In a 1L reaction flask equipped with mechanical stirring, thermometer and reflux condenser, 53.0g (0.46mol) of 2-ethoxyoxazoline, 56.0g (0.50mol) of bicyclopropylmethylamine and 200mL of toluene were added sequentially, stirred thoroughly, then the temperature was raised to reflux and the reaction was kept at reflux for 8h. At the end of the reaction, the temperature was lowered to 25, to which 5% sodium bicarbonate solution was added. 200 mL was washed, stratification, the organic phase was then washed with 200 mL saturated saline and 200 mL water in turn, anhydrous sodium sulfate drying, filtration, concentration to 76.2 g of the crude product, the crude product was then recrystallized with cyclohexane to obtain 75.0 g of white solid, content of 99.7%, m.p. 105.5~107 , yield 90.5%. Rilmenidine phosphate was prepared by salting rilmenidine with phosphoric acid.
