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Camphorsulfonic acid

Camphorsulfonic acid, sometimes abbreviated CSA or 10-CSA is an organosulfur compound. Like typical sulfonic acids, it is a relatively strong acid that is a colorless solid at room temperature and is soluble in water and a wide variety of organic substances.

Camphorsulfonic acid
Wireframe model of camphorsulfonic acid
Preferred IUPAC name
(7,7-dimethyl-2-oxobicyclo[2.2.1]heptan-1-yl)methanesulfonic acid
Other names
Reychler's acid; 2-Oxobornane-10-sulfonic acid
3D model (JSmol)
ECHA InfoCard 100.025.024
EC Number
  • 227-527-0
MeSH 10-Camphorsulfonic+acid
UN number 1759
Molar mass 232.29 g·mol−1
Melting point 195 °C (decomposes)
Acidity (pKa) 1.2
Safety data sheet External MSDS
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

This compound is commercially available. It can be prepared by sulfonation of camphor with sulfuric acid and acetic anhydride:[1]

10-CSA synthesis.png

Although this reaction appears to be a sulfonation of an unactivated methyl group, the actual mechanism is believed to involve a retro-semipinacol rearrangement, elimination of a proton from the tertiary carbocation to form an alkene, sulfonation of the alkene intermediate, and finally, semipinacol rearrangement to re-establish the ketone function.[2]

In organic synthesis, CSA and its derivatives can be used as resolving agents for chiral amines and other cations.[3][4] The synthesis of osanetant was an example of this. 3-bromocamphor-8-sulfonic acid was used in the synthesis of enantiopure devazepide.[5]

Camphorsulfonic acid is used in some pharmaceutical formulations, where is it referred to as camsilate or camsylate, including trimetaphan camsilate and lanabecestat camsylate.


  1. ^ Paul D. Bartlett and L. H. Knox (1973). "D,L-10-Camphorsulfonic acid (Reychler's Acid)". Organic Syntheses.; Collective Volume, 5, p. 194
  2. ^ 1955-, Brückner, Reinhard (2002). Advanced organic chemistry : reaction mechanisms. San Diego: Harcourt/Academic Press. ISBN 9780080498805. OCLC 269472848.
  3. ^ D. Clark, Robin; R. Kern, John; J. Kurz, Lilia; T. Nelson, Janis (1990). "Preparation of Enatiomerically Pure Decahydro-6H-isoquino[2,1-g][1,6]naphthyridines Utilizing the Openshaw-Whittaker Hexahydrobenzo[a]quinolizinone Resolution". Heterocycles. 31 (2): 353. doi:10.3987/COM-89-5250.
  4. ^ André B. Charette "3-Bromocamphor-8-sulfonic Acid" Encyclopedia of Reagents for Organic Synthesis 2001, John Wiley & Sons. doi:10.1002/047084289X.rb283
  5. ^ Reider, Paul J.; Davis, Paul; Hughes, David L.; Grabowski, Edward J. J. (1987). "Crystallization-induced asymmetric transformation: Stereospecific synthesis of a potent peripheral CCK antagonist". J. Org. Chem. 52 (5): 955–957. doi:10.1021/jo00381a052.