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Previous work by these authors found that ageing was necessary to convert the starting precursors of calcium diethoxide [Ca(OEt)(2)] and triethyl phosphite [P(OEt)(3)] Sol-gel system to more reactive intermediates, These conclusions provided the impetus to examine an alternative phosphorous precursor that will not entail a 24-hour ageing period. The use of diethyl phosphite [HOP(OEt)(2)] as an alternate precursor it was possible to produce hydroxyapatite which did not require ageing of the Sol. [1]. The solution-state P-31 NMR spectroscopy was successfully applied to monitor the reaction during the ageing period that provided the vital characteristics of the alternate phosphorous precursor. However, no attempts were made to postulate mechanism(s) and identification of the intermediate species formed in these sol-gel systems. This report encompasses both these aspects; mechanism and identification of the reaction intermediates for P(OEt)3 and [HOP(OEt)(2)] sol-gel systems

31P nuclear magnetic resonance (NMR) spectroscopy was used to determine the structure of the intermediate species of sol derived from triethyl phosphite, calcium diethoxide and acetic acid. NMR spectral data revealed that the reaction proceeds via a dialkyl phosphite intermediate. The use of a dialkyl phosphite precursor (diethyl phosphite) with calcium diethoxide eliminated the aging time required in triethylphosphite method and offered an effective sol-gel procedure for monophasic hydroxyapatite.