Butenes, addition radiolysis

Enhancement of the total butene yield is observed when various additives whose ionization potential falls below about 9.4 e.v. are present during ethylene radiolysis (35). This is consistent with the above interpretation (Figure 2). In the vacuum ultraviolet photolysis of cyclobutane the yield of butenes varies with the ionization potential of the additives in the same way as observed here (12). The maximum enhancement corresponds closely to the yield of C4H8+, as expected from our mechanism. 

The radiolysis of propane has been studied extensively in experiments that have included a wide range of techniques. The gas-phase radiolysis in the absence of inhibitors yields the products hydrogen, ethane, propene, 2,3-dimethylbutane, methane, ethylene, isobutane, acetylene, isopentane and n-butane as well as small quantities of butene-1, -pentane, 2-methylpentane and -hexane ° ° . At high conversions the yield of ethylene, propene, 2,3-dimethylbutane and isobutane are all reduced. The reduction in ethylene arises from hydrogen atom addition, while the reduction in the other products may arise from the reaction of propyl ions with propene to remove both C3H6 and the source of isopropyl radicals. 

Lipsky (237), Sandros (181), and Russian workers (238,239) observed triplet energy transfer from benzene to biacetyl for dilute benzene solutions. This indicates that the triplet lifetime in solution is also concentration dependent as is the case for o-xylene (240) where the lifetime Increased from a few nanoseconds to microseconds or more, on dilution. This has been confirmed for benzene (175,189) and further, additional evidence from photochemical (173) and pulse radiolysis (241) systems demonstrate the very short lifetime of the triplet state in pure benzene liquid. It is believed (175) that decay proceeds via the triplet excimer which is only inefficiently quenched by butene-2. Results of electron impact excitation (242) and pulse radiolysis (243) have indicated a triplet lifetime of 500 ps for gaseous benzene at low and high pressures. 

We have cited several examples which illustrate characteristic ionic polymerization reactions of unsaturated compounds, which may be contrasted with the behavior of alkanes, for which the initial ion-molecule reactions usually lead to stable ion products which do not react further. It was therefore of interest to investigate ionic reactions in cyclobutane, the saturated hydrocarbon isomeric with the unsaturated butenes, to establish whether cyclanes could properly be classified in either of these categories. Additional impetus for such a study was provided by radiolysis data on cyclobutane which suggested that the cyclobutane parent ion rearranges prior to reaction. ... 

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