Phosphines halophosphines

Preparation and Properties of Organophosphines. AUphatic phosphines can be gases, volatile Hquids, or oils. Aromatic phosphines frequentiy are crystalline, although many are oils. Some physical properties are Hsted in Table 14. The most characteristic chemical properties of phosphines include their susceptabiUty to oxidation and their nucleophilicity. The most common derivatives of the phosphines include halophosphines, phosphine oxides, metal complexes of phosphines, and phosphonium salts. Phosphines are also raw materials in the preparation of derivatives, ie, derivatives of the isomers phosphinic acid, HP(OH)2, and phosphonous acid, H2P(=0)0H. 

Halophosphines can be reduced to phosphines. Various methods have been employed to recover the product, but yields are only fair. Triphenylphosphine [603-35-0] is prepared from ben2ene and phosphoms trichloride ... 

In general, if the desired carbon—phosphoms skeleton is available in an oxidi2ed form, reduction with lithium aluminum hydride is a powerful technique for the production of primary and secondary phosphines. The method is appHcable to halophosphines, phosphonic and phosphinic acids as well as thein esters, and acid chlorides. Tertiary and secondary phosphine oxides can be reduced to the phosphines. 

Halophosphines can be treated with organometaUic reagents, eg, Grignard reagents, organomercuries, and organolithiums, to produce tertiary phosphines. 

Primary and secondary phosphines can be treated with halogenating agents to produce halophosphines. 

Tertiary phosphines and primary and secondary phosphines can be oxidized by elemental halogen to halophosphine halides. 

Organophosphinates (90) may also be prepared by the oxidation of secondary phosphines or halophosphines with hydrogen peroxide or sulfur ... 

Reduction of halophosphines [34-37] or alkyl phosphonates [38] using lithium aluminum hydride is commonly employed for the preparation of alkyl or aryl substituted primary phosphines (Eqs. 1-4) ... 

ALKYLHALOPHOSPHINES, ALKYLPHOSPHINES tert-BUTYL PEROXOPHOSPHATE ESTERS iV-CHLORINATED PHOSPHORUS AMIDES HALOPHOSPHINES, METAL PHOSPHINATES METAL PHOSPHORUS TRISULFIDES NON-METAL OXIDES, NON-METAL SULFIDES PHOSPHINES, PHOSPHORUS ESTERS... 

Chromophores based on aryl moieties can be easily grafted on to halophosphines via simple nucleophilic substitutions, as illustrated by the synthesis of 114 (Scheme 4.34). As a result, numerous phosphines bearing extended jt-conjugated substituents have been prepared. The aim of this section is not to give a comprehensive account of all derivatives that have been synthesized, but rather to illustrate how phosphorus fragments can be used either to influence or to organize the Jt-conjugated systems, with special emphasis upon fluorescence and NLO properties. 

Protonation of phosphinic acid, phosphites, or halophosphines by FSOjH or FSOjH-SbFj in SOj at low T yields phosphonium ions, as observed in H and P NMR spectra, e.g. ... 

Specialty-chemical level production (kilograms) of phosphines is achieved by hydride reductions of halophosphines, phosphonyl halides and esters and phosphinyl halides and esters, e.g. ... 

Organophosphorus compounds find wide use in the chemical industry as catalysts, intermediates, complexes, and end-use products. Arylphosphines and phosphine oxides are often produced by the reaction of a preformed Grignard reagent with a halophosphine or phosphine oxide. Yields are reduced by the production of unwanted side-reaction products such as biaryls. These unwanted products are reduced when the reaction is conducted under Barbier conditions. When alkyl and aryl halides are reacted with magnesium metal, a trihalophosphine or phosphine oxide, a metal halide or amine catalyst, in THE benzene mixtures, at reflux, good yields of phosphines or phosphine oxides are obtained [74]. For example, triphenylphosphine can be prepared in a 97.2% yield from the reaction of bromobenzene, trichlorophosphine, magnesium metal, aluminum chloride, and sodium chloride in THF-benzene at 70 80 C. 

Phosphines react vigorously with halogens to give halophosphines (6.80,6.81). The halogenation of some primary and secondary phosphines can be effected by treatment with phosgene. 

Halophosphines are produced by the cleavage of P-P bonds in diphosphines (6.670), and phosphines may be halogenated by the use of phosgene, COCI2 (6.82,6.83). Hydrogen chloride will add to methinophosphide (6.558), and another simple method is to use a tertiary phosphine as a reducing... 

Trifluoromethylphosphonous acid is obtained by hydrolysis of the halophosphine, but its sodium salt is sodium trifluoromethyl phosphinate. 

Phosphonium salts are produced by acidification of an appropriate ylid (6.422) or by adding halophosphines or alkyl halides to ylids (6.377, 6.378). Phosphonium cations are obtained by reacting phosphorus pentachloride with phosphorus pentaphenyl (6.477) or with lithio biphenyl (480). Oxiranes react with phosphines to produce betaines which, in the presence of acids, give hydroxy-alkyl phosphonium salts (3.114). 

Methylphosphinite boranes react smoothly with organolithium reagents to afford the corresponding tertiary phosphine boranes, as will be discussed in the next section. However, phosphinite boranes are not electrophilic enough to react with other weaker nucleophiles such as alcohols, amines or thiols. More reactive precursors, capable of producing a wide variety of phosphorus compounds, were needed. In phosphorus chemistry halophosphines, and chlorophosphines 27 in particular, are essential synthons (Scheme 4.12) as nucleophilic (after transformation into metal phosphides 28) and electrophilic building blocks. 

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