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 2 to 6 eq/kg measured according to DIN 54403 and the average pore diameter of the catalyst particles being 10 to 32 nm measured according to ASTM D 4222, and the content of polynuclear compounds in the reaction mixture being >10 and ˜15% by weight.
1. A process for preparing at least one bis(aminophenyl)alkane in a catalytic reaction, 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, wherein:
the catalyst is a mesoporous acidic ion exchanger based on a divinylbenzene/styrene copolymer;
the catalyst has acidic centers, measured in accordance with DIN 54 403, in a concentration of 2 to 6 eq/kg;
an average pore diameter of catalyst particles, measured in accordance with ASTM D 4222, is 10 to 32 nm, and
a polynuclear compound content of a reaction mixture formed is >10% and ≦15% by weight and
N methyl compounds content is ≦1% by weight.
2. The process according to claim 1 , wherein formaldehyde is employed as the aldehyde.
3. The process according to claim 1 , wherein aniline is the aromatic amine.
4. The process according to claim 1 , wherein bis(aminophenyl)methane is prepared.
5. The process according to claim 1 , wherein a isomer ratio of the bis(aminophenyl)alkane obtained is distributed as follows:
64% to 85%
by weight
4,4′ diaminodiphenylalkane,
3% to 20%
by weight
2,4′ diaminodiphenylalkane, and
≧1.0% to ≦2%
by weight
2,2′ diaminodiphenylalkane.
6. The process according to claim 5 , wherein the isomer ratio of bis(aminophenyl)alkane obtained is distributed as follows:
64% to 85%
by weight
4,4′ diaminodiphenylmethane,
3% to 20%
by weight
2,4′ diaminodiphenylmethane, and
≧1.0% to ≦2%
by weight
2,2′ diaminodiphenylmethane.
7. The process according to claim 1 , wherein a reaction temperature of the catalytic reaction is in a range from 80 to 140° C.
8. The process according to claim 1 , wherein a reaction time for the catalytic reaction is 30 min to 5 hours.
9. The process according to claim 1 , wherein a molar ratio of amine to aldehyde is 5:1 to 15:1.
10. The process according to claim 1 , wherein the catalyst is employed in dry or moist form.
11. The process according to claim 1 , wherein the process is carried out continuously, batchwise, or semi-batchwise.
12. 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.
13. The process according to claim 1 , wherein sulfonic acid groups are employed as acidic centers for the catalyst.
14. The process according to claim 1 , wherein a concentration of the acidic centers of the mesoporous acidic ion exchanger is 4.4 to 5.7 eq/kg, measured in accordance with DIN 54 403.
15. The process according to claim 1 , wherein the pore diameter of the ion exchanger, measured in accordance with ASTM D 4222, is 15 up to and including 30 nm.
16. The process according to claim 1 , wherein reaction temperature of the catalytic reaction is in a range from 80 to 130° C.
17. The process according to claim 1 , wherein a concentration of the acidic centers of the mesoporous acidic ion exchanger is 4.7 to 5.6 eq/kg, measured in accordance with DIN 54 403.
18. The process according to claim 1 , wherein the pore diameter of the ion exchanger, measured in accordance with ASTM D 4222, is 22 up to and including 30 nm.
19. The process according to claim 1 , wherein the diaminodiphenylalkane is produced in a yield of 80 to 95%.
20. The process according to claim 1 , wherein the N methyl compounds content is ≦0.5% by weight.
21. The process according to claim 1 , wherein the N methyl compounds content is ≦0.3% by weight.
22. The process according to claim 1 , wherein the N methyl compounds content is ≦0.06% by weight.
23. The process according to claim 1 , wherein the N methyl compounds content is ≦0.03% by weight.