Enthalpies of combustion and formation of α-D-glucoheptono-1,4-lactone and α,β-glucooctanoic-1,4-lactone

The standard molar energies of combustion, ΔcUm0(cr,298.15K), of α-D-glucoheptono-1,4-lactone (GH) and α,β-glucooctanoic-1,4-lactone (GO) were obtained by micro-combustion calorimetry. The obtained values are -(2924.6 ± 2.3) kJ . mol-1 and -(3459.5 ± 2.5) kJ . mol-1, respectively. From combustion energies, the standard molar enthalpies of formation in crystalline phase, ΔfHm0(cr,298.15K), for GH and GO were determined as -(1546.2 ± 2.5) kJ . mol-1 and -(1690.6 ± 2.7) kJ . mol-1, respectively. Also it was found that when the hydroxyl group number increases in the aldonolactones their standard molar enthalpies of formation increase too