Examination of the Reaction Products in the Aqueous-Phase Preparation of Hydrated Calcium Diphosphates

概要

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The formation of by-products during the preparation of hydrated calcium diphosphates(Ca_2P_2O_7・nH_2O, n=2 or 4) was examined in samples which were obtained through the literature methods. When CaH_2P_2O_7 was used as the reactant (2CaH_2P_2O_7+nH_2O→Ca_2P_2P_7・nH_2O+H_4P_2O_7), the product contained not only hydrated calcium diphosphate but also calcium ammonium diphosphate and/or acidic calcium diphosphate, depending on the reaction medium(0.05M NH_4OH, 2.2M Ca(CH_3COO)_2,or water). When K_4P_2O_7 and CaCl_2 were reacted in an aqueous solution of KCl, a significant amount of diphosphate ion (ca. 57%) was hydrolyzed to orthophosphate ion. The product was amorphous when the molar ratio of the reactant Ca^<2+> to diphosphate ion was higher than 1.0. Several kinds of crystalline calcium potassium diphosphate were found in the product when the ratio was lower than 1.0. Therefor, it was concluded that hydrated calcium diphosphates prepared in the aqueous phase by the literature methods are generally contaminated with several kinds of by-product.
社団法人日本薬学会の論文
1986-06-25