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Stage #1: With n-butyllithium In diethyl ether at -78℃; for 1 h; Inert atmosphere Stage #2: With iodine In diethyl ether at -78 - 25℃; for 1 h;
1) Prepared according to the flow chart in Figure 1 1)3,4-dibromothiophene (24.2 g, 100 mmol) was dissolved in anhydrous diethyl ether,N2 protection,Cooling to -78 ,N-BuLi (66 ml, 105 mmol, 1.6 M) was slowly added dropwise,After reaction for 1 h at -78 & lt; 0 & gt; C, I2 (26.67 g, 105 mmol)Continue stirring for 1 h and warm to room temperature (25 ° C).The reaction solution was quenched with NaHSO3, extracted with ether, dried over Mg2SO4, dried and distilled under reduced pressure to give 3-bromo-4-iodothiophene (22.55 g, 78percent)Color liquid 2.
Reference:
[1] Patent: CN106317070, 2017, A, . Location in patent: Paragraph 0104; 0105; 0106
[2] Journal of Heterocyclic Chemistry, 1980, vol. 17, # 1, p. 171 - 174
[3] Journal of Organic Chemistry, 1982, vol. 47, # 16, p. 3177 - 3180
With copper(I) bromide; In methanol; at 70 - 97℃;Inert atmosphere;
21 g of sodium methoxide and 72 g of methanol were added to a 100 ml four-necked flask (the concentration of sodium methoxide relative to the methanol solvent was 22.6percent by weight based on the total amount of sodium methoxide before the reaction) and dissolved at 70 under an argon atmosphere.After addition of 0.83 g of cuprous bromide, 15 g of 3,4-dibromothiophene was added dropwise, and the reaction solution became colorless transparent to black. After completion of the dropwise addition, 50 g of methanol was distilled off (sodium methoxide to methanol solvent The concentration was 48.8 wtpercent based on the total amount of sodium methoxide before the reaction)The reaction was heated to reflux at 97 .When the reaction was traced by gas chromatography, 3,4-dibromothiophene and 3-bromo-4-methoxythiophene were found to be below the detection limit at the reflux starting time of 5 hours.After water was added to the reaction mixture and the mixture was filtered, the crude product was extracted from toluene, and the toluene layer was washed with water, and then the toluene layer was dried with magnesium sulfate.After the magnesium sulfate was removed by filtration, the toluene layer was concentrated by a rotary evaporator and then subjected to vacuum distillation to obtain 7.28 g (yield: 81.5percent) of 3,4-dimethoxythiophene. The purity of its 3,4-dimethoxythiophene was 98.01percent by gas chromatography.The purity (concentration) by gas chromatography in the present invention was indicated by the area ratio of the peak area obtained by the detection device by FID using Agilent 6890N network GC manufactured by Aglient Technologies.
60%
With copper(l) iodide; In methanol; at 80℃; for 72h;
Step 3: 3,4-dibromothiophene (10 g, 41.2 mmol) is added to 30 g of a methanol-sodium methoxide solution with a mass percent of 30percent and stirred. Then CuI (1.96 g, 10.3 mmol) is added quickly, and refluxed at 80° C. for 72 hrs. The mixture is cooled to room temperature, to which a saturated NaCl solution is added. The mixture is extracted with ethyl acetate several times, and dried over anhydrous sodium sulfate to remove solvents. The crude is passed through a separation column, to give a oily liquid, 3,4-dimethoxythiophene (compound 3), yield 60percent, purity 95percent.
EXAMPLE 1: Synthesis of Chloromethyl-3,4-ethylenedioxythiophene for conversion to EDOT-MEOH:; 1) 3,4-dimethoxythiophene synthesis from 3,4-dibromothiophene for the improved EDOT-MeOH synthesis:; [0084] Sodium methoxide was prepared by slow addition of small cubes of sodium metal (25 g, 1.05 mol) to ice bath cooled anhydrous methanol (600 mL) in a 1 L 3-necked flask equipped with a reflux condenser under a nitrogen blanket. Between additions of the sodium it was covered in kerosene to exclude moisture. After complete dissolution of the sodium, 50 g (0.207 mol) of 3,4- dibromothiophene, 16.5 g (0.207 mol) copper (II) oxide, and 1.37 g (0.00827 mol) potassium iodide was added to the reaction mixture. The reaction was refluxed for three days. The reaction was then cooled to room temperature and filtered through a sintered glass fritted funnel. The resulting solid was rinsed with ether and the filtrate was poured into 500 mL water. The solution was then extracted with ether. The organic fractions were combined and dried with magnesium sulfate. Solvent removal gave a light yellow oil. Vacuum distillation gave 26.2 g of a clear, colorless oil whose structure and purity were confirmed by ^H and ^C NMR and GC-MS. Yield was 88percent of theoretical.