C - Chemistry – Metallurgy – 07 – C
Patent
C - Chemistry, Metallurgy
07
C
202/58, 260/482.
C07C 69/54 (2006.01) C07C 51/48 (2006.01)
Patent
CA 1131657
ABSTRACT OF THE DISCLOSURE Methacrylic acid esters are effectively obtained from a feedstock dilute aqueous solution of methacrylic acid containing by-produced acetic acid and others, obtained by gas phase catalytic oxidation of at least one member of isobutylene, tert.butyl alcohol and methacrolein, by (1) subjecting said feedstock to extraction in a methacrylic acid extracting zone (a) using an extracting solvent prepared by adding to a water-insoluble, inert organic solvent having a boiling point above 120°C, 15 - 50% by weight of a methacrylic acid ester, (2) separating the resulting extract solution into a mixed solvent of the methacrylic acid ester and most of the organic solvent and a methacrylic acid solution on the remaining organic solvent by distillation in an extracting solvent-separating zone (b), (3) subject- in the resulting organic solvent solution containing methacrylic acid to esterification reaction in the presence of an acid catalyst together with an excess amount of an alcohol having a boiling point below 100°C in an esterification reaction zone (c), while removing water formed by the esterification reaction by azeotropic boiling with the organic solvent together with a part of the formed methacrylic acid ester as a distillate solution, thereby making an acid catalyst concentration of the remaining reaction solution constant, (4) separating the reaction solution discharged from the bottom of the esterification reaction zone (c) into an organic solvent layer containing the methacrylic acid ester and an aqueous layer containing the acid catalyst in a decanting zone (d), (5) recycling the aqueous layer at the constant acid catalyst concentration to the esterification reaction zone (c) after separating by- produced polymerization products therefrom, (6) Joining the organic solvent layer with the distillate solution in step (3), (7) subjecting the resulting mixture alcohol extraction using an aqueous solution of an inorganic salt in an alcohol extraction zone (e) to recover unreacted alcohol, (8) recycling the recovered alcohol to the esterification reaction zone (c), (9) separating low boiling materials from a raffinate organic solvent phase leaving the top Or the alcohol extraction zone (e) by distillation, (10) separating the raffinate organic solvent phase freed from the low boiling materials into a high purity methacrylic acid ester product and the organic solvent containing unreacted methacrylic acid, and (11) recycling the organic solvent containing methacrylic acid to an appropriate position Or the methacrylic acid-extracting zone (a) in step (1) or to a feedstock to be separated in step (2).
321785
Abe Tadashi
Kato Michio
Kawaguchi Tsunejiro
Sakakibara Yasuhito
Marks & Clerk
Sumitomo Chemical Co. Ltd.
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