Ethyl vinyl ether → 3-(Trifluoromethyl)pyrazole

To a solution of 4.4 moles hydrazine.hydrochloride in 2.2 L of methanol in a 3-necked flask, equipped with a mechanical stirrer, a reflux condenser and a dropping funnel an equimolar amount of ETFBO which had been manufactured by addition of trifluoroacetyl chloride to ethyl vinyl ether was added dropwise over about 4 hours under N2 atmosphere. The temperature of the reaction mixture was kept below 15° C. After 12 h of reflux, the reaction batch was filtered in a 2 L flask and concentrated under vacuum (An identical batch was made under the same conditions, yield of both crude products was ca. 95%). Subsequently, the combined crude product was purified by shortpass-vacuum distillation at 27 mbar. The yield was 1105 g, which corresponded to 92% of the theoretical yield.

1. additionwas added dropwise over about 4 hours under N2 atmosphere
2. customwas kept below 15° C
3. temperatureAfter 12 h of reflux
4. filtrationthe reaction batch was filtered in a 2 L flask
5. concentrationconcentrated under vacuum (An identical batch
6. distillationSubsequently, the combined crude product was purified by shortpass-vacuum distillation at 27 mbar

ORD record

ord-0c82a5db2a7542659b61c211f2138390

Source dataset

uspto-grants-2013_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08431710B2