Hydrochloric Acid → 3-Amino-1-(2,4-dichlorophenyl)-5-methyl-2-pyrazoline

A mixture of 7.8 g. of 2,4-dichlorophenylhydrazine (prepared from 2,4-dichlorohydrazine hydrochloride by treatment with 1 N sodium hydroxide), 9.9 g. of crotononitrile and 3 drops of choline (45% in methanol) is heated on a steam bath for 18 hours. The solution is mixed with 200 ml. of water then 20 ml. of concentrated hydrochloric acid is added and the mixture is refluxed for 1/2 hour, cooled and made basic with 10% sodium hydroxide to give a gummy solid. The solid is placed on a chromatography column containing 300 g. of a 200 mesh synthetic magnesium silicate adsorbent. The column is eluted with 1% acetone-hexane, 5% acetone-hexane and 10% acetone-hexane to remove most of the less polar material. The elution procedure is monitored by thin layer chromatography using the upper phase of a mixture of 2 parts benzene, one part acetone and 2 parts water; then the column is eluted with acetone to remove the crude product as a dark oil which partly crystallizes on standing. This material is chromatographed again using another 200 g. of the magnesium silicate adsorbent and eluting a colored impurity with 5% acetone-hexane. The column is then eluted with 50% acetone-hexane to collect a tan oil which solidifies on standing. The solid is recrystallized 3 times from ether-hexane to give 0.5 g. of the product of the Example as tan crystals, m.p. 109°-111° C.

1. additionA mixture of 7.8 g
2. additionThe solution is mixed with 200 ml
3. temperaturethe mixture is refluxed for 1/2 hour
4. temperaturecooled
5. customto give a gummy solid
6. additioncontaining 300 g
7. washThe column is eluted with 1% acetone-hexane, 5% acetone-hexane and 10% acetone-hexane
8. customto remove most of the less polar material
9. washThe elution procedure
10. additionthe upper phase of a mixture of 2 parts benzene, one part acetone and 2 parts water
11. washthen the column is eluted with acetone
12. customto remove the crude product as a dark oil which
13. custompartly crystallizes
14. customThis material is chromatographed again
15. washof the magnesium silicate adsorbent and eluting a colored impurity with 5% acetone-hexane
16. washThe column is then eluted with 50% acetone-hexane
17. customto collect a tan oil which
18. customThe solid is recrystallized 3 times from ether-hexane
19. customto give 0.5 g

ORDレコード

ord-cdb8d7245a3b4adc9a6ac4762e50abfb

出典データセット

uspto-grants-1984_05

DOI

10.6084/m9.figshare.5104873.v1

特許番号

US04451479