Difference between revisions of "Phosphorus triiodide"
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| MeltingPt_ref = | | MeltingPt_ref = | ||
| MeltingPt_notes = | | MeltingPt_notes = | ||
| + | | Odor = Acrid (moist air) | ||
| pKa = | | pKa = | ||
| pKb = | | pKb = | ||
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| SolubleOther = Reacts with alcohols<br>Soluble in [[benzene]], [[carbon disulfide]], [[hexane]], [[1,2-Dichloroethane|1,2-dichloroethane]]<br>Poorly soluble in [[acetonitrile]], [[sulfur dioxide]]<br>Insoluble in [[dichloromethane]] | | SolubleOther = Reacts with alcohols<br>Soluble in [[benzene]], [[carbon disulfide]], [[hexane]], [[1,2-Dichloroethane|1,2-dichloroethane]]<br>Poorly soluble in [[acetonitrile]], [[sulfur dioxide]]<br>Insoluble in [[dichloromethane]] | ||
| Solvent = | | Solvent = | ||
| − | | VaporPressure = | + | | VaporPressure = ~0 mmHg |
}} | }} | ||
| Section3 = {{Chembox Structure | | Section3 = {{Chembox Structure | ||
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}} | }} | ||
| Section4 = {{Chembox Thermochemistry | | Section4 = {{Chembox Thermochemistry | ||
| − | | DeltaGf = | + | | DeltaGf = -44.8 kJ/mol |
| DeltaHc = | | DeltaHc = | ||
| − | | DeltaHf = -45 | + | | DeltaHf = -45.6 kJ/mol |
| − | | Entropy = | + | | Entropy = 192 J·K<sup>−1</sup>·mol<sup>−1</sup> |
| HeatCapacity = | | HeatCapacity = | ||
}} | }} | ||
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| LD50 = | | LD50 = | ||
| LC50 = | | LC50 = | ||
| − | | MainHazards = | + | | MainHazards = Corrosive |
| NFPA-F = | | NFPA-F = | ||
| NFPA-H = | | NFPA-H = | ||
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}} | }} | ||
}} | }} | ||
| − | '''Phosphorus triiodide''' is chemical compound, a red solid which reacts violently with water, releasing | + | '''Phosphorus triiodide''' is chemical compound, a red solid which reacts violently with water, releasing phosphorous acid and [[hydroiodic acid]]. It is a powerful reducing agent, with the chemical formula '''PI<sub>3</sub>'''. |
==Properties== | ==Properties== | ||
===Chemical=== | ===Chemical=== | ||
| + | Phosphorus triiodide readily hydrolyzes in water, producing phosphorous acid (H<sub>3</sub>PO<sub>3</sub>) and [[hydroiodic acid]] (HI), along with smaller amounts of [[phosphine]] and traces of diphosphanes. | ||
| + | |||
| + | : PI<sub>3</sub> + 3 H<sub>2</sub>O → 3 HI + H<sub>3</sub>PO<sub>3</sub> | ||
| + | |||
Phosphorus triiodide will react with alcohols to form alkyl iodides: | Phosphorus triiodide will react with alcohols to form alkyl iodides: | ||
: 3 R-OH + PI<sub>3</sub> → 3 RI + H<sub>3</sub>PO<sub>3</sub> | : 3 R-OH + PI<sub>3</sub> → 3 RI + H<sub>3</sub>PO<sub>3</sub> | ||
| + | |||
| + | PI<sub>3</sub> is also an exceptionally powerful reducing agent and deoxygenating agent, capable of rapidly reducing sulfoxides to sulfides, even at temperatures as low as −78 °C.<ref>[https://pubs.rsc.org/en/content/articlelanding/1980/C3/c39800000544 J. N. Denis; A. Krief (1980). "Phosphorus tri-iodide (PI3), a powerful deoxygenating agent". J. Chem. Soc., Chem. Commun. (12): 544–5]</ref> | ||
| + | |||
| + | Heating a 1-iodobutane solution of PI<sub>3</sub> with red [[phosphorus]] causes reduction to P<sub>2</sub>I<sub>4</sub>. | ||
===Physical=== | ===Physical=== | ||
| Line 122: | Line 131: | ||
===Legality=== | ===Legality=== | ||
| − | Although it's made from two DEA List I chemicals ([[phosphorus]] and [[iodine]]) and upon standing in air/hydrolysis releases another List I chemical ([[hydroiodic acid]]), phosphorus triiodide is curiously not listed in the DEA List of chemicals. However, PI<sub>3</sub>'s status is covered by the same legislation that covers phosphorus halides and individuals normally cannot purchase it. | + | Although it's made from two DEA List I chemicals ([[phosphorus]] and [[iodine]]) and upon standing in air/hydrolysis releases another List I chemical ([[hydroiodic acid]], as well as elemental iodine), phosphorus triiodide is curiously not listed in the DEA List of chemicals. However, PI<sub>3</sub>'s status is covered by the same legislation that covers phosphorus halides and individuals normally cannot purchase it. |
==Preparation== | ==Preparation== | ||
| − | Phosphorus triiodide can be made by reacting elemental phosphorus (red preferably) with iodine, in a P:I ratio of 1:3. The reaction best takes place in a solvent, such as [[carbon disulfide]], [[carbon tetrachloride]], [[1,2-Dichloroethane|dichloroethane]]. Since the reaction is exothermic, cooling is required to keep it under control. Due to its low boiling point, carbon disulfide is a good choice, and crystallizing the resulting PI<sub>3</sub> from the solution is safe and gives good yield. If the reaction is done without a solvent, the resulting product is impure and the yield is poor. | + | Phosphorus triiodide can be made by reacting elemental phosphorus (red preferably) with iodine, in a P:I ratio of 1:3. |
| + | |||
| + | : 2 P + 3 I<sub>2</sub> → 2 PI<sub>3</sub> | ||
| + | |||
| + | The reaction best takes place in a solvent, such as [[carbon disulfide]], [[carbon tetrachloride]], [[1,2-Dichloroethane|dichloroethane]]. Since the reaction is exothermic, cooling is required to keep it under control. Due to its low boiling point, carbon disulfide is a good choice, and crystallizing the resulting PI<sub>3</sub> from the solution is safe and gives good yield. If the reaction is done without a solvent, the resulting product is impure and the yield is poor. | ||
Another route involves the reaction of [[phosphorus trichloride]] with [[hydrogen iodide]]: | Another route involves the reaction of [[phosphorus trichloride]] with [[hydrogen iodide]]: | ||
| Line 140: | Line 153: | ||
==Handling== | ==Handling== | ||
===Safety=== | ===Safety=== | ||
| − | Phosphorus triiodide reacts with water to release | + | Phosphorus triiodide reacts with water to release hydroiodic acid and phosphorous acid, which are corrosive and harmful. Direct contact with skin will cause chemical burns. The reaction will also release small amounts of [[phosphine]] which is highly toxic, as well as diphosphanes which can be pyrophoric. |
===Storage=== | ===Storage=== | ||
| Line 146: | Line 159: | ||
===Disposal=== | ===Disposal=== | ||
| − | Phosphorus triiodide can be neutralized with a solution of [[sodium thiosulfate]]. | + | Phosphorus triiodide can be neutralized with a solution of [[sodium thiosulfate]]. This should be done slowly, since PI<sub>3</sub> reacts exothermically with water. |
==References== | ==References== | ||
<references/> | <references/> | ||
===Relevant Sciencemadness threads=== | ===Relevant Sciencemadness threads=== | ||
| + | *[http://www.sciencemadness.org/talk/viewthread.php?tid=100471 Solid Phosphorus Triiodide] | ||
| + | *[http://www.sciencemadness.org/talk/viewthread.php?tid=66609 Phosphorus triiodide and DEA List] | ||
*[http://www.sciencemadness.org/talk/viewthread.php?tid=12475 Preparation of Iodomethane] | *[http://www.sciencemadness.org/talk/viewthread.php?tid=12475 Preparation of Iodomethane] | ||
Latest revision as of 19:36, 20 June 2023
| Names | |
|---|---|
| IUPAC names
Phosphorus triiodide
Phosphorus(III) iodide | |
| Other names
Phosphorus iodide
Triiodophosphine | |
| Identifiers | |
| Jmol-3D images | Image |
| |
| Properties | |
| PI3 | |
| Molar mass | 411.68717 g/mol |
| Appearance | Dark red solid |
| Odor | Acrid (moist air) |
| Density | 4.18 g/cm3 |
| Melting point | 61.2 °C (142.2 °F; 334.3 K) |
| Boiling point | 200 °C (392 °F; 473 K) (decomposes) |
| Reacts | |
| Solubility | Reacts with alcohols Soluble in benzene, carbon disulfide, hexane, 1,2-dichloroethane Poorly soluble in acetonitrile, sulfur dioxide Insoluble in dichloromethane |
| Vapor pressure | ~0 mmHg |
| Thermochemistry | |
| Std molar
entropy (S |
192 J·K−1·mol−1 |
| Std enthalpy of
formation (ΔfH |
-45.6 kJ/mol |
| Hazards | |
| Safety data sheet | Guidechem |
| Flash point | Non-flammable |
| Related compounds | |
| Related compounds
|
Phosphorus trichloride Phosphorus tribromide |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Phosphorus triiodide is chemical compound, a red solid which reacts violently with water, releasing phosphorous acid and hydroiodic acid. It is a powerful reducing agent, with the chemical formula PI3.
Contents
Properties
Chemical
Phosphorus triiodide readily hydrolyzes in water, producing phosphorous acid (H3PO3) and hydroiodic acid (HI), along with smaller amounts of phosphine and traces of diphosphanes.
- PI3 + 3 H2O → 3 HI + H3PO3
Phosphorus triiodide will react with alcohols to form alkyl iodides:
- 3 R-OH + PI3 → 3 RI + H3PO3
PI3 is also an exceptionally powerful reducing agent and deoxygenating agent, capable of rapidly reducing sulfoxides to sulfides, even at temperatures as low as −78 °C.[1]
Heating a 1-iodobutane solution of PI3 with red phosphorus causes reduction to P2I4.
Physical
Phosphorus triiodide is an unstable dark red solid, with a melting point of 61.2 °C and decomposes when heated to 200 °C. It is soluble in benzene, carbon disulfide and fairly soluble in hexane. Its density is 4.18 g/cm3 at standard conditions.
Availability
Phosphorus triiodide is sold by various chemical entities, though it's almost impossible for the amateur chemist to purchase it.
Legality
Although it's made from two DEA List I chemicals (phosphorus and iodine) and upon standing in air/hydrolysis releases another List I chemical (hydroiodic acid, as well as elemental iodine), phosphorus triiodide is curiously not listed in the DEA List of chemicals. However, PI3's status is covered by the same legislation that covers phosphorus halides and individuals normally cannot purchase it.
Preparation
Phosphorus triiodide can be made by reacting elemental phosphorus (red preferably) with iodine, in a P:I ratio of 1:3.
- 2 P + 3 I2 → 2 PI3
The reaction best takes place in a solvent, such as carbon disulfide, carbon tetrachloride, dichloroethane. Since the reaction is exothermic, cooling is required to keep it under control. Due to its low boiling point, carbon disulfide is a good choice, and crystallizing the resulting PI3 from the solution is safe and gives good yield. If the reaction is done without a solvent, the resulting product is impure and the yield is poor.
Another route involves the reaction of phosphorus trichloride with hydrogen iodide:
- PCl3 + 3 KI → PI3 + 3 KCl3
This reaction takes place in glacial acetic acid.[2][3]
Projects
- Make alkyl iodides
- Diphosphorus tetraiodide synthesis
- Organic reductions
Handling
Safety
Phosphorus triiodide reacts with water to release hydroiodic acid and phosphorous acid, which are corrosive and harmful. Direct contact with skin will cause chemical burns. The reaction will also release small amounts of phosphine which is highly toxic, as well as diphosphanes which can be pyrophoric.
Storage
Phosphorus triiodide can be stored in glass air-tight containers, though it's not recommended to be stored for long periods of time and used as soon as it's made.
Disposal
Phosphorus triiodide can be neutralized with a solution of sodium thiosulfate. This should be done slowly, since PI3 reacts exothermically with water.
References
- ↑ J. N. Denis; A. Krief (1980). "Phosphorus tri-iodide (PI3), a powerful deoxygenating agent". J. Chem. Soc., Chem. Commun. (12): 544–5
- ↑ Ritter, H.; Liebigs Annalen der Chemie; vol. 95; (1855); p. 208 - 211
- ↑ Germann, F. E. E.; Traxler, R. N.; Journal of the American Chemical Society; vol. 49; (1927); p. 307 - 312
Relevant Sciencemadness threads
- Chemical pages without CAS Registry Number
- Articles without EBI source
- Chemical pages without ChemSpiderID
- Chemical pages without DrugBank identifier
- Articles without KEGG source
- Articles without InChI source
- Articles without UNII source
- Articles containing unverified chemical infoboxes
- Chembox articles without image
- Chemical compounds
- Inorganic compounds
- Phosphorus compounds
- Iodine compounds
- Phosphorus halides
- Iodides
- Materials that react with water
- Materials unstable in basic solution
- Materials unstable in acidic solution
- Unstable materials
