A 500 mL reactor was charged at 25 ??C with 50 g (268.5 mmol) methyl tosylate and 100 mL acetone to which a solution of 25.1 g (281.6 mmol) N,N-dimethyl ethanolamine in 50.3 g acetone was added continuously at 25 ??C over 3 h. The dropping funnel was rinsed with additional acetone. The reaction mixture was stirred at 25 ??C for 20 h and the reaction progress was monitored by HPLC. When the level of methyltosylate was lower than 500 ppm the resulting suspension was cooled to 0 ??C over 150 min and the suspension was stirred at 0 ??C for 60 min. The product was collected by fdtration, washed two times with 175 mL acetone and dried under vacuum at 25 ??C to obtain 73.1 g (99 %) of choline tosylate as a white crystalline solid.
