Phosphorus trioxide

Phosphorus trioxide, P4O6, can be made by burning phosphorus in a restricted supply of oxygen. It is a colourless crystalline material with mp = 23.8°C and bp = 175.4°C, and it can be crystallised from carbon disulphide solution. The solid is built from tetrahedral units (4.41e) which are similar to those established in the vapour by electron diffraction and vapour density measurements. 

This oxide has an unpleasant smell and is very poisonous. It oxidises rapidly in air to the pentox-ide and takes fire if heated. The vapour is considerably less stable than that of the pentoxide, and if the solid is heated strongly in the absence of air, it decomposes to the tetroxide and red phosphorus. 

White phosphorus will dissolve in P4O6 to the extent of 1.7 g per 100 g of P4O6. Each molecule retains its identity but the phosphorus can be removed by conversion to the red form by UV light. It can then be separated from the oxide by solution of the latter on CS2. With an excess of cold water the hydrolysis product is phosphorous acid (4.68). With hot water the process is more complex, and the products include phosphoric acid, phosphine and phosphorus. The cold water hydrolysis may proceed in a manner analogous to that of the pentoxide (4.69). 

The action of water on P4O6 and P40,o can be compared to its action on the corresponding oxides of nitrogen. 

S4 H3P03 (phosphorous acid) N2O3—(nitrous acid) (4.70) P4O10—4H3PO4 (phosphoric acid) N2O5— HN03 (nitric acid) (4.71) 

This oxide exists in the vapour state as tetrahedral molecules, P4O6, at moderate temperatures the structure of crystalline P2O3 is not known. The results of e.d. studies of the vapour of this oxide and related molecules are given in Table 19.5, and the structure of the P4O6 molecule is illustrated in Fig. 19.7. 

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Phosphorus(lII) oxide, P4O6, phosphorus trioxide, m.p. 24°C, b.p. 174 C. A waxy material (burn P in deficiency of O2)- It burns in excess O2 to P2OJ, reacts with, e.g. CI2 to POCI3 and dissolves in water to give phosphorus(TII) oxyacids. The structure is similar to that of P40,o but without the terminal oxygens. 

Dimethylformamide Halocarbons, inorganic and organic nitrates, bromine, chromium(VI) oxide, aluminum trimethyl, phosphorus trioxide... 

Hydrogen fluoride Acetic anhydride, 2-aminoethanol, ammonia, arsenic trioxide, chlorosulfonic acid, ethylenediamine, ethyleneimine, fluorine, HgO, oleum, phosphorus trioxide, propylene oxide, sodium, sulfuric acid, vinyl acetate... 

Phosphorigsaureanhydrid, n. phosphorous anhydride (phosphorus trioxide, phosphorus-(III) oxide). 

One process to form ethane-1-hydroxy-1,1-diphosphonic acid is the treatment of acetic acid with phosphorus trioxide [124] see Eq. (67) ... 

Borondiiodophosphide, phosphine, phosphorus trioxide and trimercury tetraphosphide all ignite in contact with chlorine at ambient temperature. Trimagnesium diphosphide and trimanganese diphosphide ignite in warm chlorine [1], while ethylphosphine explodes with chlorine [2], Unheated boron phosphide incandesces in chlorine. 

Copper(II) sulfate Cumene hydroperoxide Cyanides Cyclohexanol Cyclohexanone Decaborane-14 Diazomethane 1,1-Dichloroethylene Dimethylformamide Hydroxylamine, magnesium Acids (inorganic or organic) Acids, water or steam, fluorine, magnesium, nitric acid and nitrates, nitrites Oxidants Hydrogen peroxide, nitric acid Dimethyl sulfoxide, ethers, halocarbons Alkali metals, calcium sulfate Air, chlorotrifluoroethylene, ozone, perchloryl fluoride Halocarbons, inorganic and organic nitrates, bromine, chromium(VI) oxide, aluminum trimethyl, phosphorus trioxide... 

P406 PHOSPHORUS TRIOXIDE -9.1727 -1.7181E+03 6.7269E+00 -5.0441E-03... 

Most reactions of bromine are highly exothermic which can cause incandescence or sudden increase in pressure and rupture of reaction flasks. There are a number of cases of explosions documented in the literature. (NFPA. 1986. Fire Protection Guide on Hazardous Materials, 9th ed. Quincy, MA National Fire Protection Association) Reactions of liquid bromine with most metals (or any metal in finely divided state), metal hydrides, carbonyls and nitrides can be explosive. Many oxides and halides of nonmetals, such as nitrogen triiodide or phosphorus trioxide, react explosively or burst into flame in contact with liquid bromine. 

The fact that the light from glowing phosphorus and that from phosphorus trioxide both give the same spectrum supports the analogy between these two oxidations, already well established in other respects. These observations, however, cannot be taken as proof of the identity of the chemical processes. They indicate rather that there is some radiating system involved in them all, which gives rise to a definite band spectrum. Such a system may well have a connection with the chemical anomalies common to the low temperature oxidation of these phosphorus compounds. 

This triozonide, prepared from phosphorus trioxide, decomposes from 35°C in solution evolving oxygen. The solid, isolable at —78°C, tends to explode on heating. 

Property Phosphorus trioxide Phosphorus pentoxide Ortho-phosphorus acid Ortho-phosphoric acid Phosphine... 

The combustion of white phosphorus felt or red phosphorus butyl rubber will produce smoke. Smoke is an aerosol comprised of oxides of phosphorus (phosphorus pentoxide and phosphorus trioxide), some of their transformation products (see Section 3.2), and a small amount of unburnt phosphorus. The aerosol components in the smoke will undergo dispersion and chemical transformation in air to form acids or phosphorus, and will ultimately deposit from air to the hydrosphere and the lithosphere. The main components of the aerosol deposited over water and soil are acids of phosphorus. Under oxidizing conditions in soil and water, phosphorus acids will be transformed to phosphate or polyphosphates. Under reducing conditions, the disproportionation reaction of phosphorus acid can produce phosphine, and the gas may be released to the atmosphere. The fate of deposited unbumt phosphorus in water and soil has already been discussed in the preceding paragraph. 

Phosphorus Trioxide. This reaction is very violent.5... 

Phosphorus Compounds. Phosphine and phosphorus trioxide ignite on contact with chlorine ethylphosphine explodes.30... 

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