Take 1.17 kg (10 mol) of L-valine, 5 L of 2 mol/L sodium hydroxide solution, and 1.06 kg (10 mol) of sodium carbonate and add them to a 20 L reactor. Start stirring and wait until L-valine is completely dissolved. Then, lower the solution temperature to below 0 °C and add 5 L of 1,4-dioxane solution containing 2.05 kg (12 mol) of benzyl chloroformate dropwise. Keep the solution temperature below 20 °C during the dropwise addition process. After the dropwise addition is complete, react at room temperature for 8 h. After the reaction was complete, the reaction solution was extracted with 2.5 L of dichloromethane, the organic phase was discarded, and the aqueous phase was cooled to below 10 °C. Concentrated hydrochloric acid was added dropwise until the pH reached 2, and the mixture was stirred at 10 °C for 30 min, precipitating a large amount of white solid. The solid was filtered, the residue was washed with water, and the white solid was dried in a vacuum drying oven to obtain 2.35 kg of white N-Carbobenzyloxy-L-valine, with a yield of 93.7% and a purity of 99.6% (HPLC), and an optical rotation of -4.1° (C = 2, glacial acetic acid, T = 20 °C).
