(inorganic chemistry) SOCl2 A toxic, yellowish to red liquid with a pungent aroma, soluble in benzene, decomposes in water and at 140°C; boils at 79°C; used as a chemical intermediate and catalyst. Also known as sulfur oxychloride; sulfurous oxychloride.
Thionyl chloride
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(′thī·ən·əl ′klör′īd)
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| Thionyl chloride | |
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| Other names | thionyl dichloride, sulfurous oxychloride, sulfurous dichloride, sulfinyl chloride, sulfinyl dichloride, dichlorosulfoxide |
| Identifiers | |
| CAS number | 7719-09-7  |
| EC number | 231-748-8 |
| UN number | 1836 |
| RTECS number | XM5150000 |
| Properties | |
| Molecular formula | SOCl2 |
| Molar mass | 118.97 g/mol |
| Appearance | clear to yellow odorous liquid |
| Density | 1.638 g/cm3, liquid |
| Melting point |
−104.5 °C |
| Boiling point |
74.6 °C |
| Solubility in water | reacts |
| 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, S36/37/39, S45 |
| 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 |
| (what is this?) (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Thionyl chloride is an inorganic compound with the formula SOCl2. It is a reactive chemical reagent used in chlorination reactions. It is a colorless, distillable liquid at room temperature and pressure 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/yr of SOCl2 were produced in the early 1990s.[2]
Contents |
Properties and structure
The molecule SOCl2 is pyramidal, indicating the presence of a lone pair of electrons on the sulfur(IV) center. In contrast, the stoichiometrically related species COCl2 is planar. SOCl2 reacts with water to release hydrogen chloride and sulfur dioxide.
- H2O + SOCl2 → SO2 + 2 HCl
Production
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 three reactions also affords phosphorus oxychloride (phosphoryl chloride), which resembles thionyl chloride in many of its reactions.
Applications
Thionyl chloride is mainly used in the industrial production of organochlorine compounds, which are often intermediates in pharmaceuticals and agrichemicals.
Organic chemistry
Thionyl chloride is widely used in organic synthesis. For some applications, it requires purification.[4]. Classically, it converts carboxylic acids to acyl chlorides:[5]
Alcohols react with thionyl chloride to give the corresponding alkyl chlorides.[6]. This reaction proceeds via an internal nucleophilic substitution.
It is preferred over other reagents such as phosphorus pentachloride because the products of the thionyl chloride reactions, HCl and SO2, are gaseous, which simplies the purification of the product. Excess thionyl chloride can be readily removed by distillation.
Sulfonic acids react with thionyl chloride to produce sulfonyl chlorides.[7][8] Sulfonyl chlorides have also been prepared from the direct reaction of the corresponding diazonium salt with thionyl chloride.[9] Likewise, thionyl chloride will transform sulfinic acids into sulfinyl chlorides[10] and phosphonic acids into phosphoryl chlorides. Thionyl chloride will react with primary formamides to form isocyanides.[11] Amides will react with thionyl chloride to form imidoyl chlorides. However, primary amides under heating with thionyl chloride will continue on to form nitriles.[12]
Inorganic chemistry
Anhydrous metal chlorides may be obtained from hydrated metal chlorides by refluxing in freshly distilled thionyl chloride:[13]
- MCln·xH2O + x SOCl2 → MCln + x SO2 + 2x HCl
Other applications
Thionyl chloride is a component of prototype lithium-thionyl chloride batteries, where it forms the anode with lithium as the cathode.
Safety
SOCl2 is a reactive compound that can 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.
References
- ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398
- ^ Hans-Dietrich Lauss, Wilfried Steffens “Sulfur Halides” in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2005.doi:10.1002/14356007.a25_623
- ^ N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, Pergamon Press, 1984.
- ^ Friedman, L. and Wetter, W. P., "Purification of Thionyl Chloride", J. Chem. Soc. A, 1967, 36-8.doi:10.1039/J19670000036
- ^ Allen, C. F. H.; Byers, Jr., J. R.; Humphlett, W. J. (1963), "Oleoyl chloride", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv4p0739; Coll. Vol. 4: 739; Rutenberg, M. W.; Horning, E. C. (1963), "1-Methyl-3-ethyloxindole", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv4p0620; Coll. Vol. 4: 620
- ^ Mondanaro, K. R.; Dailey, W. P. (2004), "3-Chloro-2-(chloromethyl)-1-propene", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=v75p0089; 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., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv9p0034; 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: 312. doi:.
- ^ Weinreb, S. M.; Chase, C. E.; Wipf, P.; Venkatraman, S. (2004), "2-Trimethylsilylethanesulfonyl chloride (SES-Cl)", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=v75p0161; 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., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv9p0400; 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:.
- ^ 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., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv7p0495; Coll. Vol. 7: 495; Kurzer, F. (1963), "p-Toluenesulfinyl chloride", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv4p0937; 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., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6p0751; Coll. Vol. 6: 751
- ^ Krynitsky, J. A.; Carhart, H. W. (1963), "2-Ethylhexanonitrile", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv4p0436; Coll. Vol. 4: 436
- ^ Alfred R. Pray, Richard F. Heitmiller, Stanley Strycker (1990). "Anhydrous Metal Chlorides". Inorganic Syntheses 28: 321–323. doi:.
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