Phosphine 1

PhosphineThis article is about the chemical. For the class of compounds used as ligands, see metal phosphine complex. For thevisual phenomenon, see phosphene."Phosphane" redirects here. For pentavalent organophosphorus compounds, see phosphorane.Not to be confused with phosphene or phosgene.

Phosphine

Identifiers

CAS number 7803-51-2 [1] 

PubChem 24404 [2]

ChemSpider 22814 [3] 

EC number 232-260-8 [4]

UN number 2199

ChEBI CHEBI:30278 [5] 

RTECS number SY7525000

Jmol-3D images Image 1 [6]

Properties

Molecular formula PH3

Molar mass 33.99758 g/mol

Appearance colorless gas

Density 1.379 g/l, gas (25 °C)

Melting point −132.8 °C (−207.0 °F; 140.3 K)

Boiling point −87.7 °C (−125.9 °F; 185.5 K)

Solubility in water 31.2 mg/100 ml (17 °C)

Viscosity 1.1 x 10−5 Pa s

Structure

Molecular shape Trigonal pyramidal

Phosphine 2

Dipole moment 0.58 D

Thermochemistry

Std molarentropy So

298

210 J·mol−1·K−1

Std enthalpy offormation ΔfH

o298

5 kJ·mol−1

Hazards

MSDS ICSC 0694 [7]

EU Index 015-181-00-1

EU classification Highly flammable (F+)Very toxic (T+)Corrosive (C)Dangerous for the environment (N)

R-phrases R12, R17, R26, R34, R50

S-phrases (S1/2), S28, S36/37, S45, S61, S63

NFPA 704

Flash point flammable gas

Autoignition temperature 38 °C (100 °F; 311 K)

Explosive limits 1.8% – ?

Related compounds

Other cations AmmoniaArsineStibineBismuthine

Related compounds TrimethylphosphineTriphenylphosphine

Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)

 (verify) [8] (what is:  / ?)

Infobox references

Phosphine (IUPAC name: phosphane) is the compound with the chemical formula PH3. It is a colorless,flammable, toxic gas. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor likegarlic or rotting fish, due to the presence of substituted phosphine and diphosphane (P2H4). With traces of P2H4present, PH3 is spontaneously flammable in air, burning with a luminous flame. Phosphines are also a group oforganophosphorus compounds with the formula R3P (R = organic derivative). Organophosphines are important incatalysts where they complex to various metal ions; complexes derived from a chiral phosphine can catalyzereactions to give chiral, enantioenriched products.

Phosphine 3

HistoryPerhaps because of its strong association with elemental phosphorus, phosphine was once regarded as a gaseousform of the element, but Lavoisier (1789) recognised it as a combination of phosphorus with hydrogen and describedit as “hydruyet of phosphorus, or phosphuret of hydrogen”.Wikipedia:Citation neededThénard (1845) used a cold trap to separate diphosphine from phosphine that had been generated from calciumphosphide, thereby demonstrating that P2H4 is responsible for spontaneous flammability associated with PH3, andalso for the characteristic orange/brown color that can form on surfaces, which is a polymerisation product. Heconsidered diphosphine’s formula to be PH2, and thus an intermediate between elemental phosphorus, the higherpolymers, and phosphine. Calcium phosphide (nominally Ca3P2) produces more P2H4 than other phosphides becauseof the preponderance of P-P bonds in the starting material.

Structure and propertiesPH3 is a trigonal pyramidal molecule with C3v molecular symmetry. The length of the P-H bond is 1.42 Å, theH-P-H bond angles are 93.5°. The dipole moment is 0.58 D, which increases with substitution of methyl groups inthe series: CH3PH2, 1.10 D; (CH3)2PH, 1.23 D; (CH3)3P, 1.19 D. In contrast, the dipole moments of aminesdecrease with substitution, starting with ammonia, which has a dipole moment of 1.47 D. The low dipole momentand almost orthogonal bond angles lead to the conclusion that in PH3 the P-H bonds are almost entirely pσ(P) –sσ(H) and phosphorus 3s orbital contributes little to the bonding between phosphorus and hydrogen in this molecule.For this reason, the lone pair on phosphorus may be regarded as predominantly formed by the 3s orbital ofphosphorus. The upfield chemical shift of the phosphorus atom in the 31P NMR spectrum accords with theconclusion that the lone pair electrons occupy the 3s orbital (Fluck, 1973). This electronic structure leads to a lack ofnucleophilicity and an ability to form only weak hydrogen bonds.The aqueous solubility of PH3 is slight; 0.22 mL of gas dissolve in 1 mL of water. Phosphine dissolves more readilyin non-polar solvents than in water because of the non-polar P-H bonds. It acts as neither an acid nor a base in water.Proton exchange proceeds via a phosphonium (PH4

+) ion in acidic solutions and via PH2− at high pH, with

equilibrium constants Kb = 4 × 10−28 and Kz = 41.6 × 10−29.

Preparation and occurrencePhosphine may be prepared in a variety of ways. Industrially it can be made by the reaction of white phosphoruswith sodium hydroxide, producing sodium hypophosphite and sodium phosphite as a by-product. Alternatively theacid-catalyzed disproportioning of white phosphorus may be used, which yields phosphoric acid and phosphine.Both routes have industrial significance; the acid route is preferred method if further reaction of the phosphine tosubstituted phosphines is needed. The acid route requires purification and pressurizing. It can also be made (asdescribed above) by the hydrolysis of a metal phosphide, such as aluminium phosphide or calcium phosphide. Puresamples of phosphine, free from P2H4, may be prepared using the action of potassium hydroxide on phosphoniumiodide (PH4I).Phosphine is probably a constituent of the atmosphere at very low and highly variable concentrations and hence maycontribute to the global phosphorus biochemical cycle. The origin(s) of atmospheric phosphine is not certain.Possible sources include bacterial reduction of phosphate in decaying organic matter and the corrosion ofphosphorus-containing metals.

Phosphine 4

PhosphinesSee also: metal phosphine complexRelated to a PH3 is the class of organophosphorus compounds commonly called phosphines. These alkyl and arylderivatives of phosphine are analogous to organic amines. Common examples include triphenylphosphine((C6H5)3P) and BINAP, both used as ligands in homogeneous catalysis or triisopropylphosphine. Phosphines areeasily oxidized to phosphine oxides as exemplified by the directed synthesis of a phospha-crown, the phosphorusanalogue of an aza crown where it is not possible to isolate the phosphine itself.

In step 1 diphosphinoethane coordinates to a ferrocene containing additional carbon monoxide ligands and anacetonitrile ligand. The next step is a hydrophosphination with trivinylphosphine followed by alkylation with ethylbromide and hydrogenation with hydrogen over palladium on carbon. In the final step the iron template is removedby bromine but oxidation of the phosphine groups is unavoidable.

When modified with suitable substituents as in certain (rare) diazaphospholenes (scheme 3) the polarity of the P-H bond can be inverted (see: umpolung) and the resulting phosphine hydride can reduce a carbonyl group as in the

Phosphine 5

example of benzophenone in yet another way.

Applications

Organophosphorus chemistryPhosphine is mainly consumed as an intermediate in organophosphorus chemistry. In an illustrative reaction,formaldehyde adds in the presence of hydrogen chloride to give tetrakis(hydroxymethyl)phosphonium chloride,which is used in textiles.

MicroelectronicsSmall amounts of phosphine are used as a dopant in the semiconductor industry, and a precursor for the deposition ofcompound semiconductors.

FumigantFor farm use, pellets of aluminium phosphide, calcium phosphide, or zinc phosphide release phosphine upon contactwith atmospheric water or rodents' stomach acid. These pellets also contain agents to reduce the potential for ignitionor explosion of the released phosphine.Because the previously popular fumigant methyl bromide has been phased out in some countries under the MontrealProtocol, phosphine is the only widely used, cost-effective, rapidly acting fumigant that does not leave residues onthe stored product. Pests developing high levels of resistance toward phosphine have become common in Asia,Australia and Brazil. High level resistance is also likely to occur in other regions, but may not have been as closelymonitored.

SafetyPhosphine gas is more dense than air and hence may collect in low-lying areas. It can form explosive mixtures withair and also self-ignite. When phosphine burns it produces a dense white cloud of phosphorus pentoxide – a severerespiratory irritant.Phosphine can be absorbed into the body by inhalation. Direct contact with phosphine liquid – although unlikely tooccur – may cause frostbite, like other cryogenic liquids. The main target organ of phosphine gas is the respiratorytract. According to the 2009 U.S. National Institute for Occupational Safety and Health (NIOSH) pocket guide, andU.S. Occupational Safety and Health Administration (OSHA) regulation, the 8 hour average respiratory exposureshould not exceed 0.3 ppm. NIOSH recommends that the short term respiratory exposure to phosphine gas shouldnot exceed 1 ppm. The Immediately Dangerous to Life or Health level is 50 ppm. Overexposure to phosphine gascauses nausea, vomiting, abdominal pain, diarrhea; thirst; chest tightness, dyspnea (breathing difficulty); musclepain, chills; stupor or syncope; pulmonary edema. Phosphine has been reported to have the odor of decaying fish orgarlic at concentrations below 0.3 ppm. The smell is normally restricted to laboratory areas or phosphine processingsince the smell comes from the way the phosphine is extracted from the environment. However, it may occurelsewhere, such as in industrial waste landfills. Exposure to higher concentrations may cause olfactory fatigue.On January 2014, a whole family in Jerusalem was poisoned from phosphine after a section of their apartment wasfumigated for pests, and some of the young children died from the poisoning.

Phosphine 6

References[1] http:/ / www. commonchemistry. org/ ChemicalDetail. aspx?ref=7803-51-2[2] http:/ / pubchem. ncbi. nlm. nih. gov/ summary/ summary. cgi?cid=24404[3] http:/ / www. chemspider. com/ Chemical-Structure. 22814. html[4] http:/ / esis. jrc. ec. europa. eu/ lib/ einecs_IS_reponse. php?genre=ECNO& entree=232-260-8[5] https:/ / www. ebi. ac. uk/ chebi/ searchId. do?chebiId=30278[6] http:/ / chemapps. stolaf. edu/ jmol/ jmol. php?model=P[7] http:/ / www. inchem. org/ documents/ icsc/ icsc/ eics0694. htm[8] http:/ / en. wikipedia. org/ w/ index. php?title=Special:ComparePages& rev1=464205019& page2=Phosphine

Further reading• Fluck, E. (1973). "The Chemistry of Phosphine". Topics in Current Chemistry. Fortschritte der Chemischen

Forschung 35: 1–64. doi: 10.1007/BFb0051358 (http:/ / dx. doi. org/ 10. 1007/ BFb0051358).ISBN 3-540-06080-4.

• WHO (World Health Organisation) (1988). Phosphine and Selected Metal Phosphides (http:/ / www. inchem. org/documents/ ehc/ ehc/ ehc73. htm). Environmental Health Criteria 73. Geneva: Joint sponsorship of UNEP, ILOand WHO.

External links• International Chemical Safety Card 0694 (http:/ / www. inchem. org/ documents/ icsc/ icsc/ eics0694. htm)• CDC - Phosphine - NIOSH Workplace Safety and Health Topic (http:/ / www. cdc. gov/ niosh/ topics/ phosphine/

)

Article Sources and Contributors 7

Article Sources and ContributorsPhosphine  Source: http://en.wikipedia.org/w/index.php?oldid=604946074  Contributors: 1YlGC6dsynvm, A. Carty, A876, AMVStecker, Adl9999, Anthonyhcole, Attilios, B07, Beetstra,Benjah-bmm27, Bryan Derksen, Card, Carnildo, Chem-awb, ChemMater, Christopherlin, Cpiral, Curb Chain, DMacks, Darrien, DePiep, Deglr6328, Denelson83, Diglett11, DimaBorger,Drbogdan, Dripp, DuncanHill, Edgar181, Edward, Ferkelparade, Freestyle-69, GRAHAMUK, Gauss, Giftlite, Gilliam, GoingBatty, Hellbus, Herbee, Hydro, Icairns, Ihope127, Ipatrol, Itub,Ixfd64, JSquish, JZNIOSH, Japo, Jeffreywriter, Jim1138, Jmcmanus33061, John, John Nevard, Joshsteelersfan98, Jynto, Karlhahn, Kay Dekker, Keber, KnightRider, Kupirijo, KyleRGiggs,Kzhr, La goutte de pluie, LegacyOfValor, Liamdavies, Luís Felipe Braga, Magioladitis, Mancunion, Mark viking, Materialscientist, MiPe, Mikedelsol, Mikespedia, Mimihitam, Mortense,Mstromb, Nbound, Nihiltres, Nirmos, Oatmeal batman, Obsidian Soul, Oktanyum, OldAlchemistElf, P.G.Antolinos, Pdcook, Physchim62, Pion, Pizza Puzzle, Polonium, Puppy8800, Purdygb,Quantockgoblin, Quibik, Rich Farmbrough, Rifleman 82, Robbin' Knowledge, S0me l0ser, Shaddack, Shaliya waya, Shoefly, Shoy, Smartse, Smokefoot, StephenPratt, Stephenpratt, Steve Quinn,Susurrus, TangParadise, Tgbguava, The High Fin Sperm Whale, Thricecube, Tkbx, Trusilver, UninvitedCompany, UnitedStatesian, V8rik, Vchorozopoulos, Vuo, WVhybrid, Walkerma,Wavelength, Yyy, 112 ,حسن علي البط anonymous edits

Image Sources, Licenses and ContributorsFile:Monophosphan.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Monophosphan.svg  License: Public Domain  Contributors: NEUROtikerFile:Phosphine-3D-balls.png  Source: http://en.wikipedia.org/w/index.php?title=File:Phosphine-3D-balls.png  License: Public Domain  Contributors: Ben MillsFile:Phosphine-underside-3D-vdW.png  Source: http://en.wikipedia.org/w/index.php?title=File:Phosphine-underside-3D-vdW.png  License: Public Domain  Contributors: Benjah-bmm27File:Yes check.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Yes_check.svg  License: Public Domain  Contributors: AnomieFile:X mark.svg  Source: http://en.wikipedia.org/w/index.php?title=File:X_mark.svg  License: Public Domain  Contributors: User:GmaxwellFile:Phosphacrown.png  Source: http://en.wikipedia.org/w/index.php?title=File:Phosphacrown.png  License: GNU Free Documentation License  Contributors: Original uploader was V8rik aten.wikipediaFile:Phosphine umpolung.png  Source: http://en.wikipedia.org/w/index.php?title=File:Phosphine_umpolung.png  License: GNU Free Documentation License  Contributors: Original uploaderwas V8rik at en.wikipedia

LicenseCreative Commons Attribution-Share Alike 3.0//creativecommons.org/licenses/by-sa/3.0/