2,5-Dibromoterephthalic acid

1074-24-4

13731-82-3

This embodiment describes a process for the synthesis of 2,5-dibromoterephthalic acid using 2,5-dibromo-1,4-dimethylbenzene as a starting material. NaBr (5 mmol) in 500 g of 97% acetic acid solution. The mixture was stirred at a constant rate using a gas dispersion stirrer to optimize the gas mixing, and then the mixture was heated to 150 °C and maintained for 2 h (this stage is labeled as "TI" in Table 1), after which it was warmed up to 180 °C to continue the reaction for 4 h (this stage is labeled as "T -2"). During the heating process, air is continuously vented at 400 psig (2.76 MPa) back pressure. At the end of the reaction, the pressure was released and the reactor was cooled to 50°C. The product was drained and the reactor was rinsed with 50 g of acetic acid in two passes to collect the residual product. The white solid product was collected by diafiltration, washed with water, and dried under vacuum to yield 310 g (84% yield) of 2,5-dibromoterephthalic acid as a white solid with 99% purity as determined by 1H NMR. Examples 2-5 explored the effect of different reaction stages, time and temperature conditions on the net yield and purity of 2,5-dibromoterephthalic acid, all following the procedure of Example 1, with the specific conditions adjusted as shown in Table 1. In all cases, the resulting 2,5-dibromoterephthalic acid was a white solid of not less than 99 mol% purity.