Determination of the Lipophilicity Parameters R M0 and LogP of New Azaphenothiazines by Reversed‐Phase Thin‐Layer Chromatography†

Abstract

The lipophilicity parameters (R M0 and logP TLC) of three types of azaphenothiazines 1–3 were determined by reversed‐phase thin‐layer chromatography on RP‐18 silica plates with acetone‐aqueous TRIS (tris(hydroxymethyl)aminomethane) buffer as the mobile phase. The R M values were linearly dependent on the concentration of acetone, and extrapolated to 0% of acetone, gave the lipophilicity parameter R M0. The parameter R M0 and specific hydrophobic surface area b were significantly intercorrelated showing a congeneric class of azaphenothiazines 1–3. The parameter logP TLC was determined from the R M0 values by use of a calibration curve obtained for five standards. The determined parameters were discussed in the terms of structure lipophilicity relationships and compared with data obtained from seven calculation programs.