Synthesis steps of Riboflavin-5'-phosphate sodium salt dihydrate: in 1000ml three-necked bottle add 20ml water, 250ml tetrahydrofuran and 48g riboflavin stirring to dissolve into a mixture, cooled to 5 ~ 10 , slowly add 100ml of aqueous sodium metaphosphate (20.4g sodium metaphosphate dissolved in 100ml water), the temperature is controlled in the 28 ~ 30 , add the end of the temperature to 40 , the reaction 2 ~ 3 hours, stop the reaction, the reaction solution was poured into a large beaker, add 250ml of water with stirring while taking care of cooling to remove the insoluble material. ~3 hours, stop the reaction, cooled to 15 ~ 25 , the reaction solution was poured into a large beaker, added 250 ml of water, stirring at the same time pay attention to cooling, remove insoluble material. In the filtrate add 10% sodium hydroxide solution, adjust the PH value of 9, stirring at room temperature for 0.5 hours, filtration, mother liquor with hydrochloric acid to adjust the PH to 5 ~ 6, filtration, a white solid, with a small amount of 50% ethanol rinse, and then dissolve the product in 95% ethanol, filtration, crystallization and drying of the orange-yellow solid 59.2 grams, the yield is 92%.
