Ring strain energy and enthalpy of formation of oxiranone: an ab initio theoretical determination

Abstract

The enthalpy of formation ∆H o f,298 for oxiranone is estimated as Ϫ190 ± 10 kJ mol Ϫ1 by means of ab initio molecular orbital calculations at the QCISD(T)᎐ ᎐ full/6-311G(2df,p)//MP2᎐ ᎐ full/6-311G(d,p) level of theory, corresponding to a conventional ring strain energy of 169 kJ mol Ϫ1 . The QCISD(T) calculated enthalpy of formation of cyclopropanone is 6.3 kJ mol Ϫ1 . The oxiranone ring is probably slightly less strained than the cyclopropanone ring.

Catalytic Cracking of Lactide and Poly(Lactic Acid) to Acrylic Acid at Low Temperatures

“…An E2C mechanism with bromide ions acting as a weak base is more likely to be operative . Alternatively, an intramolecular carboxylic acid‐assisted E1‐type elimination pathway involving a hypothetical oxiranone intermediate has also been proposed …”

Theoretical characterization of the chemical bonds of some three-membered ring compounds through QTAIM theory

“…Wiberg et al [19], through measurements of the enthalpies of combustion, estimated strain energy for methylenecyclopropane about 56 kJ mol -1 greater than that for cyclopropane. Rodriquez et al [20] estimated that cyclopropanone is about 66 kJ mol -1 more strained than cyclopropane and calculated oxirane-2-one to have a ring strain energy 55 kJ mol -1 greater than that of oxirane (ethylene oxide). Turning to endocyclic double bonds, Johnson and Borden [17] and Wiberg et al [19] suggested the strain energy of cyclopropene is ca.…”

l-Lactide polymerization catalysed by tin(ii) 2-ethyl-hexanoate. A deeper look at chain transfer reactions

“…In the first one the three-membered α-lactone ring is formed (reaction 5) and consumed instantly due to its high ring strain (169 kJ·mol -1 from ab initio molecular orbital calculations). 15 Thus in real systems it can exists only at extremely low concentration. 16,17 However, as it was shown by Monte Carlo modelling, this reaction also explains some aspects of the process kinetics.…”