Combustion energies and formation enthalpies of 2-SH-benzazoles

The experimental determinations of combustion energies and the standard molar enthalpies of formation of 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, and 2-mercaptobenzoxazole are presented. The combustion energies of compounds were determined by using a rotating-bomb calorimeter. The calorimeter used in the present work has been assembled, calibrated, and tested recently in our laboratory with desired results. As combustion auxiliary material, polyethene was used and its combustion energy was determined by using a static-bomb calorimeter. The combustion energies of 2-SH-benzazoles were used to derive the correspondent formation enthalpies in condensate phase at T = 298.15 K. The values of Delta H-f degrees(m) for the compounds are (48.6 +/- 1.4) kJ . mol(-1), (85.3 +/- 1.5) kJ . mol(-1), and (- 112.7 +/- 1.4) kJ . mol(-1), respectively. (C) 2008 Elsevier Ltd. All rights reserved.