The Substituent Effect. X. Solvolysis of 3- and 4-Substituted 1-(1-Naphthylethyl) Chlorides

The rates of the solvolysis of eleven 3- and 4-substituted 1-(1-naphthylethyl) chlorides were determined in 80% (v/v) aqueous acetone solution at 45 °C. The effect of substituents in 3- and 4-positions of the naphthalene can be correlated with the LArSR relationship (logk⁄k0)3α,4α=−5.12(σ0+1.04ΔσR+)−0.12 (correlation coefficient, 0.999; standard deviation, ±0.12). The ρ value in the naphthalene is slightly larger and the r value is slightly smaller than values in the corresponding benzene system under the same condition (ρ=−4.95, r=1.15). The difference is reasonably interpreted in terms of the steric effect for the peri-hydrogen relative to the reaction center at the α-position of the naphthalene. The effect of substituents can be correlated with the LSFE relationship for conjugatively electron releasing groups with high precision (R>0.999) in the series, 3α and 4α; (logk⁄k0=ρiσi+ρπ+σπ+). In this solvolysis, the 3α/4α inductive ratio, ρi,3α/ρi,4α was 1.37, only slightly larger than the meta/para inductive ratio of 1.17 for the corresponding reaction in the benzene series. The applicability of these equations to 3- and 4-substituted α-naphthyl system is also shown for some other reactivities.