Chromatographic behaviour and lipophilicity of some benzimidazole derivatives

Abstract

The retention behaviour of 2-amino-5,6- dimethylbenzimidazoles, 2-aminobenzimidazoles, and 5,6- dimethylbenzimidazoles has been studied on thin layers of rice starch, cellulose, and Aminoplast. The mobile phases used were cc ammonia-n-propanol, 40 + x, x = 1-9 (v/v) for cellulose and rice starch layers and cyclohexane-acetone-cc ammonia, 40 + x + 0.5; x = 2-14 (v/v) for on Aminoplast layers. Normal-phase chromatography occurred on Aminoplast layers whereas reversed- phase chromatography was obtained on cellulose and rice starch layers. Determination of lipophilicity by TLC is mainly based on the linear relationship between R(M) values and the concentration of organic solvent in the mobile phase, in accordance with well known TLC equations. Retention constants, R(M) 0 , were determined by extrapolation. Good correlation was found between the retention constants, R(M) 0 , and logP, and between R(M) 0 and the biological activity of the compounds investigated.