(+-)-2-Butanol → 2-[2-Hydroxy-3-(1,1-diphenylethyl)-5-tert-butylphenyl]-2H-benzotriazole

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To a 500 mL three-necked flask fitted with a mechanical stirrer, 3 g of sodium hydroxide pellets and 50 mL of 2-butanol are charged and heated to 82° C. To this solution, a slurry of 200 mL of 2-butanone, 15 g of the benzotriazole N-oxide prepared in Example 4, and 0.67 g of 2,3-dichloro-1,4-naphthoquinone is added over 40 minutes. The mixture is refluxed at 88° C. for five hours while distilling off 2-butanone. Additional 2-butanol (50 mL) is added to replace what is lost during distillation of the 2-butanone. After cooling the reaction mixture to ambient temperature, 25 g of water and 30 mL of ethyl acetate are added at which time the pH is reduced to 2 with 30% aqueous sulfuric acid. After splitting off the aqueous layer, the solvent is removed by distillation and the crude solid purified by silica gel chromatography using heptane/ethyl acetate as the eluent. After collecting the desired fractions and crystallization from methanol/toluene, 14 g of the title compound is obtained after drying as a light yellow solid melting at 172-173° C. The structure is confirmed by 1H nmr and mass spectroscopy.

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