbonate species (HCO
4
−
) responsible of the oxidation by oxygen transfer, which indicated that the CO
2
/H
2
O
2
mixture is a useful reagent system. The decrease of both the selectivity of the enone and epoxide in favor of that of diol at higher conversions indicated that the diol was formed from the epoxide by consecutive reaction and/or directly from cyclohexene.