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|Section2= |Section3= |Section8= }} Calcium pyrophosphate (Ca2P2O7) is a chemical compound, an insoluble calcium salt containing the pyrophosphate anion. There are a number of forms reported: an anhydrous form, a dihydrate, Ca2P2O7·2H2O and a tetrahydrate, Ca2P2O7·4H2O. Deposition of dihydrate crystals in cartilage are responsible for the severe joint pain in cases of calcium pyrophosphate deposition disease (pseudo gout) whose symptoms are similar to those of gout.〔(【引用サイトリンク】 publisher = Medscape )〕 Ca2P2O7 is commonly used as a mild abrasive agent in toothpastes.〔 ==Preparation== Crystals of the tetrahydrate can be prepared by reacting sodium pyrophosphate, Na4P2O7 with calcium nitrate, Ca(NO3)2, at carefully controlled pH and temperature:〔 :Na4P2O7(aq) +2Ca(NO3)2(aq) → Ca2P2O7·4H2O + 2Na2NO3 The dihydrate, sometimes termed CPPD, can be formed by the reaction of pyrophosphoric acid with calcium chloride:〔 :CaCl2 + H4P2O7(aq) → Ca2P2O7·2H2O + HCl. The anhydrous forms can be prepared by heating dicalcium phosphate:〔 :2CaHPO4 → Ca2P2O7 + H2O At 240-500 °C an amorphous phase is formed, heating to 750°C forms β-Ca2P2O7, heating to 1140 - 1350 °C forms the α-Ca2P2O7. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Calcium pyrophosphate」の詳細全文を読む スポンサード リンク
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