Effects of methoxy and formyl substituents on the energetics and reactivity of α-naphthalenes: a calorimetric and computational study.
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 (p(o)=0.1 MPa) molar enthalpies of formation, in the liquid phase, ΔfHm(o)(l), and of vaporization, Δl(g)Hm(o), at T=298.15K, 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, ΔfHm(o)(g), of 1-methoxynaphthalene, (-3.0 ± 3.1)kJmol(-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 ΔfHm(o)(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.
Centro de Investigação em Química, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 687, P-4169-007 Porto, Portugal.
Ana L R
ALR
Silva
Centro de Investigação em Química, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 687, P-4169-007 Porto, Portugal.
Vera L S
VLS
Freitas
Centro de Investigação em Química, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 687, P-4169-007 Porto, Portugal. Electronic address: mdsilva@fc.up.pt.
Maria D M C
MDMC
Ribeiro da Silva
D002151:Calorimetry; D005740:Gases / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D009281:Naphthalenes / Q000737:chemistry*; D013816:Thermodynamics; D014835:Volatilization
D005740:Gases; D009281:Naphthalenes
1-Methoxynaphthalene; 1-Naphthaledehyde; Electrostatic potential energy maps; Enthalpy of formation; Frontier orbitals; Intramolecular hydrogen bonds