Camphorsulfonic acid

{{Chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 460015608

| ImageFileL1 = 10-camphorsulfonic acid.svg

| ImageSizeL1 = 100px

| ImageNameL1 = Wireframe model of camphorsulfonic acid

| ImageFileR1 = Camphorsulfonic-acid-from-xtal-3D-bs-17-view-5.png

| ImageSizeR1 = 125px

| PIN = (7,7-dimethyl-2-oxobicyclo[2.2.1]heptan-1-yl)methanesulfonic acid

| OtherNames = Reychler's acid; 2-Oxobornane-10-sulfonic acid

|Section1={{Chembox Identifiers

| CASNo_Ref = {{cascite|correct|CAS}}

| CASNo = 5872-08-2

| CASNo1_Ref = {{cascite|correct|CAS}}

| CASNo1 = 35963-20-3

| CASNo1_Comment = (1R)

| CASNo2_Ref = {{cascite|correct|CAS}}

| CASNo2 = 3144-16-9

| CASNo2_Comment = (1S)

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = D8D049375Q

| UNII1_Ref = {{fdacite|correct|FDA}}

| UNII1 = Y6075I4FXE

| UNII1_Comment = (1R)

| UNII2_Ref = {{fdacite|correct|FDA}}

| UNII2 = 9TLZ01S15L

| UNII2_Comment = (1S)

| PubChem = 18462

| PubChem1 = 131278

| PubChem1_Comment = (1R)

| PubChem2 = 218580

| PubChem2_Comment = (1S)

| PubChem3 = 43833349

| PubChem3_Comment = (4R)

| PubChem4 = 3057042

| PubChem4_Comment = (4S)

| ChemSpiderID = 17438

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID1 = 116050

| ChemSpiderID1_Comment = (1R)

| ChemSpiderID1_Ref = {{chemspidercite|correct|ChemSpider}}

| ChemSpiderID2 = 189449

| ChemSpiderID2_Comment = (1S)

| ChemSpiderID2_Ref = {{chemspidercite|correct|ChemSpider}}

| ChemSpiderID3 = 2318313

| ChemSpiderID3_Comment = (4S)

| ChemSpiderID3_Ref = {{chemspidercite|correct|ChemSpider}}

| EINECS = 227-527-0

| UNNumber = 1759

| MeSHName = 10-Camphorsulfonic+acid

| ChEBI_Ref = {{ebicite|correct|EBI}}

| ChEBI = 55379

| SMILES = CC1(C2CCC1(C(=O)C2)CS(=O)(=O)O)C

| SMILES1 = O=S(=O)(O)CC12C(=O)CC(CC1)C2(C)C

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/C10H16O4S/c1-9(2)7-3-4-10(9,8(11)5-7)6-15(12,13)14/h7H,3-6H2,1-2H3,(H,12,13,14)

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = MIOPJNTWMNEORI-UHFFFAOYSA-N

| Beilstein = 2216194

}}

|Section2={{Chembox Properties

| C=10 | H=16 | O=4 | S=1

| Appearance =

| Density =

| MeltingPt = 195 °C (decomposes)

| BoilingPt =

| Solubility =

| pKa = 1.2

}}

|Section3={{Chembox Hazards

| ExternalSDS = [https://fscimage.fishersci.com/msds/33354.htm External MSDS]

| FlashPt =

| AutoignitionPt =

}}

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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.

This compound is commercially available. It can be prepared by sulfonation of camphor with sulfuric acid and acetic anhydride:{{OrgSynth | title = D,L-10-Camphorsulfonic acid (Reychler's Acid) | first1 = Paul D.| last1= Bartlett | first2= L. H.| last2= Knox | doi = 10.15227/orgsyn.045.0012 | year = 1965 | volume = 45 | pages = 12}}

:File: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, deprotonation next to the tertiary carbocation to form an alkene, sulfonation of the alkene intermediate, and finally, semipinacol rearrangement to re-establish the ketone function.{{Cite book|title=Advanced organic chemistry : reaction mechanisms|last=Brückner|first=Reinhard|date=2002|publisher=Harcourt/Academic Press |isbn= 9780080498805 |location= San Diego |oclc=269472848}}

In organic synthesis, CSA and its derivatives can be used as resolving agents for chiral amines and other cations.{{cite journal | journal = Heterocycles | volume = 31 | pages = 353 | year = 1990 | doi = 10.3987/COM-89-5250 | title = Preparation of Enatiomerically Pure Decahydro-6H-isoquino[2,1-g][1,6]naphthyridines Utilizing the Openshaw-Whittaker Hexahydrobenzo[a]quinolizinone Resolution | last1 = Clark | first1 = Robin D. | last2 = Kern | first2 = John R. | last3 = Kurz | first3 = Lilia J. | last4 = Nelson | first4 = Janis T. | issue = 2| doi-access = free }}{{cite encyclopedia| first1= André B.| last1= Charette |title= 3-Bromocamphor-8-sulfonic Acid| encyclopedia= Encyclopedia of Reagents for Organic Synthesis |year= 2001| publisher= John Wiley & Sons| doi= 10.1002/047084289X.rb283| isbn= 0471936235}} The synthesis of osanetant was an example of this. 3-bromocamphor-8-sulfonic acid was used in the synthesis of enantiopure devazepide.{{cite journal | journal = J. Org. Chem. | doi = 10.1021/jo00381a052 | title = Crystallization-induced asymmetric transformation: Stereospecific synthesis of a potent peripheral CCK antagonist | year = 1987 | last1 = Reider | first1 = Paul J. | last2 = Davis | first2 = Paul | last3 = Hughes | first3 = David L. | last4 = Grabowski | first4 = Edward J. J. | volume = 52 | issue = 5 | pages = 955–957}}

Camphorsulfonic acid is also being used for the synthesis of quinolines.{{cite journal | journal = Eur. J. Org. Chem. | doi = 10.1002/ejoc.201900325 | title = Microwave-Assisted Metal-Free Rapid Synthesis of C4-Arylated Quinolines via Povarov Type Multicomponent Reactiont | year = 2019 | last1 = Chandra | first1 = Devesh | last2 = Dhiman | first2 = Ankit K | last3 = Kumar | first3 = Rakesh | last4 = Sharma | first4 = Upendra | volume = 2019 | issue = 16 | pages = 2753–2758| s2cid = 107383202 }} Camphorsulfonic acid is used in some pharmaceutical formulations, where is it referred to as camsilate or camsylate, including trimetaphan camsilate and lanabecestat camsylate. Some studies (c.f. Lednicer) support that D-CSA was used for the resolution of Chloramphenicol.