3-Chlorobenzoic Acid → 5-Benzenesulfinyl-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole

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Reaction Steps

A solution of 10.8 g (0.025 mole) of 5-phenylthio-2-(2-hydroxy-3,5-di-tert-butyl-phenyl)-2H-benzotriazole, prepared in Example 2, in 80 mL of methylene chloride is cooled to 3°-5° C. Over a period of 30 min. is added a solution of 5.1 g (0.025 mole) of m-chloroperoxybenzoic acid (MCPBA) 85% in 80 mL of methylene chloride at 3°-5° C. The reaction is stirred for 2 hours at 0°-5° C. with precipitation of m-chlorobenzoic acid. The starting material is shown to be absent. Upon removal of the solvent the residue is dissolved in 200 mL of toluene, m-chlorobenzoic acid is removed by filtration and subsequent washing with 10% aqueous sodium carbonate solution and water. The toluene solution is dried over anhydrous magnesium sulfate, filtered and the solvent removed. The resulting amorphous residue is dissolved in 60 mL of petroleum ether and crystallized. Filtration and washing of the crystals with cold petroleum ether affords 9.8 g (87.6% yield) of the title compound as a solid melting at 152°-154° C.

Provenance & Evidence