At zero temperature, 120.0 mL of glacial acetic acid was used to dissolve the compound of formula 6, 2-methylthiophene (24.50 g, 250.00 mmol), and then placed into a 250.0 mL single-necked flask, and under rapid stirring, 30.0 mL of a mixture of liquid bromine and 30.0 mL of glacial acetic acid was added to it slowly through a constant-pressure funnel, and the mixture was slowly dripped out over a period of 5 h, and then the reaction continued for another 12 h. The reaction was completed with the addition of 100.0 mL of water. After the reaction was completed, 100.0 mL of water was added to terminate the reaction, so that the organic phase and the aqueous phase were separated, and the aqueous phase was adjusted to pH=7 with sodium hydroxide solution, and then extracted with ether, and all the organic phases were combined, and then washed with saturated sodium carbonate for 3 times, and added anhydrous drying for 12h, and a light-yellow color product was obtained by means of distillation under reduced pressure, 54.20g, with a yield of 82%.
