Thionyl chloride
| Thionyl chloride | |
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Sulfurous dichloride |
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Other names
Thionyl dichloride |
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| Identifiers | |
| CAS number | 7719-09-7  |
| PubChem | 24386 |
| ChemSpider | 22797 |
| EC number | 231-748-8 |
| UN number | 1836 |
| ChEBI | CHEBI:29290 |
| RTECS number | XM5150000 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | SOCl2 |
| Molar mass | 118.97 g/mol |
| Appearance | clear, colorless to yellow liquid with unpleasant odor |
| Density | 1.638 g/cm3, liquid |
| Melting point |
−104.5 °C |
| Boiling point |
74.6 °C |
| Solubility in water | exothermic reaction |
| Solubility | soluble in benzene, chloroform, CCl4 |
| Refractive index (nD) | 1.517 (20 °C) [1] |
| Viscosity | 0.6 cP |
| Structure | |
| Molecular shape | pyramidal |
| Dipole moment | 1.4 D |
| Hazards | |
| MSDS | External MSDS |
| EU Index | 016-015-00-0 |
| EU classification | Corrosive (C) |
| R-phrases | R14, R20/22, R29, R35 |
| S-phrases | (S1/2), S26, S30, S36/37/39, S45 |
| Main hazards | Water- and moisture- sensitive, reactive. Never add water to this product as the hydrolysis reaction with water is violent. |
| NFPA 704 |
 0
4
2
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| Flash point | Non-flammable |
| Related compounds | |
| Related thionyl halides | Thionyl fluoride Thionyl bromide |
| Related compounds | Sulfuryl chloride Selenium oxydichloride |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
- "SOCl2" redirects here.
Thionyl chloride is an inorganic compound with the formula SOCl2. It is a reactive chemical used as a reagent in chlorination reactions. It is a colorless, distillable liquid at room temperature and pressure with a nauseating pungent odor that decomposes above 140 °C. Thionyl chloride is sometimes confused with sulfuryl chloride, SO2Cl2, but the properties of these compounds differ significantly. Approximately 45,000 tons per year of SOCl2 were produced in the early 1990s.[2]
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Properties and structure [edit]
The molecule SOCl2 is pyramidal, indicating the presence of a lone pair of electrons on the sulfur(IV) center. In contrast, the stoichiometrically related COCl2 is planar. SOCl2 reacts with water to release hydrogen chloride and sulfur dioxide.
- SOCl2 + H2O → 2 HCl + SO2
Production [edit]
The major industrial synthesis involves the reaction of sulfur trioxide and sulfur dichloride:[3]
- SO3 + SCl2 → SOCl2 + SO2
Other methods include syntheses from phosphorus pentachloride, chlorine, or phosgene:
- SO2 + PCl5 → SOCl2 + POCl3
- SO2 + Cl2 + SCl2 → 2 SOCl2
- SO3 + Cl2 + 2 SCl2 → 3 SOCl2
- SO2 + COCl2 → SOCl2 + CO2
The first of the above four reactions also affords phosphorus oxychloride (phosphoryl chloride), which resembles thionyl chloride in many of its reactions.
Applications [edit]
Thionyl chloride is mainly used in the industrial production of organochlorine compounds, which are often intermediates in pharmaceuticals and agrichemicals.
Organic chemistry [edit]
Thionyl chloride is widely used in organic synthesis and is preferred over other reagents, such as phosphorus pentachloride, as its by-products (HCl and SO2) are gaseous, which simplifies purification of the product. Classically, it converts carboxylic acids to acyl chlorides[4]
Mechanism:
It also converts alcohols to alkyl chlorides although in some cases it may require purification prior to use.[6]
Many of the products of thionyl chloride are themselves highly reactive, which in combination with its easily removed by-products makes thionyl chloride well suited to one pot synthesis. Examples include the synthesis of oxazoline rings and the Darzens reaction[7] (shown below) which proceeds via an internal nucleophilic substitution.
Thionyl chloride can facilitate numerous chemical transformations, some of which are shown below. Going clockwise from the top: Thionyl chloride will transform sulfinic acids into sulfinyl chlorides[8] and phosphonic acids into phosphoryl chlorides. Thionyl chloride will react with primary formamides to form isocyanides[9] Amides will react with thionyl chloride to form imidoyl chlorides. However, primary amides under heating with thionyl chloride will continue on to form nitriles.[10] and can also produce nitriles from amides via E2 elimination.[11] Thionyl chloride can be used in variations of the Pummerer rearrangement. Sulfonic acids react with thionyl chloride to produce sulfonyl chlorides.[12][13] Sulfonyl chlorides have also been prepared from the direct reaction of the corresponding diazonium salt with thionyl chloride.[14]
Inorganic chemistry [edit]
Anhydrous metal chlorides may be obtained from hydrated metal chlorides by refluxing in freshly distilled thionyl chloride:[15]
- MCln·xH2O + x SOCl2 → MCln + x SO2 + 2x HCl
Other applications [edit]
Thionyl chloride is a component of lithium-thionyl chloride batteries, where it acts as the positive electrode (cathode) with lithium as the negative electrode (anode), see lithium battery.
Safety [edit]
SOCl2 is a reactive compound that can violently and/or explosively release dangerous gases upon contact with water and other reagents. Industrial production of thionyl chloride is controlled under the Chemical Weapons Convention, where it is listed in Schedule 3. Thionyl chloride is used in the "di-di" method of producing G-series nerve agents.
See also [edit]
- Oxalyl chloride
- Phosphorus pentachloride
- Phosgene
- Sulfur dichloride
- Thionyl bromide
- Arndt-Eistert reaction
References [edit]
- ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
- ^ Hans-Dietrich Lauss, Wilfried Steffens “Sulfur Halides” in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2005.doi:10.1002/14356007.a25_623
- ^ Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. p. 820. ISBN 0-08-022057-6..
- ^ Allen, C. F. H.; Byers, Jr., J. R.; Humphlett, W. J. (1963), "Oleoyl chloride", Org. Synth.; Coll. Vol. 4: 739; Rutenberg, M. W.; Horning, E. C. (1963), "1-Methyl-3-ethyloxindole", Org. Synth.; Coll. Vol. 4: 620
- ^ Clayden, Jonathan (2005). Organic chemistry (Reprinted (with corrections). ed.). Oxford [u.a.]: Oxford Univ. Press. p. 295. ISBN 978-0-19-850346-0.
- ^ Friedman, L. and Wetter, W. P., "Purification of Thionyl Chloride", J. Chem. Soc. A, 1967, 36-8.doi:10.1039/J19670000036
- ^ Mondanaro, K. R.; Dailey, W. P. (2004), "3-Chloro-2-(chloromethyl)-1-propene", Org. Synth.; Coll. Vol. 10: 212; Krakowiak, K. E.; Bradshaw, J. S. (1998), "4-Benzyl-10,19-diethyl-4,10,19-triaza-1,7,13,16-tetraoxacycloheneicosane", Org. Synth.; Coll. Vol. 9: 34; Feng Xu, Bryon Simmons, Robert A. Reamer, Edward Corley, Jerry Murry, and David Tschaen (2008). "Chlorination/Cyclodehydration of Amino Alcohols with SOCl2: An Old Reaction Revisited". J. Org. Chem. 73 (1): 312–5. doi:10.1021/jo701877h. PMID 18052293.
- ^ Hulce, M.; Mallomo, J. P.; Frye, L. L.; Kogan, T. P.; Posner, G. H. (1990), "(S)-(+)-2-(p-toluenesulfinyl)-2-cyclopentenone: Precursor for enantioselective synthesis of 3-substituted cyclopentanones", Org. Synth.; Coll. Vol. 7: 495; Kurzer, F. (1963), "p-Toluenesulfinyl chloride", Org. Synth.; Coll. Vol. 4: 937
- ^ Niznik, G. E.; Morrison, III, W. H.; Walborsky, H. M. (1988), "1-d-Aldehydes from organometallic reagents: 2-methylbutanal-1-d", Org. Synth.; Coll. Vol. 6: 751
- ^ Krynitsky, J. A.; Carhart, H. W. (1963), "2-Ethylhexanonitrile", Org. Synth.; Coll. Vol. 4: 436
- ^ John E. McMurry (2010). Fundamentals of Organic Chemistry (7th ed.). Cengage Learning. p. 767. ISBN 1-4390-4971-8.
- ^ Weinreb, S. M.; Chase, C. E.; Wipf, P.; Venkatraman, S. (2004), "2-Trimethylsilylethanesulfonyl chloride (SES-Cl)", Org. Synth.; Coll. Vol. 10: 707
- ^ Hazen, G. G.; Bollinger, F. W.; Roberts, F. E.; Russ, W. K.; Seman, J. J.; Staskiewicz, S. (1998), "4-Dodecylbenzenesulfonyl azides", Org. Synth.; Coll. Vol. 9: 400
- ^ Philip J. Hogan and Brian G. Cox (2009). "Aqueous Process Chemistry: The Preparation of Aryl Sulfonyl Chlorides". Org. Process Res. Dev. 13 (5): 875–879. doi:10.1021/op9000862.
- ^ Alfred R. Pray, Richard F. Heitmiller, Stanley Strycker (1990). "Anhydrous Metal Chlorides". Inorganic Syntheses. Inorganic Syntheses 28: 321–323. doi:10.1002/9780470132593.ch80. ISBN 978-0-470-13259-3.
