| 摘要 |
A previously unknown, stable derivative of ascorbic acid, i.e. ascorbate-2-polyphosphate, together with a process for synthesizing it at a high yield. The process preferably comprises steps in which an ascorbic acid, such as L-ascorbic acid or a derivative thereof, such as 5,6-O-isopropylidene-L-ascorbic acid, is reacted 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 greater than 9 in order to obtain 2-polyphosphylation of the ascorbic acid. In specially preferred embodiments, 1 M L-ascorbic acid is reacted in water with 1.5-3 equivalents of sodium trimetaphosphate or potassium trimetaphosphate at a temperature of 25-55 degree C, and an alkali metal hydroxide, such as potassium hydroxide, is added at intervals to the reaction mixture, as required and over a reaction period of 1-10 hours, in order to keep the pH of the reaction mixture at a level of approx. 10.5-12 during the whole of the reaction. After utilisation, the reaction mixture does not contain any harmful or toxic materials and the whole mixture can be added to foodstuffs for animals or humans. Pure salts of ascorbate-2-triphosphate can be isolated readily by using conventional chromatographic technology. It has also been found that the compound according to the invention are more difficult to oxidise and liberate ascorbic acid more slowly, and are hydrolysed more slowly, than is the monophosphate derivative of ascorbic acid. |
