Process for preparation of alkyl and...

Details Process for preparation of alkyl and... Process for preparation of alkyl and...

C - Chemistry, Metallurgy

07

C

C07C 253/32 (2006.01) C07C 255/23 (2006.01)

Patent

CA 2608183

This invention is related to the preparation of alkyl or alcoxyalkyl-.alpha.- cyanoacrylates in monomeric form by depolymerisation of the corresponding poly(alkyl-.alpha.-cyanoacrylates) or poly(alcoxyalkyl-.alpha.-cyanoacrylates) (PCA). The PCA's are obtained preferably by base-catalyzed condensation of a cyanoacetate with formaldehyde (or a polymer of the latter). According to the invention, the poly(alkyl-.alpha.-cyanoacrylate) or poly(alcoxyalky-.alpha.- cyanoacrylate), the condensation product, is mixed with a depolymerisation system comprising phosphorus pentoxide P2O5, hydroquinone, ortho-phosphoric acid and para-toluenesulfonic acid. This process is realized in a batch reactor fitted with a condenser, heated at a temperature in the range of 100- 300~C, under a vacuum of 0.5-50 Torr (7.10-5 - 7.10-3 MPa) and gives rise to monomeric alkyl-.alpha.-cyanoacrylates or monomeric alcoxyalkyl-.alpha.- cyanoacrylates, being stable in both gaseous and liquid phase. After an additional purification by vacuum distillation, these cyanoacrylates can be used as fast setting technical or medical adhesives.

L'invention concerne la préparation d'alkyles ou d'alcoxyalkyl-a-cyanoacrylates sous forme monomère par dépolymérisation des poly(alkyl-a-cyanoacrylates) ou des poly(alcoxyalkyl-a-cyanoacrylates) (PCA) correspondants. Les PCA sont de préférence obtenus par condensation catalysée par base d'un cyanoacétate avec un formaldéhyde (ou un polymère de ce dernier). Selon l'invention, le poly(alkyl-a-cyanoacrylate) ou le poly(alcoxyalky-a-cyanoacrylate), le produit de la condensation, est mélangé à un système de dépolymérisation comprenant un pentoxyde de phosphore P2O5, une hydroquinone, de l'acide ortho-phosphorique et de l'acide para-toluènesulfonique. Ce processus s'effectue dans un réacteur à fonctionnement discontinu équipé d'un condensateur, chauffé à une température comprise entre 100 et 300 °C, sous un vide de 0,5 à 50 Torr (7,10-5 7,10-3 MPa) et donne naissance à des alkyl-a-cyanoacrylates monomériques ou des alcoxyalkyl-a-cyanoacrylates monomériques, stables tant en phase gazeuse qu'en phase liquide. Après une purification supplémentaire par distillation sous vide, on peut utiliser ces cyanoacrylates comme adhésifs techniques ou médicaux à prise rapide.

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