Formic Acid → 5-phenylsulfonyl-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a one-liter jacketed glass reactor are charged 150 g (0.42 mol) of 5-chloro-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole and 275 g (2.78 mol) of N-methylpyrrolidinone. With agitation, the resultant slurry is heated to 90-95° C. At this time, 104.5 g (0.84 mol) of potassium hydroxide and 51.3 g (0.47 mol) of thiophenol are added. Heating is continued till the temperature reaches 170° C. while distilling off water through an overhead condenser. After two hours at 170° C., the temperature is cooled to 95° C. and the reaction mixture is neutralized with 120 g (0.49 mol) of hydrochloric acid. To this mixture is then added 100 g of water and 200 g of xylene. The brine layer is removed and the xylene phase is washed once with 150 g of water and separated off. The temperature of the xylene solution is reduced to 70° C. and 1.8 g (0.0055 mol) of sodium tungstate and 49.1 g (1.07 mol) of formic acid are added. To the reaction mixture is slowly added over a 60-minute period 83 g (1.22 mol) of 50% hydrogen peroxide at a rate such that a temperature of 70-80° C. is maintained. At the end of the addition of hydrogen peroxide, the reaction mass is held at 70-80° C. for 30 minutes and sampled for any residual sulfoxide by HPLC. After the reaction is complete, the xylene phase is then washed once with aqueous sodium sulfite solution and twice with water. The temperature is reduced to 65° C. and 500 g of methanol are added. The temperature is further reduced to 30-32° C. to induce crystallization. The yellow slurry formed is filtered and the solid material isolated is washed with 150 g of methanol. The yellow needles isolated are dried to constant weight in a vacuum oven to afford 172 g (88.6% yield based on the chloro-benzotriazole starting material) of the title compound. A HPLC scan of the product shows an assay of 99.3% of the desired sulfone compound.

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