Summary.
The influence of reaction conditions (temperature, type of catalyst, time) on the base-catalyzed reaction of mono-, di-, and trialkylphosphates (alkyl = methyl, ethyl, i-propyl, n-butyl) with Ca2+ ions and on the structure and composition of the reaction products was studied. The composition of the calcium phosphates depends mainly on the reaction temperature. At temperatures below 100°C, a nanocrystalline solid product transforming into dicalcium phosphate by heating (calcination) was found. Pure nanocrystalline hydroxyapatite was prepared by hydrothermal synthesis at 160°C from mono- and dialkylphosphates. The size of hydroxyapatite crystallites was about 1 nm, the particle size about 150 nm. Agglomerated particles of hydroxyapatite larger than 2 μm were prepared at 200°C. Hydrothermal reaction of trialkylphosphates with Ca2+ ions at 200°C produced CaHPO4. The experimental results were used to propose a reaction mechanism for base-catalyzed hydrothermal reactions of alkylphosphates with Ca2+ ions.
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Received October 4, 2001. Accepted (revised) November 19, 2001
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Cihlar, J., Castkova, K. Direct Synthesis of Nanocrystalline Hydroxyapatite by Hydrothermal Hydrolysis of Alkylphosphates. Monatshefte fuer Chemie 133, 761–771 (2002). https://doi.org/10.1007/s007060200048
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DOI: https://doi.org/10.1007/s007060200048