Investigation of the Lipophilicity of Antiphlogistic Pyrazole Derivatives: Relationships Between Log Kw and Log P Values of 5-Arylamino and Arylhydrazono-3-Methyl-4-Nitro-1-Phenylpyrazoles

Abstract

The log kw values of a series of 3-methyl-4-nitro-1-phenylpyrazoles substituted at C-5 with arylamino and arylhydrazono moieties were obtained through extrapolation to 100% water from capacity factors data from reversed-phase HPLC. the partition coefficients for some key compounds were obtained through the “shake-flask” method and used to calculate, with aid of fragmental constants, the values expected for the series. the log P data showed a definite correlation with log Kw, confirming the feasibility of using the latter as hydrophobicity descriptors. This study indicates also the need for reassignment of the fragmental constant value for the hydrazono (-NH-N=CH-) group.