Synthesis
The general procedure for the synthesis of 3-carboxy-5-nitrophenylboronic acid from 3-carboxyphenylboronic acid is as follows: first, 7.5 g of 3-carboxyphenylboronic acid (45.2 mmol) was mixed with 25 ml of concentrated sulphuric acid, and 25 ml of fuming nitric acid was slowly added under rapid stirring conditions while cooling using an ice water bath. The reaction mixture was stirred for 15 min, then the ice water bath was removed and the reaction continued to be stirred for 15 min. Subsequently, the reaction solution was poured into ice water to produce a precipitate, which was filtered and then the precipitate was washed with ice water for 5 times, and finally 6.01 g of 3-nitro-5-carboxyphenylboronic acid as a white solid was obtained by aqueous recrystallization in 63.0% yield. Next, 1.50 g of 3-carboxy-5-nitrophenylboronic acid (7.1 mmol) was dissolved in 20 ml of methanol, and 2 g of 10% Pd/C catalyst was added in a 50 ml three-necked flask for a catalytic hydrogenolysis reaction for 6 hours. After completion of the reaction, the Pd/C catalyst was removed by filtration and the filtrate was evaporated to dryness to give 1.25 g of 3-amino-5-carboxyphenylboronic acid as a white powdery solid in 97.1% yield.
References
[1] Patent: CN103497211, 2016, B. Location in patent: Paragraph 0190
[2] Organic Preparations and Procedures International, 1991, vol. 23, # 6, p. 729 - 734
[3] Journal of the American Chemical Society, 1959, vol. 81, p. 3017
[4] Arkiv foer Kemi, 1957, vol. 10, p. 497,503
