The phosphorous oxide (v) It is an inorganic solid formed by phosphorus (P) and oxygen (O). Its empirical formula is PtwoOR5, while its correct molecular formula is P4OR10. It is a very hygroscopic white solid, that is, it can absorb water from the air very easily, reacting immediately with it. The reaction can be dangerous as it causes a rapid increase in temperature.
Its high tendency to absorb water has led to it being used as a drying agent in chemical laboratories, as well as a dehydrating agent for some compounds, that is, to remove water from its molecules..
Phosphorous oxide (v) is also used to accelerate the binding reactions of various hydrocarbon molecules, a reaction called condensation. In addition, it allows to convert certain organic acids into esters.
It has been used for example to refine gasoline, to prepare phosphoric acid H3PO4, to obtain compounds that serve to retard fire, to make glass for vacuum applications, among many other uses.
Phosphorous oxide (v) should be kept in tightly closed containers to prevent it from coming into contact with moisture in the air. It is corrosive and can damage eyes, skin and mucous membranes..
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Phosphorous oxide (v) is made up of phosphorus (P) and oxygen (O), where phosphorus has a valence of +5 and oxygen -2. The phosphorus oxide molecule (v) has four phosphorus and ten oxygen atoms and that is why its correct molecular formula is P4OR10.
It exists in three crystalline forms, as amorphous powder and in a vitreous form (as glass). In the hexagonal crystalline form, each of the phosphorous atoms is found at the vertices of a tetrahedron..
- Phosphorous oxide (v)
- Phosphorus pentoxide
- Diphosphorus pentoxide
- Phosphoric pentoxide
- Phosphoric anhydride
- Tetraphosphorus decaoxide
Crystalline white solid. The most common form is that of hexagonal crystals.
283.89 g / mol
562 ºC
360 ºC at 1 atmosphere pressure. It means that at this temperature it goes from solid to gas without going through the liquid state.
2.30 g / cm3
Very soluble in water. Soluble in sulfuric acid. Insoluble in acetone and ammonia.
Phosphorous oxide (v) absorbs and reacts with water in the air extremely rapidly, forming phosphoric acid H3PO4. This reaction is exothermic, which means that heat is produced during the reaction..
The reaction of P4OR10 with water leads to the formation of a mixture of phosphoric acids whose composition depends on the amount of water and the conditions.
The reaction with alcohols leads to the formation of esters of phosphoric acid or of polymeric acids depending on the experimental conditions..
P4OR10 + 6 ROH → 2 (RO)twoPO.OH + 2 RO.PO (OH)two
With basic oxides it forms solid phosphates.
It is corrosive. May react dangerously with formic acid and inorganic bases such as sodium hydroxide (NaOH), calcium oxide (CaO) or sodium carbonate NatwoCO3.
If you pour a solution of perchloric acid HClO4 and chloroform CHCl3 in phosphorous oxide (v) P4OR10 a violent explosion occurs.
It is not flammable. It does not promote combustion. However, its reaction with water is so violent and exothermic that there may be a risk of fire..
It can be prepared by direct oxidation of phosphorus in a stream of dry air. Phosphorus when it comes into contact with excess oxygen oxidizes forming phosphorus oxide (v).
P4 + 5 Otwo → P4OR10
Phosphorous (v) oxide is found in minerals such as ilmenite, rutile, and zircon.
Ilmenite is a mineral that contains iron and titanium and sometimes has phosphorus (v) oxide in concentrations that vary between 0.04 and 0.33% by weight. Rutile is a titanium oxide mineral and can contain about 0.02% by weight of PtwoOR5.
Zircon sands (a mineral of the element zirconium) have phosphorus oxide (v) in 0.05-0.39% by weight.
Due to its great greed for water, it is one of the best known dehydrating agents and very effective at temperatures below 100 ° C..
It can extract water from substances that are themselves considered dehydrating agents. For example, you can remove water from sulfuric acid HtwoSW4 turning it into SO3 and nitric acid HNO3 turning it into NtwoOR5.
Basically it can dry all those liquids and gases with which it does not react, so it allows to remove traces of humidity from vacuum systems.
Phosphorous oxide (v) serves to close rings of organic compounds and other condensation reactions.
It allows to esterify organic acids with the possibility of distinguishing between primary aliphatic carboxylic acids (carbon chain without rings with the -COOH group at one end) and aromatic acids (-COOH group attached to the benzene ring), since the latter do not react.
It also serves to remove a molecule of HtwoO of the amides R (C = O) NHtwo and converts them into R-CN nitriles. In addition, it catalyzes or accelerates oxygenation, dehydrogenation and polymerization reactions of bitumen.
Since the 30s of the 20th century, certain studies indicated that phosphorus (v) oxide exerted a refining action on gasoline, increasing its octane number.
The refining action of P4OR10 it is mainly due to condensation reactions (union of different molecules) and not polymerization (union of equal molecules).
The p4OR10 accelerates the direct alkylation of aromatic hydrocarbons with olefins, the conversion of olefins to naphthenes and their partial polymerization. The alkylation reaction increases the octane number of gasoline.
In this way a high quality refined gasoline is obtained.
Phosphorous oxide (v) is used to:
- Prepare phosphoric acid H3PO4
- Obtain acrylate esters and surfactants
- Prepare phosphate esters that are used as flame retardants, solvents, and diluents
- Conversion of phosphorous trichloride to phosphorus oxychloride
- Laboratory reagent
- Manufacture special glasses for vacuum tubes
- Increase the melting point of asphalt
- Serve as a standard molecule in the determination of phosphorus or phosphates in phosphate rock, fertilizers and Portland cement, in the form of PtwoOR5
- Improve the bonds between certain polymers and the ivory layer that teeth have
Phosphorous oxide (v) should be kept in sealed containers and in cool, dry and well-ventilated places..
This serves to prevent it from coming into contact with water, as it can react violently with it, generating a lot of heat, to the point of burning nearby materials that are combustible..
Phosphorous (v) oxide dust is irritating to the eyes and respiratory tract and corrosive to the skin. May cause eye burns. Ingestion causes fatal internal burns.
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