Uses
1-Butyl-3-methylpyridinium bromide is a 1-alkyl-3-alkyl-pyridinium halide compound. 1-alkyl-3-alkyl-pyridinium halides can be used as bromine-complexing agents in aqueous zinc bromide solutions used in zinc/bromine rechargeable batteries (i.e., both membrane-equipped and membraneless zinc/bromine flow batteries). It has been found that complexes formed by using 1-alkyl-3-methylpyridinium bromide or mixtures thereof do not solidify at temperatures as low as 0°C or even -5°C, thereby maintaining the fluidity of electrolyte solutions with different compositions corresponding to different states of charge of the battery over a wide operating temperature range.
Synthesis
Equip the double-sided reactor with a magnetic stirrer, condenser, thermowell and dropping funnel. The reactor was purged with nitrogen during the entire step. 3-Methylpyridine (465 g) was charged to the reactor and the reactor was heated to 79C. Then, n-butane bromide (718 g) was added dropwise for 4 hours. The reaction mixture was heated at 80C for 0.5 hours. DIW (500 mL) was added; the mixture was cooled and the volatiles were evaporated in a rotary evaporator. Additional DIW (500 g) was added and the mixture was re-evaporated. DIW was added to make up the dilution (correct). Final product 1-butyl-3-methylpyridinium bromide, 1431 g, 77.5 wt% (silver titration); yield, 96.5%.
