Preparing oxalic acid esters
AssigneeSnamprogetti S.p.A.
InventorsUgo Romano, Franco Rivetti
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Abstract
A method for the preparation of organic esters of oxalic acid by reaction of carbon monoxide under pressure with the corresponding alcohol is disclosed, the improvement consisting in the use of a quite particular catalyst system. The catalyst is a binary system in which the principal member is a palladium complex and the co-catalyst is a compound, preferably an organic compound having an acidic nature, no matter how weak.
Claims14
The method of preparing an ester of oxalic acid from carbon monoxide and an alcohol, wherein the reaction is carried out in the presence of a catalyst consisting of a complex of palladium selected from the group consisting of:
- (a) the complexes of bivalent palladium of the formula LL'PdXX' or L"PdXX' in which L and L' are monodentate neutral ligands, L" is a chelating neutral ligand, X and X', the same or different, are anionic ligands;
- (b) the complexes of zerovalent palladium having the formula PdL'".sub.n in which n can be varied from 2 to 4, and L'" is a neutral ligand;
- and
- (c) the complexes of zerovalent palladium of the formula Pd.sub.x (CO).sub.y L.sup.IV .sub.Z wherein x is 1 or 3, y is 1 or 3, z is 3 or 4 and L.sup.IV is a tertiary phosphine;
- and
- a co-catalyst consisting of a compound having acidic properties selected from the group consisting of amine salts, carboxylic acids, phenol, succinimide and phthalimide.
Dependencies are inferred from the claim text.