Directive effects in benzylic hydrogen atom abstraction. Part VI. Halogenation of arethyl fluorides
Abstract
The relative rates of halogenation of XC6H4CH2CH2F with N-bromosuccinimide in CCI4 at 80° and with sulphuryl chloride in benzene at 40° are correlated by the Hammett equation to give ρ+–1·43 (r0·996) and ρ–0·96 (r0·985), respectively. The different nature of the transition states of atomic bromine and the benzene-complexed chlorine atom with the substrates XC6H4CH2Y previously noted has been consistently observed. Deuterium isotope effects in the N-bromosuccinimide bromination of PhCHDY and PhCD2Y have been measured for Y = Ph, CH2Cl, CH2F, and Cl and these values are related to the relative reactivity of the undeuteriated compounds.