Patent ID: 6559339
Filing Date: 2003-05-06
Classification: C07C

Abstract:
A process for treating the reaction mixture obtained from the direct oxidation of hydrocarbons into carboxylic acids, in the liquid phase, in a solvent and in the presence of a catalyst dissolved in the reaction medium, said process comprising:separating when the composition of the reaction mixture allows it, the phases by settling into two liquid phases: a nonpolar upper phase, comprising the unconverted hydrocarbon, and polar lower phase comprising the solvent, the acids formed, the catalyst and some of the other reaction products and the unconverted hydrocarbon; distilling the polar lower phase or, where appropriate, all of the reaction mixture, thus separating, on the one hand, a distillate comprising at least some of the most volatile compounds, the solvent, the reaction intermediates and substantially all of the water, and, on the other hand, the distillation residue comprising the carboxylic acids formed and the catalyst; adding to the distillation residue an organic solvent in which the carboxylic acid has a solubility of less than or equal to 15% by weight at 20Â° C. or a mixture comprising at least one of said organic solvent, said organic solvent being selected from the group consisting of ethers, alcohols, esters, nitriles, amides, sulphoxides, carbonates, and halogen, nitro or phosphorous-containing compounds; optionally filtering the medium obtained; and recovering said carboxylic acids by crystallization of the acids formed by cooling and/or evaporation of the said organic solvent.