Biphenyl Sulfonic and Disulfonic Acids with Perfluorinated Alkyl Residues

Abstract

Sulfonic acids serve as interesting, yet not intensively studied alternatives to carboxylic acids as linker units in coordination polymers. In this study, we present the synthesis of hybrid sulfonic acids with polar, rigid biphenyl moieties and disordered highly fluorinated alkyl chains. Consequently, eight biphenyl sulfonic and disulfonic acids with one or two perfluoroalkyl chains were prepared. The key steps within the synthesis include two palladium catalyzed C–C bond formations: The perfluoroalkyl residue is installed by Heck reaction (up to 91 %) using 1H,1H,2H‐perfluorinated alkenes (C6 and C8) and the biphenyl unit is established by a Suzuki coupling (up to 88 %) of boronic acids bearing one or two protected thiol groups. Finally, these thiol groups are converted into the sulfonic acids by N‐chlorosuccinimide mediated oxidation followed by hydrolysis of the respective sulfonyl chloride.