Correlation of the radiation chemistry of liquid hydrocarbons with the energetics of molecular-ion reactions

Abstract

Exothermic reactions involving alkane parent ions are considered to precede the neutralization process in the liquid state. Thermochemical calculations show that carbon-carbon scission is energetically preferred for branched alkane ions whereas the corresponding dissociation of linear hydrocarbon ions is less favoured. Hydrogenatom detachment from a parent ion is not a facile process but the removal of molecular hydrogen to produce an olefin ion is exothermic in trans-vinylene group formation. A reaction of the parent ion with a molecule is often exothermic and can lead to dimer formation. These considerations afford a rational basis for the interpretation of the radiation chemistry of hydrocarbons as a function of molecular structure ; an explanation is derived for the occurrence of either cross-linking or degradation in irradiated vinyl polymers.

Radiation and Photochemistry

“…By means of a very elegant isotopic label ling technique, Holroyd & Klein (99) measured the radicals produced in the liquid phase radiolysis of a number of alkanes. Because in the case of neopen tane, the yield of CH3 radicals largely exceeds that of the corresponding t-butyl radicals, they concurred with the mechanism proposed previously by Williams (100). …”

Oxidation of solid polyethylene films: Effects of backbone branching

“…The reproducible, higher peroxyl yield from PP implies more bond scission in highly branched molecules, as has been previously reported. 23 Oxidation products may be directly observed by FTIR analysis of polyolefin films. However, several types of--OH species (alcohols and hydroperoxides) give broad, overlapped absorptions at --~ 3400 cm-1 and the absorptions of many carbonyl species merge together at 1780 1700cm 1.24 The use of NO and SF4 gas treatments allows the more precise FTIR identification and quantification of alcohols and hydroperoxides (as nitrites and nitrates, respectively, after NO reaction), carboxylic acids (after SF4 treatment to produce acid fluorides) and ketones (after removal of the overlapping acid absorptions and hydrogen bonding effects with --OH groups by SF 4 reactions).…”

The Ranges of Interactions in the Radiolysis of Solid Hydrocarbon Mixtures

“…'I'hermodynamically possible ion-molecule reactions can be written for the production of I-ID and Dz in mixtures of light and heavy hydrocarbons (14,15). As we have argued, these should have small values of RED, -25 A, as observed in the (C6D12)/(C6H14) system.…”