Photolysis of Nitromethane in Gas Phase at 313 nm

Photolysis of nitromethane in gas phase at 313.0 nm was studied at 55°C. Methyl nitrite, formaldehyde, nitrosomethane and NO were obtained as main products, their quantum yields being determined to be φCH3ONO=0.22, φHCHO=0.20, φCH3NO=0.06 and φNO=0.10. The dependence of the quantum yields on the pressure of quenching gases such as ethylene, cis-2-butene, CO2 and NO were investigated. The quantum yields of products except formaldehyde decrease with increase in pressure of ethylene or cis-2-butene. The sensitized isomerization of 2-butene was also observed. The quantum yield of triplet nitromethane was determined by the Gundall method and compared with that by product analysis. Both give the identical value 0.6. Since φHCHO is not affected by any quencher, it is concluded that formaldehyde is formed directly from singlet excited nitromethane.