The Substituent Effect. 14. The Solvolysis of 6- and 7-Substituted 1-(2-NaphthyI)ethyl Chlorides

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Abstract
Nine of the title compounds were synthesized, and their solvolysis rates were determined in 80%(v/v) aq acetone at 45 °C. The effects of the pi-donor substituents for each substituent position are shown to be excellently described in terms of inductive(I) and pi-electronic(Pi) effects by means of the LSFE equation (logk⁄k0=ρiσi+ρπ+σπ+), Just as with those in the 1-naphthyl systems. When those data are joined with all our substituent effects data for the phenyl, 4-biphenylyl, 2-fluorenyl, and 1-naphthyl systems under identical conditions, it is clear that the overall correspondence between the ρi values and Dewar’s simple-field-effect function (1⁄r) is satisfactory. On the other hand, the ρπ+ values appear to give slightly different responses (separate correlations for the 1- and 2-naphthyl systems) to the SCF-π charge difference values; this may be ascribed to the steric effects on the Pi effect in only the 1-naphthyl-solvolysis sets. Furthermore, the position constancy of the I effect (ρi,6−X−2⁄ρi,7−X−2=0.85) has been observed in the present solvolysis and the available data for dissociation of 2-naphthalenecarboxylic acids involving relatively weak Pi effects; the figure is in good agreement with the ratio of ρi,para⁄ρi,meta=0.85. Analogous results were also achieved by the same treatment to 2-benzo[b]thienyl reactivities. All the results are discussed with respect to the validity of the LSFE equation.