Chlorodiphenylphosphine
Chlorodiphenylphosphine is an organophosphorus compound with the formula (CH)PCl, abbreviated PhPCl. It is a colourless oily liquid with a pungent odor that is often described as being garlic-like and detectable even in the ppb range. It is useful reagent for introducing the PhP group into molecules, which includes many ligands. Like other halophosphines, PhPCl is reactive with many nucleophiles such as water and easily oxidized even by air. Synthesis and reactions. Chlorodiphenylphosphine is produced on a commercial scale from benzene and phosphorus trichloride (PCl). Benzene reacts with phosphorus trichloride at extreme temperatures around 600 °C to give  dichlorophenylphosphine (PhPCl) and HCl. Redistribution of PhPCl in the gas phase at high temperatures results in chlorodiphenylphosphine. Alternatively such compounds are prepared by redistribution reactions starting with triphenylphosphine and phosphorus trichloride. Chlorodiphenylphosphine hydrolyzes to give diphenylphosphine oxide. Reduction with sodium affords tetraphenyldiphosphine: With ammonia and elemental sulfur, it converts to the thiophosphorylamide: Uses. Chlorodiphenylphosphine, along with other chlorophosphines, is used in the synthesis of various phosphines. A typical route uses Grignard reagents: The phosphines produced from reactions with PhPCl are further developed and used as pesticides (such as EPN), stabilizers for plastics (Sandostab P-EPQ), various halogen compound catalysts, flame  retardants (cyclic phosphinocarboxylic anhydride), as well as UV-hardening paint systems (used in dental materials) making PhPCl an important intermediate in the industrial world. Precursor to diphenylphosphido derivatives. Chlorodiphenylphosphine is used in the synthesis of sodium diphenylphosphide via its reaction with sodium metal in refluxing dioxane. Diphenylphosphine can be synthesized in the reaction of PhPCl and LiAlH, the latter usually used in excess. Both PhPNa and PhPH are also used in the synthesis of organophosphine ligands. Characterization. The quality of chlorodiphenylphosphine is often checked by 31P NMR spectroscopy.