Method for synthesizing hexazinone through continuous solvent-free reaction

Abstract

The invention discloses a method for synthesizing hexazinone through continuous solvent-free reaction. The method comprises the following steps: preparing a cyclic acid ester compound, synthesizing hexazinone and purifying hexazinone. According to the invention, N-ethylcarbonyl-N,N',N'-trimethylguanidine and cyclohexyl isocyanate are subjected to a reaction according to a certain ratio (molar ratio of 1:1) in a static mixer A at normal temperature, a mixed solution passes through a static mixer B to generate hexazinone under the action of a catalyst sodium methoxide, the generated hexazinone is subjected to acid washing neutralization through a static mixer, an organic phase enters a melt crystallizer, crystallizing is performed, and slicing is performed after qualification, so that hexazinone with the content of more than 99% and the yield of about 95% can be obtained; and n-hexane and toluene solvents do not need to be added, so that the problem of solvent volatilization does not need to be considered in the processes of neutralizing, water washing, distilling and drying of hexazinone, the production cost can be saved, and the problem that during solvent crystallization, a part of hexazinone is taken away from the mother liquor does not need to be considered so as to improve the yield.

Description

technical field [0001] The invention relates to the technical field of preparation of hexazinone, in particular to a method for synthesizing hexazinone through continuous solvent-free reaction. Background technique [0002] Hexazinone is a herbicide that kills herbicides, and its mechanism of action is to inhibit the photosynthesis of the plants to be controlled, and inhibit the absorption of the roots and leaves of the plants to be controlled, so as to achieve the control effect. [0003] Regarding its synthesis method, there are mainly three kinds of cyanide amine method, S-methylisothiourea method and methyl isothiocyanate method, among which the important synthetic route is through N-ethylcarbonyl-N,N ',N'-Trimethylguanidine and cyclohexyl isocyanate are reacted in a tubular mixing reactor, and then mixed with sodium methoxide in a tubular reactor to form hexazinone. The reaction is as follows: [0004] [0005] In the patent CN201310729322.5, the synthesized N-ethox...

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Problems solved by technology

[0007] In the above two patents, solvents such as toluene and n-hexane are used in the synthesis and crystallization, and the use of solvents will cause the loss of solvents in the processes of neutralization of hexazinone and water washing, distillation and drying, and in the process of distillation and drying When, also can increase energy consumption, also take away part of hexazinone product in the mother liquor of the mixed solvent crystallization of normal hexane and toluene simultaneously, can cause yield and reduce, thereby increased the cost of synthetic hexazinone, toluene and n-hexane The use of alkane will also cause certain damage to the environment and the human body, so it is particularly important to invent a method for the continuous solvent-free reaction synthesis of hexazinone