110-86-1

143-15-7

104-73-4

Ionic liquids (ILs) were synthesized from pyridine and dodecyl bromide by direct alkylation reaction in a round-bottomed flask (5.4 cm in diameter and 60 mL in total volume) equipped with a reflux condenser, a magnetic stirrer (250 rpm), and a heating device. The reaction was carried out in an oil bath at 80 °C with continuous stirring of the reaction mixture for 3 h to 17 h. The reaction was carried out under the protection of N2 atmosphere. During the reaction, the formation of a second lower phase containing the ionic liquid was observed. After completion of the reaction, the mixture was cooled to room temperature. For different bromo alkanes the synthesis conditions were as follows: 1. n-Butylpyridinium bromide: Heating for 3 hours. After the reaction, excess reagent was removed under reduced pressure and the resulting solid pyridinium salt was washed with ether and dried to give 17.3 g of the target product [BuPy][Br] in 80% chemical yield. 2. n-Hexylpyridinium bromide: Heated for 3 hours. After cooling, the white precipitate formed was filtered, washed and dried with about 350 mL of diethyl ether to give 21.2 g of [HePy][Br] ionic liquid in 87% chemical yield. 3. n-Octylpyridinium bromide: heated for 3 hours. 21.4 g [OcPy][Br] was obtained as a light brown liquid in 79% chemical yield. 4. n-Dodecylpyridinium bromide: Heated for 17 hours. After cooling, the white precipitate formed was filtered, washed and dried with 100 mL of ether to give 22.0 g of [DoDePy][Br] ionic liquid in 67% chemical yield.