Application of phosphate compound in preparation of nitrophenylboronic acid

Abstract

The application of the phosphate compound in preparation of nitrophenylboronic acid is characterized by comprising the following steps: adding phenylboronic acid and an organic solvent into a reactioncontainer in a protective gas atmosphere, uniformly stirring the reactants, controlling the temperature of the system to be 0-25 DEG C, adding a catalyst phosphate compound, continuously stirring for1-2 minutes, and slowly dropwise adding fuming nitric acid into the system; then keeping the temperature, continuously reacting for 0.5-1 h until the reaction is finished, adding ice water into the system, continuously stirring the system for 5-10 min until the system is uniform, carrying out reduced pressure concentration, adding ice water again when the volume is reduced to 1/3, continuously stirring the system until the system is uniform; performing standing treatment, layering the system, filtering out the solid, washing the solid with ice water, and carrying out vacuum drying to obtain o-nitrophenylboronic acid. By using the phosphate catalyst, the nitrophenylboronic acid is easier to control in the preparation process. The preparation is mild in reaction, simple in post-treatment, high in yield and purity, capable of guaranteeing large-batch production, high in yield and purity and more suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of organic synthesis, in particular to a preparation method of nitrophenylboronic acid, more specifically to a preparation method of o-nitrophenylboronic acid. Background technique [0002] O-nitrophenylboronic acid is an important chemical intermediate, an important raw material for the synthesis of organic light-emitting diodes, and an important intermediate for the synthesis of many pharmaceutical compounds. [0003] The preparation method of reporting nitrophenylboronic acid in the prior art mainly contains following several kinds: [0004] (1) Chinese patent CN 103214489A discloses a method for preparing o-nitrophenylboronic acid. In the acetic anhydride solution of phenylboronic acid, fuming nitric acid containing a small amount of urea is added dropwise to react at low temperature. After the reaction is completed, crushed Ice, concentrated under reduced pressure, added water, then concentrated under reduced pr...

AI Technical Summary

Problems solved by technology

This method uses excessive nitric acid (the molar weight of nitric acid is 3 times that of phenylboronic acid), resulting in very cumbersome post-treatment steps, and the overall reaction time is long, and the yield is low, only 42%, which is not conducive to industrial production

[0005] (2) World patent WO2011132865A1 discloses a method for preparing o-nitrophenylboronic acid. Dissolve 1-iodo-2-nitrobenzene in tetrahydrofuran, cool to -78°C, slowly add phenylmagnesium chloride and stir to mix, then add boric acid Trimethyl ester, after warming up to room temperature, fully stirred, and finally added hydrochloric acid to terminate the reaction, the molar yield was 89%, but this method needs to be reacted at an extremely low temperature, resulting in harsh reaction conditions and many isomers, Product uniformity difference

This method also uses an excessive amount of fuming nitric acid, which also leads to very cumbersome post-treatment, and also produces more isomers, which is also not suitable for industrial production

[0007] (4) English literature Journal of Organic Chemistry; vol.79; nb.21; (2014); 10568-10580, which discloses a method for preparing o-nitrophenylboronic acid, which combines 2-nitroaniline and tetrahydroxydiboron Mix in water, add hydrogen chloride, sodium nitrite, and sodium acetate in order to react to obtain the product, and the final reaction molar yield is only 28%. The reaction yield of this method is low, and the raw material price is relatively expensive, so it is not suitable for industrial production

The molar amount of nitric acid in this method is also much greater than that of phenylboronic acid, which will lead to cumbersome post-treatment, and there is an excessive amount of nitric acid in the waste liquid, which is extremely troublesome to handle and extremely harmful to the environment.

In addition, this application omits the reaction or treatment time of each step in the embodiment, in fact, concentrated nitric acid and water release heat, because there is a large amount of nitric acid in the system, therefore, in the process of dropping concentrated nitric acid, in order to keep the system Low temperature, concentrated nitric acid cannot be dripped too fast, and it takes a lot of time to absorb the released heat. In addition, there is a large amount of nitric acid in the system during post-treatment, and nitric acid is very soluble in water, so , will cause great trouble to the post-processing, and it will also take a lot of time

Therefore, the overall energy consumption of this method is relatively large and time-consuming, which is also not conducive to large-scale reactions.