Assisted by Lewis acid catalyst, Friedel-Crafts methylsulfonation of aryl ring can be achieved by MsO. In contrast to MsCl, either activated or deactivated benzene derivatives can form the corresponding sulfonatesin satisfactory yields with MsO.
Examples of aromatic sulfonation with MsO:
* Sulfonation of chlorobenzene resulted in addition of methylsulfonyl group at para and ortho positions (with respect to chloride), with a ratio of 2 to 1, respectively; while reaction with Meta-dichlorobenzene gave monosulfonylated product at C4 position.
* With sulfuric acid, di-aryl sulfones were synthesized.