5-Amino-4-chloro-2-phenyl-3(2H)-pyridazinone free from 5-chloro-4-amino-2-phenyl-3(2H)-pyridazinone, as a selective weed-killer
AssigneeOxon Italia S.p.A.
InventorRaimondo Motta
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Abstract
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.
Claims6
Process for obtaining 5-amino-4-chlor-2-phenyl-3(2H)-pyridazinone (PCA) free from 5-chloro-4-amino-2-phenyl-3(2H)-pyridazinone (ISO-PCA) starting from commercial Pyrazon, that is from a mixture of the said two isomeric compounds, characterised in that commercial Pyrazon is treated with a mineral acid of suitable concentration, said concentration being suitable to dissolve the ISO-PCA but very little of the PCA, thereby to form a suspension of PCA in a solution of ISO-PCA, and thereafter filtering said suspension to remove PCA in the form of particles from said solution.
Dependencies are inferred from the claim text.