Benzenesulfonic Anhydride1

[512-35-6]  · C12H10O5S2  · Benzenesulfonic Anhydride  · (MW 298.33)

(mild sulfonating agent; useful for the preparation of sulfonamides, sulfones, and sulfonate esters)

Physical Data: mp 65-80 °C; 88-91 °C after recrystallization from ether.

Solubility: sol diethyl ether, benzene, toluene; insol H2O.

Preparative Methods: prepared on a large scale by heating benzenesulfonic acid with excess phosphorus pentoxide mixed with an inert support.1 An inert support of 1:1 Supercel kieselguhr and Gooch asbestos was mixed with phosphorus pentoxide and slowly added to benzenesulfonic acid, first at rt then heating to 100 °C. The resultant mixture was heated at 100 °C for 5 h, 1,2-dichloroethane was added, and the solution was refluxed for 10 min. After cooling and successive filtrations, benzenesulfonic anhydride was recovered in 70% yield.

Handling, Storage, and Precautions: the reagent can be stored at rt for extended periods under anhydrous conditions. Liquefication occurs upon exposure to air for 2.5 h. Explosive when mixed with 90-95% H2O2.

General Reactions.

Arenesulfonic anhydrides have been used as precursors for a variety of substituted sulfones, sulfonate esters, and sulfonamides. The Friedel-Crafts reaction of benzenesulfonic anhydride and benzene in the presence of AlCl3 provided diphenyl sulfone in 99% yield (eq 1).1 This has proved to be milder and more efficient than the similar reaction using Benzenesulfonyl Chloride.1,2

Azoxybenzene is known to rearrange in concentrated sulfuric acid to p-hydroxyazobenzene.3 This acid-catalyzed Wallach rearrangement4 has been extended by using arenesulfonic anhydrides to furnish the corresponding p-arenesulfonyloxyazobenzenes in reasonable yields (eq 2).5

Solvolysis of Benzenesulfonic Anhydride.

Solvolysis of various arenesulfonic anhydrides in aqueous acetone revealed the reaction mechanism to be SN2 in accord with established results for similar systems.6


1. Lamar, F. JACS 1952, 74, 394.
2. Beckurts, O.; Otto, R. CB 1878, 11, 2066.
3. Wallach, O.; Belli, L. CB 1880, 13, 525.
4. Shemyakin, M. M.; Agadzharyan, T. E.; Maimind, V. I.; Kundryavtsen, R. V. IZV 1963, 1339.
5. Oae, S.; Maeda, T. T 1972, 28, 2127.
6. Christensen, N. H. ACS 1966, 20, 1955.

Raj K. Raheja & Carl R. Johnson

Wayne State University, Detroit, MI, USA



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