Abstract: In a distillation process 2-pyrrolidones obtained from succinonitrile are purified by treating the impure liquid pyrrolidone with a strong base, fractionally distilling this product to yield, as distillate, polymerization grade purified 2-pyrrolidone, mixing the 2-pyrrolidone-containing residue from the fractional distillation with water and an acid, and extracting purified 2-pyrrolidone from the water/acid mixture. The latter purified 2-pyrrolidone products are suitable for recycling to the pyrrolidone synthesis or to make other products.

Abstract: A process for the recovery of 2-pyrrolidone from the aqueous reaction product obtained in the preparation of 2-pyrrolidone from the hydrogenation of succinonitrile and subsequent reaction with water of the hydrogenation product thus obtained. The aqueous reaction mixture is adjusted to a pH value of 7 or lower and extracted with chloroform or methylene chloride to form an organic phase containing substantially all of the 2-pyrrolidone. The 2-pyrrolidone can be recovered from the organic phase by distillation, or by further extraction with water followed by crystallization from the aqueous phase thus formed or by evaporation of water.

Abstract: A method of recovering .epsilon.-caprolactam from the residue remaining from the distillation of impure .epsilon.-caprolactam wherein the residue is treated with sulphuric acid or oleum at a temperature between about 80.degree. C. and about 140.degree. C. and the resultant mixture neutralized. The lactam is then extracted with an organic solvent with the lactam then recovered from the resultant solution.

Abstract: The process is directed to recovering .epsilon.-caprolactam from a reaction mixture containing .epsilon.-caprolactum and sulfuric acid by separating the caprolactam from the sulfuric acid by an extraction. Extraction includes the steps of neutralizing a part of said sulfuric acid with ammonia, ammonium sulfate, ammonium hydrogen sulfate or mixture thereof, to form an ammonium salt of at least part of said sulfuric acid as a neutralization product, thermally decomposing a part of the ammonium salt formed to produce a gaseous mixture of ammonia and sulfur dioxide and contacting another portion of the neutralization product with said gaseous mixture to produce ammonium hydrogen sulfate, ammonium sulfate or both, and neutralizing at least a part of the sulfuric acid in the reaction mixture with said ammonium hydrogen sulfate, ammonium sulfate or both.

Abstract: A process for removing sulfuric acid from reaction mixtures containing sulfuric acid and .epsilon.-caprolactam by treating the sulfuric acid with ammonia and sulfur dioxide to produce ammonium sulfate salts and reducing the ammonium sulfate salts to ammonia and sulfur dioxide.

Abstract: A process for recovering substantially pure .epsilon.-caprolactam from a contaminated solution thereof is disclosed by concentrating, if needed, the caprolactam content of the solution to about 60-75 weight percent then extracting the concentrated solution with an organic solvent such as benzene or the like, then recovering the resulting caprolactam-laden organic solution.

Abstract: Polymerizable quality .epsilon.-caprolactam having an alkalinity of less than 0.05 meq. per kg. of lactam is produced in the improved disclosed process which includes extracting an aqueous lactam-rich solution with an organic solvent having a high distribution coefficient for the lactam with respect to the aqueous solution, and evaporating the lactam-rich organic solvent solution and recovering by distillation the lactam. Evaporation of the organic solvent requires considerably less thermal energy than evaporation of a similar aqueous solution.