1-置換プロパン類およびCH₃CMe_nCl_3-n(n=0～3)型化合物の遊離基的塩素化

Homolytic Chlorination of 1-Substituted Propanes and CH₃CMe_nCl_3-n Type Compounds

抄録

1-Chloropropane, 1, 1-dichloropropane, 1, 1, 1-trichloropropane, neohexane, and t-butyl chloride were photochlorinated at 40°C in the presence of 2, 2-dichloropro-pane, and relative amounts of the chlorinated products determined by g.l.c. The reactivities of C-H bonds toward hydrogen abstraction by the chlorine atom were compared with that of a C-H bond in 2, 2-dichloropropane. A linear free energy relationship was found to exist between the reactivities of methyl hydrogens and the Taft's σ constants for the substituents (CH₃, CH₂Cl, CHCl₂, CCl₃, CH₂CMe₃, CH₂CH₂Cl, CH₂CHCl₂, CH₂CCl₃, CMe₃, CMe₂Cl, CMeCl₂). p=-0.85. Results show that the reactivities of methyl hydrogens are mainly affected by the polar nature of the substituents, and resonance stabilization of the incipient radical by hyperconjugations is of minor importance.