| 摘要 |
A new stable derivative of ascorbic acid, ascorbate 2-polyphosphate, is disclosed, together with a high-yield method of synthesis thereof. The method preferably includes steps of reacting an ascorbic acid such as L-ascorbic acid or a derivative thereof such as 5,6-O-isopropylidene-L-ascorbic acid with salts of metaphosphoric acid in an aqueous system and in the presence of sufficient base to maintain the pH of the reaction mixture at a level of at least above 9 to obtain 2-polyphosphorylation of the ascorbic acid. In particularly preferred forms, 1 M L-ascorbic acid is reacted in water with 1.5-3 equivalent of sodium or potassium trimetaphosphate at a temperature of 25 DEG -55 DEG C., and an alkali metal hydroxide such as potassium hydroxide is intermittently added to the reaction mixture as needed over a 1-10 hr. reaction period to maintain the pH thereof at a level of about 10.5-12 during the entire reaction. After neutralization the reaction mixture contains no noxious or toxic materials, and the entire mixture may be added to food or feed. Pure salts of ascorbate 2-triphosphate can be isolated readily using conventional chromatographic techniques. It has also been found that the compounds of the invention are more difficult to oxidize, and release ascorbic acid and are more slowly hydrolyzed than the monophosphate derivative of ascorbic acid. |
