Synonyms: 2-Pyrazolin-5-one,1-(3,4-dichlorophenyl)-3-methyl- (6CI,8CI); 1-(3,4-Dichlorophenyl)-3-methyl-2-pyrazolin-5-one;1-(3,4-Dichlorophenyl)-3-methyl-4,5-dihydropyrazole-5-one;1-(3',4'-Dichlorophenyl)-3-methyl-5-pyrazolone;3-Methyl-1-(3,4-dichlorophenyl)-5-pyrazolone