4-Nitro-3-phenyl-L-alanine

63-91-2

949-99-5

General steps: 1. dissolve L-phenylalanine (16.5 g, 100 mmol) in 85% sulfuric acid (50 ml). 2. under stirring conditions, add slowly and dropwise a pre-prepared and cooled to room temperature acid mixture of concentrated nitric acid and concentrated sulfuric acid (1.4:1.1 by volume). 3. Stir the reaction mixture continuously for 5 hours at room temperature. 4. The pH of the reaction solution was adjusted to 2-3 using 40% sodium hydroxide solution, at which time a large amount of precipitate was formed. 5. Collect the precipitate by filtration and wash with deionized water until the filtrate is neutral. 6. 6. Dry the precipitate under reduced pressure to obtain 4-nitro-L-phenylalanine (20 g, yield 95.2%).