PROCESS FOR PREPARING TEREPHTHALIC ACID Russian patent published in 1997 - IPC

FIELD: manufacture of polymeric fiber. SUBSTANCE: product: C₈H₆O₄- terephthalic acid. Reaction condition. Reagent 1: p- xylene. Reagent 2: oxygen. Reaction conditions: liquid reaction medium comprising acetic acid. The latter is purified in aqueous phase and purified product is recovered by precipitation from aqueous phase and purified product is recovered by precipitation from aqueous phase, mother liquor is then cooled in the aqueous phase or evaporated to give additional less purified residue and second mother liquor, and the less purified residue is recycled to reaction medium, and/or water of the second mother liquor is used to dissolve crude solid product and/or the second mother liquor is treated to recover water which is used to wash residue recovered from aqueous solution. The claimed process gives higher yield of terephthalic acid. Reduced consumption of water and minimized problems associated with removal of contaminated water waste. EFFECT: more efficient preparation process. 4 cl, 2 dwg, 1 tbl