Sulfonyl halide

The stability of sulfonyl halides decreases in the order fluorides > chlorides > bromides > iodides, all four types being well known.

Benzenesulfonyl chloride, the most important sulfonyl halide, can also be produced by treating sodium benzenesulfonate with phosphorus pentachlorides.

[8] Using sodium sulfite as the nucleophilic reagent, p-toluenesulfonyl chloride is converted to its sulfinate salt, CH3C6H4SO2Na.

Treatment of alkanesulfonyl chlorides having α-hydrogens with amine bases can give sulfenes, highly unstable species that can be trapped: Reduction with tetrathiotungstate ions (WS2−4) induces dimerization to the disulfide.

[21] Arenesulfonyl iodides, prepared from reaction of arenesulfinates or arenehydrazides with iodine, are much more stable[20] and can initiate the synthesis of poly(methyl methacrylate) containing C–I, C–Br and C–Cl chain ends.

[22] Their reduction with silver gives the disulfone:[20] In the episode "Encyclopedia Galactica" of his TV series Cosmos: A Personal Voyage, Carl Sagan speculates that some intelligent extraterrestrial beings might have a genetic code based on polyaromatic sulfonyl halides instead of DNA.