Phosphine Oxides
Phosphine Oxides
Phosphine Oxides are normally classified as primary, secondary and tertiary oxides generally represented by the formula RPH2(O), R2PH(O) and R3P=O. The phosphine oxides are generally produced as a by-product of the Wittig reaction. Tertiary phosphine oxides are more stable than the primary and secondary phosphine oxides, and therefore least reactive of all phosphorus compounds. Phosphine oxides are employed as catalysts in the chlorination of alcohols and are also used as extractants for metals in its fluorometric determination. Generally with Lewis acids such as AlCl3 and BF3, tertiary phosphine oxides form complexes, which are useful as homogeneous catalysts in various chemical transformations (A Guide to Organophosphorus chemistry, by Quin, Louis D.).
The secondary phosphine oxides are versatile ligands, and therefore can be employed for the formation of C-C, C-N and C-S bonds in transition metal-catalyzed oxidative coupling reactions. The polymer resins such as epoxide, polyester, polyamide, and polycarbonates react with the derivatives of phosphine oxides, and the product formed can be used as flame retardants and cross linkers. Owing to its high solubility and increased response to photosensitization, the acyl derivatives of phosphine oxides are employed as photoinitiators in the polymerization of unsaturated compounds.
