A Quantitative Treatment for Electrophilic Reactions of Aromatic Derivatives^1-3

Linear Free Energy Relationships.

“…Failure of the sigma-values alone would not seem to be the answer here since the m-substituents are accommodated by a different line. The corresponding m-substituted chlorides are well correlated by the "primary" sigma-values, while Okamoto and Brown (189) report that the a+-scale accounts for the enhanced rates for electron-releasing p-substituents. The interpretation by the latter in terms of a sharp mechanistic change appears insecure in view of the previous statements and the examination in sub-section 5 of the u+-parameter .…”

Acid-catalyzed rearrangement of hydroperoxides. I. Benzhydryl hydroperoxides

“…Their logarithms are plotted in Fig. 1 against the o+ values of Brown and Okamoto (12,13) for the meta and para substituents and against the Taft o* constants (14) for the ortho substituents. Alinear relationship is evident with deviations noticeable in the case of the Can.…”

13C NMR substituent-induced chemical shifts in 4-(substituted phenyl)-3-phenyl-1,2,4-oxadiazol-5(4H)-ones (thiones)

“…The DSP-NLR analysis method is a successful equation in the modeling of long-range substituent effects, which is derivatives of Hammett equation [44]. The substituentinduced change in the chemical shift, SCS (substituent-inducted chemical shift) is based on the principles of linear free energy relationships (LFER) for SSP analysis method using substituent parameters such as the Hammett r values [45,46] and Brown Okamoto r + and r À values [46][47][48] (Eq. (1)) equations in the form:…”