4-Toluenesulfonyl chloride

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.

4-Toluenesulfonyl chloride
Names
Preferred IUPAC name
4-Methylbenzene-1-sulfonyl chloride
Other names
Tosyl chloride, p-toluenesulfonyl chloride, p-TsCl, TsCl
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.002.441
UNII
  • InChI=1S/C7H7ClO2S/c1-6-2-4-7(5-3-6)11(8,9)10/h2-5H,1H3 checkY
    Key: YYROPELSRYBVMQ-UHFFFAOYSA-N checkY
  • InChI=1/C7H7ClO2S/c1-6-2-4-7(5-3-6)11(8,9)10/h2-5H,1H3
    Key: YYROPELSRYBVMQ-UHFFFAOYAN
  • O=S(Cl)(=O)c1ccc(cc1)C
Properties
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
Reacts with water
Hazards[1]
Occupational safety and health (OHS/OSH):
Main hazards
 Releases HCl on contact with water
NFPA 704 (fire diamond)
NFPA 704 four-colored diamond
3
1
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).
☒N verify (what is checkY☒N ?)
Infobox references

Uses
Main article: Tosyl

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.

TsCl reacts with hydrazine to give p-toluenesulfonyl hydrazide.

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 and diimides.[2] In an unusual reaction focusing on the sulfur center, zinc reduces TsCl to the sulfinate, CH3C6H4SO2Na.[4]

Manufacture

This reagent is inexpensively available for laboratory use. It is a by-product from the production of ortho-toluenesulfonyl chloride (a precursor for the synthesis of the common food additive and catalyst saccharin), via the chlorosulfonation of toluene:[5]

CH3C6H5 + SO2Cl2 → CH3C6H4SO2Cl + HCl

Hazards

Tosyl chloride is considered to be a toxic and corrosive substance.[6]

References
  1. "P-TOLUENESULFONYL CHLORIDE (TOSYL CHLORIDE)".
  2. Whitaker, D. T.; Whitaker, K. S.; Johnson, C. R.; Haas, J. (2006). "P-Toluenesulfonyl Chloride". p-Toluenesulfonyl Chloride. Encyclopedia of Reagents for Organic Synthesis. New York: John Wiley. doi:10.1002/047084289X.rt136.pub2. ISBN 978-0471936237. Archived from the original on 2016-03-05. Retrieved 2013-05-28.
  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". Organic Syntheses. 83: 111.; Collective Volume, vol. 11, p. 834
  4. Whitmore, F. C.; Hamilton, F. H. (1922). "Sodium Toluenesulfinate". Organic Syntheses. 2: 89.; Collective Volume, vol. 1, p. 492
  5. Lindner, O.; Rodefeld, L. "Benzenesulfonic Acids and Their Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_507.
  6. 4-Toluenesulfonyl chloride: main hazards
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