Rates of Alkyl Radical-Radical, Alkyl Radical-Iodine, and Iodine Atom-Atom Reactions in Normal Alkanes and Cycloalkanes

Abstract

Pulse radiolysis techniques have been used to determine the second order rate constants for radical-radical reactions of the parent alkyl radicals produced in neat liquid cycloalkanes of CS to C~O and normal alkanes of c 6 to C17. Iodine solutions of these compounds were used to determine the radical scavenging rate constants, the extinction coefficients of the iodine atom produced from this reaction, and the second-order rate constants for the subsequent reactions of the iodine atoms. None of the three sets of rate constants were found to be completely proportional to the inverse of the viscosity of the media, indicating that they are not solely diffusion rate-controlled. However, it was possible to describe the observed rate constants for the alkyl radicaliodine and iodine atom-atom reactions with a combination of a diffusion-controlled rate constant which scales inversely with the viscosity of the media and an activation-controlled rate constant which is the same for all media. The same procedure also worked for the alkyl radical-radical reactions except that the diffusioncontrolled rate constant was further modified by a spin-steric factor. No significant differences were observed in all three sets of rate constants for the normal alkanes or the cycloalkanes at the same viscosity.

Heavy-Ion Radiolysis of Cyclooctane

“…x lo9 M-' s-l 18) and radical scavenging is about the same if it further assumed that cross reactions (R10 and R11) are upper limit of iodine concentration is limited by its solubility while its lower limit is restricted to the lowest amount that will not be completely depleted for the given radiation dose. One particular advantage of the use of gas chromatographic-mass spectrometric techniques is that very low doses and thereby low iodine concentrations can be used.…”

Synthesis of Zn-MOF incorporating titanium-hydrides as active sites binding H2 molecules

“…Subsequently, two C 6 H 11 • radicals are likely to be self-terminated to yield C 6 H 12 , C 6 H 10 , and C 12 H 22 (Fig. 4c), which was hypothesized based on previous reports [45,46].…”

Kinetics of the early stages of high-energy radiation initiated polymerization

“…Cyclohexyl radicals produced in the radiolysis of pure cyclohexane decay in a self-termination reaction with a rate coefficient [24] of 2 N k t = 2 N 10 9 mol -1 N dm 3 N s -1 (1). c-C 6 H 11 9 + c-C 6 H 11 9 gggs kt, CH products (1) In the presence of monomer there is a competition between the self-termination reaction of cyclohexyl radicals and the reaction with the HDDA molecules ((2) initiation step) thus forming monomer radicals.…”

“…However, on statistical average for every fourth encounter, the singlet encounters lead to product formation. [24] By increasing the time window of observation, 2 N k t values of longer and longer oligomer radicals are obtained. Fig.…”