Apatite phosphates containing heterovalent cations and their application in Knoevenagel condensation

Apatite structure type ortho phosphates of the formula NaLaCa₃(PO₄)₃OH and NaLaSr₃(PO₄)₃OH have been synthesized via a simple solution route. The compounds are isostructural with calcium hydroxyapatite. The phases are characterized by powder X-ray diffraction method and infrared spectroscopy. The unit cell parameters are: for NaLaCa₃(PO₄)₃OH, a = 9.457(3) and c = 6.90(1) Å and for NaLaSr₃(PO₄)₃OH, a = 9.720(3) and c = 7.23(3) Å, respectively. Knoevenagel condensation of selected aldehydes and molecules with activated methylene group is carried out using the phosphates as solid supports. Both phases facilitated the condensation reaction at room temperature in the absence of a solvent. An increase in the yield of the products is noticed when the supports are used with water.