Vapor-phase photochemistry of furfural

The photochemistry of furfural (furan-2-carboxaldehyde) has been studied in the vapor phase by direct irradiation at a number of wavelengths from 3130 to 2225 Å as well as by sensitization by Hg(3P1) atoms. The products that were obtained were furan, methylacetylene, aliène, cyclopropene, and carbon monoxide. The quantum yield for decomposition was ∼5×10-a at 2225 and 2654 Å and was equally small in the first absorption region at 3130 Å Two primary processes are proposed, one of which may lead to furan and CO by a hydrogen migration, and the other to C3H4+2CO. The possibility exists that the latter process proceeds through an excited molecule of furan as an intermediate. Evidence is presented which suggests that much of the observed photochemistry involves a low energy triplet of furfural.