Directive effects in benzylic hydrogen atom abstraction. Part IV. Halogenation of 2-arylethyl chlorides

Abstract

The relative rates of benzylic hydrogen abstraction from XC₆H₄CH₂CH₂Cl by atomic bromine, the trichloromethyl radical, and by the benzene-complexed chlorine atom have been measured by means of competitive reactions with N-bromosuccinimide, with bromotrichloromethane in carbon tetrachloride at 80°, and with sulphuryl chloride in benzene at 40°. The results, correlated by the Hammett equation, gave ρ values of –1·10, –0·93, and –0·76, respectively by use of σ⁺ constants for atomic bromine and σ constants in the other two cases.