Rate constants of solvolysis of 3′- and 4′-substituted 1-(4-biphenylyl) ethyl chlorides were measured in 80% (v/v) aqueous acetone. The effect of substituents could be correlated excellently with the LArSR relationship.log k⁄k0=−1.56(σ0+0.84Δ\barσR+)The ρ and r+ values are smaller than those in the corresponding phenyl system under identical conditions (ρ=−4.95, r+=1.15). The difference of the r+ values