white phosphorus in an aqueous solution of
potash (potassium carbonate).
[For further information about the early history of phosphine, see:
* ''The Encyclopædia Britannica'' (1911 edition), vol. 21, p. 480:]
Phosphorus: Phosphine.
* Thomas Thomson, ''A System of Chemistry'', 6th ed. (London, England: Baldwin, Cradock, and Joy, 1820), vol. 1
p. 272.
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).
[Note:
*]
On p. 222
of his ''Traité élémentaire de chimie'', vol. 1, (Paris, France: Cuchet, 1789), Lavoisier calls the compound of phosphorus and hydrogen ''"phosphure d'hydrogène"'' (hydrogen phosphide). However
on p. 216
, he calls the compound of hydrogen and phosphorus ''"Combinaison inconnue."'' (unknown combination), yet in a footnote, he says about the reactions of hydrogen with sulfur and with phosphorus: ''"Ces combinaisons ont lieu dans l'état de gaz & il en résulte du gaz hydrogène sulfurisé & phosphorisé."'' (These combinations occur in the gaseous state, and there results from them sulfurized and phosphorized hydrogen gas.)
* In Robert Kerr's 1790 English translation of Lavoisier's ''Traité élémentaire de chimie'' ... — namely, Lavoisier with Robert Kerr, trans., ''Elements of Chemistry'' ... (Edinburgh, Scotland: William Creech, 1790) — Kerr translates Lavoisier's ''"phosphure d'hydrogène"'' as "phosphuret of hydrogen"
p. 204
, and whereas Lavoisier — on p. 216 of his ''Traité élémentaire de chimie'' ... — gave no name to the combination of hydrogen and phosphorus, Kerr calls it "hydruret of phosphorus, or phosphuret of hydrogen"
p. 198
. Lavoisier's note about this compound — ''"Combinaison inconnue."'' — is translated: "Hitherto unknown." Lavoisier's footnote is translated as: "These combinations take place in the state of gas, and form, respectively, sulphurated and phosphorated oxygen gas." The word "oxygen" in the translation is an error because the original text clearly reads ''"hydrogène"'' (hydrogen). (The error was corrected in subsequent editions.)
In 1844, Paul Thénard, son of the French chemist
Louis Jacques Thénard
Louis Jacques Thénard (4 May 177721 June 1857) was a French chemist.
Life
He was born in a farm cottage near Nogent-sur-Seine in the Champagne district
the son of a farm worker. In the post-Revolution French educational system , most boys rec ...
, used a
cold trap to separate diphosphine from phosphine that had been generated from
calcium phosphide, thereby demonstrating that is responsible for spontaneous flammability associated with , and also for the characteristic orange/brown color that can form on surfaces, which is a polymerisation product. He considered diphosphine's formula to be , and thus an intermediate between elemental phosphorus, the higher polymers, and phosphine.
Calcium phosphide (nominally ) produces more 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 ().
[In 1857, August Wilhelm von Hofmann announced the synthesis of organic compounds containing phosphorus, which he named "]trimethylphosphine
Trimethylphosphine is a neutral organophosphorus compound with the formula P(CH3)3, commonly abbreviated as PMe3. This colorless liquid has a strongly unpleasant odor, characteristic of alkylphosphines. The compound is a common ligand in coordin ...
" and "triethylphosphine
Triethylphosphine is the organophosphorus compound with the formula P(CH2CH3)3, commonly abbreviated as PEt3. It is a colorless liquid with an unpleasant odor characteristic of alkylphosphines. The compound is a common ligand in organometallic c ...
", in analogy with "amine" (organo-nitrogen compounds), "arsine" (organo-arsenic compounds), and "stibine" (organo-antimony compounds). The gas was named "phosphine" by 1865 (or earlier).
Structure and properties
is a
trigonal pyramid
In geometry, a pyramid () is a polyhedron formed by connecting a polygonal base and a point, called the apex (geometry), apex. Each base edge and apex form a triangle, called a ''lateral face''. It is a cone, conic solid with polygonal base. A ...
al molecule with ''C''
3''v'' molecular symmetry
Molecular symmetry in chemistry describes the symmetry present in molecules and the classification of these molecules according to their symmetry. Molecular symmetry is a fundamental concept in chemistry, as it can be used to predict or explain m ...
. The
length
Length is a measure of distance. In the International System of Quantities, length is a quantity with dimension distance. In most systems of measurement a base unit for length is chosen, from which all other units are derived. In the Interna ...
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
Substitution may refer to:
Arts and media
*Chord substitution, in music, swapping one chord for a related one within a chord progression
* Substitution (poetry), a variation in poetic scansion
* "Substitution" (song), a 2009 song by Silversun Pi ...
of
methyl groups in the series: , 1.10 D; , 1.23 D; , 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 the P−H bonds are almost entirely 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 of phosphorus. The upfield chemical shift of the phosphorus atom in the
31P NMR spectrum 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 (p''K''
aH = –14), as well as an ability to form only weak
hydrogen bonds
In chemistry, a hydrogen bond (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing a ...
.
The aqueous
solubility of is slight; 0.22 cm
3 of gas dissolves in 1 cm
3 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 () ion in acidic solutions and via
phosphanide
Phosphanides are chemicals containing the H2sup>− anion. This is also known as the phosphino anion or phosphido ligand. The IUPAC name can also be dihydridophosphate(1−).
It can occur as a group phosphanyl -PH2 in organic compounds or ligand ...
() at high pH, with equilibrium constants ''K''
b = and ''K''
a = .
Water
Phosphine upon contact with water at high pressure and temperature produces
phosphoric acid and hydrogen:
:
Burning
Burning phosphine in the air produced
phosphorus pentoxide (P
2O
5) (which reacts with water to produce
phosphoric acid):
:
Preparation and occurrence
Phosphine may be prepared in a variety of ways. 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.
Laboratory routes
It is prepared in the laboratory by
disproportionation of
phosphorous acid:
:
Phosphine evolution occurs at around 200 °C.
Alternative methods are the hydrolysis of
tris(trimethylsilyl)phosphine, or of metal phosphides such as
aluminium phosphide, or
calcium phosphide:
:
Pure samples of phosphine, free from , may be prepared using the action of
potassium hydroxide on
phosphonium iodide :
:
Occurrence
Phosphine is a worldwide constituent of the Earth's atmosphere at very low and highly variable concentrations. 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.
It is also found in
Jupiter's atmosphere.
Possible extraterrestrial biosignature
In 2020 a spectroscopic analysis was reported to show signs of phosphine in the
atmosphere of Venus
The atmosphere of Venus is the layer of gases surrounding Venus. It is composed primarily of supercritical carbon dioxide and is much denser and hotter than that of Earth. The temperature at the surface is 740 K (467 °C, 872 ° ...
in quantities that could not be explained by known
abiotic processes.
Later re-analysis of this work showed interpolation errors had been made, re-analysis of data with the fixed algorithm either do not result in the detection of phosphine
or detect it with a much lower concentration of 1 ppb.
Applications
Organophosphorus chemistry
Phosphine is a precursor to many
organophosphorus compounds
Organophosphorus compounds 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 ins ...
. 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 adds of
Michael acceptors. Thus with
acrylonitrile, it reacts to give
tris(cyanoethyl)phosphine
Tris(cyanoethyl)phosphine is the organophosphorus compound
Organophosphorus compounds are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environm ...
:
: (Z is , CN, or )
Acid catalysis is applicable to hydrophosphination with
isobutylene and related analogues:
: (R is , alkyl, etc.)
Microelectronics
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
Indium phosphide (InP) is a binary semiconductor composed of indium and phosphorus. It has a face-centered cubic ("zincblende") crystal structure, identical to that of GaAs and most of the III-V semiconductors.
Manufacturing
Indium phosphide ca ...
.
Fumigant
For
farm use, pellets of
aluminium phosphide (AlP),
calcium phosphide (Ca
3P
2), or
zinc phosphide (Zn
3P
2) release phosphine upon contact with atmospheric water or rodents' stomach acid. These pellets also contain agents to reduce the potential for
ignition
Ignition may refer to:
Science and technology
* Firelighting, the human act of creating a fire for warmth, cooking and other uses
* Combustion, an exothermic chemical reaction between a fuel and an oxidant
* Fusion ignition, the point at which a ...
or
explosion
An explosion is a rapid expansion in volume associated with an extreme outward release of energy, usually with the generation of high temperatures and release of high-pressure gases. Supersonic explosions created by high explosives are known ...
of the released phosphine. A more recent alternative is the use of phosphine gas itself which requires dilution with either or 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.
Because the previously popular
fumigant methyl bromide
Bromomethane, commonly known as methyl bromide, is an organobromine compound with formula C H3 Br. This colorless, odorless, nonflammable gas is produced both industrially and biologically. It has a tetrahedral shape and it is a recognized ozon ...
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
Resistance may refer to:
Arts, entertainment, and media Comics
* Either of two similarly named but otherwise unrelated comic book series, both published by Wildstorm:
** ''Resistance'' (comics), based on the video game of the same title
** ''T ...
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.
Identification of this gene now allows rapid molecular identification of resistant insects.
Toxicity and safety
Deaths have resulted from accidental exposure to fumigation materials containing
aluminium phosphide or phosphine.
It can be absorbed either by
inhalation
Inhalation (or Inspiration) happens when air or other gases enter the lungs.
Inhalation of air
Inhalation of air, as part of the cycle of breathing, is a vital process for all human life. The process is autonomic (though there are exceptions ...
or
transdermally.
[ As a respiratory poison, it affects the transport of oxygen or interferes with the utilization of oxygen by various cells in the body.][ Exposure results in pulmonary edema (the lungs fill with fluid).][ Phosphine gas is heavier than air so it stays near the floor.][
Phosphine can be absorbed into the body by inhalation. Direct contact with phosphine liquid – although unlikely to occur – may cause frostbite, like other cryogenic liquids. The main target organ of phosphine gas is the respiratory tract. 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. 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.]
Explosiveness
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.
See also
* Diphosphane, , simplified to
* Diphosphene, HP=PH
Notes
References
Further reading
*
*
External links
International Chemical Safety Card 0694
!-- Syntax: -->
CDC – Phosphine – NIOSH Workplace Safety and Health Topic
{{Authority control
Fumigants
Functional groups
Industrial gases
*
Phosphorus hydrides
Phosphorus(−III) compounds
Blood agents