| 摘要 |
The compound 5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone free from 5-chloro-4-amino-2-phenyl-3(2H)-pyridazinone is used as selective weed-killer in a remarkably more efficacious and remarkably less phytotoxical way than the presently known "pyrazon" (mixture of 5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone and 5-chloro-4-amino-2-phenyl-3(2H)-pyridazinone). The 5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone is obtained from pyrazon by treating said pyrazon with a mineral acid of pre-fixed concentration, obtaining a suspension and filtering such a suspension. The use thereof as weed-killer is carried out in suitable formulations. |
