1,2-DIAMINOCYCLOHEXANE AND CHEMICAL PROCESS
Disclosed is a process for the preparation of 1,2-cycloaliphatic diamines from 1,2-aromatic diamines. In one embodiment, the process provides a method for making 1,2-diaminocyclohexane by the reaction of 1,2-phenylenediamine contained in a polar, protic solvent with hydrogen in the presence of a supported rhodium catalyst, ammonia, and a trialkylamine, and having enhanced overall conversion and selectivity.
1 . A process for making 1,2-cycloaliphatic diamines comprising contacting a 1,2-aromatic diamine with hydrogen in polar, protic solvent in the presence of a tertiary alkylamine, ammonia and a heterogeneous catalyst comprising at least one selected selected from the group consisting of Ru, Rh, Pd and Pt.
2 . The process of claim 1 wherein said polar, protic solvent has the structure ROH where R is hydrogen or an alkyl group.
3 . The process of claim 2 wherein said alkyl group has from 1 to 6 carbons.
4 . The process of claim 1 wherein said tertiary alkylamine has is a trialkylamine where the alkyl group has from 1 to 20 carbon atoms.
5 . The process of claim 4 wherein said tertiary alkylamine is selected from the group consisting of triethylamine, tripropylamine and tributylamine.
6 . The process of claim 5 wherein said tertiary alkylamine is triethylamine.
7 . The process of claim 1 wherein said heterogeneous catalyst comprises at least one selected from the group consisting of Ru and Rh.
8 . The process of claim 1 wherein the sum of the weights of Ru, Rh, Pd and Pt comprises from 1 to 10 weight percent of said heterogeneous catalyst.
9 . The process of claim 8 wherein the sum of the weights of Ru, Rh, Pd and Pt comprises from 3 to 5 weight percent of said heterogeneous catalyst.
10 . The process of claim 1 wherein said heterogeneous catalyst comprises an oxide of at least one selected from the group consisting of Ru, Rh, Pd and Pt.
11 . The process of claim 10 wherein said heterogeneous catalyst consists essentially of said oxide.
12 . The process of claim 8 wherein said heterogeneous catalyst comprises a support that is substantially inert to amines under reaction conditions for converting 1,2-aromatic diamines to cycloaliphatic diamines.
13 . The process of claim 8 wherein said heterogeneous catalyst comprises at least one support selected from the group consisting of alumina, titania, zeolites and microporous layered materials.
14 . The process of claim 1 further comprising contacting with hydrogen at a temperature from about 120° to about 200° C., and at a pressure of from about 1000 to about 2500 psig.
15 . A process for making 1,2-diaminocyclohexane comprising contacting 1,2-phenylenediamine contained in a polar, protic solvent with hydrogen in the presence of a tertiary alkylamine, ammonia and a supported rhodium catalyst, wherein said polar, protic solvent is selected from the group consisting of water, methanol, ethanol, isopropanol, and mixtures thereof.
16 . The process of claim 15 further comprising contacting with hydrogen at a temperature from about 120° to about 200° C., and at a pressure of from about 1000 to about 2500 psig.
17 . The process of claim 15 wherein said supported rhodium catalyst comprises rhodium on carbon and wherein said supported rhodium catalyst contains from about 1 to about 10 weight percent rhodium.
18 . The process of claim 15 wherein said supported rhodium catalyst contains from about 3 to about 5 weight percent rhodium.