Partial molar heat capacities and volumes of some mono-, di- and tri-saccharides in water at 298.15, 308.15 and 318.15 K

Abstract

Partial molar heat capacities (C̄_p,2⁰) and partial molar volumes (V̄₂⁰) of seven monosaccharides [D(−)-ribose, D(−)-arabinose, D(+)-xylose, D(+)-glucose, D(+)-mannose, D(+)-galactose and D(−)-fructose], seven disaccharides [sucrose, D(+)-cellobiose, lactulose, D(+)-melibiose hemihydrate, D(+)-maltose monohydrate, D(+)-lactose monohydrate, D(+)-trehalose dihydrate] and one trisaccharide [D(+)-raffinose pentahydrate] have been determined at 298.15, 308.15 and 318.15 K using a Picker flow microcalorimeter and a vibrating-tube densimeter respectively. From these data partial molar expansion coefficients (∂V̄₂⁰/∂T)_P, isothermal compressibilities (K_T,2⁰), excess partial molecular volumes (v̄₂^0,ex) and partial molar heat capacity coefficients (∂C̄_p,2⁰/∂T )_p of the various sugars have been calculated. The C̄_p,2⁰ and V̄₂⁰ values were found to be highly positive and increased with increase in temperature. High positive values of C̄_p,2⁰ showed that the dissolution of the sugars was accompanied by the enhancement of the structural order in water. The results have been rationalized in terms of the specific hydration model.