Phosphonium, quaternary ions, substituents

A closely related solvent effect can be achieved by use of phase transfer catalysis. These catalysts are salts in which one of the ions has large nonpolar substituent groups which confer good solubility in nonpolar solvents. The most familiar examples are quaternary ammonium and quaternary phosphonium salts with several long-chain alkyl substituents. In a two-phase solvent system consisting of water and a nonpolar organic solvent containing a salt, there will be virtually no ions present... 

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