Halophosphines reactions

Reactions of halophosphines with conjugated heterodienes leading toP,0-, P,N-, and P,N,0-heterocycles 99UK167. 

Data from this laboratory and others8,9,10 indicate that the general procedure outlined for the synthesis of F2PX compounds may be extended to the synthesis of the oxy derivatives of pentavalent phosphorus such as F2C1P0 and Cl2FPO, but the detailed directions are not given here. The mixed oxyhalides of phosphorus, like the corresponding mixed halophosphines, have not been obtained easily in pure form from complex reaction mixtures.11,12... 

The reaction of a diphosphine with a dihalo compound, resulting in the formation of a di- or tetra-phosphonium salt2c, is a special case because if fits well with a cyclization on phosphorus, but also at the same time with a cyclization between two chains already linked to the second phosphorus (reaction 102). Another kind of ring closure on the phosphorus results from the biphilic character of halophosphines toward dienic392 or acetylenic28,393 systems (reaction 105). 

A theoretical study of nucleophilic substitution of halophosphines by halide anions indicates the involvement of an anionic tetra-coordinated intermediate species (X-PH2-Y) , rather than a transition state structure. The authors predict that this intermediate should be detectable, and that the Sn2 reaction at trivalent phosphorus is exothermic when the reactant halide anion is more electronegative... 

Complexation of the latter at phosphorus with borane, followed by methanolysis of the siloxyether function, gives the related o-hydroxyaryl diazaphospholidines. The cage-like triaminophosphine (109) has been obtained from the reaction of tri(2-pyrrolyl)methane with phosphorus trichloride, in the presence of triethylamine. This compound is stable to methanolysis, hydrolysis, and aerial oxidation at room temperature. Phosphorylation of various 1,2,4-triazoles with halophosphines has given a route to the heterocyclic system (110), and routes to various [2,4,l]benzodiazaphosphinines, e.g., (Ill), have also been developed. ... 

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. 

By far the most important type of reaction displayed by halophosphines is nucleophilic substitution. This is pivotal to the preparation of many other three-coordinate compounds containing either solely P—C, P—O, P—N bonds, or mixed combinations. These reactions are often exothermic and frequently carried out at low temperatures. For the synthesis of phosphorus(III) compounds containing a P—O or P—N bond it is often necessary to add a base (triethylamine or pyridine are frequently used) to capture the hydrogen halide eliminated from these condensation reactions. In the case of P—C bond formation, a variety of routes are possible using various carbon-derived nucleophiles. 

The first characterization of simple halophosphines as the primary products of the direct reaction of white or red phosphorus with trifluoromethyl iodide at 200-220 °C under pressure was reported in 1953 by Bennett, Emeleus and Haszeldine ... 

Halophosphines are produced by reactions of phosphorus with alkyl chlorides, alkyl bromides, or aryl bromides in solution (12) and by reaction of red phosphorus in tlie presence of copper with alkyl halides in tlie vapor phase (13). Both methods require temperatures in excess of 2 )0°. The preparation of halopliosphines in solution is illustrated by the results of uncatalyzed white phosphorus reactions summarized in Table I (12). Alkyl dihalopliosphiues are the predominant products under these conditions, but appreciable yields of dialkylmonohalophos-phines are also obtained. The reaction temperature requirement de-... 

Aminophosphines are mostly prepared by one of two routes the reaction of halophosphines (normally chlorophosphines) with amines or silylated amines (equation 32), or the... 

Due to the lack of both a metal centred lone pair and an available coordination site, a nucleophilic substitution reaction is obviously inoperative here. Therefore, a direct insertion into the central M-H bond is responsible for the formation of the phosphonium salt. Such a reactivity has been explained recently, by Nikonov et al, in terms of a new and interesting concept, which considers the carbenoid nature of halophosphines. ... 

The phenyl derivatives PhPClj, PhjPCl and PCI3 itself are commercially available and a useful review of halophosphines has been published. The reaction of PCI3 with Grignard or organo-... 

Fluorophosphoranes and halophosphines usually break Si-N linkages and replace them with P-N, without forming either Si-P or Si-N-P linkages (7.135,7.179,7.256,7.458,7.488,7.489). In the absence of these reagents, however, the grouping P = N-Si is relatively stable (7.490) and (7.529). Some reactions of silyl iminophosphoranes are given in Chapter 7.10. 

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