PROCESS FOR RECOVERY OF BENZENESULFOACID ANTIPYRINE Russian patent published in 1994 - IPC

FIELD: manufacture of antipyrine. SUBSTANCE: in order to reduce waste water and simplify the process, the reaction mixture is treated with benzenesulfoacid antipyrine under different conditions. Benzenesulfoacid antipyrine is recovered from the reaction mixture obtained by methylation of phenylmethyl pyrazolone in the form of a melt which is cooled to 80 C, and a mother liquor heated to 50 C is added from the monomethylamino antipyrine preparation stage. The latter compound contains 7-10% sodium sulfate. The mixture is then cooled to 10-14 C to be crystallized. The yield of benzenesulfoacid antipyrine is not higher than 98% and meets the manufacture recruitments. The use of said mother liquor simplifies the process and reduces the amount of waste water. Additionally, as in the prior art, the stage for the preparation of a NaCl solution can be ruled out. EFFECT: greater efficiency of the process. 1 tbl