Phosphorus compounds, tervalent

Two papers have appeared on the reactions of halogenophosphines with tervalent phosphorus compounds. In a detailed study of the reactions at 20 °C of a range of tertiary phosphines with phosphorus trichloride, dichlorophenylphosphine, and chlorodiphenylphosphine, it has been shown that, in general, 1 1 adducts are formed, provided that the tertiary phosphine is a good nucleophile. With diphenylchlorophosphine, for example, an adduct (18) is formed with dimethylphenylphosphine, but not with diphenylmethylphosphine, although the relative importance of steric and electronic factors remains to be established. The related reactions of phosphorus trichloride and of dichlorophenylphosphine are much more complex, and the initial crystalline products are not amenable to analysis. The reactions at 280 °C of a similar system have been shown to lead to halogen exchange, e.g. the conversion of (19) to (20). 

The formation and reaction of peroxyl radicals derived by reaction of tervalent phosphorus compounds with oxygen have attracted interest. Photolysis of trialkyl phosphites in oxygenated solutions of aromatic hydrocarbons gives phenols. " Phosphorus trichloride reacts with 1,2-dichloroethylene, in the presence of oxygen, to give (17). It is tempting to suggest that both reactions occur via similar intermediates, e.g. (15) and (16). 

It will be seen that the above system of nomenclature has the virtue of simplicity and is easy to memorize. All that one has to keep in mind is phosphon- for quinquivalent phosphorus compounds and phosphin- for tervalent phosphorus compounds. In fact, the above system was successfully used in Britain until 1950 and may be summarized thus ... 

DioxaphosphoIens.—The condensation of a-diketones with tervalent phosphorus compounds has been extended to monothiobenzil.43 Hydrolysis of the resulting adducts (59) gave both P-O and P-S bond fission. Exchange reactions on the benzil-... 

The deoxygenation of aryl 2-nitrophenyl sulphides with tervalent phosphorus compounds is analogous to that of the corresponding ethers except that in many cases the anticipated phosphoranes, e.g. (87), are thermally unstable.58 The extra stability of spirophosphoranes allows them to be isolated, e.g. (13), if cyclic phos-phonites are used in deoxygenation.8... 

Further studies of the reactions of secondary and tertiary phosphites with cyclo-pentadienones have included the keto-cyclone (26), which gives the phosphonates (27) and (28), respectively.18 Ketenphosphoranes (29) have been prepared by the reaction of diphenylcyclopropenone with a variety of tervalent phosphorus compounds.19... 

Further use has been made of the reaction of disulphides with tervalent phosphorus compounds in phosphorylation reactions, e.g. in the synthesis of (57).68... 

The desulphurization of disulphides by tervalent phosphorus compounds has been the subject of a review.70 The light-induced desulphurization of benzylic sulphides by phosphites has found further use in the synthesis of cyclophanes which exhibit the formation of intramolecular charge-transfer complexes, e.g. (61) and (62).71... 

The chemistry of the JV-oxides of oxazole has not been explored as thoroughly as that of the pyridine analogues. Both types of compounds are reversibly protonated to give iV-hydroxy cations, form complexes with iodine and with tetracyanoethylene, and both are deoxygenated by triphenylphosphine and other tervalent phosphorus compounds. 

There have been a number of developments worthy of special mention in chemistry involving pentaco-ordinated compounds and intermediates. These include reports of molecular mechanics calculations to study the hydrolysis of cyclic phosphorus esters, further detailed studies of the reactions of tervalent phosphorus compounds with acetylene carboxylates and the first synthesis of a pentaco-ordinated phosphorus compound containing a three-membered (phosphirene) ring. There has also been further elegant work in the area of phosphatrane chemistry. 

In spite of its highly strained Dewar structure 1 is stable and may be kept in a refrigerator for several years. It isomerizes to the aromatic isomer at high temperature (half-life in benzene at 160 C was 5.1 h). The treatment of the Dewar thiophene with triphenylphosphine did not cause the elimination of sulfur, but instead accelerated the isomerization to the aromatic isomer. This catalytic acceleration is limited to tervalent phosphorus compounds but phosphorous trichloride or phenyldichlorophosphine are ineffective. An adduct of diphenylchlorophosphine with the Dewar thiophene was postulated to be a ff-complex with a P—S bond. It decomposed spontaneously to the thiophene and the phosphine as shown in Eq. (9).15 Recently,... 

Removing 02 is necessary for the safe operations of many reactions, especially hydrogenations. Funtional groups which are readily oxidized with 02 include mercaptans, tervalent phosphorus compounds, and some amines. Anions may also react with dissolved 02, leading to the generation of impurities during alkylation of these anions [16]. 

The synthesis of phosphoranes from tervalent phosphorus compounds, 1,2- or 1,3-diols, and iV-chlorodi-isopropylamine according to equation (1) has been extended to... 

At low temperatures, trialkyl phosphites and chloral give the 1,4,2-dioxaphos-pholans (96), which decompose above —10 °C to give the vinyl phosphates (97). 1,4,2-Dioxaphospholans are also formed from benzaldehyde and the tervalent phosphorus compounds (98). ... 

The Reporter notes an overall decrease in the number of papers in this area published during the year, although the number dealing with p -bonded phosphorus compounds continues to increase. The reactions of disulphides with tervalent phosphorus compounds have been reviewed. ... 

The reactions of a variety of tervalent phosphorus compounds with 1,2-dioxan have been investigated. Reactions with phosphites give either phosphate and THF or the phosphorane (46), depending on the phosphite used, and so are very similar to the analogous reactions with dialkyl peroxides. Penta-alkoxyphosphoranes (47)... 

As previously reported, oximes react with electrophilic tervalent phosphorus compounds to give the rearranged product (62). Hudson and his co-workers have... 

The interest in multiply bonded tervalent phosphorus compounds continues to grow, and a number of papers dealing with the reactions of phosphorus-nitrogen Pn-Pv bonds have appeared. 1,2,3 or -Diazaphospholes (63) undergo addition with... 

Several reports of the synthesis of hexaco-ordinate phosphorus compounds [e.. (81)] from tervalent phosphorus have appeared (see Chapter 2). P N.m.r. studies... 

Several tervalent phosphorus compounds readily remove selenium from triphenylmethyl isoselenocyanate (54) at room temperature forming the isocyanide quantitatively. ... 

Ethyl benzenesulphenate (6) reacts with a variety of tervalent phosphorus compounds to give initially ethoxythiophenoxyphosphoranes (7), which can react with a second mole of (6) to give diethoxyphosphoranes and diphenyl... 

Strong e.s.r. evidence has been obtainedfor the intermediacy of radicals in the formation of phosphoranes from tervalent phosphorus compounds and activated carbonyl compounds such as a-diketones, quinones, and ajS-unsaturated ketones. The phosphinium radical reacts rapidly with a second molecule of the ketone as shown in the Scheme. 

Details have appeared of the formation of cyclopropanes from arylidene-malononitriles and the biacetyl-trimethyl phosphite adduct. 1,2-Oxaphospholens.— Among a 3-unsaturated ketones used in the formation of 1 1 adducts with tervalent phosphorus compounds are the sulphone (42) ... 

The reaction of tervalent phosphorus compounds with iV-bromosuccinimide in the presence of alcohols provides an alternative route to the alkoxy-phosphonium salt (74) and hence to alkyl halides. In the absence of alcohols. 

An overall decrease in the number of publications on this topic is apparent, although the volume of patent literature is still increasing. Notable developments include the synthesis of a monophosphazene, (Me3Si)2NP=NSiMea, containing tervalent phosphorus and of a three-co-ordinated quinquevalent phosphorus compound (Me3Si)2NP(=NSiMe3)2, > and the incorporation of a phosphazene unit in a four-membered ring. ... 

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