ISSN:
0538-8066
Schlagwort(e):
Chemistry
;
Physical Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Benzylic H-atom abstraction rates by diphenylmethyl radicals from a series of donors were determined in nonpolar liquids at elevated temperatures. Relative rates were converted to absolute rates via available equilibrium constant data for the dimerization of diphenylmethyl radicals. Abstraction by diphenylmethyl from 1, 2, 3, 4-tetrahydronaphthalene (tetralin) was studied over the temperature range 489-573 K. Its Arrhenius expression is 109.9±0.3 exp{-(10183 ± 373)/T} M-1 s-1. Abstraction from other donors was studied at 548 K. Rate constant values ranged from a low of 3.6 M-1 s-1 for toluene to a high of 3000 M-1 s-1 for 9, 10-dihydroanthracene. Similar reactions with the fluorenyl radical were also studied. In this case, relative rates were converted to absolute rates with an equilibrium constant for fluorenyl dimerization determined from the observed homolysis rate of the dimer and an assumed recombination rate. In addition, forward and reverse rate measurements yielded the equilibrium constant for hydrogen transfer between fluorenyl and diphenylmethyl. At 548 K, fluorenyl is favored by a factor of 13 over diphenylmethyl.
Zusätzliches Material:
5 Tab.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/kin.550191006
Permalink
