Tosyl

Tosyl (abbreviated as Ts or Tos) refers to the functional group with the chemical formula CH₃C₆H₄SO₂. This group is derived from toluene through the substitution of one hydrogen atom on the methyl group with a sulfonyl functional group. Tosyl groups are widely used in organic chemistry as protecting groups for alcohols and as a precursor to forming tosylates, which are useful intermediates in various chemical reactions including nucleophilic substitution and elimination reactions.

The tosyl group is attached to an alcohol via a reaction with tosyl chloride (TsCl), in the presence of a base, typically pyridine. The resulting tosylate is an excellent leaving group for nucleophilic substitution reactions, due to the stability of the tosyl group. This property is exploited in the synthesis of various organic compounds, including drugs and polymers.

Tosylates are also used in the preparation of amines through the displacement of the tosyl group by ammonia or an amine in a nucleophilic substitution reaction. This method is particularly useful for the synthesis of tertiary amines.

In addition to its role as a protecting group and intermediate, the tosyl group is also used in the purification of amines. Amines can be converted to their corresponding tosylamides, which are more crystalline and easier to purify than the original amine.

The use of tosyl groups is not limited to organic synthesis. In biochemistry, tosyl-activated magnetic beads are used for the isolation and purification of proteins and nucleic acids. This application takes advantage of the ability of the tosyl group to form stable covalent bonds with amine groups on biomolecules.