INTERMOLECULAR AND INTRAMOLECULAR ENERGY TRANSFER IN GAMMA-IRRADIATED ALKYLBENZENES AND RELATED MIXTURES.
From radiolysis studies of various hydrocarbon mixtures (principally cyclohexane-benzene), intermolecular energy transfer has been proposed to explain deviations of product yields from those expected on the basis of noninteraction of constituents of the mixtures (1, 2). Similarly, intramolecular energy transfer from alkyl group to phenyl group has been proposed to explain low radiolysis product yields from alkylbenzenes (3-5). In this study, hydrogen yields for a series of alkylbenzenes have been measured in an effort to determine the effect of side-chain length on intramolecular energy transfer. These data, in addition to hydrogen yields measured for related twocomponent hydrocarbon systems, provide a basis for comparison of intermolecular and intramolecular energy transfer.
THE REACTIVITY OF HYDROGEN ATOMS IN THE LIQUID PHASE
A method is described in which hydrogen atoms, produced in situ by the radiolysis of a saturated hydrocarbon as solvent, are allowed to react competitively wlth a reactive solute and the solvent. A kinetic expression is derived whereby the relative rate constants for the competing reactions can be calculated from a measurement of the hydrogen gas yield as a function of solute concentration. From previous measurements of the absolute rate constants of H + solute, absolute rate constants for the reaction H + paraffin solvent are obtained. These rate constants show an effect of the molecular structure of the paraffin solvent. Specific values can be assigned to primary, secondary, and tertiary groups, from which the absolute rate constant of the reaction of hydrogen atoms wlth any saturated liquid hydrocarbon may be calculated. If rate constants so measured or calculated are compared with the corresponding published values of H + paraffln in the gas phase, reasonable agreement is found It is thus concluded that such radicalmolecule reactions occur at thc same rate in the gas phase as in hydrocarbon solvent. (auth)
Life Strategies, Human Evolution, Environmental Design
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