Structure and thermochemical properties of 2-methoxyfuran, 3-methoxyfuran, and their carbon-centered radicals using computational chemistry

Document Type

Article

Publication Date

8-5-2010

Abstract

Methoxyfurans are known components in a number of biofuel synthesis processes and their thermochemical properties are important to the stability, reaction paths, and chemical kinetics of these species. Enthalpies (ΔH°f298), entropies (S°298), and heat capacities (Cp(T)) are reported for 2-methoxyfuran and 3-methoxyfuran, cyclic ethers with possible biofuel implications, and their radicals corresponding to loss of hydrogen atoms. Standard enthalpies of formation are calculated at the B3LYP/6-31G(d,p), B3LYP/6-311G(2d,2p), CBS-QB3, G3MP2B3, and G3 levels of theory with isodesmic reactions to minimize calculation errors. Structures, vibrational frequencies, and internal rotor potentials are calculated at the B3LYP/6-31G(d,p) density functional level and are used to determine the entropy and heat capacities. The recommended ideal gas phase enthalpy of formation, from the average of the CBS-QB3 and G3MP2B3 levels of theory, for 2-methoxyfuran is -45.0 kcal mol-1 and for 3-methoxyfuran is -41.1 kcal mol-1. Bond dissociation energies are also calculated. The C-H bonds of the furan ring are approximately 120 kcal mol-1, which is consistent with recent data on several alkylfurans; they are significantly stronger than non-aromatic, stable heterocyclic structures. The bond energy decreases to 98 kcal mol-1 for the methoxy-methyl C-H bonds making this methyl site a favorable abstraction target and an important site for initial decomposition paths during combustion. Group additivity for furan is discussed and groups for furan and methoxyfuran carbon radicals are derived. © 2010 American Chemical Society.

Identifier

77955104639 (Scopus)

Publication Title

Journal of Physical Chemistry A

External Full Text Location

https://doi.org/10.1021/jp102996d

e-ISSN

15205215

ISSN

10895639

First Page

7984

Last Page

7995

Issue

30

Volume

114

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