Thermodynamic properties of aqueous 4-hydroxyproline at different temperatures

Specific heat capacities (cp) and apparent molar heat capacities (Cp,2,ϕ) of aqueous 4-hydroxyproline have been measured from T = (298.15 to 328.15) K over the molality range of (0.101708 to 2.031524) mol · kg−1 using micro differential scanning calorimetry. The values of density (ρ), apparent molar volume (V2,ϕ), speed of sound (u), and adiabatic apparent molar compressibility (KS,2,ϕ) have also been determined for aqueous 4-hydroxyproline from T = (288.15 to 313.15) K over the molality range of (0.037934 to 0.786476) mol · kg−1. The results of these measurements have been used to calculate the following standard partial molar quantities and their temperature derivatives for aqueous 4-hydroxyproline as a function of temperature: Cp,2,m∘,(∂Cp,2,m∘/∂T)p,(∂2Cp,2,m∘/∂T2)p,V2,m∘,(∂V2,m∘/∂T)p,(∂2V2,m∘/∂T2)p,KS,2,m∘,(∂KS,2,m∘/∂T)p, and (∂2KS,2,m∘/∂T2)p. Isothermal titration calorimetry has been used to determine the heat of dilution (q) of aqueous 4-hydroxyproline and aqueous l-proline in water over the temperature range from (288.15 to 308.15) K. The results have been discussed in terms of the changes in interactions of 4-hydroxyproline and l-proline molecules in the aqueous form, and their water structure promoting ability with rise in temperature.