Acetonitrile → 1-(5-Carboxy-pentyl)-4-methyl-quinolinium iodide

To a 250 mL flask were added lepidine (7.5 g, 52.4 mmol), acetonitrile (40 mL) and 6-iodohexanoic acid (14.0 g, 57.9 mmol). The mixture was heated at reflux under argon for 40 h and then was cooled to rt. The mixture was poured into stirred ether (700 mL) and the stirring was continued until the supernatant liquid was clear. The supernatant was decanted and the residue was dissolved in DCM (60 mL). The solution was poured slowly into stirred ether (700 mL). The initially formed oil solidified after stirring for approx. 3 h. The solid was crushed to a powder and stirring was continued for 1 h. The solid was filtered off, washed with ether (2×60 mL), and dried under vacuum to afford 14 as a tan colored solid (17.6 g, 87%).