Use | 3-fluoro-2-carboxylate methyl thiophene is an important thiophene derivative. Thiophene and its derivatives, such as bithiophene, dithiophene, trithiophene, benzodithiophene, etc., have excellent power supply and carrier transport characteristics, and are often used in conjugated polymers and electron donor-acceptor systems Construction, and apply it to organic photovoltaic cell materials and devices, organic light-emitting diodes, organic field effect transistors and electrochromic displays. |
preparation | using 2,3-dichloropropiononitrile as the starting material, the key intermediate 3-amino -2-thiophene formate methyl ester is prepared, and 3-fluoro-2-carboxylic acid methyl ester thiophene is prepared by diazotization and fluorination reaction. The synthesis roadmap is as follows: Figure 1 3-fluoro -2-carboxylate methyl thiophene synthesis roadmap 2,3-dichloropropiononitrile preparation acrylonitrile and N,N-dimethylformamide are put into a 250mL four-mouth bottle equipped with a stirrer, thermometer, ventilation cannula and condenser, stirring and cooling to about 5 ℃, slowly passing chlorine gas, passing chlorine temperature 5~10 ℃, when passing chlorine is 120.0, stop passing chlorine, heat preservation reaction at 10~15 ℃ for 5 hours, nitrogen is introduced to remove excess chlorine gas, the reaction is finished, weighing, 2, 3-dichloropropiononitrile is obtained. Preparation of methyl 2-mercaptoacetate In a 500mL four-mouth bottle equipped with a stirrer, a thermometer, a drop-on funnel and a condenser, 2-mercaptoacetic acid and methanol are added, concentrated sulfuric acid is added dropwise at 40 ℃, and after dropping, heat preservation at 35~40 ℃ for 8 hours. Rest to separate water to obtain crude ester. The crude ester was distilled under reduced pressure to collect methyl 2-mercaptoacetate fraction from 42 to 43°C at 1333Pa. Preparation of 3-Amino -2-Thiophene Methyl 28% 200g of sodium methoxide is added to a 500mL four-mouth bottle equipped with a stirrer, a thermometer, a dropping funnel and a condenser, 53.8g of methyl 2-mercaptoacetate is added dropwise between 10 and 15 ℃ in the reaction system, and 100mL of methanol solution dissolved in 2, 3-dichloropropiononitrile 65.0g is still added dropwise between 10 and 15 ℃ after dropping, after dropping, heat preservation reaction is carried out at this temperature for 6 hours, methanol is distilled under reduced pressure, 200mL of cold water is added dropwise, stirred, washed and filtered, the filter cake is washed once with cold water, filtered by suction, and dried to obtain methyl 3-amino -2-thiophene formate. 97.8% mass fraction, 84.7% yield, melting point 60~63 ℃[1]. Preparation of methyl 3-fluoro-2-thiophene carboxylic acid Methyl 3-amino-2-thiophene formate first reacts with NaNO2 and HBr to generate brominated diazobenzene, and brominated diazobenzene is catalyzed by cuprous bromide. Bromobenzene and nitrogen are decomposed by a free radical mechanism. The product is halogen replaced with anhydrous KF to obtain methyl 3-fluoro-2-thiophene carboxylate. |