Thermodynamics of proton dissociation in dilute aqueous solution. Part XV. Proton dissociation from several monosaccharides at 10 and 40 °C

Abstract

The calorimetric titration method has been used to study proton dissociation from lyxose, ribose, 2-deoxyribose, xylose, arabinose, mannose, fructose, glucose, 2-deoxyglucose, and galactose at 10 and 40 °C. Decomposition of the sugars was found to be significant at 40 °C except in the cases of mannose and deoxyglucose. Thermodynamic pK, ΔH°, and ΔS° values are reported for proton ionization from all compounds at 10 °C and from mannose and deoxyglucose at 40 °C. The changes in the thermodynamic quantities as a function of temperature are discussed and ΔC_p values of –29 and –37 cal mol^–1 K^–1, respectively, are reported for proton dissociation from mannose and deoxyglucose over the temperature range 10–40 °C.