Diphosphorus tetraiodide
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| Names | |
|---|---|
| IUPAC name
Diphosphorus tetraiodide
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| Preferred IUPAC name
Tetraiododiphosphane | |
| Other names
phosphorus(II) iodide
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| Identifiers | |
| ECHA InfoCard | 100.033.301 |
CompTox Dashboard (EPA)
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| Properties | |
| P2I4 | |
| Molar mass | 569.57 g mol−1 |
| Appearance | orange crystalline solid |
| Density | ? g cm−3, solid |
| Melting point | 124-127 °C |
| Boiling point | Decomposes |
| Decomposes | |
| Hazards | |
| Flash point | non-flammable |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Diphosphorus tetraiodide, P2I4, is an orange crystalline solid, and a versatile reducing agent. The phosphorus atom has an NMR chemical shift of about +100 ppm (downfield of H3PO4) (+108 ppm in CS2). Phosphorus contains a rare oxidation state of +2 in this compound.
Synthesis
Diphosphorus tetraiodide is easily generated by the disproportionation of phosphorus triiodide in dry ether:
- 2PI3 → P2I4 + I2
It can also be obtained by reacting phosphorus trichloride and potassium iodide in anhydrous conditions[1].
Reactions
P2I4 reacts with bromine to form a mixture of PI3, PBr3, PBr2I and PBrI2[2].
Applications
Diphosphorus tetraiodide is used in organic chemistry for converting carboxylic acids to nitriles[3], for deprotecting acetals and ketals to aldehydes and ketones, and for converting epoxides into alkenes and aldoximes into nitriles. It can also cyclize 2-aminoalcohols to aziridines[4] and to convert α,β-unsaturated carboxylic acids to α,β-unsaturated bromides[5].
In the Kuhn-Winterstein Reaction diphosphorus tetraiodide is used in the conversion of glycols to alkenes [6].
References
- ^ H. Suzuki, T. Fuchita, A. Iwasa, T. Mishina (1978). "Diphosphorus Tetraiodide as a Reagent for Converting Epoxides into Olefins, and Aldoximes into Nitriles under Mild Conditions". Synthesis. 1978 (12): 905–908. doi:10.1055/s-1978-24936.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ A. H. Cowley and S. T. Cohen (1965). "The Iodides of Phosphorus. II. The Reaction of Bromine with Diphosphorus Tetraiodide". Tetrahedron Letters. 4 (8): 1221–1222. doi:10.1021/ic50030a029.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Vikas N. Telvekar and Rajesh A. Rane (2007). "A novel system for the synthesis of nitriles from carboxylic acids". Tetrahedron Letters. 48 (34): 6051–6053. doi:10.1016/j.tetlet.2007.06.108.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ H. Suzuki, H. Tani (1984). "A mild cyclization of 2-aminoalcohols to aziridines using diphosphorus tetraiodide". Chemistry Letters. 13 (12): 2129–2130. doi:10.1246/cl.1984.2129.
{{cite journal}}: Cite has empty unknown parameter:|month=(help) - ^ Vikas N. Telvekar, Somsundaram N. Chettiar (2007). "A novel system for decarboxylative bromination". Tetrahedron Letters. 48 (26): 4529–4532. doi:10.1016/j.tetlet.2007.04.137.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Über konjugierte Doppelbindungen I. Synthese von Diphenyl-poly-enen Richard Kuhn, Alfred Winterstein Helvetica Chimica Acta Volume 11 Issue 1, Pages 87 - 116 1928 doi:10.1002/hlca.19280110107
See also
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