3,4-Di:hydroxy-6-phenyl-4,5-di:hydro-pyridazine - useful as intermediate for herbicidal 6-phenyl-3-pyridazinone cpds.

摘要

(I) and its tautomer 4-hydroxy-4,5-dihydro-6-phenyl-3(2H)-pyridazinone are new: (I) are useful as an intermediate for 6-phenyl-3(2H)-pyridazinone (II). The halo derivs. of (II) are selective herbicides (GB 1368414). (I) is prepd. by reacting 2-hydroxy-3-benzoylpropionic acid with hydrazine hydrate in an aq. or aq.-alcoholic medium and cyclising the product by heating, and (II) is prepd. by dehydrating (I) with a strong acid in an aq. or aq.-alcoholic medium. (I) need not be isolated from the reaction mixt.