Question

Column Chromatography Lab:

Explain what would happen if you first used the mixed solvent (CH2Cl2/EtOAc), instead of hexane to elute the column filled with the mix of ferrocene and acetylferrocene?1

Answer 1

In column chromatography stationary phase has a very high polarity while mobile phase (CH2Cl2/EtOAc) has a higher polarity and hexane is non polar solvent. Ferrocene is less polar then acetylferrocene. This means that ferrocene will have a higher affinity to the less polar mobile phase like hexane than the more polar stationary phase. However, as the polarity of the mobile phase increases more easily acetylferrocene will elute. Therfore, when you first used the mixed solvent (CH2Cl2/EtOAc), instead of hexane to elute the column filled with the mix of ferrocene and acetylferrocene, you can expect both ferrocene and acetylferrocene will elute as mixture only. You must use hexane first to elute ferrocene followed by CH₂Cl₂/EtOAc to elute acetylferrocene.