II, Synthesis of 3-methylamino-1,2-propanediol
(1) Pressure test: the reactor is subjected to pressure test to ensure that all test indexes are qualified before use.
(2) feeding: start the hydraulic vacuum pump, vacuum the autoclave to 0.03MPa, then add the raw material into the high-pressure reactor according to the ratio of glycerol and liquid monomethylamine molar ratio of 1:10.
(3) Reaction conditions: the temperature of the amination reactor was raised to 50℃±5℃, the pressure was maintained at 4.1-4.2MPa, and the reaction lasted 40 minutes.
(4) Monomethylamine recovery: After the reaction is completed, monomethylamine is recovered by vacuum at 0.080 MPa, and the monomethylamine recovery device is utilized to recover the monomethylamine to the storage tank for reuse.
(5) Distillation and purification:
(1) Primary distillation: cool the autoclave to below 30℃, transfer the reaction mixture to the distillation kettle. Start the water jet vacuum pump, pass steam heating to the jacket of the distillation kettle, control the vacuum in the kettle to 0.06~0.07MPa. When the condensate starts to flow out, switch to the high-vacuum root-water ring unit, adjust the vacuum of the receiving tank to 0.0990~0.0998MPa, and monitor the temperature of the gas phase to 98.0℃ in order to remove the pre-fraction.
(2) Main fraction collection: when the distillation temperature exceeds 98.1°C, switch to the finished product condensate tank, keep the vacuum degree to 0.0990~0.0998MPa, collect the fraction with condensing vapor temperature of 98.1-101.0°C, which is the target product of 3-methylamino-1,2-propanediol. The product was a colorless transparent viscous liquid with 98.99% yield, 99.96% purity, 0.04% impurity content and 0.35% moisture content.