Quaternary compound

In <a href="/facts/Chemistry/SrNqkGVm">chemistry</a>, a quaternary compound is a compound consisting of exactly four chemical elements. 
In another use of the term in <a href="/facts/Organic_chemistry/djxhxaNg">organic chemistry</a>, a quaternary compound is or has a <a href="/facts/Cation/wrbwhF3z">cation</a> consisting of a central positively charged atom with four substituents, especially <a href="/facts/Organic_compound/gqCNaN45">organic</a> (<a href="/facts/Alkyl/vmEk8X4v">alkyl</a> and <a href="/facts/Aryl/M3z7QRXd">aryl</a>) groups, discounting <a href="/facts/Hydrogen/BoYHjl0J">hydrogen</a> atoms.
The best-known quaternary compounds are <a href="/facts/Quaternary_ammonium_cation/bNpF1goc">quaternary ammonium</a> salts, having a <a href="/facts/Nitrogen/Nf1QpGDz">nitrogen</a> atom at the center. For example, in the following reaction, the nitrogen atom is said to be quaternized as it has gone from 3 to 4 substituents:

R
            
              3
            
            
              
            
          
          N
          +
          RCl
          ⟶
          
            R
            
              4
            
            
              
            
          
          
            N
            
              +
            
          
          
            Cl
            
              −
            
          
        
      
    
    {\displaystyle {\ce {R3N + RCl -> R4N+Cl-}}}

Other examples include substituted <a href="/facts/Phosphonium_salt/uS2PCt7X">phosphonium salts</a> (R4P+), substituted <a href="/facts/Arsonium_salt/MkkQcCz9">arsonium salts</a> (R4As+) like <a href="/facts/Arsenobetaine/xHS3JvTH">arsenobetaine</a>, as well as some <a href="/facts/Arsenic/k1c4f44D">arsenic</a>-containing <a href="/facts/Superconductor/pqQAlSzJ">superconductors</a>. Substituted stibonium (R4Sb+) and bismuthonium salts (R4Bi+) have also been described.

Quaternary compound open-in-new

Quaternary compound