Effects of methoxy and formyl substituents on the energetics and reactivity of α-naphthalenes: A calorimetric and computational study

•Experimental and computational molecular energetics of α-naphthalenes.•Intramolecular hydrogen interaction on α-formylnaphthalene.•Influence of different substituents on the energetics and reactivity of α-naphthalene.•Molecular energetics of α-naphthalene derivatives.

A combined experimental and computational study was developed to evaluate and understand the energetics and reactivity of formyl and methoxy α-naphthalene derivatives. Static bomb combustion calorimetry and the Calvet microcalorimetry were the experimental techniques used to determine the standard (po = 0.1 MPa) molar enthalpies of formation, in the liquid phase, ΔfHmo(l), and of vaporization, ΔlgHmo, at T = 298.15 K, respectively, of the two liquid naphthalene derivatives. Those experimental values were used to derive the values of the experimental standard molar enthalpies of formation, in the gaseous phase, ΔfHmo(g), of 1-methoxynaphthalene, (−3.0 ± 3.1) kJ mol−1, and of 1-formylnaphthalene, (36.3 ± 4.1) kJ mol−1. High-level quantum chemical calculations at the composite G3(MP2)//B3LYP level were performed to estimate the values of the ΔfHmo(g) of the two compounds studied resulting in values in very good agreement with experimental ones. Natural bond orbital (NBO) calculations were also performed to determine more about the structure and reactivity of this class of compounds.

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