METHOD FOR PRODUCING PURIFIED (METH)ACRYLIC ACID

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a purified (meth)acrylic acid from a crude (meth)acrylic acid containing maleic acids and aldehydes as impurities in which maleic acids and aldehydes can be sufficiently removed and which can be operated continuously for a long period of time. SOLUTION: The method for producing a purified (meth)acrylic acid by distillation of a crude (meth)acrylic acid containing maleic acids and aldehydes as impurities in turn comprises before distillation the steps of (A) adding hydrazines to a crude (meth)acrylic acid in a temperature range from the melting point of acrylic acid to 50°C to react hydrazines with maleic acids, (B) heat-treating a reaction mixture from the step (A) in a temperature range of 60-90°C to convert a reaction product obtained to a substance which is soluble in the reaction mixture , and (C) adding hydrazines to a heat-treated mixture from the step (B) in a temperature range from the melting point of acrylic acid to 50°C to react hydrazines with aldehydes to produce a substance which is soluble in the reaction mixture. COPYRIGHT: (C)2005,JPO&NCIPI