742 7. MERCURIALS 



Organic Mercurials 



It will be convenient to discuss some of the general properties of the or- 

 ganic mercurials before coming to the important problem of the reaction of 

 mercurials with SH groups. Many organic mercurials were developed for 

 chemotherapy, disinfection, and diuretic activity and, although some of 

 these have been occasionally used in inhibition work, mercurial inhibitors 

 are generally simpler structurally. The chemical properties and structure- 

 action relationships will be taken up later for the antiseptics (page 970) 

 and diuretics (page 917). The aryl mercurials (such as p-chloromercuri- 

 benzoate) were introduced as enzyme inhibitors by Hellerman (1937) and 

 the alkyl mercurials (such as methylmercuric chloride) as protein reactants 

 by W. L. Hughes (1950). The accompanying formulas are for the ions which 



V\ A^Hg H3C-Hg 



Phenylmercuric ion Methylmercuric ion 



^-Mercuribenzoate ion /'-Mercuriphenylsulfonate ion 



eventually complex with SH groups and other ligands. They are used as 

 chlorides, hydroxides, nitrates, or acetates but, once they have been added 

 to the medium, the ions as formulated complex with various ligands which 

 may be present, essentially as Hg-^+ does. Thus it is correct to speak of 

 phenylmercuric acetate or p-chloromercuribenzoate as the mercurial used, 

 but this terminology does not give an accurate representation of the forms 

 present in solution. For example, it makes no difference in the final inhi- 

 bition whether one uses p-chloromercuribenzoic acid or sodium p-hydro- 

 xymercuribenzoate, the two forms of the p-mercuribenzoate ion commonly 

 available. For the sake of compression, we shall use the abbreviations shown 

 in the following tabulation in the remainder of this chapter. 



Ion Abbreviation 



Phenylmercuric PM 



Methylmercuric MM 



p-Mercuribenzoate p-MB 



p-Mercuriphenylsulfonate p-MPS 



