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  • Author or Editor: S. Belopushkin x
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Abstract  

ESR spectra for -irradiated at 77 K solutions /0.02–16%/ of tetramethylurea /TMU/ in CFCl3 and Freon-113 have been studied. TMU+. radical cations radiolytically produced in dilute solutions have been shown to undergo intramolecular hydrogen transfer upon photobleaching resulting in CH2N= type radical. Evidence for intermolecular proton transfer in TMU+. radical cations after annealing to phase transition temperature /110–120 K/ in Freon-113 was obtained. Primary radical cations of TMU+. at their ground state take part in ion-molecular reaction via proton transfer. Molecular cations in their excited states may undergo fragmentation producing Me2N radicals, which were trapped in liquid phase by t-BuNO as a spin trap.

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Abstract  

ESR spectra of -irradiated, at –196 °C, solutions of acetic and propionic aldehydes in freon-11 and freon-113 affected by aldehyde concentration, temperature, and the action of light have been studied. It has been shown that the radical cations CH3CHO+ are converted into neutral radicals CH3 O and CH3 HOH and the cations CH3CH2CHO+. are converted to RO and CH3 HCHO due to ion-molecular reactions of proton transfer /CH3 O and CH3 HCHO/ of hydrogen atom transfer /CH3 HOH/.

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Abstract  

The ESR spectra of -irradiated, at –196 °C, solutions of acetic acid and acetic anhydride were studied depending on their concentrations in CFCl3. The structure of thus produced radical cations is confirmed with the deuterium substituted analogues. It has been shown that the ion-molecular reaction of the radical cation CH2COOH+ in the isolated dimer takes place for the dilute solutions of acetic acid in CFCl3 resulting in the formation of CH3COO follwed by its decomposition to CH3+CO2 while the radicals CH2COOH are formed via secondary processes. The reactions of radical cations of acetic oxide have been also studied.

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Abstract  

ESR spectra of -irradiated, at 77 K, acetone and CH3COEt solutions /0.1–22%/ in CFCl3 were studied. The yields of monomer and dimer radical cations of ketones and RCHCOCH3 radicals depend on ketone concentration in CFCl3. When exposed to light the dimeric radical cations are transformed into RCHCOMe, while the monomeric radical cations disappear without further radical production. Different types of solid phase ion-molecular reaction for monomer and dimer radical cations are discussed.

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Abstract  

The radiolysis of some esters /formates and acetates/ has been studied both in liquid and in solid states using a number of different spin traps. Specific deuteration was applied to elucidate the mechanism of radical formation. The radicals were found to result from the reactions of ester radical cations, radical anions and excited molecules. Evidence for intramolecular rearrangement in the radical cations of esters in condensed phase was obtained.

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