Synthesis Of 1-Methylamino-1-Methylthio-2-Ni-Troethylene

A selective H2 receptor antagonist Ranitidine, the price of which is low, has significant results in treating peptic ulcer. In recent years, Ranitidine has been found have good performances in treating other diseases, for example urinary system diseases, respiratory diseases and so on. Therefore, the quality of Ranitidine that the market demand for will continuously increasing.1-methylamino-1-methylthio-2-nitroethylene, an important intermediate for synth-esising Ranitidine. The demanded quatity of 1-methylamino-1-methylthio-2-nitroethyl-ene is increasing year by year, with the market of Ranitidine expanding. In recent years, the profits of the product become lower, for the fiercely competitive among 1-methylamino-1-methylthio-2-nitroethylene production enterprises. So improve curre-nt technics, reduce production costs can make enterprises get more profits.CH3NO2, CS2, anhydrous C2H5OH, CH3NH2, Me2SO4 are chosen as raw materials in the experiment. The technics condensation-ammoniation-methylation is used to synthesis 1-methylamino-1-methylthio-2-nitroethylene.In ammoniation and methylation reactions, organic solvent was insteaded by water, can save solvent, reduce costs. In ammoniation reaction the TLC method is used to monitor reaction process, which can accurately and easilv identified the reaction endpoint.A better technics is obtained. In condensation reaction, solvent is anhydrous C2H5OH. m(anhydrous C2H5OH)/m (CH3NO2)=5, reaction temperature is 39～41℃, reaction time is 1.5～2.0 h. n (CS2)/n (CH3NO2)= 1.2, n (KOH) /n (CH3NO2)=2.2, the yield of this step is 93.2%. Compared with the original technics, reaction time shortened 1.5h yield increased 8.7%. In ammoniation reaction, m (CH3NH2)/m (condensation product)= 1.4. the reaction temperature below 72℃, use TLC method to monitor ammoniation process. The original method that remove sample to do text in ammoniation process was instead. Determined ammoniation reaction time is 4h, shortened 8h compared with original technics. Me2SO4 was used as methylation reagent, the reaction temperature is 13～15℃. The reaction is completed, when the pH=After the product is refined, melting point and infrared spectra are consistent with the literature reported. Using HPLC to measure the content of the productis 9 8.4%. The overall yield of the three steps is 40.5%, get to the reported yield in the literature.