Methanol → 4-chloro-1-(difluoromethyl)-1H-pyrazole-3-carboxylic acid

A solution of 4-chloro-1-difluoromethyl-1H-pyrazole-3-carboxylic acid methyl ester (540 mg, 2.6 mmol) in tetrahydrofuran (18 ml) was treated at room temperature with a solution of lithium hydroxide (135 mg, 5.6 mmol) in a 1:1-mixture of water and methanol (12 ml). After 1 hour the reaction was complete, and the solvents were evaporated at reduced pressure. The residue was dissolved in water (10 ml) and acidified with hydrochloric acid (2M). Extraction with ethyl acetate, drying of the organic layer over sodium sulphate, and evaporation at reduced pressure yielded a white solid (555 mg) which was triturated with pentane (10 ml). The solid material was filtered, washed with pentane and dried. After drying at reduced pressure the 4-chloro-1-difluoromethyl-1H-pyrazole-3-carboxylic acid was obtained as a white solid (477 mg, 95%); (calculated) C5H3ClF2N2O2 [196.540]; (found) [M'H]−=195.

1. customthe solvents were evaporated at reduced pressure
2. dissolutionThe residue was dissolved in water (10 ml)
3. extractionExtraction with ethyl acetate
4. dry with materialdrying of the organic layer over sodium sulphate, and evaporation at reduced pressure

ORD record

ord-645ac7c264b54906ba68a5c0c7d24142

Source dataset

uspto-grants-2016_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09242943B2