Kinetics for the Reaction of a Secondary Alkyl Radical with Tri-n-butylgermanium Hydride and Calibration of a Secondary Alkyl Radical Clock Reaction

Article abstract of DOI:10.1021/jo00392a003

Arrhenius parameters for the reaction of a secondary alkyl radical with tri-n-butylgermanium hydride have been measured by using the cyclization of 1-methyl-5-hexenyl radical as a "clock" reaction.At 298 K the rate constant is 1.8*10⁴ M^-1s^-1, which makes the secondary alkyl radical/n-Bu3GeH reaction about 80 times slower than the corresponding reaction with tri-n-butyltin hydride.The secondary alkyl radical clock reaction has been rather precisely calibrated by using new data and data from the literature.At attempt to carry out similar experiments with 1,1-dimethyl-5-hexenyl yielded much less precise data for the cyclization o f this tertiary alkyl radical.Reliable kinetic data for hydrogen abstraction from n-Bu3GeH by tertiary alkyl radicals could not be obtained by using either the parent bromide or appropriate N-hydroxypyridine-2-thione esters as alkyl radical sources.