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Aerobic oxidation of methyl vinyl ketone to acetal in supercritical carbon dioxide are achieved in high conversion and high selectivity when oxygen pressure reaches to 0.5 MPa. The effects of cocatalysts, additive, pressure and temperature of the reaction are studied in detail.

Pd(II)-catalyzed acetalization of terminal olefins with electron-withdrawing groups was carried out smoothly in supercritical carbon dioxide under oxygen atmosphere when polystyrene-supported benzoquinone (PS-BQ) or CuII (CuI) chloride was employed as cocatalyst. The higher selectivity was achieved, without any chlorinated by-product detected, when using PS-BQ instead of CuII (or CuI) chloride. PS-BQ could be recycled with excellent catalytic activity remaining after each simple filtration. Chlorine ion was demonstrated to be a promoter. The different acetalization mechanisms were revealed by the subtle relationship of chlorine ion and benzoquinone (BQ) to the catalytic activity of PdCl2/PS-BQ, PdII-CuCl2 or Pd(OAc)2/PS-BQ.

5-(1′-Chlorovinyl)-1,2,3,4,5-pentachloromethylcyclopentadiene was prepared regioselectively via palladium chloride-catalyzed [2+2+1] trimerization of 1,4-dichloro-2-butyne in excellent yield.

The Pd-catalyzed addition of carbon monoxide and carbon tetrachloride to 1-octene gave coadduct [alkyl 2-(2, 2, 2-trichloroethyl)octanoate] as the major product in supercritical carbon dioxide by using pyridine as the base. It was found that the selectivity and the yield of coadduct were greatly affected by the pressure of carbon dioxide, the reaction temperature and the amounts of alcohol and base used.

It was found that tert-BuNH2 is an efficient catalyst for epoxidation of α,β-unsaturated ketones with 30% H2O2 under mild conditions. For most of the cyclic unsaturated ketones used, moderate to excellent yields (45%–93%) were obtained within 24 h period.