Isolating pure anhydrous 2-6C carboxylic acid, especially (meth)acrylic acid for polymer production, involves complexing from the gas phase with high-boiling amine followed by thermal cleavage of the complex

摘要

A method for complexing 2-6C carboxylic acids (I) involves bringing an acid phase containing (I) into contact with a phase containing amine(s) with boiling point(s) higher than that of (I) as complexing agent(s), to give a complex with a b.pt. higher than that of some of the components in the acid phase. Independent claims are also included for: (i) a method for isolating (I) by treating a gaseous carboxylic acid phase with a liquid complexing phase as above, in which (a) at least some of the components other than (I) in the acid phase are separated as residual gas by heating the complex to a separation temperature at which the complex is still liquid and (b) at least part of the acid (I) is separated as gas in a temperature range within which the complex undergoes cleavage and the complexing phase is liquid; (ii) a process for the production of carboxylate esters by esterification of acids (I) isolated by the above method.