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The rates of decarboxylation of 4-methyl-, 4-methoxy-, and unsubstituted anthranilic acids have been determined in aqueous buffers over the p H range 2.5-3.8. Electron-releasing substituents increase the rates of ring-protonation about equally for an acid and its anion, and decrease the ratio of decarboxylation to deprotonation of the protonated acid. Rates, 13C-carboxyl kinetic isotope effects, and deuterium solvent isotope effects have been determined for the decarboxylation of anthranilic acid in aqueous sulfuric acid up to 10 M. N o evidence for decarboxylation by cleavage of the unionized carboxyl group was obtained.

Studies of aprotic solvent effects on substituent fluorine nuclear magnetic resonance (F nmr) shifts of p-fluorophenyl labeled systems have provided evidence of general significance regarding the nature of solvation of molecules. The correlation of the aprotic polar solvent F nmr shifts with the parameter of the substituent and the Et solvent polarity parameter is shown to be highly general. It is concluded that local fields of aprotic Recent investigations of structural and medium . effects on F nmr substituent shifts have prompted(1) This work was supported in part by the National Science Foundation. We also gratefully acknowledge their support in making available the nmr spectrometer of the University of California, Irvine, Chemistry Department. this further study. Relatively effective transmission of the effects of substituents, X, through a variety of neutral and charged cavities for structure I has been found.2 These F nmr substituent shifts were usefully(2) S.