Process for continuously producing an aromatic carbonate

Details Process for continuously producing an aromatic carbonate Process for continuously producing an aromatic carbonate

C - Chemistry, Metallurgy

07

C

C07C 68/06 (2006.01) B01D 3/34 (2006.01) C07C 69/96 (2006.01)

Patent

CA 2041646

Disclosed is a process for producing an aromatic carbonate or aromatic carbonate mixture by a transesterification reaction between a starting material selected from a dialkyl carbonate, an alkyl aryl carbonate and a mixture thereof and a reactant selected from an aromatic hydroxy compound, an alkyl aryl carbonate and a mixture thereof, wherein the starting material and the reactant are continuously fed to a continuous multi-stage distillation column to effect a transesterification reaction therebetween in the presence of a catalyst in the distillation column, while continuously withdrawing the produced aromatic carbonate or aromatic carbonate mixture as a high boiling point product in a liquid form from a lower portion of the distillation column and continuously withdrawing the by-product as a low boiling point product in a gaseous form from an upper portion of the distillation column by distillation, thereby enabling the aromatic carbonate or aromatic carbonate mixture to be produced continuously. By the method of the present invention, an aromatic carbonate, which is useful as a material for the production of aromatic polycarbonates without using poisonous phosgene or as a material for 117 the production of various isocyanates without using poisonous phosgene, can be produced not only at a high reaction rate but also in a high yield with a high selectivity.

Un procédé permet de produire en continu un carbonate aromatique ou un mélange de carbonates aromatiques à partir d'un matériau de départ composé de carbonate de dialkyle, de carbonate d'arylalkyle ou d'un mélange de ceux-ci et d'un réactif constitué par un composé hydroxyle aromatique, du carbonate d'arylalkyle ou un mélange de ceux-ci. Selon le procédé, on fournit en continu le matériau de départ et le réactif à une colonne de distillation en continu à étages multiples afin de provoquer la transestérification entre le matériau de départ et le réactif en présence d'un catalyseur et on extrait en continu de la partie inférieure de la colonne, sous forme liquide, le carbonate aromatique ou son mélange, qui se forme en tant que produit à point d'ébullition élevé, tout en retirant en continu de la partie supérieure de la colonne, par distillation et sous forme gazeuse, les produits secondaires à point d'ébullition réduit, afin d'obtenir la transestérification entre le matériau de départ et le réactif. Ce procédé permet d'obtenir avec un rendement élevé, à une vitesse élevée de réaction, un carbonate aromatique utile comme matériau de départ pour produire un polycarbonate aromatique ou différents isocyanates, sans qu'il soit nécessaire d'utiliser du phosgène toxique.

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