Energetics and Reactivity of Morpholine and Thiomorpholine: A Joint Experimental and Computational Study

Abstract

The influence of the heteroatoms in the conformational, energetic, and reactivity trends exhibited by morpholine and thiomorpholine isosteres was obtained from computational and experimental thermochemical studies. For those purposes, the gas-phase standard (p° = 0.1 MPa) molar enthalpies of formation of the compounds, at T = 298.15 K, were determined from the experimental values of the standard molar enthalpies of formation, in the liquid phase, and of the standard molar enthalpies of vaporization, obtained by calorimetric techniques, and also from composite G3­(MP2)//B3LYP calculations making use of appropriate working reactions. A very good agreement was found between the calculated and the experimental gas-phase enthalpies of formation. The computational study was further extended to the calculation of other gas-phase thermodynamic properties of these compounds, namely, the N–H or C–H bond dissociation enthalpies, gas-phase acidities and basicities, proton affinities and adiabatic ionization enthalpies, and the energies and structures of the conformational stereoisomers of morpholine and thiomorpholine.

Efficient Ab Initio Estimation of Formation Enthalpies for Organic Compounds: Extension to Sulfur and Critical Evaluation of Experimental Data

“…Comparison of the computed (QZ version) and experimental enthalpies of formation of compounds, for which the combustion energies were published after 2013: diamonds, determined in the Porto laboratory; − ,,,− circles, determined in the Puebla laboratory. ,,, The value for 1,3-dihydroimidazole-2-thione has a deviation of −32 kJ·mol –1 and is not shown.…”

The effect of halogen atoms at propanoate anion on thermo physical, vibrational spectroscopy, chemical reactivity, biological properties of morpholinium propionate Ionic Liquid

“…The second key point of morpholine is a heterocyclic chemical compound containing both of nitrogen and oxygen atoms, which indicates amine and ether functional groups. Morpholine is a base due to the presence of the amine showing nucleophilic character typical of secondary amines (Wang and Tabor, 1988;Freitas et al, 2014). Recently, biodegradation and isolation of pure cultures of degrading bacteria of morpholine has been established.…”