Phosphorus compounds oxoacids

White phosphorus, P4, is highly toxic, very reactive, and flammable the polymeric red phosphorus, (P4), is more stable. Phosphorus forms oxides and hahdes with oxidation numbers of +3 and +5 and several oxoacids. The phosphates are the most important phosphorus compounds. 

Oxides can be defined as binary compounds formed between various elements and oxygen, while phosphates can be defined as salts based formally on phosphorus (V) oxoacids and in particular salts of phosphoric (V) acid, H3PO4. Both oxides and phosphates are among the most important classes of inorganic compounds. For example, silicon dioxide (Si02) is the main compound in the Earth s crust, and apatite, a complex mineral form of calcium phosphate, Ca5(P04)3 (OH, F, Cl) is the main compound on the enamel of teeth [1-3],... 

A review has appeared on the kinetics of hydrolysis of phosphate esters. Hydroxyphosphoranes have long been postulated as intermediates in the hydrolysis of esters of oxoacids of phosphorus. Compound (4), which is a possible model for such species, has been synthesized. Nucleophilic substitution at cis-and /raiij-isomers of (5) (X=/ N02CeH4) by nucleophilic oxoanions in aprotic solvents gives complex results. The degree of retention/inversion is strongly dependent upon the cation, and on the solvent. The inversion process involves an Ssl tbp-type transition state, while the retention process is suggested to involve the addition of an ion pair across the P=0 bond to form a square-pyramidal species. ... 

Phosphorus forms oxides and halides with oxidation numbers of +3 and +5 and several oxoacids. The phosphates are the most important phosphorus compounds. 

Many compounds containing the P-N link can be considered formally as derivatives of the oxoacids of phosphorus and their salts (pp. 510 -31) in which there has been isoclccironic replacement of ... 

Formation of Phosphorus Oxoacids with P-P-P-P-P-P and P-P-P-P-P Frameworks and Related Compounds... 

It was very difficult to obtain the new compound of P d or P d as a solid salt, because a very small amount of P d or P d was present in very dilute aqueous solution. However, the preparation of a small volume of P d solution of relatively high concentration was successfully achieved by the following procedure the enrichment of phosphorus oxoacid species into a certain amount of an anion-exchange resin and the subsequent elution with a calculated volume of potassium chloride solution of a proper concentration. By adding small volumes of magnesium chloride solution and methyl alcohol to the resulting P d solution, 4 mg of magnesium salt of Pgd was obtained. 

Many possible compounds of phosphorus exist. The simplest are listed in Table I. Even more complicated oxoacids of phosphorus were studied and reported in the paper by Ohashi and Yoza (3). Their study of oxoacids of phosphorus with molybdenum ion was done in neutral and acid solutions in the presence and absence of a reducing agent. Their results showed that acids containing a -P-P-P straight or cyclic chain gave color development similar to those we found in... 

Table 14.7 lists selected oxoacids of phosphorus. This is an important group of compounds, but the acids are difficult to classify in a straightforward manner. It should be remembered that the basicity of each acid corresponds to the number of OH-groups, and not simply to the total number of hydrogen atoms, e.g. H3PO3 and H3PO2 are dibasic and monobasic respectively (Table 14.7). Diagnostic absorptions in the IR spectra of H3PO3 and H3PO2 confirm the presence of P—H bonds the P-attached hydrogens do not ionize in aqueous solution.

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