Patent ID: 11904279
Assignee: BASF SE
Field: Chemical engineering (Chemistry)
Classification: CPC B  C | IPC B  C

Claim 0:
1. A process for isolating 2,4-bis-(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-1,3,5-triazine (DIOPAT) from an aqueous alkaline mixture M having a pH of 10 or more and comprising
(i) the 2,4-bis-(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-1,3,5-triazine;
(ii) 2,4-dihydroxybenzophenone;
(iii) aluminum salts;
wherein the process comprises the steps of
a) separating the 2,4-bis-(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-1,3,5-triazine from the aluminum salts and the 2,4-dihydroxybenzophenone by nanofiltration of the alkaline mixture M, wherein the 2,4-bis-(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-1,3,5-triazine is obtained in the form of an alkaline aqueous solution S as the retentate;
b) precipitating the 2,4-bis-(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-1,3,5-triazine by modifying the pH of the aqueous solution S to a value of 9.5 or lower;
c) separating the precipitated 2,4-bis-(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-1,3,5-triazine from the aqueous solution S by filtration, wherein the 2,4-bis-(2,4-dihydroxyphenyl)-6-(4-methoxyphenyl)-1,3,5-triazine is obtained in the form of an aqueous suspension SP as the retentate;
wherein the nanofiltration step a) is performed at a pressure of from 10 to 30 bar and at a temperature in the range of from 20 to 60° C.; and
wherein the nanofiltration step a) is performed with a nanofiltration membrane having a sodium chloride retention rate of 60 to 75%, as measured at 25° C. and 10 bar at a starting concentration of sodium chloride of 500 ppm and with 10-15 permeate yield.