| 摘要 |
<p>Prepn. of calcium ascorbate comprises reacting ascorbic acid and calcium carbonate in water, the water being present at the start of the reaction in amt. 25-50% of the theoretical ascorbic acid soln. requirement at 60 deg. C. Ascorbic acid and water are mixed in the reaction zone and then CaCO3 is added incrementally at such a rate that the reaction zone is maintained satd. with CO2 (by-prod.) and that the reaction zone is blanketed with a layer of CO2 foam. Mole ratio of CaCO3: ascorbic acid is 1.02-1.15:2 (stoichiometric ratio is 1:2). When reaction has terminated (as shown by subsiding of the foam), there is obtd. a syrupy soln. contg. 50-75% of dissolved Ca ascorbate. Since calcium ascorbate has Vitamin C activity, the syrup can be stored in closed containers and used as a Vitamin C material. Also, upon cooling, the syrup spontaneously crystallises; and when this process takes place in the presence of atmospheric air and with removal of residual water at not above 65 deg. C (pref. below 60 deg. C), there are obtd. crystals which comprise ca. 85% Ca ascorbate and 12-14% calcium ascorbate oxidisate (believed to be Ca bis dihydroxyascorbate). Oxidisate relieves pain caused by arthritis, phlebitis and gout.</p> |
