Enthalpies of formation of N-substituted pyrazoles and imidazoles

• Tipo: Artigo em Revista Científica Internacional
• Data: 1999

Autores

Mo, O (Autor) Outra; Yanez, M (Autor) Outra; Roux, MV (Autor) Outra; Jimenez, P (Autor) Outra; Davalos, JZ (Autor) Outra; da Silva, MAVR (Autor) FCUP; da Silva, MDMCR (Autor) FCUP; Matos, MAR (Autor) FCUP; Amaral, LMPF (Autor) Outra; Sanchez Migallon, A (Autor) Outra; Cabildo, P (Autor) Outra; Claramunt, R (Autor) Outra; Elguero, J (Autor) Outra; Liebman, JF (Autor) Outra

Revista

Título: Journal of Physical Chemistry A

Vol. 103

Páginas: 9336-9344

ISSN: 1089-5639

Editora: American Chemical Society

Indexação

ISI Web of Knowledge - 63 Citações

Scopus - 70 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Química

Outras Informações

ID Authenticus: P-001-2TH

DOI: 10.1021/jp992244f

Abstract (EN): Accurate experimental enthalpies of formation measured using static bomb combustion calorimetry, the "vacuum sublimation" drop calorimetry method, and the Knudsen-effusion method are reported for the first time for four azoles: 1-methylimidazole (1MeIMI), 1-methylpyrazole (1MePYR), 1-benzylimidazole (1BnIMI), and 1-benzylpyrazole (1BnPYR). These values and those corresponding to imidazole (1HIMI), pyrazole (1HPYR), 1-ethylimidazole (1EtIMI), 1-ethylpyrazole (1EtPYR), 1-phenylimidazole (1PhIMI), and 1-phenylpyrazole (1PhPYR) are compared with theoretical values using the G2(MP2) and the B3LYP/ 6-311*G(3df,2p)//6-31G(d) approaches. In general, there is a very good agreement between calculated and experimental values for the series of N-substituted imidazoles, while the agreement is less good for the series of the N-substituted pyrazoles. Experimentally, the gap between the enthalpies of formation of imidazoles and pyrazoles decreases significantly upon N-substitution, while the theoretical estimates indicate that this decrease is smaller.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 9