Question

Which one would elute first from the column chromotographythat has a stationary phase and a weak polar solvent? Explain your answer.

Hexane

Hexan-1-ol

Hexene

Hexan-1-one

Answer 1

Polarity: Hexane < Hexene < Hexanone < Hexanol

If in column chormatography, a stationary phase is polar phase (without modified silica column) then most polar hexan-1-ol will elute last as it will interact strongly with stationary phase and least polar compound Hexane will elute first as it will interact weakly with stationary phase.

Now, if you use modified column and reversed the polarity of stationary phase from polar to non-polar then least polar compound, hexane will elute at last and most polar compound hexanol will elute first.

In case of normal column chromatography we use silica gel as a stationary phase and hence it is strongly polar stationary phase. Hence, hexane being least polar compound will interact less with stationary phase and elute first. Whereas, hexanol being most polar, will elute at last.