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 1H 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.
Key words
amino acids - green chemistry - ionic liquids - cations - protonation