Isotope effect in diffusion of perdeuteriobenzene and carbon-14-substituted benzenes in unlabeled benzene at 25.deg.

1975 ◽  
Vol 79 (13) ◽  
pp. 1319-1320 ◽  
Author(s):  
Ian R. Shankland ◽  
Peter J. Dunlop
Keyword(s):  
Isotope Effect ◽  
Substituted Benzenes ◽  
Carbon 14

A tracer study of di- tert . butyl peroxide as an initiator for polymerization

1961 ◽  
Vol 262 (1309) ◽  
pp. 271-286 ◽  
Keyword(s):  
Isotope Effect ◽  
High Temperatures ◽  
Benzene Solution ◽  
Tracer Study ◽  
Polymer Molecules ◽  
Carbon 14 ◽  
Low Concentrations ◽  
End Groups ◽  
Butyl Peroxide ◽  
Butoxy Radical

Di- tert . butyl peroxide labelled with carbon-14 has been used to initiate the polymerization of styrene, and the resulting polymers have been analyzed for fragments derived from the peroxide. Polymers prepared in benzene solution contain both tert . butoxy and methyl end-groups, the proportions depending upon the conditions prevailing during polymerization; except at low concentrations of styrene and high temperatures, initiation is chiefly by the tert . butoxy radical giving polymer molecules with ether end-groups. In some diluents, initiation is largely by an indirect process in which the primary radicals abstract hydrogen from the diluent. There is an isotope effect in the dissociation of the tert . butoxy radical; introduction of carbon-14 into the radical reduces by about 7% the velocity constant for dissociation to give acetone at 130°C. Allowance must be made for this effect when using the labelled peroxide as a source of tert . butoxy radicals to be used in competitive studies of the reactivities of substances towards these radicals.

Carbon-14 isotope effect in the decomposition of p-nitrophenethyl-l-14C-trimethylammonium iodide

1967 ◽  
Vol 32 (12) ◽  
pp. 4116-4116
Author(s):  
Ernst M. Hodnett ◽  
William J. Dunn
Keyword(s):  
Isotope Effect ◽  
Carbon 14
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