Method for producing diaminodiphenyl alkanes
View Patent ↗The invention relates to a method for producing diaminodiphenyl alkanes, wherein an aromatic amine, which can be substituted or unsubstituted, is reacted with a C1-C3 aldehyde in the presence of a heterogeneous catalyst, said catalyst being a mesoporous acidic ion exchanger based on a divinylbenzene/styrene copolymer and the catalyst having acid centers in a concentration of 4 to 6 eq/kg as measured according to DIN 54 403 and the average pore diameter of the catalyst particles being 10 to 32 nm as measured according to ASTM D 4222 10, and the content of polynuclear compounds in the reaction mixture being ≦10% by weight.
1. A process for preparing a bis(aminophenyl)alkane, comprising reacting an aromatic amine, which may be substituted or unsubstituted, with a C 1 -C 3 aldehyde in the presence of a heterogeneous catalyst, the catalyst being a mesoporous acidic ion exchanger based on a divinylbenzene/styrene copolymer, and the catalyst comprising an acidic center, measured in accordance with DIN 54 403, in a concentration of 4 to 6 eq/kg, and the average pore diameter of the catalyst particles, measured in accordance with ASTM D 4222, being 10 to 32 nm, and the polynuclear compound content of the reaction mixture formed being 10% by weight.
2. The process according to claim 1 , wherein the aldehyde is formaldehyde.
3. The process according to claim 1 , wherein the amine is aniline.
4. The process according to claim 1 , wherein the bis(aminophenyl)alkane obtained is diaminodiphenylmethane.
5. The process according to claim 1 , wherein the isomer ratio of the bis(aminophenyl)alkane obtained is distributed as follows:
74% to 85% by weight
4,4′-bis(aminophenyl)alkane
3% to 20% by weight
2,4′-bis(aminophenyl)alkane
≦1.0% by weight
2,2′-bis(aminophenyl)alkane.
6. The process according to claim 5 , wherein the isomer ratio of the bis(aminophenyl)alkane obtained is distributed as follows:
74% to 85% by weight
4,4′-bis(aminophenyl)alkane
3% to 20% by weight
2,4′-bis(aminophenyl)alkane
≦1.0% by weight
2,2′-bis(aminophenyl)alkane.
7. The process according to claim 1 , wherein the N-methyl compound content is ≦1% by weight.
8. The process according to claim 1 , wherein the polynuclear compound content is <10% by weight.
9. The process according to claim 1 , wherein the reaction temperature of the catalytic reaction is situated in the range from 80 to 140° C.
10. The process according to claim 1 , wherein the reaction time for the catalytic reaction is 30 min to 5 hours.
11. The process according to claim 1 , wherein the molar ratio of amine to aldehyde is 5:1 to 15:1.
12. The process according to claim 1 , wherein the catalyst is in dry or moist form.
13. The process according to claim 1 , wherein the process is carried out continuously, batchwise or semi-batchwise.
14. The process according to claim 1 , wherein the reaction is carried out in a stirred tank, a stirred-tank cascade, a flow tube, a fixed-bed reactor or in a column.
15. The process according to claim 1 , wherein the acidic center comprises a sulfonic acid group.
16. The process according to claim 1 , wherein the concentration of the acidic centers of the ion exchanger is 4.4 to 5.7 eq/kg and very preferably 4.7 to 5.6 eq/kg, measured in accordance with DIN 54 403.
17. The process according to claim 1 , wherein the pore diameter of the ion exchangers, measured in accordance with ASTM D 4222, is 15 up to and including 30 nm.
18. The process according to claim 1 , wherein the reaction temperature of the catalytic reaction is in the range from 80 to 130° C.