Chemistry of condensed thiophenes. V . Sulfonation and sulfonyl bridging of m ‐terphenyl. Conversion to sulfonamides

Reaction of m ‐terphenyl with 20% oleum at 100° gives both disulfonation and double sulfonyl bridging to yield benzo[1]thieno[2,3‐ b ]dibenzothiophene‐3,9‐disulfonic acid 5,5,7,7‐tetraoxide, isolated as the disodium salt (24%) and convertible ( via the disulfonyl chloride) to the bis‐sulfonanilide (44%) and the bis‐ N ‐butylsulfonamide (40%). Analogously, reaction of m ‐terphenyl with chlorosulfonic acid at 100° gives disulfonation plus only single sulfonyl bridging to produce 2‐(4‐chlorosulfonyl)‐7‐chlorosulfonyldibenzothiophene 5,5‐dioxide (80%), convertible to the corresponding bis‐sulfonanilide (63%) and the bis‐ N ‐butylsulfonamide (45%).