Chlorosulfuric Acid - Applications

Applications

ClSO₂OH is used to prepare sulfonic acids, which are useful in detergents and as chemical intermediates:

ROH + ClSO₃H → ROSO₃H + HCl

An early synthesis of saccharin begins with the reaction of toluene with ClSO₂OH to give the ortho- and para-toluene sulfonyl chloride derivatives:

CH₃C₆H₅ + 2ClSO₂OH → CH₃C₆H₄SO₂Cl + H₂SO₄

Oxidation of the ortho isomer gives the benzoic acid derivative that then is cyclized with ammonia and neutralized with base to afford saccharin.

Chlorosulphonic acid has been used as an anti-contrail agent in Ryan Model 147 reconnaissance drones, and to produce smoke screens.