Assessment of Thermochemical Data of γ-Butyrolactone from Experimental and Computational Studies

Abstract

Relevant thermochemical data of γ-butyrolactone (GBL), a compound of considerable industrial and environmental significance, obtained from experimental and computational studies are reported in this work. The standard (p° = 0.1 MPa) molar enthalpy of formation, at T = 298.15 K, in the gaseous phase, was determined from the enthalpy of combustion and vaporization, obtained by static bomb calorimetry in oxygen and by Calvet microcalorimetry, respectively. The enthalpy of formation in the gaseous phase was also determined from G3 calculations. The excellent agreement between the experimental and computational thermochemical data provided a critical literature review of GBL and the proposal of new reference values for this lactone.

Abstraction and addition reactions of four γ‐lactones with H‐atoms and methyl radicals

“…The isodesmic reaction: GHL + HCHO = GBL + CH 3 CH 2 CH 2 CHO has a reaction enthalpy of $$-7.41 \pm 0.97$$ kJ mol −1 ; in conjunction with the well‐known formation enthalpies of formaldehyde ($$-109.229 \pm 0.096$$), n‐butanal 32 ($$-205.7 \pm 0.92$$), and γ‐butyrolactone or GBL 30 ($$-370.0 \pm 1.5$$), this yields a heat of formation of −439.5 ± 1.7 kJ mol −1 .…”

“…For GVL, the two isodesmic reactions used, in combination with the reference molecule GBL for which the thermochemistry is known, 30 were $$$$\begin{eqnarray} {\rm GVL + HCHO} & = & {\rm GBL} + {\rm HC(O)CH_3}\end{eqnarray}$$$$ $$$$\begin{eqnarray} {\rm GVL} + {\rm HC(O)CH_3} & = & {\rm GBL} + {\rm CH_3C(O)CH_3} \end{eqnarray}$$$$with reaction enthalpies of $$-11.89 \pm 0.68$$ and $$-7.87 \pm 1.78$$ kJ mol −1 , respectively, computed from four composite methods, 31 namely CBS‐QB3, CBS‐APNO, G3, and G4. Formation enthalpies of formaldehyde ($$-109.229 \pm 0.096$$), acetaldehyde ($$-165.55 \pm 0.23$$), and propanone ($$-216.93 \pm 0.27$$) 32 give an average value of −413.97 ± 2.01 kJ mol −1 (298.15 K).…”

“…Adopting formation enthalpies of −188.7 ± 0.75 for propanal, 33 and −238.46 ± 0.79 for methyl ethyl ketone 32 yields a heat of formation (298.15 K) from Equation (3) of −442.7 ± 1.7 and from Equation (4) of −436.3 ± 1.7 resulting in a grand-weighted average of −439.5 ± 1.7 kJ mol −1 . The isodesmic reaction: GHL + HCHO = GBL + CH 3 CH 2 CH 2 CHO has a reaction enthalpy of −7.41 ± 0.97 kJ mol −1 ; in conjunction with the well-known formation enthalpies of formaldehyde (−109.229 ± 0.096), n-butanal 32 (−205.7 ± 0.92), and 𝛾-butyrolactone or GBL 30 (−370.0 ± 1.5), this yields a heat of formation of −439.5 ± 1.7 kJ mol −1 . The (298.15 K) value decreases as the alkyl chain on the five-membered ring structure lengthens from methyl (GVL) to ethyl (GCL) to propyl (GHL); the same trend is observed for straight-chain aldehydes from formaldehyde through to butanal, 32,33…”

“…For GVL, the two isodesmic reactions used, in combination with the reference molecule GBL for which the thermochemistry is known, 30 were For GCL, the two isodesmic reactions employed were…”

“…GBL,30 Aldehydes 32. with reaction enthalpies of −11.89 ± 0.68 and −7.87 ± 1.78 kJ mol −1 , respectively, computed from four composite methods,31 namely CBS-QB3, CBS-APNO, G3, and G4.…”