Question

Which compound will have the larger rf value on a si02 tlc plate using 10 % ethyl acetate/ hexane as eluent: 3-decanone or 3-decanol, toluene or benzoic acid, cyclooctane or cyclooctanone? why?

Answer 1

The formula of determining the
`R_f` value is:

`R_f = (distance travelled by the solute)/(distance travelled by the solvent)`

where both the distance are measured from the common origin.

10 % ethyl acetate/ hexane means it has 10 % ethyl acetate and 90 % hexane which are non-polar in nature. Hence, the non-polar compound will travel farther in the TLC plate along with the eluent and the polar compound will travel less as they remain attracted to the polar adsorbent
`SiO_2`.

Among 3-decanone and 3-decanol, 3-decanone will have high
`R_f` as it is non-polar.

Among toluene and benzoic acid, toluene will have high
`R_f` as it is non-polar.

Among cyclooctane and cyclooctanone, cyclooctane will have high
`R_f` as it is non-polar.