Secondary reactions in the γ-radiolysis of hydrocarbons with electron scavengers

Abstract

Secondary reactions in the liquid phase radiolysis of cyclohexane in the presence of NzO and SF6 have been examined by determining the yields of liquid products. When we added up t o 0.3 M NzO, the hydrogen yield was reduced from its initial yield of 5.5 G units t o 2.5 G units.The nitrogen yields were about twice the decrease in hydrogen yields. Bicyclohexyl and cyclohexene yields increased from their initial values t o 2.27 and 3.50 G units respectively. When we added up to 0.12 M SFe, all the vields were decreased t o about one half of their initial value.These results may be interpreted in terms of Dyne's general mechanism for the radiolysis of hydrocarbons if two cyclohexyl radicals are produced for every electron scavenged by Nz0, b u t if none are produced for electrons scavenged by S F + I t is suggested that the total electron yield in pure cyclohexane is about 4.1 G units, of which only 3.0 G units produce hydrogen. The other 2.5 G units of hydrogen from the radiolysis of pure cyclohexane are presumed t o arise from direct excitation.

γ-Radiolysis of cyclohexane with electron scavengers. IV. CO2 as an electron scavenger

“…Yields of nitrogen which are larger than the normally accepted value of G(e-) are obtained from the liquid phase radiolysis of the cyclohexane-N20 system (3)(4)(5)(6). The origin of this extra nitrogen yield is uncertain, although the suggestion has been made that reaction [3] is responsible (1,5).…”

γ-Radiolysis of cyclohexane with electron scavengers. VII. Perfluorocyclohexane and perfluorobenzene as electron scavengers

“…Recent work by one of us (10) leads to an anion which does not produce hydrogen on neutralization and, before or during neutralization, does produce two cyclohexyl radicals, a C,Fll radical, and, as shown by Rajbenbach (9), a molecule of HF. These products could conceivably be produced by dissociation of the C,F12-anion (reaction [2]) [ (20) in the gas phase, because of solvation effects. However, we have shown (15) that C6FllH is produced in the gas phase radiolysis of the cyclohexane -C6F12 system where reaction [2] cannot occur.…”

“…These products could conceivably be produced by dissociation of the C,F12-anion (reaction [2]) [ (20) in the gas phase, because of solvation effects. However, we have shown (15) that C6FllH is produced in the gas phase radiolysis of the cyclohexane -C6F12 system where reaction [2] cannot occur. Hence it now appears that these products are produced mainly in the neutralization step (reaction [3])…”

“…Since they lose energy rapidly, only a small number of electrons escape completely from the fields of their parent ions and become uniformly distributed in the liquid. Typically, the total ion yield for aliphatic hydrocarbons is 4.3 ion pairs for each 100 eV absorbed (4.3 G units) (2,3) and the free ion yield is about 0.1 G units (4). One method of studying this phenomenon is to add solutes which react with or scavenge electrons before they can be captured by a positive ion.…”

The γ-Radiolysis of Ethane. III. The Effect of Density on Ion Scavenging Reactions above the Critical Temperature

“…This illustrates the present lack of knowledge of the secondary reactions which occur after neutralization by SF6-. For example Bansal and Schuler (28) find that electron scavenging by sulfurhexafluoride in liquid cyclohexane does not affect the yield of cyclohexyl radicals whereas Sagert and Blair (29) find that the normal products of radical combination and disproportionation are reduced in yield. In the present work formation of butane and propane subsequent to neutralization of hydrocarbon cations by SF6-cannot be ruled out.…”