Stable polymorphs of...

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C - Chemistry, Metallurgy

07

C

C07C 255/07 (2006.01)

Patent

CA 2551791

The present invention relates to stable crystalline polymorphic forms C and D of (E)-N,N-diethyl-2-cyan-3-(3,4-dihydroxy-5-nitrophenyl)acrylamide (Entacapone) and their preparation processes. (E)-Entacapone Form C is obtained by condensing 3,4-Dihydroxy-5-nitrobenzaldehyde and N,N- Diethylcyanoacetamide in presence of a base followed by addition of acetic acid after the reaction is over and crystallization step. (E)-Entacapone Form D is prepared from Entacapone Form C, Crystallographically pure (E)-Entacapone Form A or Crystallographically essentially pure From A. Polymorphic forms C and D of (E)-Entacapone are characterized by specific Infra Red (IR) and X-ray powder diffraction peak values.

L'invention concerne les polymorphes cristallins stables C et D de (E)-N,N-diéthyl-2-cyan-3-(3,4-dihydroxy-5-nitrophényl)acrylamide (Entacapone) et leur préparation. (E)-Entacapone de forme C est obtenue par condensation de 3,4-dihydroxy-5-nitrobenzaldehyde et N,N-diéthylcyanoacetamide en présence d'une base suivi par l'addition de l'acide acétique après la réaction et une cristallisation subséquente. (E)-Entacapone de forme D est obtenue à partir de l'entacapone de forme C, (E)-entacapone de forme A pur ou sensiblement pur d'un point de vue cristallographique. Les polymorphes C et D de (E)-entacapone sont caractérisées par valeurs crêtes d'infra rouge (IR) et diffraction des rayons X sur poudre.

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