| |||
Names | |||
---|---|---|---|
IUPAC name Phosphane | |||
Other names Hydrogen phosphide Phosphamine Phosphorus trihydride Phosphorated hydrogen | |||
Identifiers | |||
3D model (JSmol) | |||
ChEBI | |||
ChemSpider | |||
ECHA InfoCard | 100.029.328 | ||
EC Number |
| ||
287 | |||
PubChem CID | |||
RTECS number |
| ||
UNII | |||
UN number | 2199 | ||
CompTox Dashboard (EPA) | |||
| |||
| |||
Properties | |||
PH3 | |||
Molar mass | 33.99758 g/mol | ||
Appearance | Colourless gas | ||
Odor | odorless as pure compound; fish-like or garlic-like commercially [1] | ||
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) | ||
31.2 mg/100 ml (17 °C) | |||
Solubility | Soluble in alcohol, ether, CS2 slightly soluble in benzene, chloroform, ethanol | ||
Vapor pressure | 41.3 atm (20 °C) [1] | ||
Conjugate acid | Phosphonium (chemical formula PH+ 4) | ||
Refractive index (nD) | 2.144 | ||
Viscosity | 1.1×10−5 Pa⋅s | ||
Structure | |||
Trigonal pyramidal | |||
0.58 D | |||
Thermochemistry | |||
Heat capacity (C) | 37 J/mol⋅K | ||
Std molar entropy (S⦵298) | 210 J/mol⋅K [2] | ||
Std enthalpy of formation (ΔfH⦵298) | 5 kJ/mol [2] | ||
Gibbs free energy (ΔfG⦵) | 13 kJ/mol | ||
Hazards | |||
GHS labelling: | |||
NFPA 704 (fire diamond) | |||
Flash point | Flammable gas | ||
38 °C (100 °F; 311 K) (see text) | |||
Explosive limits | 1.79–98% [1] | ||
Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) | 3.03 mg/kg (rat, oral) | ||
LC50 (median concentration) | 11 ppm (rat, 4 hr) [3] | ||
LCLo (lowest published) | 1000 ppm (mammal, 5 min) 270 ppm (mouse, 2 hr) 100 ppm (guinea pig, 4 hr) 50 ppm (cat, 2 hr) 2500 ppm (rabbit, 20 min) 1000 ppm (human, 5 min) [3] | ||
NIOSH (US health exposure limits): | |||
PEL (Permissible) | TWA 0.3 ppm (0.4 mg/m3) [1] | ||
REL (Recommended) | TWA 0.3 ppm (0.4 mg/m3), ST 1 ppm (1 mg/m3) [1] | ||
IDLH (Immediate danger) | 50 ppm [1] | ||
Safety data sheet (SDS) | ICSC 0694 | ||
Related compounds | |||
Other cations | |||
Related compounds | |||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula P H 3, classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting fish, due to the presence of substituted phosphine and diphosphane (P2H4). With traces of P2H4 present, PH3 is spontaneously flammable in air (pyrophoric), burning with a luminous flame. Phosphine is a highly toxic respiratory poison, and is immediately dangerous to life or health at 50 ppm. Phosphine has a trigonal pyramidal structure.
Phosphines are compounds that include PH3 and the organophosphines, which are derived from PH3 by substituting one or more hydrogen atoms with organic groups. [4] They have the general formula PH3−nRn. Phosphanes are saturated phosphorus hydrides of the form PnHn+2, such as triphosphane. [5] Phosphine, PH3, is the smallest of the phosphines and the smallest of the phosphanes.
Philippe Gengembre (1764–1838), a student of Lavoisier, first obtained phosphine in 1783 by heating white phosphorus in an aqueous solution of potash (potassium carbonate). [6] [NB 1]
Perhaps because of its strong association with elemental phosphorus, phosphine was once regarded as a gaseous form of the element, but Lavoisier (1789) recognised it as a combination of phosphorus with hydrogen and described it as phosphure d'hydrogène (phosphide of hydrogen). [NB 2]
In 1844, Paul Thénard, son of the French chemist Louis Jacques Thénard, used a cold trap to separate diphosphine from phosphine that had been generated from calcium phosphide, thereby demonstrating that P2H4 is responsible for spontaneous flammability associated with PH3, and also for the characteristic orange/brown color that can form on surfaces, which is a polymerisation product. [7] He considered diphosphine's formula to be PH2, and thus an intermediate between elemental phosphorus, the higher polymers, and phosphine. Calcium phosphide (nominally Ca3P2) produces more P2H4 than other phosphides because of the preponderance of P-P bonds in the starting material.
The name "phosphine" was first used for organophosphorus compounds in 1857, being analogous to organic amines (NR3). [NB 3] [8] The gas PH3 was named "phosphine" by 1865 (or earlier). [9]
PH3 is a trigonal pyramidal molecule with C3v molecular symmetry. The length of the P−H bond is 1.42 Å, the H−P−H bond angles are 93.5°. The dipole moment is 0.58 D, which increases with substitution of methyl groups in the series: CH3PH2, 1.10 D; (CH3)2PH, 1.23 D; (CH3)3P, 1.19 D. In contrast, the dipole moments of amines decrease with substitution, starting with ammonia, which has a dipole moment of 1.47 D. The low dipole moment and 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 P-H bonding. For this reason, the lone pair on phosphorus is predominantly formed by the 3s orbital of phosphorus. The upfield chemical shift of it 31P NMR signal accords with the conclusion that the lone pair electrons occupy the 3s orbital (Fluck, 1973). This electronic structure leads to a lack of nucleophilicity in general and lack of basicity in particular (pKaH = –14), [10] as well as an ability to form only weak hydrogen bonds. [11]
The aqueous solubility of PH3 is slight: 0.22 cm3 of gas dissolves in 1 cm3 of water. Phosphine dissolves more readily in non-polar solvents than in water because of the non-polar P−H bonds. It is technically amphoteric in water, but acid and base activity is poor. Proton exchange proceeds via a phosphonium (PH+4) ion in acidic solutions and via phosphanide (PH−2) at high pH, with equilibrium constants Kb = 4×10−28 and Ka = 41.6×10−29. Phosphine reacts with water only at high pressure and temperature, producing phosphoric acid and hydrogen: [12] [13]
Burning phosphine in the air produces phosphoric acid): [14] [12]
Phosphine may be prepared in a variety of ways. [15] Industrially it can be made by the reaction of white phosphorus with sodium or potassium hydroxide, producing potassium or sodium hypophosphite as a by-product.
Alternatively, the acid-catalyzed disproportionation of white phosphorus yields phosphoric acid and phosphine. Both routes have industrial significance; the acid route is the preferred method if further reaction of the phosphine to substituted phosphines is needed. The acid route requires purification and pressurizing.
It is prepared in the laboratory by disproportionation of phosphorous acid: [16]
Alternative methods are the hydrolysis zinc phosphide:
[17] Some other metal phosphides could be used including aluminium phosphide, or calcium phosphide. Pure samples of phosphine, free from P2H4, may be prepared using the action of potassium hydroxide on phosphonium iodide:
Phosphine is a worldwide constituent of the Earth's atmosphere at very low and highly variable concentrations. [18] It may contribute significantly to the global phosphorus biochemical cycle. The most likely source is reduction of phosphate in decaying organic matter, possibly via partial reductions and disproportionations, since environmental systems do not have known reducing agents of sufficient strength to directly convert phosphate to phosphine. [19]
It is also found in Jupiter's atmosphere. [20]
In 2020 a spectroscopic analysis was reported to show signs of phosphine in the atmosphere of Venus in quantities that could not be explained by known abiotic processes. [21] [22] [23] Later re-analysis of this work showed interpolation errors had been made, and re-analysis of data with the fixed algorithm do not result in the detection of phosphine. [24] [25] The authors of the original study then claimed to detect it with a much lower concentration of 1 ppb. [26] [ disputed – discuss ]
Phosphine is a precursor to many organophosphorus compounds. It reacts with formaldehyde in the presence of hydrogen chloride to give tetrakis(hydroxymethyl)phosphonium chloride, which is used in textiles. The hydrophosphination of alkenes is versatile route to a variety of phosphines. For example, in the presence of basic catalysts PH3 adds of Michael acceptors. Thus with acrylonitrile, it reacts to give tris(cyanoethyl)phosphine: [27]
Acid catalysis is applicable to hydrophosphination with isobutylene and related analogues:
where R is CH3, alkyl, etc.
Phosphine is used as a dopant in the semiconductor industry, and a precursor for the deposition of compound semiconductors. Commercially significant products include gallium phosphide and indium phosphide. [28]
Phosphine is an attractive fumigant because it is lethal to insects and rodents, but degrades to phosphoric acid, which is non-toxic. As sources of phosphine, for farm use, pellets of aluminium phosphide (AlP), calcium phosphide (Ca
3P
2), or zinc phosphide (Zn
3P
2) are used. These phosphides release phosphine upon contact with atmospheric water or rodents' stomach acid. These pellets also contain reagents to reduce the potential for ignition or explosion of the released phosphine.
An alternative is the use of phosphine gas itself which requires dilution with either CO2 or N2 or even air to bring it below the flammability point. Use of the gas avoids the issues related with the solid residues left by metal phosphide and results in faster, more efficient control of the target pests.
One problem with phosphine fumigants is the increased resistance by insects. [29]
Deaths have resulted from accidental exposure to fumigation materials containing aluminium phosphide or phosphine. [30] [31] [32] [33] It can be absorbed either by inhalation or transdermally. [30] As a respiratory poison, it affects the transport of oxygen or interferes with the utilization of oxygen by various cells in the body. [32] Exposure results in pulmonary edema (the lungs fill with fluid). [33] Phosphine gas is heavier than air so it stays near the floor. [34]
Phosphine appears to be mainly a redox toxin, causing cell damage by inducing oxidative stress and mitochondrial dysfunction. [35] Resistance in insects is caused by a mutation in a mitochondrial metabolic gene. [29]
Phosphine can be absorbed into the body by inhalation. The main target organ of phosphine gas is the respiratory tract. [36] According to the 2009 U.S. National Institute for Occupational Safety and Health (NIOSH) pocket guide, and U.S. Occupational Safety and Health Administration (OSHA) regulation, the 8 hour average respiratory exposure should not exceed 0.3 ppm. NIOSH recommends that the short term respiratory exposure to phosphine gas should not exceed 1 ppm. The Immediately Dangerous to Life or Health level is 50 ppm. Overexposure to phosphine gas causes nausea, vomiting, abdominal pain, diarrhea, thirst, chest tightness, dyspnea (breathing difficulty), muscle pain, chills, stupor or syncope, and pulmonary edema. [37] [38] Phosphine has been reported to have the odor of decaying fish or garlic at concentrations below 0.3 ppm. The smell is normally restricted to laboratory areas or phosphine processing since the smell comes from the way the phosphine is extracted from the environment. However, it may occur elsewhere, such as in industrial waste landfills. Exposure to higher concentrations may cause olfactory fatigue. [39]
Phosphine is used for pest control, but its usage is strictly regulated due to high toxicity. [40] [41] Gas from phosphine has high mortality rate [42] and has caused deaths in Sweden and other countries. [43] [44] [45]
Because the previously popular fumigant methyl bromide has been phased out in some countries under the Montreal Protocol, phosphine is the only widely used, cost-effective, rapidly acting fumigant that does not leave residues on the stored product. Pests with 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 has not been as closely monitored. Genetic variants that contribute to high level resistance to phosphine have been identified in the dihydrolipoamide dehydrogenase gene. [29] Identification of this gene now allows rapid molecular identification of resistant insects.
Phosphine gas is denser than air and hence may collect in low-lying areas. It can form explosive mixtures with air, and may also self-ignite. [12]
In the 2008 pilot of the crime drama television series Breaking Bad , Walter White poisons two rival gangsters by adding red phosphorus to boiling water to produce phosphine gas. However, this reaction in reality would require white phosphorus instead, and for the water to contain sodium hydroxide. [46]
Arsine (IUPAC name: arsane) is an inorganic compound with the formula AsH3. This flammable, pyrophoric, and highly toxic pnictogen hydride gas is one of the simplest compounds of arsenic. Despite its lethality, it finds some applications in the semiconductor industry and for the synthesis of organoarsenic compounds. The term arsine is commonly used to describe a class of organoarsenic compounds of the formula AsH3−xRx, where R = aryl or alkyl. For example, As(C6H5)3, called triphenylarsine, is referred to as "an arsine".
In chemistry, the term phosphonium describes polyatomic cations with the chemical formula PR+
4. These cations have tetrahedral structures. The salts are generally colorless or take the color of the anions.
Phosphorus pentachloride is the chemical compound with the formula PCl5. It is one of the most important phosphorus chlorides/oxychlorides, others being PCl3 and POCl3. PCl5 finds use as a chlorinating reagent. It is a colourless, water-sensitive solid, although commercial samples can be yellowish and contaminated with hydrogen chloride.
Phosphorus trichloride is an inorganic compound with the chemical formula PCl3. A colorless liquid when pure, it is an important industrial chemical, being used for the manufacture of phosphites and other organophosphorus compounds. It is toxic and reacts readily with water to release hydrogen chloride.
Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to PPh3 or Ph3P. It is versatile compound that is widely used as a reagent in organic synthesis and as a ligand for transition metal complexes, including ones that serve as catalysts in organometallic chemistry. PPh3 exists as relatively air stable, colorless crystals at room temperature. It dissolves in non-polar organic solvents such as benzene and diethyl ether.
Stibine (IUPAC name: stibane) is a chemical compound with the formula SbH3. A pnictogen hydride, this colourless, highly toxic gas is the principal covalent hydride of antimony, and a heavy analogue of ammonia. The molecule is pyramidal with H–Sb–H angles of 91.7° and Sb–H distances of 170.7 pm (1.707 Å). The smell of this compound from usual sources (like from reduction of antimony compounds) is reminiscent of arsine, id est garlic-like.
Hydrogen selenide is an inorganic compound with the formula H2Se. This hydrogen chalcogenide is the simplest and most commonly encountered hydride of selenium. H2Se is a colorless, flammable gas under standard conditions. It is the most toxic selenium compound with an exposure limit of 0.05 ppm over an 8-hour period. Even at extremely low concentrations, this compound has a very irritating smell resembling that of decayed horseradish or "leaking gas", but smells of rotten eggs at higher concentrations.
Iodomethane, also called methyl iodide, and commonly abbreviated "MeI", is the chemical compound with the formula CH3I. It is a dense, colorless, volatile liquid. In terms of chemical structure, it is related to methane by replacement of one hydrogen atom by an atom of iodine. It is naturally emitted by rice plantations in small amounts. It is also produced in vast quantities estimated to be greater than 214,000 tons annually by algae and kelp in the world's temperate oceans, and in lesser amounts on land by terrestrial fungi and bacteria. It is used in organic synthesis as a source of methyl groups.
Hypophosphorous acid (HPA), or phosphinic acid, is a phosphorus oxyacid and a powerful reducing agent with molecular formula H3PO2. It is a colorless low-melting compound, which is soluble in water, dioxane and alcohols. The formula for this acid is generally written H3PO2, but a more descriptive presentation is HOP(O)H2, which highlights its monoprotic character. Salts derived from this acid are called hypophosphites.
Organophosphorus chemistry is the scientific study of the synthesis and properties of organophosphorus compounds, which are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment. Some organophosphorus compounds are highly effective insecticides, although some are extremely toxic to humans, including sarin and VX nerve agents.
Aluminium phosphide is a highly toxic inorganic compound with the chemical formula AlP, used as a wide band gap semiconductor and a fumigant. This colorless solid is generally sold as a grey-green-yellow powder due to the presence of impurities arising from hydrolysis and oxidation.
Zinc phosphide (Zn3P2) is an inorganic chemical compound. It is a grey solid, although commercial samples are often dark or even black. It is used as a rodenticide. Zn3P2 is a II-V semiconductor with a direct band gap of 1.5 eV and may have applications in photovoltaic cells. A second compound exists in the zinc-phosphorus system, zinc diphosphide (ZnP2).
Organophosphines are organophosphorus compounds with the formula PRnH3−n, where R is an organic substituent. These compounds can be classified according to the value of n: primary phosphines (n = 1), secondary phosphines (n = 2), tertiary phosphines (n = 3). All adopt pyramidal structures. Organophosphines are generally colorless, lipophilic liquids or solids. The parent of the organophosphines is phosphine (PH3).
Diphosphane, or diphosphine, is an inorganic compound with the chemical formula P2H4. This colourless liquid is one of several binary phosphorus hydrides. It is the impurity that typically causes samples of phosphine to ignite in air.
Tetrakis(hydroxymethyl)phosphonium chloride (THPC) is an organophosphorus compound with the chemical formula [P(CH2OH)4]Cl. It is a white water-soluble salt. THPC has applications as a precursor to fire-retardant materials, as well as a microbiocide in commercial and industrial water systems.
Iron phosphide is a chemical compound of iron and phosphorus, with a formula of FeP.< Its physical appearance is grey needles.
Aluminium phosphide poisoning is poisoning that occurs as a result of excessive exposure to aluminium phosphide (AlP), which is readily available as a fumigant for stored cereal grains and sold under various brand names such as QuickPhos, Salphos and Celphos. Aluminium phosphide is highly toxic, especially when consumed from a freshly opened container. Acute aluminium phosphide poisoning (AAlPP) is a large though under-reported problem throughout the world, particularly in the Indian subcontinent.
Methylphosphine is the simplest organophosphorus compound with the formula CH3PH2, often written MePH2. It is a malodorous gas that condenses to a colorless liquid. It can be produced by methylation of phosphide salts:
In organophosphorus chemistry, an aminophosphine is a compound with the formula R3−nP(NR2)n where R = H or an organic substituent, and n = 0, 1, 2. At one extreme, the parents H2PNH2 and P(NH2)3 are lightly studied and fragile, but at the other extreme tris(dimethylamino)phosphine (P(NMe2)3) is commonly available. Intermediate members are known, such as Ph2PN(H)Ph. These compounds are typically colorless and reactive toward oxygen. They have pyramidal geometry at phosphorus.
Phosphonium iodide is a chemical compound with the formula PH
4I. It is an example of a salt containing an unsubstituted phosphonium cation. Phosphonium iodide is commonly used as storage for phosphine and as a reagent for substituting phosphorus into organic molecules.
(From page 524:) The bases Me3P and E3P, the products of this reaction, which we propose to call respectively trimethylphosphine and triethylphosphine, ...