CalciumphosphatVerbindungen

Calcium phosphate refers to a family of inorganic compounds that contain calcium ions and phosphate groups. The term encompasses several mineral phases, including monocalcium phosphate Ca(H2PO4)2, dicalcium phosphate CaHPO4, tricalcium phosphate Ca3(PO4)2, and hydroxyapatite Ca5(PO4)3(OH). The most biologically important member is hydroxyapatite, the principal mineral component of bone and tooth enamel.

These compounds are typically white crystalline solids that are sparingly soluble in water. Solubility varies by phase and pH, with monocalcium phosphate generally more soluble than dicalcium phosphate and hydroxyapatite. In physiological environments, calcium phosphate phases can dissolve and redeposit, contributing to mineralization and demineralization processes in tissues.

Occurrence and uses include naturally occurring minerals such as apatite and whitlockite. In biology, hydroxyapatite forms the mineral framework of bone and enamel. Industrially, calcium phosphates are used as dietary calcium supplements, components in toothpaste and dental sealants, and materials for bone grafts and bone cements. They also appear as additives in phosphate fertilizers, providing phosphorus and calcium to soils.

Preparation and transformations are commonly achieved by reacting phosphoric acid with calcium sources such as calcium hydroxide or calcium carbonate, followed by precipitation and drying. The resulting phase composition depends on reactant ratios, pH, temperature, and drying conditions; heating can induce phase conversions (for example, between different calcium phosphate forms).

Safety and environmental aspects note that these compounds are generally safe when used as directed in consumer products. However, inhalation of powder or prolonged skin contact can be irritating, and excessive phosphate release into water systems can contribute to nutrient pollution.