Column Chromatography

What compound can undergo an aromatic organometallic compound which can undergo electrophilic substitution (Friedel-Crafts acylation) reaction like benzene?

Ferrocene can undergo electrophilic substitution reaction like benzene

What compound is obtained by the friedal-crafts acylation of ferrocene?

Acetylferrocene is obtained by friedel-crafts acylation of ferrocene

Ferrocene is a yellow colored __________ with the formula Fe(C5H5)2

Organometallic compound: Chemical compounds containing at least one bond between a metal atom and a carbon atom from an organic molecule

What color is acetylferrocene?

Acetylferrocene is orange

Is aluminum chloride a lewis acid or lewis base catalyst?

Acetyl Chloride is a lewis acid

In this reaction, what is the aromatic compound, electrophile, lewis acid catalyst, and solvent?

Aromatic compound: Ferrocene

Electrophile: Acetyl chloride (CH3COCl)

Lewis acid catalyst: Aluminum chloride (AlCl3)

Solvent: Methylene Chloride (CH2Cl2)

What is column chromatography?

This is a LIQUID-SOLID chromatography method used to seperate and purify individual chemical compounds from mixtures of compounds

How does seperation occur in column chromatography?

Seperation occurs by distributing components of a mixture between two phases: the mobile phase (liquid organic solvents of different polarities) and stationary phase (solid: silica or alumina)

What is the stationary phase for the column chromatography v.s. TLC?

Column Chromatography: solid-alumina (polar)

TLC: solid-silica gel

What products are in the mobile phase in TLC?

Liquid organic solvent such as chloroform, hexane

What products are the mobile phase in column chromatography?

• Hexane to elute non-polar ferrocene component

• Methylene chloride to elute polar acetylferrocene component

More polar solvents move further up on the TLC. Name compound from most polar to least

Most Polar: Methanol, Acetone, Chlororform, ether, toluene, hexane :Least Polar

Which compound elutes first then next? Why?

• Ferrocene being LESS POLAR elutes first- travels down faster along the column when non-polar hexane used as a mobile phase

• Acetyl ferrocene being MORE POLAR elutes 2nd: travels down next when a more polar solvent methylene chloride (dichloromethane) is used as a mobile phase

How do you determine if the seperation is successful?

Perform a TLC and seperation is based on the parting of the mixture between stationary and a mobile phase

How do you achieve seperation in a column chromatography?

Change the pilarity of the mobile phase