ACIDIC PROPERTIES OF N-HETARYLACETIC ACIDS AND INDUCTIVE CONSTANTS OF N-HETARYL SUBSTITUENTS

Article abstract of DOI:10.1007/BF00513265

The inductive constants of the corresponding heterocyclic fragments were calculated on the basis of data on the pK_a values obtained by potentiometric titration of derivatives of indole, carbazole, 3-methylcarbazole, tetrahydrocarbazole, 6-methyltetrahydrocarbazole, and phenothiazine.The ?⁰_R constant of the 9-carbazolyl group was also calculated.The enthalpy and entropy of acidic dissociation were calculated from data on the effect of temperature on the pK_a of 9-carbazolylacetic acid.It is shown that the entropy contribution to the free energy of dissociation of 9-carbazolylacetic acid predominates.