Process for the preparation of intermediates

Details Process for the preparation of intermediates Process for the preparation of intermediates

C - Chemistry, Metallurgy

07

C

C07C 17/093 (2006.01) C07C 25/02 (2006.01)

Patent

CA 2596590

The present invention provides a process for the production of intermediate compounds of formula (I), wherein the substituents are as defined herein. The process comprises reacting a substituted aniline with aqueous HX, followed by removal of water by azeotropic distillation and diazotization and pyrolysis with an organic nitrite at elevated temperatures in the absence of a copper catalyst. Alternatively, gaseous HX can be used to substitute aqueous HX in the process. Consequently, a step of water removal by azeotropic distillation can be eliminated. The intermediate compounds of formula I are suitable as intermediates in the preparation of herbicidally active 3-hydroxy-4-aryl-5- oxopyrazoline derivatives.

La présente invention concerne un procédé pour la fabrication d~intermédiaires de formule (I), dans laquelle les substituants sont tels que définis ici. Le procédé comprend la mise en réaction d~une aniline substituée avec un HX aqueux, suivi de l~élimination d~eau par distillation azéotropique et diazotation et pyrolyse avec un nitrite organique à températures élevées en l~absence d~un catalyseur de cuivre. En variante, on peut utiliser dans le procédé un HX gazeux à la place du HX aqueux. En conséquence, on peut omettre l'étape consistant à éliminer l~eau par distillation azéotropique. Les composés intermédiaires de formule I sont appropriés en tant qu~intermédiaires dans la préparation de dérivés de 3-hydroxy-4-aryl-5-oxopyrazoline, actifs du point de vue herbicide.

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