A mixture of
sodium hydroxide
(0.78 g, 19.5 mmol), naproxen (4.60 g, 20.0 mmol), and ethanol (40
mL) was placed in the flask and shaken vigorously for 0.5 h, and the
ethanol was distilled off. The solid cake was treated with ethyl acetate.
The solid white powder of naproxen sodium was obtained with a constant
weight under vacuum at 45 °C. Naproxen sodium with the equimolecular
[Omim]Br, benzalkonium chloride, or choline chloride was dissolved
in ethanol. The mixture solution was stirred under the protection
of nitrogen at 35 °C for 24 h and then naturally cooled to room
temperature and filtered with a sand core funnel (bore diameter 3–4
μm). After removing the solvent by reduced pressure distillation,
the oily or waxy substances were obtained and dried under reduced
pressure at 45 °C to a constant weight (about 60 h). The faint
yellow viscous liquids ([Ben][Nap] or [Omim][Nap]) or white waxy ([Ch][Nap])
substances, naproxen-based ILs, were obtained (Scheme 1 ), and the yield was above 90%.
All naproxen-based ILs were completely characterized by 1H NMR (Bruker AVANCE 600 MHz, DE) to confirm the expected cation/anion
ratios. A sand core funnel can filter the precipitates (NaCl or NaBr)
better. High-performance liquid chromatography (HPLC) (Agilent 1260,
USA) was used to check the structure and final purity of the obtained
naproxen-based ILs. The purity was 99.6% (wt %) with the naproxen
reference substance (ID: Y15D8C505 69).
sodium hydroxide
(0.78 g, 19.5 mmol), naproxen (4.60 g, 20.0 mmol), and ethanol (40
mL) was placed in the flask and shaken vigorously for 0.5 h, and the
ethanol was distilled off. The solid cake was treated with ethyl acetate.
The solid white powder of naproxen sodium was obtained with a constant
weight under vacuum at 45 °C. Naproxen sodium with the equimolecular
[Omim]Br, benzalkonium chloride, or choline chloride was dissolved
in ethanol. The mixture solution was stirred under the protection
of nitrogen at 35 °C for 24 h and then naturally cooled to room
temperature and filtered with a sand core funnel (bore diameter 3–4
μm). After removing the solvent by reduced pressure distillation,
the oily or waxy substances were obtained and dried under reduced
pressure at 45 °C to a constant weight (about 60 h). The faint
yellow viscous liquids ([Ben][Nap] or [Omim][Nap]) or white waxy ([Ch][Nap])
substances, naproxen-based ILs, were obtained (
All naproxen-based ILs were completely characterized by 1H NMR (Bruker AVANCE 600 MHz, DE) to confirm the expected cation/anion
ratios. A sand core funnel can filter the precipitates (NaCl or NaBr)
better. High-performance liquid chromatography (HPLC) (Agilent 1260,
USA) was used to check the structure and final purity of the obtained
naproxen-based ILs. The purity was 99.6% (wt %) with the naproxen
reference substance (ID: Y15D8C505 69).
