Abstract
Comprehensive chemical characterization for two isomers of camphorsulfonic acid (CSA), occasionally used in the manufacture of active pharmaceutical ingredients (APIs), was performed by nuclear magnetic resonance (NMR) spectroscopy, high-resolution mass spectroscopy in negative electrospray ionization mode and gas chromatography/mass spectrometry (GC/MS) in electron ionization mode. Electronic circular dichroism (ECD) spectra together with quantum chemical calculations using time-dependent density functional theory (TD-DFT) were used to assign the stereochemistry for CSA for the first time and these assignments were then confirmed by single-crystal X-ray diffraction. As crystals were grown under the same conditions of high supersaturation using a mixed solvent without water removal, the crystal structures of the two enantiomers contained one ordered molecule of water in the asymmetric unit. The crystals of the (+)-enantiomer have a 1S,4R configuration and the H atom of the sulfonic acid group combines with the water molecule to form a hydronium ion, namely, hydronium (1S,4R)-(7,7-dimethyl-2-oxobicyclo[2.2.1]heptan-1-yl)methanesulfonate, H3O+·C10H15O4S−. The crystals of the (−)-enantiomer have a 1R,4S configuration. The determination of the optical purity of CSA using NMR spectroscopy with a chiral solvating agent, (1R,2R)-1,2-diphenylethane-1,2-diamine, and GC/MS with a chiral column has been well explored. The results showed that the examined samples of these two isomers of CSA proved to be enantiomerically pure. In particular, for (1R)-(−)-10-camphorsulfonic acid, this is, to our knowledge, the first description on its spectral characterization in a scientific context.
Funder
National Natural Science Foundation of China
Publisher
International Union of Crystallography (IUCr)
Subject
Materials Chemistry,Inorganic Chemistry,Physical and Theoretical Chemistry,Condensed Matter Physics
Reference38 articles.
1. D,L-10-CAMPHORSULFONIC ACID (REYCHLER'S ACID)
2. Effect of (+) or (−) camphorsulfonic acid additives to the mobile phase on enantioseparations of some basic drugs on a Chiralcel OD column
3. Borwick, S. J. & Watkin, D. J. (2002). CSD Communication (CCDC deposition number 181104). CCDC, Cambridge, England.
4. Bruhn, T., Schaumlöffel, A., Hemberger, Y. & Pecitelli, G. (2017). SpecDis. Version 1.71. Berlin, Germany. https:/specdis-software.jimdo.com.
5. Chemical Computing Group (2009). MOE2009.10. Chemical Computing Group Inc., Montreal, Canada.
Cited by
1 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献