Mercury-photosensitized decomposition of 2-azetidinone and 4,4-dimethyl-2-azetidinone

The mercury-photosensitized decompositions of 2-azetidinone(AZ) and 4,4-dimethyl-2-azetidinone(DMAZ) have been studied at 453 and 423 K and at pressures from 750 to 18000 Pa and from 640 to 5000 Pa, respectively. The major products from AZ were carbon monoxide and ethylene, while ammonia was a minor product. The yields of carbon monoxide and ethylene increased linearly with increasing reaction time and light intensity; they were independent of the AZ pressure. These results suggest that carbon monoxide and ethylene are trie primary products. The major products from DMAZ were carbon monoxide, isobutene, and 2,2dimethylaziridine; ethane, isobutane, and propylene were the minor products. The yields of carbon monoxide, isobutene, and dimethylaziridine increased linearly with increasing reaction time and light intensity at 3800 Pa, showing that these products are the primary ones. The formation of minor products was not linear with time. The quantum yields of carbon monoxide and isobutene were independent of the DMAZ pressure, while the relative yield of dimethylaziridine to that of carbon monoxide increased and those of the minor products decreased with an increase in pressure. Plausible mechanisms were proposed.