How can benzene be separated from thiophene chemically?

1 Answer
Mar 5, 2016

I can think of three methods:


They all make use of the fact that, although thiophene is aromatic, it is much more reactive than benzene.

A. Desulfurization by Raney Nickel

The reaction of thiophene with Raney nickel produces butane, which is a gas at room temperature.

B. Mercuration with mercury(II) acetate

When you reflux the impure benzene with mercury(II) acetate, the thiophene reacts rapidly to form poly mercury acetates, which precipitate out and are filtered off.

3. Sulfonation

Probably the most convenient method is to use the fact that thiophene is highly reactive toward sulfonation.

Shaking a mixture of benzene and thiophene with sulfuric acid at room temperature causes sulfonation of the thiophene but leaves the benzene untouched.

The thiophenesulfonic acid dissolves in the sulfuric acid layer, which you can separate.

You can then wash, dry, and distill the benzene in the usual way.