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, ΔcUm∘(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, ΔfHm∘(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.