Hydrochloric Acid → HCID 11993773, compound

Participants

Reaction Steps

The residue obtained from the evaporation of the mother liquors obtained from the crystallisation of (S)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4,5-dihydro-pyrazole-3-carboxylic acid with Brucine was treated with EN HCl as described above for obtaining the free acid. After evaporating the organic phase 21.86 g of a mixture with a theoretical composition of 20 mmoles (S)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4,5-dihydro-pyrazole-3-carboxylic acid and 39.9 mmoles of (R)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4,5-dihydro-pyrazole-3-carboxylic acid were obtained. A suspension of 13.82 g (39.9 mmoles) of (+)-cinchonine in 1000 ml of acetonitrile were added and the mixture was heated to reflux. More acetonitrile was added until dissolution was complete (total volume of acetonitrile 4000 ml). The mixture was then slowly cooled to room temperature to obtain crystals. After a few hours a white solid was obtained, which was filtered off and dried to give 22.42 (yield 84.5% related to the salt of (R)-5-(4-chlorophenyl)-1-(2,4dichlorophenyt)-4,5-dihydro-pyrazole-3-carboxylic acid).

Provenance & Evidence