Infrared Photochemistry of Oxetanes: Mechanism of Chemiluminescence

Article abstract of DOI:10.1021/ja00264a033

The infrared multiphoton (IRMP) induced photolysis of several oxetanes is examined at low pressures (ca. 100 mtorr) while experimental variables such as laser frequency, laser energy, bath gas, and bath gas pressure are altered.The products of the IRMP induced photolysis of 2-acyl-3 ethoxy-2-methyloxetane, Ox1, are primarily biacetyl and ethyl vinyl ether.When the photolysis is run with the collimated beam of a CO2 laser (1-3 J/cm²) luminescence is observed.The intensity of the luminescence varies with the efficiency of the unimolecular decomposition of the oxetane.On the basis of the spectral distribution and temporal behavior of the luminescence following irradiation of Ox1, the emitter is believed to be vibrationally hot electronically excited biacetyl.Similar experiments with 2,2-dimethyl-3-ethoxyoxetane give a weaker emission apparently due to excited-state acetone.Results are discussed in terms of the reverse of the Paterno-Buchi reaction - a diabatic retrophotocycloaddition.