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 ( _p,2 ⁰ ) and partial molar volumes ( ₂ ⁰ ) 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 (∂ ₂ ⁰ /∂T) _P , isothermal compressibilities (K _T,2 ⁰ ), excess partial molecular volumes ( ₂ ^0,ex ) and partial molar heat capacity coefficients (∂ _p,2 ⁰ /∂T ) _p of the various sugars have been calculated. The _p,2 ⁰ and ₂ ⁰ values were found to be highly positive and increased with increase in temperature. High positive values of _p,2 ⁰ 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.