Hydrogen Peroxide → 5-Chloro-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid

Temperature

50 °C

In a 500 ml flask, 6.0 g (31 mmol) of 5-chloro-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carbaldehyde are added to 30 ml of toluene. A solution of 2.4 g (62 mmol) of sodium hydroxide in 6 ml of water is added to the reaction mixture, followed by 103 ml of a 30% solution of hydrogen peroxide in water, whilst keeping the temperature below 37° C. After the end of the addition, the reaction mixture is stirred at 50° C. for 7 hours. Once the reaction mixture is back to room temperature, the two phases are separated and the organic phase is extracted with 100 ml of water. The combined aqueous phases are acidified to pH 2 with aqueous hydrochloric acid. The resulting white precipitate is filtered, washed twice with 20 ml of water, and dried to yield 3.2 g of 5-chloro-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid as a white solid. 1H NMR (400 MHz, DMSO-d6) δ ppm: 3.78 (s, 3H); 7.12 (t, 1H, JHF=53.60 Hz) 13.19 (s, 1H); IR (KBr): 1688 cm−1 (C═O); 2200-3200 cm−1 broad (hydrogen bond).

1. customthe temperature below 37° C
2. additionAfter the end of the addition
3. customis back to room temperature
4. customthe two phases are separated
5. extractionthe organic phase is extracted with 100 ml of water
6. filtrationThe resulting white precipitate is filtered
7. washwashed twice with 20 ml of water
8. customdried

ORD record

ord-4fe95af1dce64d0caaa6384803b0a5e0

Source dataset

uspto-grants-2013_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08614242B2