Yield:126163-56-2 90.8%

Reaction Conditions:

Stage #1: (4-ethoxy 2,3-difluorophenyl)boronic acidwith dihydrogen peroxide in water at 20 - 25; for 2 h;
Stage #2: with hydrogenchloride in water; pH=6 - 7;

Steps:

2.2; 3.2; 4.2

second step: the water system in the previous step, start stirring to control the temperature at 20-25 ° C and add 59.5g (0.525mol) of 30.0% hydrogen peroxide dropwise. After the dropwise addition, the temperature is kept for 2.0 hours. The detection of 2,3-difluoro-4-methoxybenzeneboronic acid in the liquid phase of sample delivery is less than 0.2%. After the reaction was completed, the pH value of the 15% aqueous hydrochloric acid solution was adjusted to 6-7, and the crude product was obtained by suction filtration. After distillation, 63.2g (0.36mol) of 2,3-difluoro-4-ethoxyphenol was obtained. The yield was 90.8% and the purity was 99.97%. . The maximum impurity in gas phase detection is 37ppm.

References:

CN110922306,2020,A Location in patent:Paragraph 0030; 0033; 0034; 0037; 0038; 0041