Li Wei-guo
2012
Citations
0
Influential Citations
0
Citations
Journal
Dyestuffs and coloration
Abstract
3,4-Dichlorophenylhydrazine hydrochloride was synthesized from 3,4-dichloroanilin,then 2-(3,4-dichlorophenyl)-2,4-dihydro-5-methyl-3H-pyrazol-3-one was prepared by cyclization of it with ethyl acetoacetate.Structures of products were characterized by elemental analysis,melting point,HPLC and 1H-NMR.The effects of amount of hydrochloric acid,reducing agents,reaction temperature,solvents and after treatment on the yield and purity of products were investigated.The yield of 3,4-dichloro phenylhydrazine hydrochloride was increased in the conditions of stannous chloride as reducing agent,low temperature and excess hydrochloric acid.With solvent V(ethanol):V(water)=6:1,reaction temperature 75℃,reaction time 4 hours and adjusting pH=7 with sodium carbonate,the yield of 2-(3,4-dichlorophenyl)-2,4-dihydro-5-methyl-3H-pyrazol-3-one was 82%,melting point 163~164℃,purity higher than 96%.