Method for preparing N,N′-bis(2-cyanoethyl)-1,2-ethylenediamine by using cation exchange resin as catalyst
A method for preparing N,N′-bis(2-cyanoethyl)-1,2-ethylenediamine involves using strongly acidic cation exchange resin as a catalyst for synthesis, and is advantageous for not only eliminating the need of distillation for purification and thereby reducing reaction time, but also improving the yield of N,N′-bis(2-cyanoethyl)-1,2-ethylenediamine to 97.70-98.08%; and the method benefits simplified process and reduced costs and helps to save water significantly, thereby minimizing environmental pollution.
1. A method for preparing N,N′-bis(2-cyanoethyl)-1,2-ethylenediamine, comprising steps of: taking ethylenediamine and acrylonitrile at a molar ratio therebetween of 1:1.9-2.1 as reactants to perform synthesis reaction in the presence of strongly acidic cation exchange resin for 5-30 minutes at a temperature of 20-70° C. thereby obtaining N,N′-bis(2-cyanoethyl)-1,2-ethylenediamine with a yield of 97.7% or more; wherein the strongly acidic cation exchange resin is sulfonic-acid-based or carboxylic-acid-based cation exchange resin and is used in an amount of 50-100 wt % based on a weight of the ethylenediamine reactant.
2. The method of claim 1 , wherein the strongly acidic cation exchange resin is bead-form sulfonic-acid-based or carboxylic-acid-based cation exchange resin, with an average diameter (D 50 ) of 0.1-1.0 mm and has a total exchange capacity greater than 1.7 eq/L.
3. The method of claim 1 , wherein the strongly acidic cation exchange resin is Amberlyst-15 or Amberlyst-36 cation exchange resin.
4. The method of claim 2 , wherein the strongly acidic cation exchange resin is Amberlyst-15 or Amberlyst-36 cation exchange resin.
5. The method of claim 1 , wherein the molar ratio between ethylenediamine and acrylonitrile is 1:2.06.
6. The method of claim 2 , wherein the molar ratio between ethylenediamine and acrylonitrile is 1:2.06.
7. The method of claim 1 , wherein the synthesis reaction performs continuously for 5-30 minutes at room temperature of 25° C.
8. The method of claim 2 , wherein the synthesis reaction performs continuously for 5-30 minutes at room temperature of 25° C.
9. The method of claim 1 , wherein the acrylonitrile is added dropwise into a reactor.
10. The method of claim 2 , wherein the acrylonitrile is added dropwise into a reactor.
11. The method of claim 1 , wherein the acrylonitrile is continuously added but not added dropwise into a reactor.
12. The method of claim 2 , wherein the acrylonitrile is continuously added but not added dropwise into a reactor.
13. The method of claim 11 , wherein the acrylonitrile is added into the reactor simultaneously with ethylenediamine in a continuous manner.
14. The method of claim 11 , wherein the acrylonitrile is added into the reactor simultaneously with the cation exchange resin in a continuous manner.