Question

if youre doing an analysis with a tlc plate and you use ethyl actete (polar) as the solvent please rank the distance that these molecules would move (aka which one would be the highest on the plate). They are the same molecule, the only thing that changes is the functional group. One has an alcohol functional group, one has a ketone, and the other has alkene functional group

Answer 1

Thin layer chromatography (TLC) is the most widely used technique for the monitoring the progress of the reaction.

In Thin layer chromatography, the stationary phase is the silica, which is coated on the aluminum plates (for the commercial one).

The separation of the compounds in the TLC is based on the interactions of the given compound with the absorbent silica gel.

The compounds which have more polar groups like OH, NH₂ will interact more with the absorbent silica gel through intermolecular forces. The compounds which do not have polar groups have fewer interactions with the absorbent silica gel.

When the TLC plate elute in a mobile phase (here in the given question mobile phase is ethyl acetate) the compounds which are non polar will elute fast and they will move the long distance on the TLC plate whereas the compounds having polar groups due to intermolecular forces they will not elute fast and they travel less distance when compare to non-polar compounds.

In the given compounds alkene is nonpolar than the ketone which is nonpolar than the alcohol.

Hence alkene will move faster followed by ketone, which is followed by alcohol.

Alcohol is the least traveled compound. Alkene is the most travelled compound on the TLC plate using ethyl acetate as eluent.