Calorimetric Studies on the Phenolic Glycoside D(-)-Salicin

A pure orthorhombic phase sample of D(-)-salicin was purified and characterized for calorimetric measurements. From differential scanning calorimetry (DSC) measurements it was found that the onset and maximum temperatures of the fusion peak were Ton = (473.30 ± 0.05) K and Tmax = (474.74 ± 0.05) K, respectively, and that the corresponding standard enthalpy of fusion was ΔcrlHm° = (55.5 ± 0.4) kJ mol−1. From the last two values the standard entropy of fusion is calculated as ΔcrlSm° = (116.9 ± 0.4) J mol−1 K−1. The standard molar enthalpy of formation of orthorhombic D(-)-salicin at T = 298.15 K, was determined as ΔfHm°(C13H18O7, cr, orthorhombic) = −(1366.9 ± 3.2) kJ mol−1, by combustion calorimetry. From the results of solution calorimetry obtained in this work and some auxiliary values taken from the literature the enthalpy of reaction of hydrolysis of D(-)-salicin to produce β-glucose and o-hydroxybenzyl alcohol was found marginally thermoneutral, if the uncertainty interval was considered. Additionally, specific heat capacity measurements on the orthorhombic phase, glass and liquid-quenched glass obtained by DSC was reported. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:5354-5362, 2008