Uses
2-Amino-4,6-difluorobenzoic acid is an important pharmaceutical and pesticide intermediate, and it can also be used in liquid crystal materials. It has the advantages of high value and good market prospects.
Synthesis
Stage 3: Synthesis of 2-amino-4,6-difluorobenzoic acid
A solution of sodium hydroxide (6.70 g, 167 mmol) and 30% hydrogen peroxide (6.7 mL) in water (60 mL) was added dropwise to a suspension of the stage 2 product (4.58 g, 25 mmol) in water (125 mL) and the reaction was carried out at 0 °C. Subsequently, the reaction mixture was stirred at room temperature for 20 hours. Upon completion of the reaction, the pH was adjusted to 3 with formic acid (~11 mL, taking care to control the rate of addition to prevent violent foaming), at which point the target compound began to precipitate. The precipitate was collected by filtration and dried in a desiccator using phosphorus pentoxide to give 3.72 g of white solid product (86% yield). The melting point of the product was 198-202 °C.
References
[1] Patent: US2008/293749, 2008, A1. Location in patent: Page/Page column 14
[2] Journal of Medicinal Chemistry, 2006, vol. 49, # 22, p. 6465 - 6488
[3] Organic Process Research and Development, 2010, vol. 14, # 5, p. 1078 - 1087
