Process for the oxidative carbonylation of alcohols and method for the reoxidation of reduced copper salts produced by the oxidation carbonylation

A cyclic process for the oxidative carbonylation of an alcohol having from 1 to 20 carbon atoms which comprises the steps of

• reacting under substantially anhydrous conditions, a saturated monohydric aliphatic or alicyclic alcohol which may contain other substituents which do not interfere with the reaction or an aromatic alcohol selected from the group consisting of benzyl, chlorobenzyl and methoxy-benzyl alcohols with carbon monoxide at a pressure of between about 1 to 700 atmospheres and at a temperature in the range of about 50.degree. C. to 250.degree. C. in the presence of an effective amount of a catalyst selected from the group consisting of palladium (II), rhodium (III), platinum (II) and copper (I) or (II) salt compounds, at least a stoichiometric amount of an aliphatic, cycloaliphatic, aromatic or heterocyclic amine or ammonia, a stoichiometric quantity of a copper (II) oxalate, sulfate, acetate, or trifluroacetate oxidant salt compound, and an excess over that normally formed in the carbonylation reaction of an ammonium or substituted ammonium sulfate, acetate or trifluroacetate salt compound, to produce the desired oxalate ester;
• separating the oxalate ester by distillation leaving a distillation residue comprised of catalyst, amine, reduced oxidant salt and ammonium salt compound;
• dissolving the distillation residue in alcohol and purging the resulting solution with oxygen or an oxygen-containing gas at pressures above 0.2 atmospheres and at a temperature in the range of from 20.degree. C. to 200.degree. C. to reoxidize the reduced copper oxidant salt and form co-product water;
• removing the reoxidation co-product water by the addition of water scavengers or azeotropic distillation leaving a residue comprised of catalyst, amine, copper (II) oxidant salt and ammonium salt compound;
• and
• recovering said residue for reuse in an oxidative carbonylation process.