Question

how would you resolve the number of compounds in a mixture if the rfs of the spots under uv are 1.0, 0.52,0.0

Answer 1

Generally, the compunds in the mixture can be asily resolved through Column Chromatography depending on the Rf of the spots. According to the Rfs indicated, the one with 1.0 is non polar, followed by medium polar having 0.52 Rf value and highly polar with 0.0 Rf value. So the basic idea is increase the polarity of the solvent system such that you first get non-polar compound followed by medium polar and lastly highly polar compound.

Thus, firsly, make a slurry of the mixture with DCM (dichloromethane) and silica gel (60-120 mesh size) and evaporate DCM in rota-vap instrument. At the meantime, take a column and pack it with 60-120 silica gel by wet packing (Pass a slurry of silica gel in hexane). Place your mixture above the bed of silica and plug it with column.

Now, run the column with Hexane 2 or 3 times, which gives your first non-polar compound having 1.00 Rf value. Collect it and concentrate the solvent and check the TLC. This is followed by increasing the polarity of the solvent system by 5% or 10% (5% or 10% Ethyl acetate in pet ether). And eventually, this gives your second medium polar compound with Rf value of 0.52. Repeat the above mentioned process (Concentrate - Check the TLC). And finally run with Ethyl acetate or Methanol to get your highly Polar compound with Rf value.