Preparation background and overview of (2-nitrophenyl)potassium trifluoroborate
Potassium (2-nitrophenyl)trifluoroborate is an aryl potassium trifluoroborate boric acid derivative. Arylpotassium trifluoroborate not only has high stability and good crystallinity, but also has the closest reaction performance to the corresponding arylboronic acid. It is the most promising arylboronic acid derivative for industrial production and application.
As a safe and efficient arylation reagent, arylboronic acid has been widely used in the scientific research and development of related fine chemicals such as medicine, pesticides, liquid crystals and OLED optoelectronic materials. However, because arylboronic acid is prone to dehydration to form anhydride, and is not stable to acids, bases and oxidants, especially when air is easily oxidized or deborated, the practical use of arylboronic acid generally has problems such as short storage time and difficult measurement. , even some heterocyclic arylboronic acids gradually decompose at room temperature and need to be stored at low temperatures below -30°C, making them lose their value for use in industrial production. In order to solve the usage problems caused by the stability of arylboronic acid, it needs to be converted into derivatives of arylboronic acid esters or salts.
Preparation of potassium (2-nitrophenyl)trifluoroborate
Aqueous potassium fluoride (4 equiv, 2 mL) was added to a solution of 2-nitrobenzeneboronic acid (5 mmol) in acetonitrile (20 mL), bromopyridinium dihydrochloride, and the mixture was allowed to stand at ambient temperature. Stir for 5 minutes. L-tartaric acid (2.05 equiv) dissolved in tetrahydrofuran (THF) (10 mL) was slowly added to the mixture, and a white by-product immediately precipitated. The reaction mixture was stirred at ambient temperature for 1 hour and filtered to remove precipitate. The resulting filtrate was concentrated in vacuo to obtain the crude alkali metal salt as a solid. The crude product was purified by recrystallization to obtain pure potassium (2-nitrophenyl)trifluoroborate. 1HNMR ( MHz, CD3CN): σ 7.27 (dt, 1H, J = 7.7 Hz, 4J = 1.3 Hz, arom. H), 7.39–7.45 ( m, 2H, arom. H), 7.64 (d, 1H, 3JHH = 7.3 Hz, arom. H).
References
[1] Kazuki Iwasaki, Kazuki Yoshii, Seiji Tsuzuki, Hajime Matsumoto, Tetsuya Tsuda, and Susumu Kuwabata, The Journal of Physical Chemistry B 2016 120 (35), 9468-9476
[2] [China invention, China invention authorization] CN201611179059.7 Solvent-free twin-screw extrusion continuous synthesis process of aryl potassium trifluoroborate
