Step A: Synthesis of N-benzoyl-DL-valine
1. 0.1 mole (11.7 g) of DL-valine was dissolved in 50 mL of deionized water.
2. 0.25 moles of aqueous sodium hydroxide was added to the above solution.
3. The reaction mixture was heated to 30 °C and 0.15 mol (17.5 mL) of benzoyl chloride was added slowly and dropwise with stirring.
4. Upon completion of the reaction, the aqueous phase is extracted with ether to remove unreacted benzoyl chloride and other organic impurities.
5. The aqueous phase is acidified to pH 2-3 to induce precipitation of N-benzoyl-DL-valine crystals. 6.
6. The crystals are collected by filtration and washed with a small amount of cold water. 7.
7. N-benzoyl-DL-valine was obtained after drying and the melting point was determined to be 125° C. The yield was about 95%.
