Oxides of phosphorus

Each of the group 15 elements from P to Bi forms two oxides, E2O3 (or E4O6) and E2O5 (or E4O10), the latter becoming less stable as the group is descended  

In addition to describing the common oxides of the group 15 elements, the section below introduces several other oxides of phosphorus. 

Phosphoms(lll) oxide, P4O6, is obtained by burning white phosphorus in a restricted supply of O2. It is a colourless, volatile solid (mp 297 K, bp 447 K) with molecular stmcture 15.56. The P—O bond distances (165 pm) are consistent with single bonds, and the angles P—O—P and O—P—O are 128° and 99° respectively. The oxide is soluble in diethyl ether or benzene, but reacts with cold water (eq. 15.125). 

Each P atom in P4O6 carries a lone pair of electrons and P4O6 can therefore act as a Lewis base. Adducts with one and two equivalents of BH3 have been reported, but the 

The most important oxide of phosphoms is P4O10 (phos-phoms(V) oxide), commonly called phosphorus pentoxide. It can be made directly from P4 (eq. 15.10) or by oxidizing P4O6. In the vapour phase, phosphoms(V) oxide contains 

In addition, the discussion below introduces several other oxides of phosphorus. 

Each P atom in P4O6 carries a lone pair of electrons and P4O6 can therefore act as a Lewis base. Adducts with one and two equivalents of BH3 have been reported, but the reaction of P4O6 with one equivalent of Me2S-BH3 followed by slow crystallization from toluene solution at 244 K gives P80i2(BH3)2 (14.57) rather than an adduct of P4O5. The 

Three other oxides of phosphorus, P4O7 (14.60), P4O8 (14.61) and P4O9 (14.62) have structures that are related to those of P4O5 and P4O10. 

Arsenic(III) oxide dissolves in aqueous alkali to give salts containing the [As02] ion, and in aqueous HCl with the formation of ASCI3. The properties of Sb203 in water and aqueous alkali or HCl resemble those of AS2O3. 

These oxides are mixed P(III)P(V) species, each centre bearing a terminal oxo group being oxidized to P(V). For example, P4O8 is made by heating P4O5 in a sealed tube at 710 K, the other product being red phosphorus. 

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Other oxides of phosphorus are less well characterized though the suboxide PO and the peroxide P2O6 seem to be definite compounds. PO was obtained as a brown cathodic deposit when a saturated solution of Et3NHCl in anhydrous POCI3 was electrolysed between Pt electrodes at 0°. Alternatively it can be made by the slow reaction of POBrs with Mg in Et20 under reflux ... 

Production is still increasing steadily in many countries Thennar acid (made by oxidation of phosphorus in the presence of water vapour) is about 3 times as expensive as wet acid (made by treating rock phosphate with sulfuric acid). The present approximate pattern of production and uses is shown in the following scheme ... 

Of the two oxides of phosphorus, P406 and P4O10, the latter is the more stable it is formed when white phosphorus bums in air ... 

One of the most important reactions of this type involves the +5 oxide of phosphorus, P4O10. Here the product is phosphoric acid, H3P04 ... 

The oxides of phosphorus have structures based on the tetrahedral P04 unit ... 

Molecules of the oxides of phosphorus P4Oe and P4O10 also contain bridging oxygen atoms. The predicted amounts of ir-bond character, 0.73 X 0.32 = 0.23 and 0.77 X 0.32 = 0.25, respectively, lead with use of the single-bond distance... 

During steel making, preferential oxidation of phosphorus is possible if... 

Figure 1.18 Lewis structures of oxo acids and oxides of phosphorus and sulfur (a) octet rule structures according to Lewis and (b) hypervalent structures.

Loss of metal by ligand degradation. The oxidation of phosphorus ligands by peroxide impurities in the feed is an example. Purification of the feed is an obvious remedy. It is much more difficult to find a solution when ligand degradation is inherent to the catalytic reaction mechanism (e.g., phosphonium salt formation). 

HAZARDOUS DECOMPOSITION Decomposes within 6 months at 60 DEG C. Complete decomposition in 3-1/4 hours at 150 DEG C. May produce HCN. Oxides of nitrogen, oxides of phosphorus, carbon monoxide, and hydogen cyanide. 

Lower oxides of phosphorus (LOOP), 19 49 Lower temperature cure (LTC) epoxy systems, 10 444... 

Combustion of phosphorus White or red phosphorus burns to produce various oxides of phosphorus, which then attract moisture to form dense white smoke. Research and... 

Sir Edward (T. E.) Thorpe, 1845-1925. English chemist famous for his research on the specific volumes of liquids in relation to their chemical constitution, and for his work on the oxides of phosphorus and the compounds of vanadium done in collaboration with Sir Henry Roscoe. Author of excellent textbooks of chemistry and of biographies and essays in historical chemistry. 

The oxidation of phosphorus by elemental sulfur to give binary phosphorus sulfides, which is initiated by mild heating (<100 °C) or upon photolysis at 0 °C, may involve the formation of the catenaS biradical in the rate-determining first step. ... 

Binary oxides of phosphorus, arsenic and antimony are polycyclic compounds, e.g. E4O6 (E = P, As, Sb), with an adamantane-like structure. Monocyclic... 

The behaviour of acids derived from the lower oxides of phosphorus is of particular interest. It has been seen that H3P02 behaves exclusively as a monobasic acid, and H3P03 as a dibasic one, from which it can be deduced that in the latter, as well as in the former, hydrogen ions are directly bound to the phosphorus. If an ionic formula is set up for these acids, taking this fact into account, then part of the hydrogen must be shown as negative, and the following... 

Physiological Effects.—Phosphorus introduced into the etomaeh of animals acts as a cans tic poison. According to ORfila, the corrosion depends on the formation of phosphorous add, by the oxidation of phosphorus in the pulmonary canal, and the action of this acid upon the tissue with which it comes in contact. It is very rarely used in medicine, though it has been strongly recommended in oases attended with... 

The oxides of phosphorus have structures based on the tetrahedral P04 unit P406 and P4O10 are the anhydrides of phosphorous and phosphoric acid, respectively. Polyphosphates are extended structures used by living cells to store and transfer energy. 

ZPC s estimated with Equation 18 are included in the tables. As a first step in calculation it was necessary to select IEP(s) s for the common oxide components in each of the two extreme states of hydration. In most cases the value predicted from the Z/R ratio agrees fairly well with experiment. For convenience, the calculated value was used. No reliable experimental data are available for oxides of phosphorus (the reason is obvious), Al(III) in tetrahedral coordination, or for Ce(IV) or Zr(IV). For these, purely hypothetical calculated IEP(s) s were used. The IEP(s) values needed are summarized in Table IV. When it was necessary to estimate an IEP(s) for an oxide with v 4, 6, 8, a value of the constant, a, was estimated graphically from a plot of a vs. v. 

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