Question

You run a reaction with column chromatography and you find that you have multiple products (cyclohexene from cyclohexanol). You predictyou have the alcohol functionality you were trying to make and the alkene from the eliminated product (some of the alochol must have elimited to form the alkene). You run a few TLCs to find a good solvent to run a column in order to separate two products. You decide on a 10% ethyl acetate in hexanes because it allows one spot to run quite far on the plate while the other spot moves slightly. When you run the column, you find that all your fractions have only one spot showing on the TLC plate. What could have happened and what could you do to fix it? Which product is likely in the fraction at this point: alcohol, alkene? and what kind of test could you run to prove your answer?

Answer 1

alkene is non polar and alcohol is polar while running TLC plate using 10% Ethyl acetate in hexane ,

the one spot is running far (faster) because it is alkene and which moves faster in non polar hexane solvent,

the slighltly moving sopt is of an alcohol which runs slowly on TLC plate ( only polar phase is10 % EA),

While runnig coloumn chromatography the first fraction obtained at this solvent condition is alkene (its TLC plate shows only one spot and which is of alkene) ,

the alcohol is running slowly through the coloumn and it would be our second fraction.