Synthetic Technology Study Of Neonicoti-noids Imidaclothiz, Thiamethoxam And Clothianidin

Neonicotinoid compounds are a novel class of chemical properties and theunique biological activity of chemical pesticides. Imidaclothiz, thiamethoxamand clothianidin is a second-generation neonicotinoid insecticide representativespecies, they have broad market prospects. Based on the literature synthesismethods, the key intermediate2-chloro-5-chloromethyl thiazole was synthesizedby electrochemical chlorination, and optimized the synthetic processes ofimidaclothiz, thiamethoxam, clothianidin. The specific research contents andresults are as follows:1. Synthesis of2-chloro-5-chloromethyl thiazole:2,3-dichloropropene as thestarting material, acetonitrile as the solvent, and reacting with sodium thiocyanate1.15eq under the condition of80℃for5h, to get2-chloro-3-isothiocyanato-prop-1-ene, yield is92.14%; Platinum plate as cathanode,2-chloro-3-Isothiocyanato-prop-1-ene concentration of0.4M, hydrochloric acid as the chloride electrolyte,acetonitrile as the organic solvent, the mole ratio of hydrochloric acid toacetonitrile is1:1, under the room temperature for5h, to get2-chloro-5-chloromethyl-thiazole, yield is87.44%, the current efficiency is69.95%.2. Synthesis of imidaclothiz: nitroguanidine as the starting material, water asthe solvent, and reacting with ethylenediamine1.1eq under the condition of60℃for3h, to get2-nitroaminoimidazoline, yield is85.07%; K2CO3as acid bindingagent, chloroform and water as the solvent, when the mole ratio of2-chloro-5-ch--loromethyl thiazole to2-nitroaminoimidazoline is1:1.1, under the condition of45℃for6h, to get imidaclothiz, yield is80.28%.3. Synthesis of thiamethoxam: nitroguanidine as the starting material, water as the solvent, and reacting with formaldehyde1.3eq under the condition of40℃for5h, to get N-methyl-nitroguanidine, yield is88.12%; glacial acetic acid as thesolvent, when the mole ratio of N-methyl-nitroguanidine to paraformaldehyde is1:2.3under the condition of70℃for8h, to get3-methyl-4-nitroiminoperhydro-1,3,5-oxadiazine, yield is81.07%; K2CO3as acid binding agent, acetonitrile andwater as the solvent, when the mole ratio of3-methyl-4-nitroiminoperhydro-1,3,5-oxadiazine to2-chloro-5-chloromethyl thiazole is1:1.2under the condition of70℃for6h, to get thiamethoxam, yield is75.50%.4. Synthesis of clothianidin: N-methyl-nitroguanidine as the starting material,water as the solvent, reacting with formaldehyde2.3eq and methylamine1.2equnder the condition of60℃for4h, to get1,5-dimethyl-2-nitroiminohexahydro-1,3,5-triazine, yield is98.31%; K2CO3as acid binding agent, chloroform and wateras the solvent, when the mole ratio of1,5-dimethyl-2-nitroiminohexahydro-1,3,5--triazine to2-chloro-5-chloromethyl thiazole is1:1.2under the condition of45℃for8h, to get N-(1-(2-chlorothiazol-5-yl)methyl)-3,5-dimethyl-1,3,5-triazinan-2-ylidene)nitramide, yield is78.60%; hydrochloric acid concentration of2M,ethanol and water as the solvent, N-(1-(2-chlorothiazol-5-yl)methyl)-3,5-dimeth-yl-1,3,5-triazinan-2-ylidene)nitramide is reacted under the condition of50℃for8h, yield is91.84%.