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The twelve o-, m-and ^-monohalophenyldimethylcarbinyl chlorides were synthesized and their rates of solvolysis in 90% aqueous acetone (by volume) determined at several temperatures. Within each of the three isomeric series, the observed order of reactivity is F > Cl > Br < I. The observed magnitudes of the rate constants together with the observed reactivity orders can be rationalized in terms of the inductive effect, resonance and steric inhibition of resonance.Thus in the meta series it appears that the inductive effect is dominant, with a minor resonance contribution which increases the electron density at the ortho positions, whence it is relayed to the electron deficient reaction center by induction.In the para position, both induction and resonance appear to be of nearly equal (but opposite) effect. The lower rates exhibited by the ortho halogen substituents are attributed to an increased inductive effect and a reduced resonance effect, the latter arising from a partial resonance inhibition due to the conflicting steric requirements of the ortho substituents and the coplanar dimethylcarbinyl group of the incipient carbonium ions.

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