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.
The photochemical reaction of HCN at 184.9 nm is studied in the gas phase. (CN)2, H2, CH4, NH3, N2H4, C2H6, and CH3NH2 are identified as gas phase products, and a reaction mechanism is proposed. HCN polymers are also obtained as solid reaction products, and their structure is investigated by Infrared Spectorscopy, UV-Visible Spectroscopy, Mass Spectrometry, and Amino Acid Analysis. The process and nature of the formation of the polymers are discussed.
Reaction mechanism of pyrolysis of toluene was studied with toluene-d5 of high isotopic purity.duced in the pyrolysis of toluene-d5 were collected and analyzed by mass spectrometer. Formation of some amount of D2 is confirmed, and it is concluded that the fission of ring C-D bond is involved to some extent in the pyrolytic reaction of toluene-d5 at high reaction temperatures. The ratio of rate constants of abstraction type (kD-H/kH-n) is also determined, and the difference of the activation energies between kD_HH and kH_H is found to be approximately 14 kcal/mol.Since the pioneering work by Szwarc,1) the mechanism of pyrolysis of toluene has been investigated by several workers, [2][3][4][5][6] and it is now fairly established that the main primary process in this reaction is the homolytic fission of carbon-hydrogen bond of side chain. In consideration of these experiments, Price proposed the value of 85 kcal/mol for the bond dissociation energy D(C6H5CH2-H).6) However, the details of the reaction mechanism, particularly of the 1) H.
Chemiionization of excited mercury atom with 253.7 nm irradiation was studied. Results on the system Hg–N2 previously reported were further confirmed. It was found that CH4 can also induce chemiionization of Hg atoms with 253.7 nm irradiation. The dependence of ionization current on CH4 pressure and light intensity was investigated, the ionization current being found to be proportional to the square of light intensity and to increase with increase in CH4 pressure up to 30 Torr, reaching a constant value. N2 and CH4 are considered to show a similar behavior in ionization current against pressure and light intensity, and other substances such as H2, He, CO, NO, Ar, C2H4, and 1-butene to give no appreciable ionization current. Thus the mechanism in which chemiionization proceeds through the collision of Hg(3P1) with Hg(3P0) is further confirmed.
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