Hydrogen bonding Part 38. IR and thermodynamic study of phosphorylcholine chloride calcium salt tetrahydrate and monohydrate

Article abstract of DOI:10.1016/0022-2860(91)85065-B

Vapor pressure vs.H2O content studies demonstrate that phosphorylcholine chloride calcium salt forms two hydrates, a monohydrate and a tetrahydrate, in the range 0-4 mol H2O mol^-1 of salt; there is no dihydrate or trihydrate.Equilibrium vapor pressure measurements show that ΔH⁰ of dissociation per mol H2O lost is greater for the tetrahydrate (16.08 kcal mol^-1) than for the monohydrate (12.49 kcal mol^-1); the lower stability of the tetrahydrate arises from entropy effects.The IR spetrum of the tetrahydrate is that of a framework clathrate hydrate and suggests that the -PO3 group may act as a very weak hydrogen-bond acceptor.In the monohydrate the -PO3 group is not involved in hydrogen bonding.Neither hydrate contains P-OH bonds.