Quaternary phosphonium compounds

Example of a phosphonium cation. In an organic phosphonium salt, R would be an alkyl or aryl radical, and a halide would be the counterion ( anion ) not shown here .

Quaternary phosphonium compounds , including phosphonium salts , are, in analogy to quaternary ammonium compounds, onium compounds of the type [PY ₄ ] ⁺ X ^- , where Y can stand for a hydrogen atom , halogen or organic radicals and X for a halogen. The organic phosphonium salts are formed by quaternizing organophosphorus compounds. The ylides (inner salts) used in the Wittig reaction also belong to the phosphonium salts, but do not contain any halide .

The ylid (zwitterion, a quaternary phosphonium compound) and the mesomeric ylene (right, Ph = phenyl group ) play a role in the Wittig reaction.

Individual evidence

↑ Otto-Albrecht Neumüller (Ed.): Römpps Chemie-Lexikon. Volume 4: M-Pk. 8th revised and expanded edition. Franckh'sche Verlagshandlung, Stuttgart 1985, ISBN 3-440-04514-5 , p. 3160.

[RÖMPP-1] Otto-Albrecht Neumüller (Ed.): Römpps Chemie-Lexikon. Volume 4: M-Pk. 8th revised and expanded edition. Franckh'sche Verlagshandlung, Stuttgart 1985, ISBN 3-440-04514-5 , p. 3160.