Réaction #1552086

Équation de réaction

sodium hydroxide

5-chloro-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carbaldehyde

toluene

hydrogen peroxide

→

5-chloro-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid

Rendement 49.0%

Solvants

water

water

Conditions de réaction

Traitement

1. 1
   Autrethe temperature below 37° C
2. 2
   workup.ADDITIONAfter the end of the addition
3. 3
   Autreis back to room temperature
4. 4
   Autrethe two phases are separated
5. 5
   Extractionthe organic phase is extracted with 100 ml of water
6. 6
   FiltrationThe resulting white precipitate is filtered
7. 7
   Lavagewashed twice with 20 ml of water
8. 8
   Autredried

Mode opératoire

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).

Source