Sulfuric Acid → 3-Phenyllactic acid, (S)-

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L-Phenylalanine (10.00 g, 60.5 mmol) was added to a dilution of 8.88 g (90.5 mmol) of concentrated sulfuric acid in 110 g of water and then, at an inside temperature of 20° C., a mixture of 10.45 g (151.5 mmol) of sodium nitrite and 20 g of water was added over 5 hours. After addition, the mixture was stirred at 20° C. for 20 hours, 100 ml of t-butyl methyl ether was then added and, after 30 minutes of stirring at 20° C., the organic phase was separated (extract 1). Further, 50 ml of t-butyl methyl ether was added to the aqueous phase, the mixture was stirred at 20° C. for 30 minutes, and the organic phase was separated (extract 2). The extracts 1 and 2 were combined. The combined extract (116.5 g) contained 8.6 g of (2S)-2-hydroxy-3-phenylpropionic acid (yield 86%, optical purity 95.9% ee). The proton concentration (normality) in the reaction of this example was 1.7 mol/kg, the amount of the protonic acid was 3.0 equivalents (relative to L-phenylalanine), and the reaction temperature was 20° C.

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