Patent ID: 8785667

Claim:
A process for the preparation of a diacid of the formula HOOC—R′—COOH from an alcohol/aldehyde of the formula HOH 2 C—R′—(C═O)H, wherein R′ is an optionally substituted furan ring, comprising the step of: contacting the alcohol/aldehyde with an oxidant in the presence of a metal bromide catalyst and a solvent or a solvent mixture, thereby forming a mixture of an acid/aldehyde having the formula HOOC—R′—(C═O)H and the diacid, and optionally isolating at least one of the acid/aldehyde or the diacid, wherein the oxidant is selected from the group consisting of oxygen, oxygen-containing gas and mixture thereof, wherein the metal bromide catalyst comprises two or more transition metals, and wherein the solvent or the solvent mixture comprises at least one aliphatic C 2 -C 6 monocarboxylic acid compound.