Synthetic Technology Of Hymexazol, Niclosamide And Imidaosamide

The development of heterocyclic compounds and pesticides are closely related with each other. The development of heterocyclic compounds contributed significa- ntly to the development of pesticides to promote pesticidein to a super–efficient pollut- ion-free new era. Heterocyclic compounds, especially nitro-contianing heterocyclic co- mpounds havebecome the mainstream of pesticides and pharmaceutical innovation. In this thesis, we discuss three nitrogen-containing heterocyclic compounds pesticides, hymexazol, niclosamide, imidacloprid, in order to get high-yield, low cost, environmental pollution, pesticides .On the basis of a large number of domestic and foreign literatures, in the th esis, hymexazol, niclosamide, pesticide imidacloprid three kinds of heterocyclic comp- ounds synthesis routes are investigated. Obtained a variety of experimental factors on yield through researing and improved synthesis reagents and methods to optimize the process conditionst to get higher yield and reduce pollution. Determine the target prod- uct by 1HNMR, Infrared.Part one. Study on hymexazol. In an organic solvent, ethyl acetoacetate, hydrochloricacid, Sodium ethoxide through closed-loop, precipitation, recrystallization, filtration, drying and other steps synthesis hymexazol. Ethanol replaces organic solvents 1,2-dichloroethane used in the traditional methods. For increaseing the solubility of Sodium ethoxide in organic solvents, this metdod promotes more complete reaction of raw materials to improve productivity, reduce costs, reduce waste liquid pollution of environment and to obtian the purpose of more environmentally friendly process route.Part two. Study on niclosamide. In this thesis discusses the timportant intermedi- ates, 5-chloroSalicylicacid and 2-chloro-4-nitroaniline of synthesis niclosamide and obtianed a successful high-yield niclosamide through condensation reaction, in the absence of solvent system, by using tetrabutylammonium bromide as phase transfer catalyst. The process uses novel synthesis method to synthesize intermediates and target products. And through multiple comparison tests, it achieves reduce the cost of production, reduce waste emissions, reduce the production of pollution on the environment and the purpose of improving yield.Part three. Study.on imidacloprid. Current industry method of preparing imidacl -oprid in organic solvents, is using 2-chloro-5-chloromethy pyridine, 2-Nitroaminoimi- dazoline, potassium carbonate to synthesise The result is high cost, low yield. While the route of pupstream raw materials of synthesis imidacloprid Most are more complex For industrial production, the lower the cost of raw materials is also very important In this paper, we propose a new route chlorine methylation to synthesis of 2-chloro- 5-chloro–methylpyridine which use 2-pyridine as raw materials Compared with the traditional method, the method of synthesis imidacloprid inreaction system is using tetrabutyl ammonium bromide as phase transfer catalyst, the use of sodium hydroxide instead of potassium carbonate and anhydrous magnesium sulfate added as an absorbent. Experiments show: Using TBAB as phase transfer catalyst can further promote rection, reduce the amount of residual material after the reaction, and reduce the cost of purification. So that it is environmentally friendly.