Free radical processes involving electron transfer or producing [gamma]-lactones

Date
1988
Authors
Herron, Steven
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Chemistry
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Abstract

The formation constants of isopropyldichloromercurate and isopropyldiiodomercurate have been calculated to be 8.0 x 10[superscript]-2 and 8.6 dm[superscript]3/mole, respectively, using the variation of [superscript]1H NMR shift as a function of halide ion concentration. The reaction of an equilibrium solution containing approximately 55% isopropyldichlorormercurate with bromotrichloromethane was studied. Evidence is presented that supports the conclusion that the reaction is a free radical chain mechanism of considerable length (initial kinetic chain length > 38,000). The chain propagating step appears to be the reduction of the trichloromethyl radical by the isopropylmercurate. Though dialkylmercurials do not form mercurates with added iodide ion, the presence of iodide ion does significantly increase the production of alkyl bromides (in the reaction with bromotrichloromethane) by reducing the trichloromethyl radical before it can abstract a [beta]-hydrogen from the dialkylmercurial;The reaction of the 1-cyano-1-methylethyl radical with vinyl ethers was studied. In the absence of added electron acceptors, the reaction appears to be controlled by the substituent bound to the oxygen atom and can proceed via electron transfer or by radical abstractions or couplings. In substituent bound to the oxygen atom and can proceed via electron transfer or by radical abstractions or couplings. In the presence of added electron acceptors the reaction proceeds by electron transfer via an inner sphere electron transfer complex;The reaction of free radicals with tert-butyl peroxypent-4-enoate was studied. With alkyl mercurials the reaction gives moderate yields of [gamma]-lactones. With di-tert-butyl-mercury or trialkylphosphites the reaction gives 75-85% yields of the [gamma]-lactone, dihydro-5-(2,2-dimethylpropyl)-2(3H-furanone). Evidence is presented that indicates that the [gamma]-lactones are produced in a free radical chain manner.

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Chemistry, Chemistry, Organic
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