A method is provided for collecting a compound of formula (III) (in which R31 is a monovalent to trivalent organic group and n31 is an integer of 1 to 3) from a liquid phase component that is formed as a by-product in a method for producing a compound of general formula (I) (in which R11 is a monovalent to trivalent organic group and n 11 is an integer of 1 to 3), wherein the collection method contains steps (1) to (3) or steps (A) and (B), and step (4). Step (1): a step for reacting the liquid phase component with at least one active hydrogen-containing compound in a reactor. Step (2): a step for returning a condensed liquid obtained by cooling gas phase components in the reactor to the reactor. Step (3): a step for discharging gas phase components that are not condensed in the step (2) to the outside of the reactor. Step (A): a step for mixing the liquid phase component, water, and a compound of general formula (III). Step (B): a step for reacting the liquid phase component with water inside the reactor. Step (4): a step for discharging, as a liquid phase component inside the reactor, the reaction liquid containing the compound of general formula (III) to the outside of the reactor.
R.sup.11NCO).sub.n11  (I)
R.sup.31NH.sub.2).sub.n31  (III)

A method is provided for collecting a compound of formula (III) (in which R31 is a monovalent to trivalent organic group and n31 is an integer of 1 to 3) from a liquid phase component that is formed as a by-product in a method for producing a compound of general formula (I) (in which R11 is a monovalent to trivalent organic group and n 11 is an integer of 1 to 3), wherein the collection method contains steps (1) to (3) or steps (A) and (B), and step (4). Step (1): a step for reacting the liquid phase component with at least one active hydrogen-containing compound in a reactor. Step (2): a step for returning a condensed liquid obtained by cooling gas phase components in the reactor to the reactor. Step (3): a step for discharging gas phase components that are not condensed in the step (2) to the outside of the reactor. Step (A): a step for mixing the liquid phase component, water, and a compound of general formula (III). Step (B): a step for reacting the liquid phase component with water inside the reactor. Step (4): a step for discharging, as a liquid phase component inside the reactor, the reaction liquid containing the compound of general formula (III) to the outside of the reactor.
R.sup.11NCO).sub.n11  (I)
R.sup.31NH.sub.2).sub.n31  (III)

A process for producing EDA from a mixture comprising water (H2O), ethylenediamine (EDA) and N-methylethylenediamine (NMEDA) by feeding the mixture into a rectification column, wherein the rectification column is operated at the top pressure in the range of 5.0 to 7.5 bar.

A process for producing EDA from a mixture comprising water (H2O), ethylenediamine (EDA) and N-methylethylenediamine (NMEDA) by feeding the mixture into a rectification column, wherein the rectification column is operated at the top pressure in the range of 5.0 to 7.5 bar.

Provided is a method for purifying 1,5-pentanediamine comprising: providing 1,5-pentanediamine to be purified and treating the 1,5-pentanediamine to be purified by a reduction reaction to obtain purified 1,5-pentanediamine. Meanwhile, further provided is 1,5-pentanediamine prepared by the method. The purification method has a concise process and a simple operation, and is suitable for industrial production, and can significantly improve the quality of 1,5-pentanediamine.

Provided is a method for purifying 1,5-pentanediamine comprising: providing 1,5-pentanediamine to be purified and treating the 1,5-pentanediamine to be purified by a reduction reaction to obtain purified 1,5-pentanediamine. Meanwhile, further provided is 1,5-pentanediamine prepared by the method. The purification method has a concise process and a simple operation, and is suitable for industrial production, and can significantly improve the quality of 1,5-pentanediamine.

Provided is a method for purifying 1,5-pentanediamine comprising: providing 1,5-pentanediamine to be purified and treating the 1,5-pentanediamine to be purified by a reduction reaction to obtain purified 1,5-pentanediamine. Meanwhile, further provided is 1,5-pentanediamine prepared by the method. The purification method has a concise process and a simple operation, and is suitable for industrial production, and can significantly improve the quality of 1,5-pentanediamine.

The present invention relates to a process for purification of a mixture comprising water, N-alkyl-hydroxylammonium salts and some byproducts wherein from the mixture water and byproducts are distilled off until the purity of N-alkyl-hydroxylammonium salts in the residue is 95% or higher and additionally keeping the water content during and after the distillation ≥40 wt.-% according to the residue.

The present invention relates to a process for purification of a mixture comprising water, N-alkyl-hydroxylammonium salts and some byproducts wherein from the mixture water and byproducts are distilled off until the purity of N-alkyl-hydroxylammonium salts in the residue is 95% or higher and additionally keeping the water content during and after the distillation ≥40 wt.-% according to the residue.

The present invention relates to a process for purifying ethylenediamine, in which a) a mixture comprising water (H2O), ethylenediamine (EDA) and N-methylethylenediamine (NMEDA) is introduced into a rectification column (NMEDA removal column), where the mixture introduced comprises at least the amount of water as required for the formation of a high-boiling azeotrope of EDA and water at the appropriate bottom temperature; and the EDA-comprising bottom product from the NMEDA removal column is introduced into a second rectification column (EDA dewatering column), wherein the pressure at the top of the EDA dewatering column is adjusted such that the boiling temperature of the mixture obtained at the top is 10° C. or higher than the bottom temperature of the NMEDA removal column, which comprises (i) partly or fully condensing the vapors from the top of the EDA dewatering column in a condenser which is cooled with a medium which is at least partly evaporated during the condensation and the vapor thus formed is used at least partly to heat the evaporator of the NMEDA removal column; and/or (ii) introducing the vapors from the top of the EDA dewatering column into the NMEDA removal column.