2-Ethoxy-3-methyl-1-butene → Ethyl 1-(2,4-dichlorophenyl)-5-(propan-2-yl)-1H-pyrazole-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

1550 g of ethyl 2-chloroglyoxalate 2,4-dichlorophenylhydrazone are dissolved in 600 g of 2-ethoxy-3-methylbut-1-ene and 325 g of sodium carbonate, dissolved in 300 ml of water, are added such that a pH of greater than 8.0 is always maintained. After a reaction time of 4 hours (60°-80° C.), the aqueous phase is separated off and 200 ml of hydrochloric acid (pH~1) are added to the organic phase and the mixture is heated to reflux for 1 hour. After cooling to 70° C., the organic phase is separated off and crystallized using methanol/water. 1694 g of product having a purity of 96.3% are obtained, which corresponds to a yield of 94.7% of theory. The melting point is 95°-96° C.

Provenance & Evidence