A New Technology For Synthesizing Acetochlor

Acetochlor is one of the herbicides used most in the world and is produced with the chloromethyl ethyl ether at present, while the product compared with the abroad falls great behind not only the overall yield but also the quality. The overall yield can be from 85% to 90% base on 2-methyl-6-ethylamine in domestic while up to 91% in abroad. Including too much impurity, which is harm to the crops, the purity of product only reach 90% in domestic while 95% in abroad. At the same time, large amout of liquid waste is given out on the traditional process. As the protection of global enviroment in these days, the traditional process is facing a serious challenge.The paper relates to a new process for synthesizing acetochlor. First step provide a homogeneous phase liquid of contacting the paraformaldehyde with equivalent of alcohol in the presence of catalytic base. 2-methyl-6-ethylazomethine is prepared by reaction of 2-methyl-6-ethylamine with formaldehyde, in which the formaldehyde comes from the homogeneous phase liquid. At the stage, water, as a product of the formaldehyde-aniline reaction, is removed from the reaction products by azeotropic distillation with xylene (as solvent) under vacuum. The second step is to prapare the 2' -methyl-6' -ethyl-N(chloromethyl)-2-chloroacetanilide intermediate by reaction of the 2-methyl-6ethylazomethine with the chloroacetyl chloride. Followed the reaction, the anhydrous ethanol is driped into the reactor at 50℃, and then gaseous ammonia is introduced to the reaction mixture for neutralizing the HCl. After the process of filtrating, washing, distilling etc, the purity of product can reach 95% and the overall yield can be 92%, meanwhile, the ammonium chloride can be gained as a by-product.In this paper, the factor mat may affect each step is anatomied and each reaction conditions are optimized. At the same time, relative compound is comfirmed through GC-MS, LC-MS, ~1H-NMR, ~13C-NMR.Medium experiment is made about the new process on the basis of laboratory's condition and the problem met in the course is argued and analyzed. By mending the equipment, 2-methyl-6ethylazomethine is producted in a tower reactor and the quality and yield of final product conforms to lab's level in medium experiment.