Vera L. S. Freitas, Carlos A. O. Silva, Mónica A. T. Paiva
Mar 1, 2017
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Journal
Journal of Thermal Analysis and Calorimetry
Abstract
A thermochemical study of N-methylmorpholine and N-ethylmorpholine compounds was performed with the purpose of evaluating and understanding the energetic effects inherent to the replacement of the hydrogen of the amino group by an alkyl group in the morpholine scaffold. Calorimetric techniques complemented by computational calculations were used to determine the standard molar enthalpies of formation, in the gaseous phase, at T = 298.15 K, of the two morpholine derivatives. Static bomb combustion calorimetry and vacuum drop microcalorimetric techniques were used. Computational calculations of the enthalpies of hypothetical reactions in the gaseous phase, using the G3(MP2)//B3LYP composite method, were performed for the two morpholine derivatives. The values of the experimental and computational gas-phase enthalpy of formation obtained for N-alkylmorpholine compounds will be compared and discussed. The energetic effect and the structural changes resulting from the substitution of the hydrogen of the amino group by an alkyl group in the morpholine scaffold are analyzed.