Thionyl chloride

Thionyl chloride
Names
	IUPAC name Sulfurous dichloride
	Other names Thionyl dichloride; Sulfurous oxychloride; Sulfinyl chloride; sulfinyl dichloride; Dichlorosulfoxide; Sulfur oxide dichloride; Sulfur monoxide dichloride; Sulfuryl(IV) chloride
Identifiers
CAS Number	7719-09-7 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:29290 ;
ChemSpider	22797 ;
ECHA InfoCard	100.028.863
EC Number	231-748-8;
PubChem CID	24386;
RTECS number	XM5150000;
UN number	1836
CompTox Dashboard (EPA)	DTXSID3064778 ;
	InChI InChI=1S/Cl2OS/c1-4(2)3 Key: FYSNRJHAOHDILO-UHFFFAOYSA-N ; Key: FYSNRJHAOHDILO-UHFFFAOYAN;
	SMILES ClS(Cl)=O;
Properties
Chemical formula	SOCl2
Molar mass	118.97 g/mol
Appearance	clear; colorless 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)
Viscosity	0.6 cP
Structure
Molecular shape	pyramidal
Dipole moment	1.4 D
Hazards
NFPA 704 (fire diamond)	4 0 2 W
Flash point	Non-flammable
Related compounds
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Thionyl chloride is an inorganic compound with the formula S O Cl₂. 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 per year of SOCl₂ were produced in the early 1990s.^[2]

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 COCl₂ is planar. SOCl₂ reacts with water to release hydrogen chloride and sulfur dioxide.

SOCl₂ + H₂O → 2 HCl + SO₂

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 four 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]

Reaction of thionyl chloride with a carboxylic acid

Alcohols react with thionyl chloride to give the corresponding alkyl chlorides in Darzens reaction.^[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 simplifies 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]

Thionyl chloride can also produce nitriles from amides via E2 elimination.^[13]

Inorganic chemistry

Anhydrous metal chlorides may be obtained from hydrated metal chlorides by refluxing in freshly distilled thionyl chloride:^[14]

MCl_n·xH₂O + x SOCl₂ → MCl_n + x SO₂ + 2x HCl

Other applications

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).

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 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 978-0-08-022057-4..
^ 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". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 4, p. 739.; Rutenberg, M. W.; Horning, E. C. (1963). "1-Methyl-3-ethyloxindole". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 4, p. 620.
^ Mondanaro, K. R.; Dailey, W. P. (2004). "3-Chloro-2-(chloromethyl)-1-propene". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 10, p. 212.; Krakowiak, K. E.; Bradshaw, J. S. (1998). "4-Benzyl-10,19-diethyl-4,10,19-triaza-1,7,13,16-tetraoxacycloheneicosane". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 9, p. 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.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ Weinreb, S. M.; Chase, C. E.; Wipf, P.; Venkatraman, S. (2004). "2-Trimethylsilylethanesulfonyl chloride (SES-Cl)". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 10, p. 707.
^ Hazen, G. G.; Bollinger, F. W.; Roberts, F. E.; Russ, W. K.; Seman, J. J.; Staskiewicz, S. (1998). "4-Dodecylbenzenesulfonyl azides". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 9, p. 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.
^ 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". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 7, p. 495.; Kurzer, F. (1963). "p-Toluenesulfinyl chloride". Organic Syntheses; Collected Volumes, vol. 4, p. 937.
^ Niznik, G. E.; Morrison, III, W. H.; Walborsky, H. M. (1988). "1-d-Aldehydes from organometallic reagents: 2-methylbutanal-1-d". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 6, p. 751.
^ Krynitsky, J. A.; Carhart, H. W. (1963). "2-Ethylhexanonitrile". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 4, p. 436.
^ John E. McMurry (2010). Fundamentals of Organic Chemistry (7th ed.). Cengage Learning. p. 767. ISBN 1-4390-4971-8.
^ 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.{{cite journal}}: CS1 maint: multiple names: authors list (link)

External links

[1] Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8

[2] Hans-Dietrich Lauss, Wilfried Steffens “Sulfur Halides” in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2005.doi:10.1002/14356007.a25_623

[3] Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. p. 820. ISBN 978-0-08-022057-4..

[4] Friedman, L. and Wetter, W. P., "Purification of Thionyl Chloride", J. Chem. Soc. A, 1967, 36-8.doi:10.1039/J19670000036

[5] Allen, C. F. H.; Byers, Jr., J. R.; Humphlett, W. J. (1963). "Oleoyl chloride". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 4, p. 739.; Rutenberg, M. W.; Horning, E. C. (1963). "1-Methyl-3-ethyloxindole". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 4, p. 620.

[6] Mondanaro, K. R.; Dailey, W. P. (2004). "3-Chloro-2-(chloromethyl)-1-propene". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 10, p. 212.; Krakowiak, K. E.; Bradshaw, J. S. (1998). "4-Benzyl-10,19-diethyl-4,10,19-triaza-1,7,13,16-tetraoxacycloheneicosane". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 9, p. 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.{{cite journal}}: CS1 maint: multiple names: authors list (link)

[7] Weinreb, S. M.; Chase, C. E.; Wipf, P.; Venkatraman, S. (2004). "2-Trimethylsilylethanesulfonyl chloride (SES-Cl)". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 10, p. 707.

[8] Hazen, G. G.; Bollinger, F. W.; Roberts, F. E.; Russ, W. K.; Seman, J. J.; Staskiewicz, S. (1998). "4-Dodecylbenzenesulfonyl azides". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 9, p. 400.

[9] 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.

[10] 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". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 7, p. 495.; Kurzer, F. (1963). "p-Toluenesulfinyl chloride". Organic Syntheses; Collected Volumes, vol. 4, p. 937.

[11] Niznik, G. E.; Morrison, III, W. H.; Walborsky, H. M. (1988). "1-d-Aldehydes from organometallic reagents: 2-methylbutanal-1-d". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 6, p. 751.

[12] Krynitsky, J. A.; Carhart, H. W. (1963). "2-Ethylhexanonitrile". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 4, p. 436.

[13] John E. McMurry (2010). Fundamentals of Organic Chemistry (7th ed.). Cengage Learning. p. 767. ISBN 1-4390-4971-8.

[14] 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.{{cite journal}}: CS1 maint: multiple names: authors list (link)

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