The Substituent Effect. XIII. Solvolysis of 1-(7-Substituted 2-Fluorenyl)ethyl Chlorides and Alkaline Hydrolysis of Ethyl 7-Substituted 2-Fluorenecarboxylates

Two sets of rate constants for (i) solvolysis of 1-(7-substituted 2-fluorenyl)ethyl chlorides in both 90 and 80% aqueous acetone and (ii) alkaline hydrolysis of ethyl 7-substituted 2-fluorenecarboxylates in 85% aq EtOH have been determined. Both substituent effects could be correlated excellently with the LArSR relationship; the resulting r+ values (0.82 and 0.47, respectively) were comparable with the r+’s in the corresponding biphenylyl system under the same conditions. The comparison of ρπ+ values clearly indicates a more efficient transmission of the pi-electronic effect in the fluorenyl than in the biphenylyl ststem (1:0.75). This can be attributed to a factor of twisting in the latter pi-system. The attenuation of the transmission of the Pi effect was found to be characteristic of the intervening pi-systems independent of reactions: 1.00(4-X-1-phenyl), 0.55(6-X-2-naphthyl), 0.35(7-X-2-fluorenyl), and 0.25(4′-X-4-biphenylyl).