Phosphorus reaction

A common pathway has been tentatively put forward to account for both the arsenic and phosphorus reaction products (Scheme 20). Breaking of two bonds to one of the atoms in the P4 or As4 tetrahedron would lead... 

Cann, P.F., Warren, S., and Williams, M.R., Electrophilic substitution at phosphorus reactions of diphenylphosphinyl systems with carbonyl compounds, /. Chem. Soc., Perkin I, 2377, 1972. 

Holmes, R.R., Reaction mechanisms, in Pentacoordinated Phosphorus—Reaction Mechanisms, ACS Monograph 176, American Chemical Society, Washington, D.C., Volume II, Chapter 2, 1980, p. 87. 

In contrast to phosphines, dialkyl sulfides are relatively stable towards autoxidation. As we have pointed out elsewhere (25), the simplest explanation is an energetic one the over-all transfer of an oxygen atom from carbon to phosphorus (Reaction 11) is exothermic by some 33 kcal. per mole. Transfer to sulfur, in contrast, is approximately thermoneutral... 

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). 

In the case of phosphonium salts, some examples of decomposition by Hofmann elimination reactions are known. The phosphonium salts which normally undergo such a decomposition possess an activated hydrogen / to the phosphorus the salts 70, with a strong electron-withdrawing Z group on the carbon / to the phosphorus (reaction 202) and the a-hydroxyalkylphosphonium salts 71 (reaction 203)... 

The subscripts on k2, and k represent the first, second, and third phosphorus reactions, respectively. From ans and Jurinak (1976), with permission. 

Modeling of Inorganic Reactions 174 Nitrogen Reactions 174 Phosphorus Reactions 177 Potassium Reactions 181 Aluminum Reactions 183 Modeling of Soil-Pesticide Interactions 183 Modeling of Organic Pollutants in Soils 186 Supplementary Reading 189... 

Several kinetic models have appeared to describe phosphorus reactions in soils. Enfield (1978) classified models for estimating phosphorus concentrations in percolate waters derived from soil that had been treated with wastewater into three categories (1) empirical models that are not based on known theory (2) two-phase kinetic models that assume a solution phase and some adsorbed phase and (3) multiphase models, which include solution, adsorbed, or precipitated phases. Mansell and Selim (1981) classified models as shown in Table 9.2. The reader is urged to consult this reference for a complete discussion of the phosphorus kinetic models. For the purpose of this discussion, attention will be given to models that assume reversible phosphorus removal from solution, which can occur simultaneously by equilibrium and nonequilibrium reactions, and mechanistic multiphase models for reactions and transport of phosphorus applied to soils. 

TABLE 9.2 Summary of Mathematical Models for Predicting Phosphorus Reactions in Soils... 

Alkyl Halides. The classical method for converting alcohols to alkyl iodides (31) involves heating the alcohol with iodine in the presence of phosphorus (Reaction XXIII). Like other iodi-... 

These two tests can be particularly helpful. The P spray reagent was described above and can detect as little as 0.2 pg phospholipid P and yields a brilliant blue color usually within a minute. The char reaction is accomplished by spraying a separate plate (or the one after the phosphorus reaction) with concentrated sulfuric acid and then heating the plates on a hot plate at 180°C or in a muffle furnace at 400 -600°C. The difference is of course that the char reaction (first a brown and then a definite charcoal color) is complete at the higher temperature within 5 min, whereas the reaction conducted at 180°C takes perhaps 30 min. 

Derivation Reaction of acetic acid, iodine, and phosphorus reaction of acetyl chloride and hydrogen iodide. 

In a related study involving oxidative addition of perfluorodiketones to tricoordinate phosphorus, reaction of 82 with 83 gave good yields of 86a-d probably via 84 and 85 as mechanistic intermediates. The course of the reaction... 

Holmes, R. R. Pentacoordinated Phosphorus, Reaction Mechanisms, ACS Monograph 176 American Chemical Society Washington, DC, 1980 Vol. II, Chapter 2 and references cited therein. 

Phosphorus ylides containing fluorine atoms bonded to phosphorus (reactions leading to the formation of P-heterocycles) 01SL1065. 

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-... 

The five coordinate spirophosphoranes have played an important role with respect to understanding the stereochemistry of four coordinate phosphorus reactions which proceed via phos-phorane intermediates. Variable temperature NMR studies have established the apicophilicities of a wide range of groups (i.e. relative preferences of a series of groups to occupy an apical position rather than an equatorial position of a trigonal bipyramidal (t.b.p.) conformation of a phosphorane). The spiro ring system has been used to stabilize transient reaction intermediates of acyclic compounds, for example hydrolysis intermediates such as hydroxyphosphoranes. 

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