35468-44-1Relevant articles and documents
The relative rates of bromination of cyclohexane and cyclopentane with molecular bromine. Comparison of the reactions in solution and in vapor phase
Tanner, Dennis D.,Ruo, Tomoki C-S.,Takiguchi, Hideki,Guillaume, Andre
, p. 1368 - 1374 (2007/10/02)
The realtive rates of transfer of the cyclopentadienyl radical with molecular bromine and hydrogen bromide (k2'/k-1') and with hydrogen tribromide and hydrogen bromide (k3'/k-1') have been determined.The relative transfer rates are compared with the analogous values previously reported for the reactions of cyclohexyl radicals (k2/k-1 and k3/k-1).Utilizing the values of k2'/k-1' and k2/k-1 the competitive vapor phase rates of bromine atom abstraction of hydrogen from the two substrates could be obtained.An expression using a combination of the five sets of relative rate constants was used to determine the effect of competitive cage reversal which occurs in the solution phase bromination of the two substrate radicals with caged hydrogen bromide.For two structurally similar radicals, cage reversal (internal return) was found to affect the relative rates of bromination by 30 percent, while the relative transfer rates, although differing each by a factor of two, fortuitously nearly cancel each other's effect.The effect of both internal and external reversal reactions on the relative rates of bromination of structurally dissimilar substrates, halogenated alkanes and their parent hydrocarbons, is discussed.
