Free Radical Substitution in Aliphatic Compounds. Part IV. The Reaction of Trichloromethyl Radicals with Propane, n-Butane and Iso-Butane

Mixtures of bromotrichloromethane and the alkanes at circa 60 mm pressure have been irradiated in a Pyrex vessel with light from a medium pressure mercury lamp. The products, which consist solely of chloroform and monobromoalkanes, have been analysed. The reaction has been shown to be a chain process involving attack on the alkane by trichloromethyl radicals which abstract hydrogen atoms from the primary, secondary and tertiary positions in the order 1 : 80 : 2,300 at 190°.kk2/kp2 = 2.68 ± 1.48 exp (3.08 ± 0.46 k. cal/RT); kt2/k82 ≈ 5.25 × exp (5.5 k. cal/RT).