96-81-1

72-18-4

108-24-7

96-81-1

The general procedure for the synthesis of N-acetyl-L-valine from L-valine and acetic anhydride was as follows: L-valine (200 g, 1.7 mol) was dissolved in distilled water (500 mL), followed by the addition of 30% sodium hydroxide solution (170 mL). After cooling the reaction mixture to 0-5°C, acetic anhydride (32 mL, 1.4 eq.) was added slowly and dropwise. This was repeated six times (total acetic anhydride: 6 x 32 mL; 30% sodium hydroxide solution: 6 x 34 mL) by alternating dropwise additions of 30% sodium hydroxide solution (34 mL) and acetic anhydride (32 mL) while maintaining the temperature at 0-5°C. After the addition was completed, the reaction mixture continued to be stirred at 0°C for 2 hours. Subsequently, 32% hydrochloric acid (380 mL) was slowly added to adjust the pH to below 3 while maintaining the reaction temperature at 0°C. The resulting slurry was allowed to crystallize for 12 h. The solid product was collected by filtration and the filter cake was washed with 0.1 N hydrochloric acid (100 mL). Finally, the wet N-acetyl-L-valine was dried to give 233 g of white crystalline solid in 86% yield.