New aspects of the synthesis of dimethyl carbonate via carbonylation of methyl alcohol promoted bymethoxycarbonyl complexes of palladium(II)

[PdCl2(PPh3)2] suspended in MeOH reacts with carbon monoxide (40-80 atm, 50°), in the presence of a base such as\ud NEt3 to give the methoxycarbonyl complex trans-[PdCl(COOMe)(PPh3)2]. When the carbonylation reaction is carried\ud out at 90-100° redn. to Pd0 carbonyl-phosphine complexes occurs, with formation of di-Me carbonate, selectively and in\ud an almost quant. yield. The above complexes are less reactive than the acetato-analogs, which give di-Me oxalate as\ud the main org. carbonylation product even at 50°