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

Participants

Reaction Steps

1550 g of ethyl 2-chloroglyoxalate 2,4-dichlorophenylhydrazone are dissolved in 1000 g of 2-methoxy-3-methylbut-1-ene and a total of 600 g of potassium hydrogen-carbonate in 500 ml of water is added continuously at 70°-80° C. such that a pH of about 8-8.5 is always maintained. After a total reaction time of 4 hours, the excess enol ether (465 g) is distilled off and the reaction mixture is adjusted to a pH of 0.5 using 190 ml of hydrochloric acid. After heating to reflux for 1 hour, the mixture is cooled to room temperature and the precipitated crystallizate is filtered off with suction.

Provenance & Evidence