The present invention relates to a process for preparing ethylenediamine (EDA), where the process comprises the steps a) to c). In step a), formaldehyde is reacted with hydrocyanic acid (HCN) to form formaldehyde cyanohydrin (FACH), where the hydrocyanic acid is completely free or largely free of sulfur dioxide (SO.sub.2). The FACH prepared in this way is reacted with ammonia (NH.sub.3) to form aminoacetonitrile (AAN) in step b), whereupon a hydrogenation of AAN in the presence of a catalyst to form EDA is carried out in step c).

The present invention relates to a process for purifying ethylenediamine (EDA) by distillation, wherein the process comprises the steps a) and b). In step a), a mixture (G1) comprising water, EDA and N-methylethylenediamine (N-MeEDA) is fed into a distillation apparatus (D1), and the major part of the water comprised in the mixture (G1) is separated off overhead at a pressure of greater than 4.8 bara. From the bottom of (D1), the water-enriched mixture (G2) is fed into a distillation apparatus (D2) in step b). At the top of (D2), the major part of the N-MeEDA is distilled off. The stream (S3) obtained from the bottom of (D2) comprises EDA, with the components water and N-MeEDA comprised in the mixture (G1) having been largely or completely removed. Further distillation steps can optionally be carried out in order to obtain pure EDA, for example when diethylenetriamine (DETA) is additionally comprised in the mixture (G1). If ammonia is additionally comprised in the mixture (G1), an ammonia removal is preferably additionally carried out before carrying out the step a) in the process of the invention.

The present invention relates to a process for purifying ethylenediamine (EDA) by distillation, wherein the process comprises the steps a) and b). In step a), a mixture (G1) comprising water, EDA and N-methylethylenediamine (N-MeEDA) is fed into a distillation apparatus (D1), and the major part of the water comprised in the mixture (G1) is separated off overhead at a pressure of greater than 4.8 bara. From the bottom of (D1), the water-enriched mixture (G2) is fed into a distillation apparatus (D2) in step b). At the top of (D2), the major part of the N-MeEDA is distilled off. The stream (S3) obtained from the bottom of (D2) comprises EDA, with the components water and N-MeEDA comprised in the mixture (G1) having been largely or completely removed. Further distillation steps can optionally be carried out in order to obtain pure EDA, for example when diethylenetriamine (DETA) is additionally comprised in the mixture (G1). If ammonia is additionally comprised in the mixture (G1), an ammonia removal is preferably additionally carried out before carrying out the step a) in the process of the invention.