A useful sulfhydryl reagent, 4-(ChloroMercuri)benzenesulfonic Acid SodiuM Salt reacts with Histidine 225C, a residue of the NhaA-Na/H Antiporter of Escherichia Coli. More soluble than p-chloromercuribenzoic acid
The free acid is obtained by acidifying an aqueous solution, filtering off the acid, washing it with H2O and recrystallising from hot H2O to give a colourless solid which is dried in a vacuum over P2O5 and should be free of Cl-ions (AgNO3 test). The Na salt is made by dissolving it in one equivalent of aqueous NaOH and evaporating to dryness. [Nesmejanow et al. Chem Ber 67 130 1934, Boyer J Am Chem Soc 76 4331 1954.] HIGHLY TOXIC.
