A Quantum Chemical Study of the Abnormal Reactivity of 2-Methoxyfuran

The gas-phase pyrolytic and oxidative chemistry of furans has received much attention recently because of their potential as platform chemicals and biofuels. Typically these compounds exhibit very strong ring carbon to H or CH3 bonds. 2-Methoxyfuran had been reported to be exceptionally unstable in comparison to related substituted heterocycles in pyrolytic experiments. The origins of its reactivity are shown to be due to the very weak O-CH3, which at 189.5 + - 1.9 kJ mol-1 is some 200 kJ mol-1 weaker than C-H bonds in the molecule. We show that the reported reactivity is somewhat overestimated but that does not alter the fact that 2-methoxyfuran is exceptionally unstable. It may prove to be a useful alternative to azomethane as a thermal source of methyl radicals.