Method for preparing (dimethylaminomethylene) malononitrile using a micro reaction system

A method for preparing (dimethylaminomethylene) malononitrile using a micro reaction system, the micro reaction system comprising a micromixer and a microchannel reactor connected in series, and a centrifugal extraction unit consisting of a plurality of annular centrifugal extractors;

• the method comprising:
• (1) mixing cyanoacetamide, N,N-dimethylformamide and a catalyst to produce a mixture;
• and pumping the mixture and phosphorus oxychloride into the micromixer at the same time to obtain a reaction mixture;
• (2) allowing the reaction mixture outflowed from the micromixer to flow immediately into the microchannel reactor for continuous-flow reaction;
• and quenching the reaction with a quencher to produce a crude product after the reaction mixture flowed out of the microchannel reactor;
• (3) adjusting the pH of the crude product to 2-10 with a pH regulator;
• and
• (4) pumping the crude product into the centrifugal extraction unit;
• introducing an organic solvent into the centrifugal extraction unit at the same time to perform continuous liquid-liquid extraction;
• collecting the organic phase outflowed from the centrifugal extraction unit to afford the target product (dimethylaminomethylene) malononitrile (I) after necessary workup.