Yield:73936-91-1 90.3%

Reaction Conditions:

with methanesulfonic acid at 175 - 180; for 6.5 h;Inert atmosphere;Temperature;

Steps:

1.1; 1.2; 2.1; 2.2; 3.1; 3.2 Example 3
A method for preparing a UV absorber Tinuvin 928, the process steps are as follows:

(1) Product synthesis:With a stirrer, thermometer, return tube,2-[2-hydroxy-5-tert-octylphenyl)benzotriazole (UV-329) 32.34g was charged into the reactor of the metering pump.Methanesulfonic acid 12.94g,And pass nitrogen protection, under slow and constant stirring conditions,The reaction mixture was heated to 175 ° C,And at a temperature of 175 ° C ~ 180 ° C with a metering pump 19.40g of α-methylstyrene was added to the liquid level below the reaction solution at a constant rate, about 6h drip,The reaction was then incubated at 180 ° C for 0.5 h.
(2) Product purification:After the reaction is completed, the reaction mass is cooled to 95 ° C to 100 ° C.The layers were allowed to stand, the lower layer was methanesulfonic acid and unreacted UV-329, and the upper layer was a crude product.The crude product was washed twice with 100 mL of 4% aqueous sodium bicarbonate solution, then twice with 100 mL of deionized water, and then the crude product was dissolved in 80 g of toluene.Decolorization treatment was carried out with 10 g of activated clay.The decolored solution is cooled and crystallized and filtered.And dried at 90 ° C ~ 100 ° C to obtain 39.83g light yellow product (theoretical amount 44.1g),The yield is 90.3%, the purity is 99.29%,The melting point is from 107 ° C to 110 ° C (literature value of 108 ° C to 110 ° C).The product of this example was identified according to the characterization method in Example 1, and it was confirmed that the product obtained in this example was the target product Tinuvin 928.

References:

CN110003126,2019,A Location in patent:Paragraph 0031-0048