PHOSPHORUS PENTOXIDE

Phosphorus pentoxide = Diphosphorus pentoxide

CAS Number:  1314-56-3  /16752-60-6 (P4O10) 
EC number  :  215-236-1

Phosphorus pentoxide is a chemical compound with molecular formula P4O10 (with its common name derived from its empirical formula, P2O5). 
This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desiccant and dehydrating agent.

Structure
Phosphorus pentoxide crystallizes in at least four forms or polymorphs. 
The most familiar one, a metastable form (shown in the figure), comprises molecules of P4O10. 
Weak van der Waals forces hold these molecules together in a hexagonal lattice (However, in spite of the high symmetry of the molecules, the crystal packing is not a close packing). 
The structure of the P4O10 cage is reminiscent of adamantane with Td symmetry point group.
Phosphorus pentoxide is closely related to the corresponding anhydride of phosphorous acid, P4O6. 
Phosphorus pentoxide latter lacks terminal oxo groups. Its density is 2.30 g/cm3. 
Phosphorus pentoxide boils at 423 °C under atmospheric pressure; if heated more rapidly it can sublimate.
Phosphorus pentoxide form can be made by condensing the vapor of phosphorus pentoxide rapidly, and the result is an extremely hygroscopic solid.

Phosphorus pentoxide other polymorphs are polymeric, but in each case the phosphorus atoms are bound by a tetrahedron of oxygen atoms, one of which forms a terminal P=O bond involving the donation of Phosphorus pentoxide terminal oxygen p-orbital electrons to the antibonding phosphorus-oxygen single bonds. 
The macromolecular form can be made by heating the compound in a sealed tube for several hours, and maintaining the melt at a high temperature before cooling the melt to the solid.
The metastable orthorhombic "O"-form (density 2.72 g/cm3, melting point 562 °C) adopts a layered structure consisting of interconnected P6O6 rings, not unlike the structure adopted by certain polysilicates. 
The stable form is a higher density phase, also orthorhombic, the so-called O' form. 
Phosphorus pentoxide consists of a 3-dimensional framework, density 3.5 g/cm3. 
Phosphorus pentoxide remaining polymorph is a glass or amorphous form; it can be made by fusing any of the others.

Preparation
P4O10 is prepared by burning tetraphosphorus with sufficient supply of oxygen:

P4 + 5 O2 → P4O10
For most of the 20th century, phosphorus pentoxide was used to provide a supply of concentrated pure phosphoric acid. In the thermal process, the phosphorus pentoxide obtained by burning white phosphorus was dissolved in dilute phosphoric acid to produce concentrated acid.
Improvements in filter technology is leading to the "wet phosphoric acid process" taking over from the thermal process, obviating the need to produce white phosphorus as a starting material.
Phosphorus pentoxide dehydration of phosphoric acid to give phosphorus pentoxide is not possible as on heating metaphosphoric acid will boil without losing all its water.

Applications
Phosphorus pentoxide is a potent dehydrating agent as indicated by the exothermic nature of its hydrolysis:

P4O10 + 6 H2O → 4 H3PO4   (–177 kJ)
However, its utility for drying is limited somewhat by its tendency to form a protective viscous coating that inhibits further dehydration by unspent material. 
A granular form of P4O10 is used in desiccators.

Consistent with its strong desiccating power, P4O10 is used in organic synthesis for dehydration. 
Phosphorus pentoxide most important application is for the conversion of primary amides into nitriles:

P4O10 + RC(O)NH2 → P4O9(OH)2 + RCN
Phosphorus pentoxide indicated coproduct P4O9(OH)2 is an idealized formula for undefined products resulting from the hydration of P4O10.

Alternatively, when combined with a carboxylic acid, the result is the corresponding anhydride:

P4O10 + RCO2H → P4O9(OH)2 + [RC(O)]2O
Phosphorus pentoxide "Onodera reagent", a solution of P4O10 in DMSO, is employed for the oxidation of alcohols.
This reaction is reminiscent of the Swern oxidation.

The desiccating power of P4O10 is strong enough to convert many mineral acids to their anhydrides.
Examples: HNO3 is converted to N2O5;  H2SO4 is converted to SO3;  HClO4 is converted to Cl2O7;  CF3SO3H is converted to (CF3)2S2O5.

Agriculture
Phosphorus pentoxide compound can be used as crop fertilizer.

Related phosphorus oxides
Between the commercially important P4O6 and P4O10, phosphorus oxides are known with intermediate structures.

On observation it will be seen that double bonded oxygen in at 1,2 position or 1,3 position are identical and both positions have same steric hindrance. Cycle 12341 and ABCDA are identical.

Hazards
Phosphorus pentoxide itself is not flammable. Just like sulfur trioxide, it reacts vigorously with water and water-containing substances like wood or cotton, liberates much heat and may even cause fire due to the highly exothermic nature of such reactions. 
Phosphorus pentoxide is corrosive to metal and is very irritating – it may cause severe burns to the eye, skin, mucous membrane, and respiratory tract even at concentrations as low as 1 mg/m3.

Names
IUPAC names:
Phosphorus pentoxide

Other names:
Diphosphorus pentoxide
Phosphorus(V) oxide
Phosphoric anhydride
Tetraphosphorus decaoxide
Tetraphosphorus decoxide

Identifiers
CAS Number: 1314-56-3  /16752-60-6 (P4O10) 
3D model (JSmol)    
ChEBI    : CHEBI:37376 check
ChemSpider : 14128 check
ECHA InfoCard    : 100.013.852 Edit this at Wikidata
PubChem CID    : 14812
RTECS number    : TH3945000
UNII    :51SWB7223J check
CompTox Dashboard (EPA): DTXSID9047754 Edit this at Wikidata

Properties
Chemical formula:    P4O10
Molar mass    :283.9 g mol−1
Appearance    :white powder very deliquescent odorless
Density    :2.39 g/cm3
Melting point    :340 °C (644 °F; 613 K)
Boiling point    :360 °C (sublimes)
Solubility in water    :exothermic hydrolysis
Vapor pressure    :1 mmHg @ 385 °C (stable form)

Synonym(s):Phosphoric anhydride, Phosphorus(V) oxide
Linear Formula:P2O5
CAS Number:1314-56-3
Molecular Weight:141.94
EC Number:215-236-1
PubChem Substance ID:24852847
NACRES:NA.21

General description
Phosphorus pentoxide is a deliquescent compound prepared by reacting phosphorus with air. 
Phosphorus pentoxide is a commonly used as dehydrating and condensing agent in organic synthesis.
Application
Phosphorus pentachloride has been used for the vaccum distillation of 1-methyl-2-pyrrolidinone (NMP), which was employed as mobile phase in a chromatographic analysis.

Phosphorus pentoxide may be used as one of the reaction components in the synthesis of dichlorine heptoxide (Cl2O7) and transition-metal phosphides (Ni2P, Co2P and MoP). 
P2O5 supported on alumina can be used for the solvent-free and microwave-assisted preparation of 1, 5-benzodiazepine analogs. P2O5/KX (X = Br, I) reagent system may be used for the transformation of alcohols into the corresponding alkyl iodides and bromides.
Phosphorus pentoxide/methanesulfonic acid (PPMA) may be used as a condensing agent and solvent for the synthesis of:
High molecular weight poly(benzoxazole)s via direct polycondensation of aromatic dicarboxylic acids containing phenyl ether structure with 3,3′-dihydroxybenzidine dihydrochloride.
Aromatic poly(phenylene ether ether ketone)s via direct self-polycondensation of 4-(4′-phenoxyphenoxy)benzoic acids.
1,3-1H-dibenzimidazole-benzene by the reaction of isophthalic acid with 1,2-diaminobenzene.

Dehydrating agent used for halogenation with tetrabutylammonium halides.
Quality Level: 100
vapor density: 4.9 (vs air)
vapor pressure: 1 mmHg ( 384 °C)  /  10 mmHg ( 238 °C)
product line: ReagentPlus®
assay: 99%
form: powder
pH:1.5 (20 °C, 10 g/L)
mp: 340 °C (lit.)
density: 2.3 g/mL at 25 °C (lit.)
cation traces: 
As: ≤100 mg/kg
Fe: ≤100 mg/kg
heavy metals (as Pb): ≤ 0.02%

Inorganic acids and anhydrides thereof should first be diluted or hydrolyzed by stirring carefully into ice water and then neutralized (protective gloves, fume cupboard!) with sodium hydroxide solution (Cat. No. 105587). 
Before filling into container D, check the pH with pH universal indicator strips (Cat. No. 109535). 
Fuming sulfuric acid should be carefully stirred dropwise into 40 % sulfuric acid (Cat. No. 109286). 
Ensure that plenty of ice is available for cooling! When sufficiently cool, treat the highly concentrated sulfuric acid as described above. 
Analogous to this procedure, other anhydrides can be converted into their corresponding acids. 
Acid gases (e.g. hydrogen halide, chlorine, phosgene, sulfur dioxide) can be introduced into dilute sodium hydroxide solution and after neutralization disposed of in container D.

Description
Catalogue Number    100540
Synonyms    phosphoric anhydride, Phosphoric anhydride
Description    di-Phosphorus pentoxide
Product Information
CAS number    1314-56-3
EC index number    015-010-00-0
EC number    215-236-1
Hill Formula    O₅P₂
Chemical formula    P₂O₅
Molar Mass    141.95 g/mol
HS Code    2809 10 00
Quality Level    MQ200
Physicochemical Information
Density    2.5 g/cm3 (20 °C)
Melting Point    420 °C (closed capillary tube)
pH value    1.5 (10 g/l, H₂O, 20 °C)
Vapor pressure    1 hPa (384 °C)
Bulk density    700 kg/m3
Solubility    850 g/l Risk of violent reaction.

Phosphoric anhydride appears as a white amorphous powder. 
Corrosive to metals and tissue and moderately toxic.

Diphosphonate(2-) is a divalent inorganic anion obtained by removal of both protons from diphosphonic acid. 
Phosphorus pentoxide is a phosphorus oxoanion and a divalent inorganic anion. It is a conjugate base of a diphosphonate(1-).

Synonyms    : 
PHOSPHORUS PENTOXIDE
1314-56-3
Phosphorus(V) oxide
diphosphonate(2-)
Phosphorus oxide (P2O5)
Diphosphorus pentaoxide
diphosphonate
Phosphorus (V) pentoxide
MFCD00011440
Phosphorus (V) oxide
Diphosphonic acid dianion
O5P2
CHEBI:29262
8954AF
AKOS015903585
Phosphorus Pentoxide (P2O5) granular
ZINC242728172
P2H2O5(2-)
BP-21050
mu-oxido-bis(hydridodioxidophosphate)(2-)
[O2P(H)OP(H)(O)2](2-)
FT-0697548
P1746
A851563
J-006006
Q27109994
Diphosphorus pentoxide, >5% in a non hazardous diluent

Phosphorus pentoxide is a white, microcrystalline, light weight powder which is produced by the combustion of elemental phosphorus in an excess of oxygen. 
Phosphorus pentoxide is the anhydride of orthophosphoric acid, H3PO4. It is very hygroscopic and is converted by water to H3PO4 via intermediates. 
The reaction with water is very vigorous and proceeds with the evolution of a large amount of heat.

Due to its highly hygroscopic and microcrystalline character, the capability of flowing of P2O5 may vary in a certain range. 
Furthermore, the formation of soft agglomerates, which come apart under slight pressure, is not preventable.

Benefits
Wide variety of applications as a reagent in the chemical industry

What Is Phosphorus Pentoxide?
Phosphorus Pentoxide (P2O5) is a white soft powder chemical compound used in a wide variety of applications as a building block and a reagent in the chemical industry.

CAS #: 1314-56-3
EINECS #: 215-236-1
Synonyms: P2O5, Diphosphorus Pentoxide, Phosphoric Anhydride, Phosphorus(V) Oxide
Chemical Formula: P2O5
Molecular Formula: P4O10

Phosphorus is a nonmetallic element that exists in three forms: elemental phosphorus, white phosphorus, and red phosphorus. 
White phosphorus, which is also referred to asyellow phosphorus, is widely used in munitions manufacturing, in fireworks, as an ingredient in methamphetamine production, and in fertilizers. 
Historically, it has also been used as a rodenticide. 
The autoignition temperature (the temperature at which spontaneous combustion can occur) is 30°C (86°F). 
When white phosphorus comes in contact with air at temperatures above the autoignition point, the phosphorus spontaneously oxidizes, forming phosphorus pentoxide. 
Phosphorus pentoxide can combine with small amounts of moisture in the air, forming phosphoric acid. 
In wounds, oxidation of phosphorus pentoxide will continue until it is removed through débridement, neutralized, or consumed.

Phosphorus pentoxide is a dehydrating agent often used as a dessicant for bacterial cultural extracts analyzed by gas-liquid chromatography.

This monograph for Phosphorus Pentoxide provides, in addition to common physical constants, a general description including typical appearance, applications, and aqueous solubility. 
The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Insoluble Matter, Phosphorus Trioxide, Ammonium, and Heavy Metals.

Product Description
We feel immensely pleased to manufacture and supply an exclusive gamut of Phosphorus Pentoxide (P2O5). 
This product is provided to the clients in the following:

Specification:
Appearance: White Power
Physical State: White Hygroscopic Powder

Features:
Exact composition
No foreign particles
Effectiveness

Phosphorus Pentoxide (Phosphorus(V) Oxide) is a dehydrating agent used in organic synthesis, primarily in converting primary amides into nitriles and mineral acids into their anhydrides.

Phosphorus pentoxide is a phosphorous oxide. Phosphorus pentoxide is used as a strong drying and dehydrating agent. 
Many reactions that require the removal of a water molecule can utilize P2O5 such as the dehydration of amides to nitriles. 
Phosphorus pentoxide is primarily used in making optical glass and heat-insulating glass. In addition, phosphorus pentoxide is a key ingredient to produce pharmaceuticals and pesticides in the pharma and agricultural industry.

Molar Weight    283.88 g/mol
Melting Point    340 °C
Boiling Point    360 °C
Flash Point    
Specific Gravity    2.39 g/cc
Particle Size    

USES AND APPLICATIONS

Key applications
Metal working
Glass
Oil and Gas
Agricultural
Catalysts

Industries
Chemical Processing
Cleaning
Oil & Gas
Polymers
Coatings & Construction
Cosmetics

Stored phosphorus pentoxide is going to be covered with polyphosphoric acid like a skin. If this "skin" is removed with a pair of tweezers you will again find a proper compond. 
"The-more-the-better"-user will often produce this kind of problem in desiccators, where a half pound of phosphorus pentoxid used as drying agent is soon without any effect, since it is separated from the scene by the "skin".

If you attempt to deactivate phosphorus pentoxide with water, you are penalised with lots of smoke, coughing, angry lab-neighbors and maybe also a broken glas container because phosphorus pentoxide reacts vigorously with water. 
Phosphorus pentoxide  is better to leave the compond standing alone in contact with air and wait until it is hydrolysed by air moisture. 
Phosphorus pentoxide  the powder has completely changed to a syrup, you may add riskless more water.
Batches which are completely decomposed are disposed in a separate bottle.

Phosphorus pentoxide a white, deliquescent, crystalline powder, P2O5, that, depending upon the amount of water it absorbs, forms orthophosphoric acid, metaphosphoric acid, or pyrophosphoric acid, produced by the burning of phosphorus in dry air: used in the preparation of phosphoric acids, as a drying and dehydrating agent, and in organic synthesis.

Chemical & Physical Properties: White needle-like crystals. 
Density ：2.39 g / cm3, sublimation at 360oC, melting at 563 oC under pressure. Corrosive to the skin. 
Easy to absorb moisture in the air. Soluble in water release a lot of heat and generate phosphoric acid.

Application: Chip N type doping Phosphorus source of semiconductor, solar cells, raw materials of  laser crystal growth , such as KDP, KTP, DKDP , can also be used for medicine, cosmetics production and preparation of high purity phosphoric acid.

Engineering Controls
Use a fume hood when working with phosphorus pentoxide. 
Ensure the fume hood has proper air flow by checking the flow rate on the control panel and / or using a smoke match or wipe to visualize flow.

PHS - We use phosphorus pentoxide when making 100% phosphoric acid which can be a messy affair. 
In this case, the fume hood is convenient to keep everything contained for easier cleanup, not for protection against fumes.

Administrative Controls
PHS - Tape a sign to the outside of the fume hood sash indicating that you are making phosphoric acid. 
Phosphorus pentoxide  process often takes more than one day.

Personal Protective Equipment (PPE)
PHS - Wear a lab coat, nitrile gloves, and eye protection

Keep container tightly closed when not in use.
Keep away from other sources of water but recognize that you are adding phosphorus pentoxide to 85% phosphoric acid (the other 15% is water) specifically to convert the solution water to phosphoric acid. 
As such, if you add it too quickly, the solution will steam and appear aggressive. 
If you spill powdered phosphorus pentoxide, it will quickly absorb water from the atmosphere leaving a puddle of phosphoric acid.

Description of first aid measures
General advice
Consult a physician. Show this safety data sheet to the doctor in attendance.Move out of dangerous area.

If inhaled
If breathed in, move person into fresh air. If not breathing, give artificial respiration. Consult a physician.

In case of skin contact
Take off contaminated clothing and shoes immediately. Wash off with soap and plenty of water. Take victim
immediately to hospital. Consult a physician.

In case of eye contact
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.Continue rinsing eyes during transport to hospital.

If swallowed
Do NOT induce vomiting. Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician.

Most important symptoms and effects, both acute and delayed
The most important known symptoms and effects are described in the labelling (see section 2.2) and/or in section 11.

Some recalls on phosphorus pentoxide (CAS: 1314-56-3):
Also known as phosphorus anhydrous, phosphorus pentoxide (CAS: 1314-56-3) is a chemical compound that takes the form of a white crystalline solid. 
It is usually obtained by reacting phosphorus with excess dry air, followed by purification by sublimation.

Used as a chemical intermediate in the manufacture of flame retardants and pharmaceuticals, phosphorus pentoxide reacts vigorously or explosively with water to form phosphoric acids, which are irritating to the skin and mucous membranes.

Phosphorus pentoxide is often used in the pharmaceutical industry, but the compound is also used in coatings, dyes and other uses such as as a dehydrating agent.

Laboratory analysis of phosphorus pentoxide (CAS: 1314-56-3):
Expert in the field of chemical analysis, the Analytice company offers you to perform the determination of phosphorus pentoxide (CAS: 1314-56-3) in the air through a laboratory with ISO 17025 accreditation recognized by COFRAC (ILAC full member) for the phosphoric acid parameter in the working environment.

Example of determination of phosphorus pentoxide (CAS: 1314-56-3) in air:
Analytical technique: Ion chromatography
Method: NIOSH 7903 / OSHA ID-111
Sampling media: Specific filter (MCE)
LQ: 10 µg H3PO4/Filter

Water, magnesium oxide, chemically-active metals such as sodium & potassium, alkalis, amines [Note: Hydrolyzes in water (even in humid air) to form hydrochloric acid & phosphoric acid. Corrosive to metals.]

Appearance:
White, very deliquescent crystals or powder.
Odor:Pungent, sharp, irritating odor.
Solubility:Exothermic reaction with water.
Specific Gravity:2.39
pH:< 2 (0.1 N aqueous sol. of phosphoric acid)
% Volatiles by volume @ 21C (70F):0
Boiling Point:Not applicable.
Melting Point:300 - 360C (572 - 680F)
Vapor Density (Air=1):No information found.
Vapor Pressure (mm Hg):1 @ 384C (723F)
Evaporation Rate (BuAc=1):Not applicable.

Stability:Stable under ordinary conditions of use and storage. Reacts violently with water to form phosphoric acid.
Hazardous Decomposition Products:Phosphorus oxides may form when heated to decomposition.
Hazardous Polymerization:Will not occur.
Incompatibilities:Ammonia, calcium oxide, chlorine trifluoride, hydrogen fluoride, oxygen difluoride, perchloric acid, perchloric acid and chloroform, potassium, propargyl alcohol, sodium, sodium carbonate, sodium hydroxide, water, and a mixture of water and organic material.
Conditions to Avoid:Moisture and incompatibles.

Whatever cannot be saved for recovery or recycling should be handled as hazardous waste and sent to a RCRA approved waste facility. 
Processing, use or contamination of this product may change the waste management options. State and local disposal regulations may differ from federal disposal regulations. 
Dispose of container and unused contents in accordance with federal, state and local requirements.

The XPS spectra of phosphorus pentoxide were collected with a VSW HA150, which is equipped with a monochromatic Al Kα x-radiation, a 16 channel multichannel detector, and an electrostatic hemispherical analyzer with a radius of 150 mm providing an instrument with exceptional capabilities. 
Monochromatic radiation provides a distinct clarity to the rich peak structure in the valence band region which shows significant differences from the phosphates. 
The valence band, survey, and P 2s, P 2p, O 1s, and C 1s core levels are reported.

Phosphorus pentoxide Properties
Melting point:340 °C (lit.)
Boiling point:122 °C (1 mmHg)
Density 2.3 g/mL at 25 °C (lit.)
vapor density 4.9 (vs air)
vapor pressure 1 mm Hg ( 384 °C)
refractive index 1.433-1.436
Flash point:340-360°C
storage temp. no restrictions.
solubility Soluble in sulfuric acid. Insoluble in acetone and ammonia.
form Very Deliquescing Powder
color White
Specific Gravity2.39
OdorPungent odour
PH1 (5g/l, H2O, 20℃)
PH Range<2
Water Solubility Soluble in sulfuric acid. Insoluble in acetone and ammonia. Decomposes in water.
Sensitive Moisture Sensitive
Merck 14,7355
Sublimation 340-360 ºC
Stability:Stability Stable, but reacts violently with water, alcohols, metals, sodium, potassium, ammonia, oxidizing agents, HF, peroxides, magnesium, strong bases.

Phosphorus Pentoxide is used as a catalyst and reagent in the efficient and modified Biginelli-type synthesis of 3,4-dihydro-1H-indeno[1,2-d]pyrimidine-2,5-dione.
Not a dangerous good if item is equal to or less than 1g/ml and there is less than 100g/ml in the package

(oxidant for the conversion of primary and secondary alcohols to aldehydes and ketones, respectively; avoids overoxidation to carboxylic acids; modified procedure gives very good yields with short reaction times at 0 °C with minimal formation of byproducts; inexpensive).

Alternate Name: Onodera reagent.

Physical Data: DMSO: mp 18.4 °C; bp 189 °C; d 1.101 g cm−3. P2O5: sublimes 360 °C/760 mmHg.

Solubility: DMSO: sol H2O, alcohol, acetone, THF, CH2Cl2. P2O5: sol H2O.

Form Supplied in: DMSO is a colorless liquid; widely available, including ‘anhydrous’ grades of DMSO packed under N2; P2O5 (more accurately P4O10) is a white crystalline solid; widely available.

Preparative Method: the active oxidant, formulated as Me2+:SO(P2O5)−, is generated in situ from the reaction of DMSO and P2O5 in the presence of the alcohol.

Purification: DMSO: distillation from CaH2 at 56–57 °C/5 mmHg2a or 83–85 °C/17 mmHg;2b storage over 3Å molecular sieves. P2O5: sublimation.

Phosphorus pentoxide is a powerful desiccant and dehydrating agent, reacting violently with water and releasing heat. 
Phosphorus pentoxide is used as a chemical intermediate and condensing agent for organic reactions. 
It can be used in the manufacturer of phosphorus compounds including special phosphoric acid supported catalysts. 
In addition, phosphorus pentoxide can be used in the manufacturer of glass.

Polyphosphoric  acid  (PPA)  is  widely  used  in  the  indus-try. 
Phosphorus pentoxide is used, inter alia, in chemical syntheses as a semi-fi nished product, as a catalysing and water binding agent in  organic  syntheses  and  as  a  modifi  er  for  asphalts.
Obtaining  polyphosphoric  acid  in  industry  is  most  often  carried  out  in  the  process  of  concentration  of  the  phosphoric  acid  by  an  evaporation.  
Phosphorus pentoxide  conditions  of  carrying  out  this  process  in  a  high  temperature  and  strong  corrosive  properties  of  hot  phosphoric  acid,  re-quires highly specialist materials resistant to the process environment.  
Additionally,  it  is  necessary  to  apply  sources of heat that ensure high temperature that enable polycondensation of the acid. 
In this article there have been presented possibilities and conditions for production of  polyphosphoric  acids  with  concentration  up  to  118%  (in  conversion  to  H3PO4)  in  cascade  reactors  system.  
When  executing  the  targeted  project  under  name:  “Developing  highly  innovative  technology  for  obtaining  polyphosphates based on a solid P2O5”, carried out—with a fi  nancial  support  from  the  European  Union  funds  as  a  part  of  the  POIG  1.4  
Programme—in  laboratory  con-ditions and a semi-technical scale, there were examined possibilities for producing various concentration polypho-sphoric acids with the use of 85% of thermal phosphoric acid  and  solid  phosphorous  pentoxide  obtained  from  burning  Kazakhstan  phosphorous  as  raw  materials6

Phosphorus pentoxide  developed  technology  for  obtaining  a  polypho-sphoric  acid  is  based  on  dosing  an  adequate  quantity  of  a  solid  phosphorous  pentoxide  P2O5 to  the  PPA  and  subsequently  diluting  the  obtained  highly  concentrated  PPA to a desired concentration. 
Typical reaction between the solid P2O5 and diluted phosphoric acid, that contains water that is not bound chemically, is highly exoenergetic:P2O5  +  3H2O  =  2H3PO4  +  QCarrying out a direct synthesis of polyphosphoric acid from phosphoric acid and phosphorous pentoxide is not favourable in the process-apparatus aspect due to impe-tuosity of reaction, system corrosiveness and a signifi cant amount  of  the  produced  heat. 
Due  to  application  of  the  described  method  it  is  po-ssible  to  obtain  a  polyphosphoric  acid  with  a  required  concentration by diluting the initially obtained PPA with concentration  of  116–118%  (in  conversion  to  H3PO4) with  the  85%  of  phosphoric  acid.  
Opposite  to  a  direct  reaction  of  the  85%  of  the  phosphoric  acid  with  P2O5, the  reaction  between  the  85%  phosphoric  acid  and  116–118%  of  PPA  is  characterized  by  soft  conditions  of  carrying out the process in the temperature range below 100oC. 
The reaction between PPA≥100% and solid P2O5 is  characterized  by  a  simpler  process  control.
Phosphorus pentoxide PPA obtaining process was divided into two stages carried  out  in  two  tank  reactors  (R1)  and  (R2)  with  a  working  capacity  of  0.1  m3  each.  
Phosphorus pentoxide  reactors  are  equipped  with  a  heating-cooling  jacket  and  mechanical  stirrer. 
Phosphorus pentoxide entire system is thermostated with water from an  insulated  tank  (V1)  with  working  capacity  of  1  m3.
The  reaction  of  a  solid  P2O5  with  PPA≥100%  (in  co-nversion  to  H3PO4),  is  carried  out  in  the  (R1)  reactor  where  occurs  a  synthesis  of  a  highly  concentrated  PPA  (≥116%). 
When the reaction is fi nished polyphosphoric acid is drained gravitationally to reactor (R2), where PPA is diluted by phosphoric acid to a desired concentration. 
Phosphorus pentoxide  installation  diagram  is  shown  in  Figure  1.
EXPERIMENTAL:In order to initiate the discussed process it is necessary to dose into reactor (R2) a ready to use polyphosphoric acid with concentration ≥100% (in conversion to H3PO4), in the minimum amount of 50 dm3. 
Phosphorus pentoxide is also possible to run a one-time synthesis of such PPA in (R2) in reaction between  P2O5  and  phosphoric  acid  (V).
As  part  of  the  carried  out  works,  in  the  (R2)  reactor  polyphosphoric  acid  with  concentration  of  106%  was  produced in amount of approx. 70 dm3. 
Obtained polyacid was a base to start the process in the discussed manner.
With  the  use  of  a  gear  pump  the  polyphosphoric  acid  with concentration ≥100% in the amount of 50–70 dm3 is  pumped  from  reactor  (R2)  to  the  initial  synthesis  reactor  (R1).  
Next,  using  the  calculation  table,  an  ade-quate  amount  of  phosphorus  pentoxide  must  be  dosed  into  reactor  (R1)  to  obtain  an  acid  with  concentration  of  116–118%  (in  conversion  to  H3PO4).  

dosing  of  P2O5  and  reaction  with  a  polyphosphoric  acid  lasts from 4 to 6 hours. 
As a result of the reaction there is  produced  heat  that  is  carried  away  from  the  (R1)  reactor  with  water  jacket  to  the  circulating  water  tank  (V1).  
After  the  fi  rst  reaction  stage  is  fi  nished,  a  lower  discharge  valve  is  opened  in  (R1).  
This  causes  outfl ow of  the  116–118%  polyphosphoric  acid  with  the  use  of  gravity  from  the  initial  synthesis  reactor  (R1)  to  the  second  reactor  (R2).  
PPA  collected  in  the  reactor  (R2)  is  than  a  subject  to  the  process  of  diluting  with  the  use  of  85%  H3PO4,  to  the  concentration  as  needed  at  that  time.  
As  part  of  the  ongoing  works,  the  main  focus  was  to  obtain  the  105%  PPA  that  is  used  as  asphalts  modi-fi er. 
The polyphosphoric acid diluting reaction results in  emitting  extra  quantities  of  heat  carried  away  by  the  water jacket of the reactor (R2) and accumulated in the circulating  water  tank  (V1).  
Proper  circulation  between  the  tank  and  reactors  is  ensured  by  a  centrifugal  pump  (P1).  
Phosphorus pentoxide  thermostatic  circulation  is  common  for  both  reactors (R1 and R2), which causes even distribution of the  accumulated  thermal  energy  in  the  whole  process.
Phosphorus pentoxide ready to use 105% phosphoric acid is brought out from  the  reactor  (R2)  by  gravity  fl  ow  in  two  streams.  
Phosphorus pentoxide  fi  rst  one  is  the  PPA  105%  commercial  product,  whereas  the  other  is  returned  to  reactor  (R1)  through  the gear pump (P2) as a semi-fi nished product and used to  start  the  synthesis.
Phosphorus pentoxide discussed process allows for a work with PPA with concentration only above 100% (in conversion to H3PO4).

This  is  benefi cial  in fi  eld  of  maintaining  a  properly  high  polycondensation  forms  in  the  ready  to  use  PPA.  
Phosphorus pentoxide chemical  process  is  based  on  the  phosphoric  acid  polycondensation  effect  that  takes  place  after  the  93%  concentration  of  H3PO4 is  exceeded1.  
Phosphorus pentoxide  polyconden-sation starts with creation of the H4P2O7 pyrophosphoric group.  
With  further  increase  of  concentration,  due  to  P2O5  addition,  after  exceeding  100%  (in  conversion  to  H3PO4)  in  the  reaction  mixture  is  no  more  free  water,  with  which  P2O5 would  come  into  reaction.  
Due  to  this  fact  a  signifi  cant  polycondensation  process  acceleration  takes  place  and  creation  of  long  PPA  chains.  On  this  stage  of  process  a  signifi  cant  decrease  of  the  emitted  heat  is  observed.  
To  ensure  proper  speed  of  reaction,  heat  from  the  circulating  water  tank  (V1)  was  used.  
Heat  energy  buffered  in  the  tank  (V1)  is  suffi cient  to thermostate the experimental system in an optimum range of process temperatures from 50 to 90oC (depending on the  maximum  concentration  of  the  polyphosphoric  acid  in  the  system).  
When  the  discussed  process  is  ongoing,  in  the  experimental  system  there  were  observed  fl uctu-ations  of  the  circulating  water  temperature  from  60°C  on  the  stage,  where  the  process  was  solely  carried  out  in  (R2),  up  to  90oC  when  reactions  took  place  both  in  (R1)  and  (R2).
Due  to  high  viscosity  of  PPA  in  low  temperatures1  if  there  is  a  necessity  to  store  polyacid  in  reactor  (R1)  or  (R2)  in  a  liquid  form  and  with  the  fi  rst  start-up  of  the  system there is a need for additional heating/thermosta-ting of the circulating water in the minimum temperature of  60oC.  
Due  to  this,  an  additional  source  of  heat  in  the  form  of  a  steam  coil  was  installed  in  the  tank  (V1)

Phosphorus Pentoxide, Reagent, ACS is the anhydride of phosphoric acid and a powerful dehydrating and desiccant agent. 
Phosphorus pentoxide  is used extensively in organic synthesis as a dehydrating agent. 
As an ACS grade quality reagent, its chemical specifications are the de facto standards for chemicals used in many high-purity applications and typically designate the highest quality chemical available for laboratory use. 
Spectrum Chemical manufactured Reagent ACS grade products meet the toughest regulatory standards for quality and purity.

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THE structure of two forms of phosphorus pentoxide was determined several years ago. 
Indications of the existence of a third form has been found in a study of the phase diagram by Hoeflake and Scheffer. 
Actually, in our former investigations we found occasionally a third kind of crystals, and we determined their cell dimensions and space group. 
However, we were not sure that these crystals were pure phosphorus pentoxide and not a reaction product with the glass wall, to which they adhere extremely firmly. 
Hill, Faust and Hendricks5 put the existence of a third form beyond doubt. 
They considered the modification as probably tetragonal (instead of orthorhombic, as found by us), as a result of optical investigation. 
According to their powder diagram data, however, it is certain that their crystals are identical with those described by us4.

Other(deleted CASRN):    24377-84-2
ECHA EINECS - REACH Pre-Reg:    215-236-1
FDA UNII:    51SWB7223J
Nikkaji Web:    J351.175H
MDL:    MFCD00011440
XlogP3-AA:    -2.10 (est)
Molecular Weight:    141.94352400
Formula:    P2 O5

-Phosphorus along with calcium is an essential element in plant and animal growth, thus its principal source is organic ash (i.e. calcined cattle bones).

-Phosphoric oxide is normally present in only trace amounts in ceramic materials.

-Phosphorus pentoxide can act as a melter in middle to high fire, but its power-per-unit-added drops drastically beyond 5% additions.

-Small amounts can produce colloidal opacity as in Chinese chun glazes. 
The depth of Sung glazes is attributed to phosphorus.

-P2O5 is a glass network former like boric oxide and silicon dioxide. 
Phosphoric glass tends to show as a bluish flush in glazes. 
Phosphorus pentoxide does not enter the silica chain in the matrix. 
However, P2O5 by itself (with no SiO2 present in the matrix) is a glass former and the base of an entire class of glasses that can be doped with rare earths and metals for produce special purposes ranging from soluble medical implants to insoluble acid-resistance and even radiation resistance.

-Phosphorus can vitrify porcelains without softening and is the key to translucency in bone china.

-Phosphate ions are added to glaze frits as a color control agent during the melting of titania opacified frits.

- P2O5 itself can crystallize in multiple forms. 
Phosphorus pentoxide  is known to influence the rate of nucleation and/or crystallization in Li2O and MgO low expansion glaze systems.

-P2O5 combines with certain oxides of iron forms colorless compounds. 
Phosphorus pentoxide suggests that P2O5 could be used to allow the use of less pure materials in glazes and glass.

-Phosphorite mineral Ca3(PO4)2 and Apatite 3Ca3(PO4)2 Ca(Cl,F)2 are the parent rocks of phosphate fertilizers. 
Phosphorus pentoxide  latter can thus be used to introduce phosphorus into glazes and frits.

Phosphorus Pentoxide is used as a strong drying and dehydrating agent such as the dehydration of amides to nitriles. 
Phosphorus pentoxide  is also used to manufacture optical glass, heat-insulating glass, pesticides and in the pharmaceutical industry.

Phosphorus pentoxide  objective of this research was to improve the fire-retardant properties of wood in one treatment using a phosphorus pentoxide–amine system. 
Phosphorus pentoxide and 16 amines including alkyl, halophenyl, and phenyl amines were compounded in N,N-dimethylformamide and the resulting solutions containing phosphoramides were reacted with wood. 
Phosphorus pentoxide  characteristics of phosphoramide-reacted wood were analyzed by FTIR, energy-dispersive X-ray analysis, and elemental analysis. 
Fire retardancy of phosphoramide-reacted woods was evaluated by DSC and thermogravimetric analysis (TGA). 
DSC demonstrated that the modification can lower the onset of an endotherm and decrease the heat of combustion and heat flow. 
TGA showed that most of the phosphoramide-reacted woods had higher char yields than that of wood impregnated with diammonium phosphate.