Salts of (+)-deoxycholic acid with amines: structure, thermal stability, kinetics of salt formation, decomposition and chiral resolution

Abstract

(+)-Deoxycholic acid forms salts with 1-propylamine, di-n-butylamine, sec-butylamine and 3-methyl-2-butylamine. The salts were characterised using thermal analysis and single crystal X-ray diffraction. The chiral discrimination of (+)-deoxycholic acid for racemic sec-butylamine and racemic 3-methyl-2-butylamine was studied and correlated with the structural and thermal results. A mixture of (+)-deoxycholic acid and racemic sec-butylamine yielded crystals of (R)-2-butylammonium deoxycholate. (+)-Deoxycholic acid was exposed to vapours of propylamine and racemic sec-butylamine and the kinetics of absorption were determined. The kinetics of decomposition of powdered samples obtained from (+)-deoxycholic acid with di-n-butylamine and racemic sec-butylamine were investigated. Crystallisation of (+)-deoxycholic acid with racemic 3-methyl-2-butylamine resulted in crystals of (S)-3-methyl-2-butylammonium deoxycholate.