Reactions Involving Phosphorus

A reaction involving phosphorus trichloride providing a free phosphonic acid apparently involves an enolized carbonyl compound as the species attacking the phosphorus.96 Methyl aromatic ketones thus provide access to the vinylicphosphonic acids (Figure 6.26). 

The Vilsmeier-Haack formylation procedure (Scheme 24) provides the most effective synthesis of formylpyrroles and indoles. Reaction of the heterocycles with the immonium cation (72), derived from DMF or (V-methylformanilide with an acid chloride, such as phosphorus oxychloride, thionyl chloride, phosgene, oxalyl chloride, benzoyl chloride or bromotriphenylphosphonium bromide, yields the intermediate heteroarylimmonium salt (73). Under suitable reaction conditions, this salt may be isolated from the reaction involving phosphorus oxychloride as an impure chlorophosphate (78TH30500) or precipitated from the reaction system as the thermally unstable perchlorate by the addition of sodium... 

Figure 7 Characteristic reactions involving phosphorus in the sediments of Toolik Lake, Alaska. The primary processes controlling porewater phosphorus concentrations are adsorption to and desorption from iron oxyhydroxides and the precipitation of authigenic vivianite...

Interest in such compounds has arisen as a result of the extensive studies being carried out on the stereochemical aspects associated with phosphorus in coordination number five. The observation of distinct axial and equatorial P—F environments for the tetrafluorophosphoranes, by NMR techniques, is possible, whereas this observation is not common to the corresponding hydrocarbon-phosphorus bonded tetrafluorophosphoranes. Further substitution at phosphorus is possible, the tetrafluorophosphoranes and trifluorophosphoranes are reactive compounds, and it is possible to substitute further F atoms for other groups. The experimental techniques described here can be applied to the preparation of other amino fluoro phosphoranes. Further, the same techniques are applicable to other reactions involving phosphorus-fluorine compounds and silicon compounds. 

Fig. 3.4 The pathways of reactions involving phosphorus in iron-rich sediments.

Favourable thermochemistry for a particular gas-phase reaction does not guarantee that it will be kinetically viable. Although many gas-phase ion-molecule reactions are fast owing to the ion-dipole and ion-induced dipole attractive electrostatic potential, there can be significant barriers to certain reactions. Hence experimental kinetic data are important, especially for the modelling of atmospheric and interstellar processes. Those interested in the kinetics of gas-phase ion-molecule reactions involving phosphorus species are directed to a number of databases. ... 

Polyphosphazenes are inorganic polymers in which the backbone consists of alternating P and N atoms with two lateral groups. Polyphosphazene monomers are prepared by a condensation reaction involving phosphorus pentachloride... 

The possibility for the formation of hypervalents states by organo-phosphorus species could also find an application in veryfing the stereochemical outcome of reactions involving phosphorus species. An important example confirming this thesis has been recently presented by Baccolini s... 

Reactions involving phosphorus centered radicals derived from diethyl hydrogen phosphite are also initiated by DTBP under thermal conditions (eq 5). Under modified reaction conditions, diphosphonate products, resulting from further addition to the initially formed unsaturated phosphonate, were also observed. 

These reactions are involved in the catalytic recombination cycles of H atoms with the formation of Hz. It is these reactions that are responsible for the rise in the inhibition effectiveness with increasing of ( ). Under the catalytic recombination responsible for scavenging of radicals in OPC-doped flames, all the authors meant reactions involving phosphorus oxides and acids (PO, PO2, HOPO, and HOPO2). It was assumed that organophosphorus combustion intermediates play a negligible role in the inhibition processes. However, in these specific flames reactions of OPCs with active species are of importance. 

Multicomponent reactions involving phosphorus ylides were used to construct complext organic frameworks. For example, the reaction of triphenylphosphine, diallgfl acetylenedicarbojgflates, and acids such as phenols, imides, amides, enols, oximes and alcohols was described to produce stabilized phosphorus ylides. Other examples of products for multicomponent reactions involving P-ylides are shown in Fig. 9. 

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