Allotropes of phosphorus

Source: Wikipedia, the free encyclopedia.
(Redirected from
White phosphorus
)
White phosphorus (left), red phosphorus (center left and center right), and violet phosphorus (right)
allotropes

Elemental phosphorus can exist in several allotropes, the most common of which are white and red solids. Solid violet and black allotropes are also known. Gaseous phosphorus exists as diphosphorus and atomic phosphorus.

White phosphorus

This section is about the chemistry of white phosphorus. For military applications, see white phosphorus munitions.
White phosphorus

White phosphorus sample with a chunk removed from the corner to expose un-oxidized material

Tetraphosphorus molecule
Names
IUPAC names
White phosphorus
Tetraphosphorus
Systematic IUPAC name
1,2,3,4-Tetraphosphatricyclo[1.1.0.02,4]butane
Other names
  • Molecular phosphorus
  • Yellow phosphorus
Identifiers
3D model (
JSmol
)
ChemSpider
UN number 1381
  • InChI=1S/P4/c1-2-3(1)4(1)2
    Key: OBSZRRSYVTXPNB-UHFFFAOYSA-N
  • P12P3P1P23
Properties
P4
Molar mass 123.895 g·mol−1
Density 1.82 g/cm3
Melting point 44.1 °C; 111.4 °F; 317.3 K
Boiling point 280 °C; 536 °F; 553 K
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no code
4
4
2
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
White phosphorus crystal structure

White phosphorus, yellow phosphorus or simply tetraphosphorus (P4) exists as

hexagonal crystal structure.[2]

Molten and gaseous white phosphorus also retains the tetrahedral molecules, until 800 °C (1,500 °F; 1,100 K) when it starts decomposing to P
2 molecules.[3] The P
4 molecule in the gas phase has a P-P bond length of rg = 2.1994(3) Å as was determined by gas electron diffraction.[4] The β form of white phosphorus contains three slightly different P
4 molecules, i.e. 18 different P-P bond lengths — between 2.1768(5) and 2.1920(5) Å. The average P-P bond length is 2.183(5) Å.[3]

White phosphorus is a translucent

oils, carbon disulfide, and disulfur dichloride
.

Production and applications

The white allotrope can be produced using several methods. In the industrial process,

fluoroapatite
):

2 Ca3(PO4)2 + 6 SiO2 + 10 C → 6 CaSiO3 + 10 CO + P4

White phosphorus has an appreciable vapour pressure at ordinary temperatures. The vapour density indicates that the vapour is composed of P4 molecules up to about 800 °C. Above that temperature, dissociation into P2 molecules occurs.

In

base, white phosphorus spontaneously disproportionates to phosphine and various phosphorus oxyacids.[8]

It ignites spontaneously in air at about 50 °C (122 °F), and at much lower temperatures if finely divided (due to melting-point depression). Phosphorus reacts with oxygen, usually forming two oxides depending on the amount of available oxygen: P4O6 (phosphorus trioxide) when reacted with a limited supply of oxygen, and P4O10 when reacted with excess oxygen. On rare occasions, P4O7, P4O8, and P4O9 are also formed, but in small amounts. This combustion gives phosphorus(V) oxide:

P4 + 5 O2 → P4O10

Because of this property, white phosphorus is used as a weapon.

Phosphorus pentachloride is prepared by the reaction of white phosphorus with excess of dry chlorine.[9]

P4 + 10Cl2 → 4PCl5

It can also be prepared by the action of sulfuryl chloride on white phosphorus.[9]

P4 + 10SO2Cl2 → 4PCl5 + 10SO2

Non-existence of cubic-P8

Although white phosphorus converts to the thermodynamically more stable red allotrope, the formation of the cubic-P8 molecule is not observed in the condensed phase. Analogs of this hypothetical molecule have been prepared from phosphaalkynes.[10] White phosphorus in the gaseous state and as waxy solid consists of reactive P4 molecules.

Red phosphorus

Red phosphorus
Red phosphorus structure

Red phosphorus may be formed by heating

amorphous
network. Upon further heating, the amorphous red phosphorus crystallizes. Bulk red phosphorus does not ignite in air at temperatures below 240 °C (460 °F), whereas pieces of white phosphorus ignite at about 30 °C (86 °F).

Under standard conditions it is more stable than white phosphorus, but less stable than the thermodynamically stable black phosphorus. The standard enthalpy of formation of red phosphorus is −17.6 kJ/mol.[1] Red phosphorus is kinetically most stable.

It was first presented by Anton von Schrötter before the Vienna Academy of Sciences on December 9, 1847, although others had doubtlessly had this substance in their hands before, such as Berzelius.[11]

Applications

Red phosphorus can be used as a very effective

epoxy resins or polyurethanes). The flame retarding effect is based on the formation of polyphosphoric acid. Together with the organic polymer material, these acids create a char that prevents the propagation of the flames. The safety risks associated with phosphine generation and friction sensitivity of red phosphorus can be effectively minimized by stabilization and micro-encapsulation. For easier handling, red phosphorus is often used in form of dispersions or masterbatches in various carrier systems. However, for electronic/electrical systems, red phosphorus flame retardant has been effectively banned by major OEMs due to its tendency to induce premature failures.[12] One persistent problem is that red phosphorus in epoxy molding compounds induces elevated leakage current in semiconductor devices.[13] Another problem was acceleration of hydrolysis reactions in PBT insulating material.[14]

Red phosphorus can also be used in the illicit production of methamphetamine and Krokodil.

Red phosphorus can be used as an elemental

photocatalyst for hydrogen formation from the water.[15] They display a steady hydrogen evolution rates of 633 μmol/(h⋅g) by the formation of small-sized fibrous phosphorus.[16]

Violet or Hittorf's phosphorus

Violet phosphorus (right) by a sample of red phosphorus (left)
Violet phosphorus structure
Hitorff's phosphorus structure

Monoclinic phosphorus, or violet phosphorus, is also known as Hittorf's metallic phosphorus.

fibrous form exists with similar phosphorus cages. The lattice structure of violet phosphorus was presented by Thurn and Krebs in 1969.[20] Imaginary frequencies, indicating the irrationalities or instabilities of the structure, were obtained for the reported violet structure from 1969.[21] The single crystal of violet phosphorus was also produced. The lattice structure of violet phosphorus has been obtained by single-crystal x-ray diffraction to be monoclinic with space group of P2/n (13) (a = 9.210, b = 9.128, c = 21.893 Å, β = 97.776°, CSD-1935087
). The optical band gap of the violet phosphorus was measured by diffuse reflectance spectroscopy to be around 1.7 eV. The thermal decomposition temperature was 52 °C higher than its black phosphorus counterpart. The violet phosphorene was easily obtained from both mechanical and solution exfoliation.

Reactions of violet phosphorus

Violet phosphorus does not ignite in air until heated to 300 °C and is insoluble in all solvents. It is not attacked by

oxidised by nitric acid to phosphoric acid
.

If it is heated in an atmosphere of inert gas, for example

dimerize to give P4 molecules (i.e. white phosphorus) but, in a vacuum
, they link up again to form the polymeric violet allotrope.

Black phosphorus

Black phosphorus ampoule
Black phosphorus
Black phosphorus structure

Black phosphorus is the thermodynamically stable form of phosphorus at

room temperature and pressure, with a heat of formation of −39.3 kJ/mol (relative to white phosphorus which is defined as the standard state).[1] It was first synthesized by heating white phosphorus under high pressures (12,000 atmospheres) in 1914. As a 2D material, in appearance, properties, and structure, black phosphorus is very much like graphite with both being black and flaky, a conductor of electricity, and having puckered sheets of linked atoms.[22]

Black phosphorus has an orthorhombic pleated honeycomb structure and is the least reactive allotrope, a result of its lattice of interlinked six-membered rings where each atom is bonded to three other atoms.[23][24] In this structure, each phosphorus atom has five outer shell electrons.[25] Black and red phosphorus can also take a cubic crystal lattice structure.[26] The first high-pressure synthesis of black phosphorus crystals was made by the Nobel prize winner Percy Williams Bridgman in 1914.[27] Metal salts catalyze the synthesis of black phosphorus.[28]

Black phosphorus based sensors exhibit several superior qualities over traditional materials used in piezoelectric or resistive sensors. Characterized by its unique puckered honeycomb lattice structure, black phosphorus provides exceptional carrier mobility. This property ensures its high sensitivity and mechanical resilience, making it an intriguing candidate for

sensor technology.[29][30]

Phosphorene

Main article: phosphorene

The similarities to graphite also include the possibility of scotch-tape delamination (exfoliation), resulting in phosphorene, a graphene-like 2D material with excellent charge transport properties, thermal transport properties and optical properties. Distinguishing features of scientific interest include a thickness dependent band-gap, which is not found in graphene.[31] This, combined with a high on/off ratio of ~105 makes phosphorene a promising candidate for field-effect transistors (FETs).[32] The tunable bandgap also suggests promising applications in mid-infrared photodetectors and LEDs.[33][34] Exfoliated black phosphorus sublimes at 400 °C in vacuum.[35] It gradually oxidizes when exposed to water in the presence of oxygen, which is a concern when contemplating it as a material for the manufacture of transistors, for example.[36][37] Exfoliated black phosphorus is an emerging anode material in the battery community, showing high stability and lithium storage.[38]

Ring-shaped phosphorus

Ring-shaped phosphorus was theoretically predicted in 2007.[39] The ring-shaped phosphorus was self-assembled inside evacuated multi-walled carbon nanotubes with inner diameters of 5–8 nm using a vapor encapsulation method. A ring with a diameter of 5.30 nm, consisting of 23 P8 and 23 P2 units with a total of 230 P atoms, was observed inside a multi-walled carbon nanotube with an inner diameter of 5.90 nm in atomic scale. The distance between neighboring rings is 6.4 Å.[40]

The P6 ring shaped molecule is not stable in isolation.

Blue phosphorus

Single-layer blue phosphorus was first produced in 2016 by the method of

molecular beam epitaxy from black phosphorus as precursor.[41]

Diphosphorus

Main article: Diphosphorus
Structure of diphosphorus
Diphosphorus molecule

The diphosphorus allotrope (P2) can normally be obtained only under extreme conditions (for example, from P4 at 1100 kelvin). In 2006, the diatomic molecule was generated in homogeneous solution under normal conditions with the use of

complexes (for example, tungsten and niobium).[42]

Diphosphorus is the gaseous form of phosphorus, and the thermodynamically stable form between 1200 °C and 2000 °C. The dissociation of tetraphosphorus (P4) begins at lower temperature: the percentage of P2 at 800 °C is ≈ 1%. At temperatures above about 2000 °C, the diphosphorus molecule begins to dissociate into atomic phosphorus.

Phosphorus nanorods

P12 nanorod polymers were isolated from CuI-P complexes using low temperature treatment.[43]

Red/brown phosphorus was shown to be stable in air for several weeks and have properties distinct from those of red phosphorus.

Electron microscopy showed that red/brown phosphorus forms long, parallel nanorods with a diameter between 3.4 Å and 4.7 Å.[43]

Properties

Properties of some allotropes of phosphorus[44][45]
Form white(α) white(β) violet black
Symmetry Body-centred cubic
Triclinic
Monoclinic
Orthorhombic
Pearson symbol aP24 mP84 oS8
Space group I43m P1 No. 2 P2/c No. 13 Cmca No. 64
Density (g/cm3) 1.828 1.88 2.36 2.69
Bandgap (eV
) 		2.1 1.5 0.34
Refractive index 1.8244 2.6 2.4

See also

References

  1. ^
    ISBN 978-0-13-039913-7
    .
  2. ^
    ISBN 978-981-02-2634-3.{{cite book}}: CS1 maint: multiple names: authors list (link
    )
  3. ^
    doi:10.1002/cber.19971300911
    .
  4. PMID 20515032
    .
  5. ^ "A dangerous guide to beachcombing".
  6. ^ "Woman mistakes WWII-era munition for precious stone on German beach | DW | 05.08.2017". Deutsche Welle.
  7. ^ Threlfall, R.E., (1951). 100 years of Phosphorus Making: 1851–1951. Oldbury: Albright and Wilson Ltd
  8. LCCN 2003060796
    .
  9. ^
    ISBN 81-7450-648-9
    .
  10. doi:10.1002/anie.199504361
    .
  11. ISSN 0021-9584
    .
  12. ^ "Red Phosphorus Reliability Alert" (PDF). Archived from the original (PDF) on 2018-01-02. Retrieved 2018-01-01.
  13. ^ Craig Hillman, Red Phosphorus Induced Failures in Encapsulated Circuits, https://www.dfrsolutions.com/hubfs/Resources/services/Red-Phosphorus-Induced-Failures-in-Encapsulated-Circuits.pdf?t=1513022462214
  14. ^ Dock Brown, The Return of the Red Retardant, SMTAI 2015, https://www.dfrsolutions.com/hubfs/Resources/services/The-Return-of-the-Red-Retardant.pdf?t=1513022462214
  15. ^ Applied Catalysis B: Environmental, 2012, 111–112, 409–414.
  16. ^ Angewandte Chemie International Edition, 2016, 55, 9580–9585.
  17. ^ Curry, Roger (2012-07-08). "Hittorf's Metallic Phosphorus of 1865". LATERAL SCIENCE. Retrieved 16 November 2014.
  18. ^ Monoclinic phosphorus formed from vapor in the presence of an alkali metal U.S. patent 4,620,968
  19. doi:10.1002/andp.18652021002
    .
  20. ISSN 0567-7408
    .
  21. S2CID 241932000
    .
  22. PMID 29123112
    .
  23. doi:10.1107/S0365110X65004140
    .
  24. doi:10.1063/1.438523
    .
  25. PMID 25820173
    .
  26. S2CID 120578034
    .
  27. ISSN 0002-7863
    .
  28. PMID 17439206
    .
  29. PMID 36596775
    .
  30. ^ Chemistry, University of; Prague, Technology. "Black phosphorus–based human–machine communication interface: A breakthrough in assistive technology". techxplore.com. Retrieved 2023-06-16.
  31. ^ "Black Phosphorus Powder and Crystals". Ossila. Retrieved 2019-08-23.
  32. S2CID 17218693
    .
  33. S2CID 208202133
    .
  34. S2CID 5479539
    .
  35. S2CID 24648672
    .
  36. S2CID 22128620
    .
  37. ISSN 0734-2101
    .
  38. S2CID 225707528
    .
  39. PMID 17373003
    .
  40. PMID 28074606
    .
  41. PMID 27359041.{{cite journal}}: CS1 maint: numeric names: authors list (link
    )
  42. S2CID 27740669
    .
  43. ^
    PMID 15307095
    .
  44. ISBN 978-3-11-012641-9
    .
  45. ISBN 978-0-8493-8912-2
    .

External links

White phosphorus
Retrieved from "https://en.wikipedia.org/w/index.php?title=Allotropes_of_phosphorus&oldid=1220451333#White_phosphorus"