Question

Consider a sample that is a mixture composed of benzoic acid, biphenyl, and benzyl alcohol. Predict the order of elution of the components in the mixture. Assume that the chromatography uses a silica column and the solvent is hexane, with an increasing portion of methylene chloride added as a function of time.

Answer 1

In chromatography, less polar compounds have the greater rate of elution and will come out first. Where as the more polar solvents will more adhere to the silica gel and has a low rate of elution.

For given mixture of components,

biphenyl is less polar compound and will elute first on the silica gel column.

Benzoic acid is more polar compound than the other two and will elute last on the silica gel column.

So the order of elution:

Biphenyl > benzyl alcohol > benzoic acid.