Study On The Synthesis Of 3,4-Ethylene Dioxythiophene

3,4-Ethylenedioxythiophene(EDOT)is a monomer of the excellent conductive polymer Poly(3,4-ethylenedioxythiophene)(PEODT)which is no large-scale production in China.Therefore,it has important economic and social significance to research its synthetic process.Based on the existing literatures on the synthesis of 3,4-ethylenedioxythiophene at home and abroad,learn from each other and analyze the advantages and disadvantages of each synthetic route in detail,this article focuses on the synthesis methods and processes of3,4-ethylenedioxythiophene.Through this,we use "synthetic process optimization methods and principles" to explore and research the process conditions of each step from a local and global perspective,and the steps are optimized,in order to suit different scales of industrial production.It mainly involves analysis of side reactions,screening of reaction materials,determination of material ratio,selection of solvents,selection of temperature,selection of feeding order,selection and determination of post-processing methods,etc.Finally,a five-step synthesis process with ethyl chloroacetate as the starting material was determined.First,anhydrous sodium sulfide and ethyl chloroacetate were reacted in ethanol to obtain diethyl thiodiglycolate at 0~10 ?,with a yield of 90.8% and a content of 98.4%.Diethyl oxalate and the obtained diethyl thiodiacetate were reacted in an ethanolic solution of sodium ethoxide at 78 ? for 3 hours,and filtered to obtain diethyl2,5-dicarboxylate-3,4-diphenol sodium thiophene.It's yield is 92.7% and the content is99.5%.Then,diethyl 2,5-dicarboxylate-3,4-diphenol sodium thiophene was reacted with1,2-dichloroethane at 110 ? for 10 hours under the catalysis of tetrabutylammonium bromide.After processing,we can obtain Diethyl 2,5-dicarboxylate-3,4-ethylenedioxythiophene whose yield 81.3%,and content is 99.6%.Next,Diethyl 2,5-dicarboxylate-3,4-ethylenedioxythiophene was reacted in an aqueous solution of sodium hydroxide at 80 ?for 3 hours,and acidified to obtain 2,5-dicarboxylic acid-3,4-ethylenedioxythiophene,yield 92.1%,content 99.9%.Finally,2,5-dicarboxylic acid-3,4-ethylenedioxythiophene was placed in N,N-dimethylformamide and a catalyst which is copper oxide was added to react at 140 ? for 6 hours.After rectification,we can obtain 3,4-ethylenedioxythiophene.It's yield is 80.1% and the content is 99.9%.Calculated by ethyl chloroacetate,the total reaction yield was 50.5%,and the purity reached 99.9%.This process has the advantages of cheap and easy to obtain raw materials,simple operation,and high productpurity.It is suitable for industrial production and has good industrial application prospects.