PROCESS FOR SEPARATING AND UTILIZING BY-PRODUCTS FROM WASTE WATER OF 5-AMINO-4-CHLORO-2-PHENYL-3(2)-PYRIDAZINONE SYNTHESIS

摘要

A process for the separation and reutilisation of residual substances from the waste water of the synthesis of 5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone I prepared from 4,5-dichloro-2-phenyl-3(2H)-pyridazinone II and ammonia, characterised in that the residues of the product I dissolved in the waste water together with the by-products a) 4-amino-5-chloro-2-phenyl-3(2H)-pyridazinone Ia and b) 4-chloro-5-hydroxy-2-phenyl-3(2H)-pyridazinone Ib are precipitated and isolated by acidifying the waste water and the mixture thus obtained is converted into 4,5-dichloro-2-phenyl-3(2H)-pyridazinone II using a chlorinating agent.