GAS-PHASE PHOTOLYSIS OF METHYLCYCLOPROPANE AT 1470 AND 1236 A

The photolysis of methyl cyclopropane has been investigated at 1470 and 1236 Å in the presence and absence of nitric oxide and oxygen. In addition, a series of experiments was carried out in which H2S was used as a free-radical interceptor, and where Ne was used to increase collisional deactivation. Three primary processes have been postulated, where (C4H6)* represents an internally excited species and [C4H8]‡ a diradical with excess CH3 → H2 + (C4H6)* (1) CH + hv → CH4 + C3H4 (2) CH2-CH2 → [CH3CH(CH2)2]‡ (3) internal energy. Although postulation of the [C4H8]‡ diradical is primarily based on the formation of C2H5 and C3H7 radicals, it appears that nearly 90% of the products reported originate through fragmentation of the diradical. Acetylene, allene, and hydrogen decrease with increasing methyl cyclopropane pressure, which is consistent with a secondary decomposition of fragment molecules originating from the diradical.