Organic Peroxides. II. the Mechanism of the Thermal Decomposition of 6-Heptenoyl Peroxide in Toluene. the Rearrangements of the 5-Hexenyl Radical

Thermal decomposition studies of ω-iodoacyl peroxides

“…Step [4] is a n intramolecular example of radical-induced decomposition ; the formation of lactones in this manner also has been confirmed by other workers (8,9). T o explain our results, steps [5] and [6] would also be necessary and competitive with step [3] (RH represents any convenient source of CH bonds).…”

Free-Radical Rearrangements

“…Since the relevant hydrogen atom transfer steps are fast and essentially quantitative, the relative yields of methylcyclopentane and cyclohexane from the reaction of l-halohex-5-ene with tributylstannane (43,152,155,156) reflect the relative rates of the two ring-closure processes. Both thermodynamic (63,126,143) and kinetic (142,159) data indicate that cyclohexyl is more stabilized than cyclopentylcarbinyl. Both thermodynamic (63,126,143) and kinetic (142,159) data indicate that cyclohexyl is more stabilized than cyclopentylcarbinyl.…”

“…It has been firmly established that the 5-hexenyl radical, contrary to earlier indications (142), undergoes cyclization by intramolecular addition in a highly regiospecific fashion to afford mainly the cyclopentylcarbinyl radical (43,47,95,96,(143)(144)(145)(146)(147)(148)(149)(150)(151)(152)(153)(154)(155)(156)(157)(158).…”

“…In the early work, the 5-hexenyl radical was generated by thermolysis of di-6-heptenoyl peroxide (143), by interaction of 6-mercapto-l-hexene with triethyl phosphite (144), and by Kolbe electrolysis of 6-heptenoic acid (145). In each case cyclic products were formed solely or predomi nantly (>95%) by 1,5 ring closure.…”

“…Experiments (143,145,147,148) in which cyclopentylcarbinyl and cy clohexyl radicals were separately generated demonstrated the irreversibility of each mode of cyclization and the fact that they are discrete species (95,96) and not a π complex (143,144). Since the relevant hydrogen atom transfer steps are fast and essentially quantitative, the relative yields of methylcyclopentane and cyclohexane from the reaction of l-halohex-5-ene with tributylstannane (43,152,155,156) reflect the relative rates of the two ring-closure processes.…”