Use of Organic Superbases and Temperature Effects for the Development of Reversible Protic Amino Acid Salts

Novel reversible organic salts based on amino acids in the presence of organic superbases [1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and tetramethylguanidine (TMG)] have been prepared. An optimized acid-base reaction methodology allowed the preparation of novel protic amino acid salts with improved water-solubility profiles and unexpected phase behavior. Complementary differential scanning calorimetry (DSC) and thermal H-1 NMR analysis indicated that a phase separation between water and amino acid salt occurs and that the process is reversible, depending upon temperature and the selected organic superbase. These studies open the possibility for tuning miscibility and ionicity of organic salts as well as development of reversible protic chiral ionic liquids or molten salts.