Question

Describe how you would perform a column chromatographic separation of a non-polar compound A and two polar chemicals (B and C). C is slightly more polar than B.

Answer 1

column chromatography will work based on the absorption priincipal

more the polar it will bind more to the silica it will move less through the silica

you have to choose the polarity where spot is moving 0.2 Rf in the column at that particular % we can isolate that compound from column

suppose in 50% ethyl acetate and hexane spot A is moving 0.5Rf, B is moving 0.2 Rf, spot C is 0.1Rf

suppose if you use the 50% two spots will come together

now check the TLC in 20 %

now spot A will be 0.2Rf spot B and spot C both are bottom both will not move

that menas you can isolate top spot at 20%

now check the TLC in 30% wher Spot B is 0.2Rf and spot C is 0.1 Rf choos ethis % to separate the spotB

after isolating spot B you increase much polart of the mobile phase because thaere is no any other spot on bottom