My watch list  

P-Toluenesulfonic acid

Template:DISPLAYTITLE:p-Toluenesulfonic acid

p-Toluenesulfonic acid [1]

Chemical name 4-methylbenzenesulfonic acid
Other names p-toluenesulfonic acid
tosic acid
Chemical formula C7H8O3S
Molecular mass 172.20 g/mol
CAS number [104-15-4]
[6192-52-5] (monohydrate)
Melting point 106-107 °C
103-106 °C (monohydrate)
Boiling point 140 °C at 20 mmHg
SMILES Cc1ccc(S(=O)(O)=O)cc1
Appearance colorless (white) solid
Density and phase  ? g/cm³, ?
Solubility in water 67g/100 ml
Acidity (pKa) -2.8
Molecular shape tetrahedral at S
Dipole moment  ? D
MSDS External MSDS
Main hazards skin irritant
NFPA 704
R/S statement R: 36/37/38
S: 26
RTECS number  ?
Supplementary data page
Structure and
n, εr, etc.
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds
Other anions  ?
Other cations  ?
Related ?  ?
Related compounds  ?
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references

p-Toluenesulfonic acid (PTSA) is an organic compound with the formula CH3C6H4SO3H. TsOH, as it is abbreviated, is a white solid that is soluble in water, alcohols, and other polar organic solvents. Most often, TsOH refers to the monohydrate, TsOH.H2O.

TsOH is a strong organic acid, about a million times stronger than benzoic acid. It is one of the few strong acids that is solid and, hence, conveniently weighed. Also, unlike some of the strong mineral acids (especially nitric acid, sulfuric acid, and perchloric acid), TsOH is non-oxidizing.

Preparation and handling

TsOH is prepared on an industrial scale by the sulfonation of toluene. It hydrates readily. Common impurities include benzenesulfonic acid and sulfuric acid. Impurities can be removed by recrystallization from concentrated hydrochloric acid followed by azeotropic drying.[2]

Toluenesulfonic acid finds use in organic synthesis as an "organic-soluble" acid catalyst. Examples of uses:

See also

  • Tosyl
  • Collidine p-toluenesulfonate

It is also used as a catalyst with 3,4 dihydro-2H pyran in alcohol protection.


  1. ^ Merck Index, 11th Edition, 9459.
  2. ^ Perrin, D. D. and Armarego, W. L. F., Purification of Laboratory Chemicals, Pergamon Press: Oxford, 1988.
  3. ^ H. Griesser, H.; Öhrlein, R.; Schwab, W.; Ehrler, R.; Jäger, V. (2004). "3-Nitropropanal, 3-Nitropropanol, and 3-Nitropropanal Dimethyl Acetal". Org. Synth.; Coll. Vol. 10: 577. 
  4. ^ Furuta, K. Gao, Q.-z.; Yamamoto, H. (1998). "Chiral (Acyloxy)borane Complex-catalyzed Asymmetric Diels-Alder Reaction: (1R)-1,3,4-Trimethyl-3-cyclohexene-1-carboxaldehyde". Org. Synth.; Coll. Vol. 9: 722. 
  5. ^ Imwinkelried, R.; Schiess, M.; Seebach, D. (1993). "Diisopropyl (2S,3S)-2,3-O-isopropylidenetartrate". Org. Synth.; Coll. Vol. 8: 201. 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "P-Toluenesulfonic_acid". A list of authors is available in Wikipedia.
Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE