UV Absorber BP-4 CAS 4065-45-6

The synthesis unfolds in three steps:
The first step of acylation reaction to synthesize 2,4-dihydroxybenzophenone;
The second step is to methylate 2-hydroxy-4-methoxybenzophenone;
The third step is sulfonation to generate 2-hydroxy-4-methoxybenzophenone.

In the synthesis reaction of the first step, the optimal reaction conditions of BP-1 were selected: the optimal reaction temperature was 50°C; the ratio of resorcinol and trichlorotoluene was 1:1.20; the optimal reaction temperature of trichlorotoluene and aluminum trichloride was 1:1.20. The best molar ratio is 1:1.3; catalytic synthesis method; crude product BP-1 is obtained by extraction and separation with xylene;
The optimal conditions for the acylation reaction in the synthesis reaction of the second step: n(2,4-dihydroxybenzophenone): v(acetone)=1:200; n(K2C03):n(bp-1)= 0.6; n(dimethyl sulfate)/n(2,4-dihydroxybenzophenone)=1 and without adding any catalyst, the acetone is collected by distillation to obtain the crude product containing impurities bp-1 and dimethyl sulfate;
The optimum condition of the sulfonation reaction in the 3rd step synthesis reaction: the mass ratio of the acylated product and the concentrated sulfuric acid is 1:10; the sulfonation temperature is 70°C; the reaction time is 2h and the solvent in the two-step centrifugal separation For methanol, drying and packaging of the product should be strictly performed in a clean room.