反应详情

温度

62.5 °C

A 5 L, 4-necked, round-bottomed flaks, equipped with a mechanical stirrer, digital thermometer, reflux condenser, addition funnel with nitrogen inlet-outlet, and heating mantle is charged with (R)-α-methylbenzylamine (280.7 g, 2.316 mol), isopropanol (1.9 L) and ethyl acetate (1.63 L). The solution is stirred and heated to an internal temperature at 60-65° C., and a solution of (±)-2-butyl-3-hydroxypropionic acid (4, 322.5 g, 2.206 mol) in ethyl acetate (0.2 L) is added over a period of 15 min while maintaining the internal temperature at 60-70° C. The addition funnel is washed with ethyl acetate (0.2 L) and added to the mixture. The solution is cooled to 20-25° C. over a period of 2 hours and the resulting suspension is stirred at the same temperature for an additional 5 hours. The solids are collected by filtration, washed with a mixture of ethyl acetate-isopropanol (2:1 v/v) in two equal portions of 0.5 L each, and dried at 50-53° C. (13-49 mbar) to afford crude (R)-2-butyl-3-hydroxypropionic acid (R)-α-methylbenzylammonium salt (5, 246.3 g; 41.7%); (R):(S)=94.1:5.9.

1. customA 5 L, 4-necked, round-bottomed flaks, equipped with a mechanical stirrer
2. temperaturedigital thermometer, reflux
3. additioncondenser, addition funnel with nitrogen inlet-outlet
4. temperatureheating mantle
5. temperaturewhile maintaining the internal temperature at 60-70° C
6. washThe addition funnel is washed with ethyl acetate (0.2 L)
7. additionadded to the mixture
8. temperatureThe solution is cooled to 20-25° C. over a period of 2 hours
9. stirringthe resulting suspension is stirred at the same temperature for an additional 5 hours
10. filtrationThe solids are collected by filtration
11. washwashed with a mixture of ethyl acetate-isopropanol (2:1 v/v) in two equal portions of 0.5 L each
12. customdried at 50-53° C. (13-49 mbar)