4-bromo-1,5-dimethyl-1H-pyrazole-3-carboxylic acid(SALTDATA: FREE) synthesis

Yield:5775-91-7 850 g

Reaction Conditions:

with water;potassium hydroxide in methanol at 0 - 10; for 2 h;

Steps:

4-bromo-1 ,5-dimethyl-1 H-pyrazole-3-carboxylic acid

To a solution of ethyl 4-bromo-1 ,5-dimethyl-1 H-pyrazole-3-carboxylate (see Intermediate 5, 600 g, 2.43 mol, 1 eq) in methanol (6 L) was added drop wise potassium hydroxide (272.48 g, 4.86 mol, 2 eq) in water (1.5 L) at 0 . The resul ting mixture was stirred at 10 for 2 h. The reaction mixture was filtered and washed with methanol (500 ml_) to give a white solid. The solid was dissolved in water (10 L) and acified with 1 N hydrochloric acid to pH = 3. Amounts of white solid were formed. The solid was separated by filteration and washed with water (500 ml_), dried to give the desired compound (850 g, 3.88 mol, 79.91% yield, batches 2) as a white solid, which was directly used without further purification.

References:

WO2019/96911,2019,A1 Location in patent:Page/Page column 269; 270