MECHANISM OF ELECTROPHILIC SUBSTITUTION AT A SATURATED CARBON ATOM .12. REPRESSION OF ANION-CATALYSED UNIMOLECULAR ACIDOLYSIS OF 4-PYRIDIOMETHLMERCURY(II) CHLORIDE AND CHLOROMERCURATE(II) IONS - AN ANION-CATALYSED UNIMOLECULAR ONE-ALKYL MERCURY EXCHANGE

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 HgCl 2, HgCl3-, and HgCl42- as well as by H3O+. The relative rates of capture of the pyridiomethylide ion by these electrophiles have been measured and show that only HgCl42- is less reactive than H3O + as measured by the stocheiometric acidity.