4-Toluenesulfonyl chloride

4-Toluenesulfonyl chloride

Names
IUPAC name 4-methylbenzenesulfonyl chloride
Other names Tosyl chloride, p-toluenesulfonyl chloride, p-TsCl, TsCl
Identifiers
CAS Number	98-59-9
ChemSpider	7119
Jmol interactive 3D	Image
PubChem	160808444
InChI InChI=1S/C7H7ClO2S/c1-6-2-4-7(5-3-6)11(8,9)10/h2-5H,1H3 Key: YYROPELSRYBVMQ-UHFFFAOYSA-N InChI=1/C7H7ClO2S/c1-6-2-4-7(5-3-6)11(8,9)10/h2-5H,1H3 Key: YYROPELSRYBVMQ-UHFFFAOYAN
SMILES O=S(Cl)(=O)c1ccc(cc1)C
Properties
Chemical formula	C7H7ClO2S
Molar mass	190.65 g/mol
Appearance	White solid
Melting point	65 to 69 °C (149 to 156 °F; 338 to 342 K)
Boiling point	134 °C (273 °F; 407 K) at 10 mmHg
Solubility in water	Hydrolysis
Hazards[1]
Main hazards	Releases acid
NFPA 704	1 3 0
Flash point	128 °C (262 °F; 401 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

4-Toluenesulfonyl chloride (p-toluenesulfonyl chloride, toluene-p-sulfonyl chloride) is an organic compound with the formula CH₃C₆H₄SO₂Cl. This white, malodorous solid is a reagent widely used in organic synthesis.^[2] Abbreviated TsCl or TosCl, it is a derivative of toluene and contains a sulfonyl chloride (-SO₂Cl) functional group.

Uses

In characteristic manner, TsCl converts alcohols (abbreviated ROH) into the corresponding toluenesulfonate esters, or tosyl derivatives ("tosylates"):

CH₃C₆H₄SO₂Cl + ROH → CH₃C₆H₄SO₂OR + HCl

Tosylates can be cleaved with lithium aluminium hydride:

4 CH₃C₆H₄SO₂OR + LiAlH₄ → LiAl(O₃SC₆H₄CH₃)₄ + 4 RH

Thus, tosylation followed by reduction allows for removal of a hydroxyl group.

Likewise, TsCl is used to prepare sulfonamides from amines:^[3]

CH₃C₆H₄SO₂Cl + R₂NH → CH₃C₆H₄SO₂NR₂ + HCl

The resulting sulfonamides are non-basic and, when derived from primary amines, are even acidic.

The preparation of tosyl esters and amides are conducted in the presence of a base, which absorbs hydrogen chloride. The selection of the base is often crucial to the efficiency of tosylation. Typical bases include pyridine and triethylamine. Unusual bases are also used; for example, catalytic amounts of trimethylammonium chloride in the presence of triethylamine is highly effective by virtue of the trimethylamine.^[2]

Other reactions

Being a widely available reagent, TsCl has been heavily examined from the perspective of reactivity. It is used in dehydrations to make nitriles, isocyanides, diimides.^[2] In an unusual reaction focusing on the sulfur center, zinc reduces TsCl to the sulfinate, CH₃C₆H₄SO₂Na.^[4]

Manufacture

TsCl is inexpensively available for laboratory use. It is a by-product from the production of o-toluenesulfonyl chloride (a precursor for the synthesis of saccharin), via the chlorosulfonation of toluene:^[5]

CH₃C₆H₅ + SO₂Cl₂ → CH₃C₆H₄SO₂Cl + HCl

References

1. http://chemicalland21.com/specialtychem/finechem/p-TOLUENESULFONYL%20CHLORIDE.htm
2. Whitaker, D. T.; Whitaker, K. S.; Johnson, C. R.; Haas, J. (2006). "p-Toluenesulfonyl Chloride". Encyclopedia of Reagents for Organic Synthesis. New York: John Wiley. doi:10.1002/047084289X.rt136.pub2.
3. Ichikawa, J.; Nadano, R.; Mori, T.; Wada, Y. (2006). "5-endo-trig Cyclization of 1,1-Difluoro-1-alkenes: Synthesis of 3-Butyl-2-Fluoro-1-Tosylindole". Org. Synth. 83: 111.; Coll. Vol. 11, p. 834
4. Whitmore, F. C.; Hamilton, F. H. (1922). "Sodium Toluenesulfinate". Org. Synth. 2: 89.; Coll. Vol. 1, p. 492
5. Lindner, O.; Rodefeld, L. (2005), "Benzenesulfonic Acids and Their Derivatives", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a03_507