1-Methylpyrrolidine → 1-(Methoxymethyl)-1-methylpyrrolidin-1-ium bromide

A 17.0 g quantity of N-methylpyrrolidine was dissolved in 160 g of dehydrated acetone (up to 0.1% in water content), followed by nitrogen replacement. To the solution was added dropwise 24.6 g of bromomethyl methyl ether (reagent, product of Tokyo Kasei Co., Ltd.) at 5° C. over a period of 1.5 hours. The mixture was stirred at 5 to not higher than 15° C. for 4 hours to terminate the reaction. The reaction mixture was filtered, and the resulting solids were washed with 160 g of acetone, and dried in a vacuum, affording 30.9 g of the desired product (white solid).