Method for purifying lactames
AssigneeRhodia Polyamide Intermediates
InventorsPhilippe Carvin, Jean-Claude Masson
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Abstract
The invention relates to a method for purifying lactames, especially lactames obtained by cyclization hydrolysis of an aminoalkylnitrile, and more particularly, to the purification of ε-caprolactame obtained by cyclization hydrolysis of the aminocapronitrile. This crystallisation process can either be carried out directly on the cyclization reaction medium after removal of the volatile components or on a medium that has been subjected to different treatments or on a caprolactame extracted from the reaction medium, for example by distillation.
Claims13
Process for purifying lactams obtained by cyclization of an aminoalkylnitrile, characterized in that it consists in recovering the lactam by crystallization after removing the volatile compounds from the cyclization medium.
Process according to one of the preceding claims, characterized in that the cyclization medium is treated with an ion-exchange resin before recovering the lactam by crystallization.
Process according to one of the preceding claims, characterized in that the cyclization medium from which the lactam is crystallized consists of the reaction medium obtained from the cyclization reaction after removal of the volatile compounds and the high-boiling compounds.
Process according to one of the preceding claims, characterized in that the lactam is ε-caprolactam.
Process according to one of the preceding claims, characterized in that the crystallization solvent is chosen from the group comprising a lactam, an aqueous lactam solution, water, saturated hydrocarbons, alcohols, aromatic hydrocarbons, organohalogen compounds and ketones
Process according to one of the preceding claims, characterized in that the weight concentration of lactam in the solution to be crystallized is greater than 80% by weight.
Dependencies are inferred from the claim text.