Synthesis And Characterization Of Fipronil Esterification,amidation,Schiff Base And Acylhydrazone Derivatives

With the improvement of science and technology,people's awareness of environmental protection and the changes of crop pests and diseases,it is a new idea to find a new pesticides with high efficiency,low toxicity and new mechanism of action.In order to save time and combine the advantages of several active structures,we designed and synthesized a series of fipronil esterification,amidation,Schiff base and acylhydrazone derivatives.The main work of thesis are as follows:1?The fipronil amide intermediate was synthesized with the acid chloride under basic conditions,when fipronil was used as the leading compound and THF was used as the solvent.It reacts with an alcohol to form a fipronil amide and an esterified derivative.14 fipronil amides and esterified derivatives were synthesized from fipronil esterification intermediates and alcohols.Compounds A₁₁-A₁₂₁were synthesized and characterized by IR,¹H NMR and MS.The structures of compounds A₁₁ and A₁₅ were confirmed by X-Ray single crystal diffraction.The optimal synthesis conditions for fipronil amide and esterified derivatives are as follows:When10mmol of of FeCl3 is used as catalyst,the yield of the compound A₁₁ was preferably63.8%at temperature of 90°C and reaction time of 24 h.The hydrophobic parameters of compound A were detected by reversed-phase high performance liquid chromatography to lay the foundation for subsequent biological detection.2?The fipronil esterification intermediate was synthesized by reacting an alcohol with fipronil,when FeCl3 is used as a catalyst.The esterification intermediate was reacted with an aromatic aldehyde to synthesize 10 fipronil esterified and Schiff base products S₁₁-S₅₁ in the case of p-toluenesulfonic acid as a catalyst and toluene as a solvent.The structure of the product was confirmed by IR and ¹H NMR,MS and X-Ray single crystal diffraction.Based on the Pinner reaction,the mechanism of reaction of fipronil with alcohol was speculated:hydrolyzed FeCl3 provides acidity,protonation of the nitrile and after proton transfer,proton transfer can form an imine hydrochloride intermediate.Finally,the fipronil esterification product was obtained by hydrolysis of the imine hydrochloride intermediate under acidic conditions to form a carboxylate.3?The fipronil hydrazide intermediate was synthesized by fipronil esterified intermediate with 50%hydrazine hydrate.The fipronil acylhydrazone derivative D₁-D₄ was preliminary synthesized by fipronil hydrazide intermediate with an aromatic aldehyde.The structure of the 4 products were confirmed by IR,MS and ¹H NMR.This chapter optimizes the synthesis of fipronil hydrazide intermediates and the synthesis conditions of fipronil hydrazide products.When the molar ratio of the fipronil esterified intermediate to the 50%hydrazine hydrate was 1:2,the yield of the fipronil acylhydrazone intermediate was 81.5%at a reaction temperature of 90°C and a reaction time of 3 h.When the molar ratio of the hydrazide intermediate to benzaldehyde was 1:1,the yield of the compound D₁ was 94.0%in toluene as a solvent,acetic acid as a catalyst and a reaction time of 5 h.The possible mechanism of fipronil reaction of acylhydrazone was proposed,and the preliminary study on the reaction of fipronil dipyrazole derivatives was carried out.