METHOD FOR PREPARING 2-NAPHTHOLSULFOACIDS Russian patent published in 2003 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to the improved method for preparing 2-naphtholsulfoacids. 2-Naphtholsulfoacids are synthesized by sulfonation of 2-naphthol followed by precipitation of the end sulfoacid as its difficultly soluble salt and filtration of precipitate. Filtrate is acidified with sulfuric, hydrochloric or acetic acid to concentration 15-30 wt.-% as measured for sulfuric acid and 2-naphtholsulfoacids containing in filtrate are subjected for thermal hydrolysis at temperature 130-180 C under pressure 0.2-0.8 MPa for 2.5-5 h. 2-Naphthol prepared after cooling reaction mass is separated by filtration or separation and recovered to the sulfonation stage. Invention allows reducing consumption norms by 2-naphthol that provides significant economic effect. EFFECT: improved preparing method. 1 cl, 2 tbl, 6 ex