Syntheses and Reactions of 2,5-Disulfobenzene-1-diazonium Salts: Towards Functionalized Sulfonate Metal-Organic Frameworks

A preparation, separation, and purification protocol for 2-substituted 1,4-benzenedisulfonic acids by exploiting crystallization of the barium salts and their subsequent protonation with cation-exchange resin was developed. This technique was applied to the preparation of 2-chloro-, 2-bromo-, 2-iodo-, and 2-hydroxy-1,4-benzenedisulfonic acids. The iodo derivative was submitted to Suzuki coupling reactions with Pd/C as the catalyst, and the respective biphenyl derivatives were subsequently isolated. The copper(II) salt of the iododisulfonic acid was prepared. In the solid state, it was found to form polymeric chains, which interlock in two-dimensional layers. The material was found to be thermally stable up to 400 degrees C above which point the salt decomposed to afford CuI.