Why do non-polar solvents in thin layer chromatography cause lower Rf values? In this case, hexane...

Why do non-polar solvents in thin layer chromatography cause lower Rf values? In this case, hexane was used as a solvent and benzhydrol and benzophenone were added to the TCL plate. The solvent (hexane) traveled far because I'm assuming due to capillary action, but the solutes did not travel far at all. Why?

Expert Solution

In order to understand the answer, first understand the concept of TLC and the role of solvents used in the TLC. TLC is basically working with the polarities of compounds (based on the functional groups) and solvents (mobile phase) used in the TLC.

The mobile phase used in the TLC is a solvent system which is a combination of polar solvent (such as ethyl acetate, acetone, methanol, dichloromethane...) and a non- polar solvent (such as hexane, petroleum ether....etc.). This ratio of mixing usually depending on the nature of compounds which are using in the TLC. For polar compounds (ex. Carboxylic acids, alcohols, carbonyls...etc.), a mobile phase with the combination of polar solvent and a non-polar solvent is necessary.

queen_honey_blossom answered 2 years ago

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