Enthalpies of combustion of 1-hydroxynaphthalene, 2-hydroxynaphthalene, and 1,2-, 1,3-, 1,4-, and 2,3-dihydroxynaphthalenes

Abstract

The standard ( p o = 101.325 kPa) molar enthalpies of combustion in oxygen at 298.15 K were measured by static bomb calorimetry for the two hydroxynaphthalenes and for four dihydroxynaphthalenes. The standard molar enthalpies of sublimation at 298.15 K were measured by microcalorimetry for the 1,2-, 1,3-, and 2,3-dihydroxynaphthalenes. Literature values were used for the other compounds. The standard molar enthalpies of formation in the gaseous state were derived. −Δ c H m o(cr)/(kJ · mol −1) Δ f H m o(g)/(kJ · mol −1) 1-hydroxynaphthalene 4956.4 ± 0.8 −30.8 ± 1.6 2-hydroxynaphthalene 4954.3 ± 1.0 −29.9 ± 1.7 1,2-dihydroxynaphthalene 4768.6 ± 1.0 −200.5 ± 1.8 1,3-dihydroxynaphthalene 4751.2 ± 0.7 −211.2 ± 1.9 1,4-dihydroxynaphthalene 4761.0 ± 0.7 −197.0 ± 1.8 2,3-dihydroxynaphthalene 4776.0 ± 1.1 −192.8 ± 1.8 The standard molar enthalpies of formation of the 1,2-, 1,3-, and 1,4-dihydroxynaphthalenes in the gaseous state follow the same pattern as those for the corresponding dihydroxybenzenes.