OBTENTION METHOD FOR ESTERS OF THE ACID ALPHA-CYANACRILIC OF HIGH PURITY

摘要

Greater than 99.9% purity alpha-cyanoacrylic-acid-esters are prepd. from corresponding cyano-acetic-acid esters and formaldehyde by knoevenagel synthesis in presence of weakly basic catalysts. Prepolymer formed is pyrolised and the monomer obtd. is purified by distn. High purity of prods. confirmed by chromatography is ensured by the use during the condensation stage of a solid catalytic mixt. contg. a weakly basic ion exchange resin and alkaline hyroxides. The prepolymer is pyrolysed at an approximate temp. where degradation by cyclisation is limited (even though) auxiliary agents decreasing reaction mix viscosity are absent. Activity of the catalysts is maintained alkali-hydroxide dosing to ensure reaction continuity.