1. 18.1g L-glycine, 100ml water was added to the reaction flask and stirred. Add 16g of sodium hydroxide configured 0.01mol/L alkaline solution adjusted to alkaline. Then 8g of (Boc)2O was added and reacted for 2 hours, then 8g of (Boc)2O was added and reacted for 2 hours and finally 9g of (Boc)2O was added and reacted for 4 hours.
2. The impurities were extracted three times with hexane 12 ml/time. 3 mol/L hydrochloric acid was used to adjust the PH=3 and then the product was extracted three times with dioxane 0.6 L/time. Combine the ester layers and wash with brine to neutral. Add 15 g of anhydrous sodium sulfate to dry for 10 hours.
3. Filter, concentrate the filtrate dry under reduced pressure, add 60 ml of hexane and stir to crystallize. Centrifuged out the product and dried. Obtained product 25.0 g. Yield 93.87%.
