chromatographic column

Traditional column chromatographic purification of a reaction mixture. 

In organic chemistry we prepare compounds that could be usually black/brown/yellow depending on impurities and in pure form colorless. It’s a quite rare case that any color that appears in the reaction mixture is a good sign on anything. In this case the orangish spot on the column is luckily a product that was planned and it contains diazo groups that are reason of the color.

More about chromatography:

Colorful fractions just after a column chromatographic purification of a ferrocene derivative.

Ferrocene is an organometallic compound with the formula Fe(C5H5)2. It is a metallocene, a type of organometallic chemical compound consisting of two cyclopentadienyl rings bound on opposite sides of a central metal atom, it’s a  sandwich compound.

Depending on the substitution pattern, the compounds containing a ferrocene ring could vary in really different colors often between yellow and blood red.

In this case I needed to get rid of an oxidized compound what also formed from my reaction, this is in the first two-three test tubes and my target compound what has an intense orange color was in the last collected fractions. 


Column chromatographic purification of a ferrocene containing compound.

Why is this great? The reaction mixture contained at least 5-6 compounds. During the first wash I removed 3 of them, including the used ligands and minor products. With the second wash with another solvent system I removed the not reacted reactants and at the end with a third solvent I washed down my product from the column (third flask contains it)


Column chromatographic separation on larger scale. 

The previous reaction produced at least 9 compounds according to the TLC, besides of the 3 reaction products what was mentioned in the publication what we worked from, so we tried to separate them by column chromatography. After collecting dozens of fractions and wasting liters of the eluent, only a little pure substance was collected.