Radiation Chemistry of Cyclohexane: Vi. Dilute Solutions of Carbon Tetrachloride and Chloroform in Cyclohexane

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.

Section: Results a N D Discussionmentioning

confidence: 99%

“…Dyne (1) has proposed a general mechanism to explain this inhibition, and Stone and Dyne (2) have studied the action of CC14 on the radiolysis of cyclohexane in some detail (2). I t was felt that a study of the major liquid products of the radiolysis of cyclohexane with NzO or SF6 might add support to the general mechanism of Dyne.…”

Section: Introductionmentioning

confidence: 99%

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

Sagert¹,

Blair²

1967

“…We will show later that a combination of charge transfer and electron capture is consistent with the results of radiolyses in krypton matrices. Table I11 shows that G(cyc1ohexene) is reduced to the same extent as G (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) by the addition of carbon tetrachloride or benzene but G(bicyclohexy1) is reduced to a much greater extent. Since the cyclohexane molecules are isolated in the matrix, bicyclohexyl I must be formed on warming up the sample, i.e.…”

Section: (3) the Effect Of Solz~tesmentioning

confidence: 98%

Charge Transfer in the Radiolysis of Dilute Solutions of Hydrocarbons in Krypton Matrices at 77 °k

Stone¹

1965

Self Cite

“…While i t appears that many solutes inhibit the forination of hydrogen it does not follow that all other decoinpositions are inhibited. On the contrary, reactions follouring electron capture may lead t o a net increase in decon~position (as is shown in the detailed product analysis of the CGI-I1?-CC1., system (15)) even though the yields of soine products, hydrogen in particular, may be reduced. The two decomposition modes arc now interpreted as being due to the forination of ions and electrons (the inhibited yield) and to the forlnation of excited inolecules (the residual yield).…”

Section: Processes W H I C H Redzrce the Hydroge7z Yieldmentioning

confidence: 99%

“…Scholes and Sinzic decrease in hydrogen yield and suggest that "NZO can scavenge some electrons which d o not norinallj-lead to hydrogen gas." Stone and Dyne (15) found that, in solutions of CCll in CGHl?, the yield of I-ICl was greater than the decrease in hydrogen yield by as much as 1 G unit and that this was correlated with a larger number of cyclohexyl residues in the products. In their words "carbon tetrachloride enhances radiolytic action."…”

Section: The Effect Of Hydrogen Halides On the Radiolysis Of Hydrocarmentioning

confidence: 99%

Charge Transfer and Electron Capture in the Radiolysis of Aliphatic Hydrocarbons

Dyne¹

1965

Self Cite

A mechanism is suggested for the radiolysis of hydrocarbons. Both ions and excited ~nole-cules are produced in the initial excitation. Ion-electron recombination leads to the formation of excited molecules which have similar properties to thosc formed initially; all subsequent decon~position proceeds through these excited molecules. 111 ~nixtures of hydrocarbons, ions and n~olecules may undergo positive charge exchange and additives reduce the hydrogen yield by capturing electrons or reacting with the positive ion. T h e mechanism provides a ratio~lalization for a variety of observatio~ls. This paper presents a mechanism for part of the radiolytic decomposition of hydrocarbons in which electron capture and charge exchange play a dominant role. There is no novelty in postulating these reactions a s mechanistic steps. The significance of electron capture has been discussed on inany occasions by I-Iamill and his colleagues (see, for instance, refs. 1 , 2, 3). Charge exchange was proposed by Hardxirick (4) as a inechanisn~ for the reactivity transfer observed in mixtures of aliphatic hydrocarbons and has also been suggested by Hamill. The crux of this proposed mechanism lies in the combination of two hypotheses, first, that the initial act of excitation leads to the formation of both ions and excited molecules and secondly, that, in pure hydrocarbons, the recapture of the electron by the positive ion also leads to the formation of excited inolecules which are, for practical purposes, identical to these forined in the initial excitation. The mechanism provides an explanation for a variety of phenomena; viz., the rapid inhibition of part but not all of the hydrogen yield by solutes, reactivity transfer in mixtures of aliphatic and alicyclic hydrocarboils, and the effects of additives on the isotopic composition of radiolytic hydrogen produced from lnixtures containing deuterated hydrocarbons. Tlze iWeclzanism( 1 ) Radiolysis of a hydrocarbon A produces, initially, positive ions, an equivalent nuinber of electrons, and excited, un-ionized molecules A*.The yields of ions and excited inolecules are comparable and probably 3/100 eV absorbed.( 2 ) The recapture of the electron by the positive ion produces an excited species which is, for the purposes of the present discussion, identical with A* produced in [lb].