Study On The Synthesis Of Pendimethalin And Piperidine

As the third biggest selling herbicide in the world, pendimethalin is promoted and applied widely for its characteristics of low toxicity, high efficiency, low residue, etc. This thesis firstly made a detailed overview on synthesis, toxicity and residual of pendimethalin based on a study on references.The thesis mainly studied the synthesis of pendimethalin. Based on a comparison on different process routes, this thesis selected a comparatively less studied process route, which took 3,4-dimethyl-2,6-dinitrophenol as raw material, and studied the etherification process of 3,4-dimethyl-2,6-dinitrophenol. Taking water as solvent, adopting benzyl triethyl ammonium chloride as catalyst, optimizing the temperature of reaction, mixture ratio of raw materials and time of reaction, the cost was lowered and the yield improved; the yield of 3,4-dimethyl-2,6-dinitronisole was promoted to 95%.This thesis also studied aminolysis reaction of 3,4-dimethyl-2,6-dinitronisole. Adopting calcium chloride as catalyst and optimizing the condition of reaction, the target product was obtained in 97% yield.In the optimized conditions, the amount of 3-pentylamine was decreased and hence lowered the cost of produce of pendimethalin, 5% higher than the yield of previous process route; moreover,existence problem of nitrosamine in product of previous process route was solved.The synthesis of 3-pentylamine was also investigated by adopting the technique of fixed bed catalytic, a technique has the qualifications of producing good quality and high yield of products, causing less physical abrasion of catalyst, expanding production conveniently, etc. The reaction using this technique under the normal pressure gave a yield of 86%, which is 5% higher than the yield given by high pressure synthesis.In addition, this thesis studied the synthesis of Piperidine, a very useful intermediate. This study lowered the loss of methylene dichloride by adopting autoclave and improves the yield of Piperidine by selecting and optimizing the conditions of reaction such as solvent, acid-binding agent, by optimized reaction conditions the reaction gave the target product in 75% yield. One subsidiary product was departed in this study with its composition defined, laying foundation for the further researches.