No abstract

Can J Chem 57. 2578 ( 1979) The relative kinetics obtained from the decomposition products of tert-butyl-2-ethylperhexanoate, BEPH, (0.1 lW) in lnixtures of toluene and carbon tetrachloride were reinvestigated.RelatiIe reactivities calculated from the ratios of heptane to 3-chloroheptane formed from BEPH decon~positions in a varicty of substituted toluenes, with added carbon tetrachloride, gave a si~nilar Harnmett correlation to that previously reported, but with a rather poor correlation coefficient (r = 0.88, p = 0.68).From a material balance of the products formed it was determined that very few if any of the I-ethylpentyl radicals formed ultimately abstract a benzylic hydrogen from toluene or a substituted toluene. The small amounts of heptane found (<0.7%) at any of the kinetically rnea~lingful ratios of substrates, ArCH,,CCI, 2.1 to 16.3, could have potentially arisen from radical disproportionation. No appreciable amount of aromatic substitution product could be detected under these conditions.Decon~positions of BEPH carried out in neat toluene only yielded small amounts (-0.4%) of addition product; however, the absolute amounts of heptane produced in reactions run in 11-cyanotoluene were less than those formed in reactions carried out in toluene. These observations do not argue strongly for the authenticity of a relatively large positive p value (previously reported, +0.7) arising either from benzylic abstraction, or fro111 addition to the aromatic ring.On a etudie les cinetiques relatives a pal-tir des produits de decomposition de I'ethyl-2 perhexanoate de tert-butyle, EPHB (0.1 IM), dans des melanges de toluene et de tCtrachlorure de carbone. Les reactivites relatives calculCes a partir des rapports d'heptane: chloro-3 heptane forlnes par decomposition de EPHB dans des toluenes substitues auxquels on a ajoute du tetrachlorure de carbone conduisent a des correlations de Hammett semblables a celles rapportees anterieurenlent; le coefficient de correlation est toutefois mediocre (r = 0.88, p = 0.68).En se basant sur un bilan ponderal des produits formes, on peut determiner que les radicaux ethyl-1 pentyles fornles n'enlevent que peu d'hydrogenes benz>liques du toluene ou des toluenes substitues. Les faibles quantites de pentane trouvees (< 0 . 7 z ) a tous les rappol-ts de substrat presentant une signification cinetique ArCH3,CC1,: 2.1 a 16.3, pourraient pro\enir d'une dismutation du radical. Dans ces conditions on n'a pas pu detecter des quantites appreciable~ de produits de substitution aromatique.Les decompositions du EPHB effectuees dans le toluene pur ne conduisent qu'a de faibles

No abstract

SzcznmaryThe increase in the ratio of 4,4'-dimethylbibenzyl to 2,5-dimethylbiphenyl formed in the reaction of phenyl radicals with p-xylene with increasing temperature is interpreted as indicating that the formation of l-phenyl-2,5-dirnethylcyclohexadienyI radicals (1) is reversible.

Research on the chemical composition of gorgonian Pseudoterogorgia americana, which grows in the coasts of Havana, has led to the isolation of a new sesquiterpene hydrocarbon, 1,1-dimethyl-7-isopropylidene-1,2,3,4,5,6,7,8-octahydronaphthalene, named caridiene. This compound not previously reported, was found to be a major constituent of the volatile fraction. The proposed structure was confirmed by spectroscopical data (UV, IR, Raman, MS, 1H and 13C NMR techniques).