Trialkylphosphine dihalides

While tetraalkylphosphonium salts may be generated by the reaction of elemental phosphorus (white or red see Section 3.2) with haloalkanes, the reaction is complicated by the concomitant formation of trialkylphosphine dihalides. The resultant mixtme is generally converted to the corresponding trialkylphosphine oxide by treatment with ethanol under... 

Phosphorus pentabromide and various trialkylphosphine dihalides should be examined for mode of reactivity with Grignard and lithium reagents. The rare pentavalent phosphorus compounds substituted with organofunctional groups appear to offer interesting structural considerations. The preliminary x-ray diagram of pentaphenylphosphorus was published recently (193). ... 

For example, direct treatment of red phosphorus with potassium hydroxide in a mixture of dioxane and water with a phase-transfer catalyst (benzyltriethylammonium chloride) allows direct reaction with primary haloalkanes to form the trialkylphosphine oxide in moderate (60-65%) yield.1415 Allylic and benzylic halides are similarly reported to generate the corresponding tertiary phosphine oxides. When the reaction is performed with a,(o-dihalides, cyclic products are generated only with four- and five-carbon chains the third site... 

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