Riboflavin(B2), as known as vitamin B2, vitamin B2. Molecular formula C17H20N4O6. It is one of the 13 essential vitamins for the human body. As one of the members of the vitamin B family, it is slightly soluble in water, soluble in sodium chloride solution, and easily soluble in dilute sodium hydroxide solution. In 1879, the famous British chemist Bruce discovered that there is a yellow-green fluorescent pigment in the upper whey of milk. They extracted it by various methods and tried to find its chemical nature without success. For decades, although many scientists around the world have discovered this yellow substance from animals and plants from different sources, they have not been able to identify it. In 1933, American scientists Goldberg and others obtained 18 mg of this substance from more than 1,000 kilograms of milk. Later, people named it riboflavin because it had a ribitol in its molecular formula.