p-Toluenesulfonic acid
From Wikipedia, the free encyclopedia
| p-Toluenesulfonic acid[1] | |
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| IUPAC name | 4-methylbenzenesulfonic acid |
| Other names | Tosylic acid p-toluenesulfonic acid tosic acid PTSA |
| Identifiers | |
| CAS number | 104-15-4 6192-52-5 (monohydrate) |
| SMILES | Cc1ccc(S(=O)(O)=O)cc1 |
| Properties | |
| Molecular formula | C7H8O3S |
| Molar mass | 172.20 g/mol 190.22 g/mol (monohydrate) |
| Appearance | colorless (white) solid |
| Melting point |
106-107 °C |
| Boiling point |
140 °C at 20 mmHg |
| Solubility in water | 67g/100 ml |
| Acidity (pKa) | -2.8 |
| Structure | |
| Molecular shape | tetrahedral at S |
| Hazards | |
| Main hazards | skin irritant |
| R-phrases | 36/37/38 |
| S-phrases | 26 |
| Related compounds | |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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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.
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[edit] 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:
- Acetalization of an aldehyde.[3]
- Esterification of carboxylic acids.[4]
- Transesterification of an ester.[5]
[edit] See also
It is also used as a catalyst with 3,4 dihydro-2H pyran in alcohol protection.
[edit] References
- ^ Merck Index, 11th Edition, 9459.
- ^ Perrin, D. D. and Armarego, W. L. F., Purification of Laboratory Chemicals, Pergamon Press: Oxford, 1988.
- ^ 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.
- ^ 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.
- ^ Imwinkelried, R.; Schiess, M.; Seebach, D. (1993). "Diisopropyl (2S,3S)-2,3-O-isopropylidenetartrate". Org. Synth.; Coll. Vol. 8: 201.
