Mechanism of electrophilic substitution at a saturated carbon atom. Part XII. Repression of the anion-catalysed unimolecular acidolysis of the 4-pyridiomethylmercury(II) chloride and chloromercurate(II) ions; an anion-catalysed unimolecular one-alkyl mercury exchange

Abstract

The rates of acidolysis of the 4-pyridiomethylmercury(II) chloride ion in aqueous solution have been measured as a function of acid, chloride ion, and mercury(II) chloride concentration. The results show that the partly quinonoid 4-pyridiomethylide ion intermediate in the unimolecular acidolysis of the polychloropyridiomethylmercurate(II) ions is captured by the species HgCl₂, HgCl₃^–, and HgCl₄^2– as well as by H₃O⁺. The relative rates of capture of the pyridiomethylide ion by these electrophiles have been measured and show that only HgCl₄^2– is less reactive than H₃O⁺ as measured by the stocheiometric acidity.