Patent ID: 7323590

Claim:
A process for rectificatively separating a liquid II whose content of acrylic acid and/or methacrylic acid, based on the total weight of the liquid II, is at least 10% by weight, and which, in addition to methacrylic acid and/or acrylic acid, comprises both acrolein and/or methacrolein and acetone in a total amount of not more than 5% by weight, based on the amount of acrylic acid and/or methacrylic acid present in the liquid II, with the proviso that the weight ratio of acrolein present in the liquid II to acetone present in the liquid II is different from 3.5, and which has been generated without adding acrolein or methacrolein as a pure substance to a liquid I comprising acrylic acid and/or methacrylic acid, which comprises: conducting the liquid II into a rectification column where liquid II comprises, based on the total amount of acrolein and methacrolein present in the liquid II, at least 10% by weight of acetone, whose presence has an inhibitory effect on the polymerization of acrylic acid and/or methacrylic acid in liquid II.