P-Toluenesulfonic acid

p-Toluenesulfonic acid^[1]
	; Slightly impure sample of the monohydrate
Names
	Preferred IUPAC name 4-Methylbenzene-1-sulfonic acid
	Other names 4-Methylbenzenesulfonic acid; Tosylic acid ; Tosic acid; para-Toluenesulfonic acid; PTSA; pTsOH; TsOH
Identifiers
CAS Number	104-15-4 ; 6192-52-5 (monohydrate) ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:27849 ;
ChEMBL	ChEMBL541253 ;
ChemSpider	5876 ;
DrugBank	DB03120 ;
ECHA InfoCard	100.002.891
KEGG	C06677 ;
PubChem CID	6101;
UNII	QGV5ZG5741 ; 3BTO78GAFF ((monohydrate) ;
CompTox Dashboard (EPA)	DTXSID0026701 ;
	InChI InChI=1S/C7H8O3S/c1-6-2-4-7(5-3-6)11(8,9)10/h2-5H,1H3,(H,8,9,10) Key: JOXIMZWYDAKGHI-UHFFFAOYSA-N ; InChI=1/C7H8O3S/c1-6-2-4-7(5-3-6)11(8,9)10/h2-5H,1H3,(H,8,9,10) Key: JOXIMZWYDAKGHI-UHFFFAOYAG;
	SMILES Cc1ccc(cc1)S(=O)(=O)O;
Properties
Chemical formula	C7H8O3S
Molar mass	172.20 g/mol (anhydrous); 190.22 g/mol (monohydrate)
Appearance	colorless (white) solid
Density	1.24 g/cm3
Melting point	105 to 107 °C (221 to 225 °F; 378 to 380 K) (monohydrate) ; 38 °C (100 °F; 311 K) (anhydrous)
Boiling point	140 °C (284 °F; 413 K) at 20 mmHg
Solubility in water	67 g/100 mL
Acidity (pKa)	−2.8 (water) reference for benzenesulfonic acid,; 8.5 (acetonitrile)
Structure
Molecular shape	tetrahedral at S
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	skin irritant
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	P302+P352, P305+P351+P338
Safety data sheet (SDS)	External MSDS
Related compounds
Related sulfonic acids	Benzenesulfonic acid; Sulfanilic acid
	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

p-Toluenesulfonic acid (PTSA, pTSA, or pTsOH) or tosylic acid (TsOH) is an organic compound with the formula CH₃ C₆H₄ SO₃H. It is a white extremely hygroscopic solid that is soluble in water, alcohols, and other polar organic solvents.^[6] The CH₃C₆H₄SO₂ group is known as the tosyl group and is often abbreviated as Ts or Tos. Most often, TsOH refers to the monohydrate, TsOH^.H₂O.^[6]

As with other aryl sulfonic acids, TsOH is a strong organic acid. It is about one million times stronger than benzoic acid.^[6] It is one of the few strong acids that is solid and therefore is conveniently weighed and stored.

^ Merck Index, 11th Edition, 9459.
^ ^a ^b Cite error: The named reference Armarego_2003 was invoked but never defined (see the help page).
^ Guthrie, J. P. Hydrolysis of esters of oxy acids: pK_a values for strong acids. Can. J. Chem. 1978, 56, 2342-2354. doi:10.1139/v78-385
^ Eckert, F.; Leito, I.; Kaljurand, I.; Kütt, A.; Klamt, A.; Diedenhofen, M. Prediction of Acidity in Acetonitrile Solution with COSMO-RS. J. Comput. Chem. 2009, 30, 799-810. doi:10.1002/jcc.21103
^ GHS: GESTIS 510754
^ ^a ^b ^c Baghernejad, Bita (31 August 2011). "Application of p-toluenesulfonic Acid (PTSA) in Organic Synthesis". Current Organic Chemistry. 15 (17): 3091–3097. doi:10.2174/138527211798357074.

[1] Merck Index, 11th Edition, 9459.

[Armarego_2003-2] Cite error: The named reference Armarego_2003 was invoked but never defined (see the help page).

[3] Guthrie, J. P. Hydrolysis of esters of oxy acids: pK_a values for strong acids. Can. J. Chem. 1978, 56, 2342-2354. doi:10.1139/v78-385

[4] Eckert, F.; Leito, I.; Kaljurand, I.; Kütt, A.; Klamt, A.; Diedenhofen, M. Prediction of Acidity in Acetonitrile Solution with COSMO-RS. J. Comput. Chem. 2009, 30, 799-810. doi:10.1002/jcc.21103

[5] GHS: GESTIS 510754

[Baghernejad_2011-6] Baghernejad, Bita (31 August 2011). "Application of p-toluenesulfonic Acid (PTSA) in Organic Synthesis". Current Organic Chemistry. 15 (17): 3091–3097. doi:10.2174/138527211798357074.

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