Protic ionic liquids with nitrate anions were used as solvents and catalysts for a three-component oxidative dehydrogenation tandem reaction via the coupling and hydroarylation of benzaldehyde, aniline, and phenylacetylene to a quinoline derivative. The reaction was supported by air and microwave irradiation. The presence of nitrate as counter anion in the protic ionic liquids was essential for the reaction.
Piperidinium nitrate was studied by FTIR and FT Raman spectroscopy in the range 100-4000 cm-1 at 300 K. On the basis of DSC measurements which exhibit two effects indicating phase transition at 256 and 295 K, FTIR spectra were recorded down to a temperature of 90 K. Discussion of the phase transition mechanism is based on the observed changes in the FTIR spectra during cooling of the compound.