METHOD OF PURIFYING TEREPHTHALIC ACID Russian patent published in 2014 - IPC C07C51/48 C07C63/26 

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of purifying crude terephthalic acid which contains contaminants with a first concentration, which includes contacting crude terephthalic acid with a solvent which includes an ionic liquid selected from a group consisting of imidazolium ionic liquid, pyridinium ionic liquid, phosphonium ionic liquid, tetraalkylammonium ionic liquid and combinations thereof, in purification conditions to obtain solid terephthalic acid with a second concentration of contaminants which is lower than the first concentration, wherein the solvent further includes a carboxylic acid having 1-7 carbon atoms, and weight ratio of the ionic liquid to the carboxylic acid in the solvent is about 1:1000-1000:1.

EFFECT: invention enables to produce dry end terephthalic acid with 4-carboxybenzaldehyde concentration less than 25 ppmw.

9 cl