Process for the preparation of urethanes
View Patent ↗The invention relates to a method for producing urethanes or ureas or mixtures of urethanes and ureas by oxidative carbonylation of organic amines in the presence of carbon monoxide, oxygen and a catalyst, where the catalyst used is a transition metal complex containing the structural feature: [Mn+(O˜N˜O)2−](n−2)+(L)m(Z−)n−2 and the method is carried out under halogen-free reaction conditions. The invention further relates to transition metal complexes containing said structural feature and also to the use of such transition metal complexes as catalysts in the production of urethanes or ureas or mixtures of urethanes and ureas.
1. A process for the preparation of urethane or urea or mixtures of urethane and urea by the oxidative carbonylation of organic amines containing primary amino groups in the presence of carbon monoxide, oxygen and a catalyst, comprising utilizing as the catalyst a transition metal complex containing the structural feature [M n+ (O˜N˜O) 2− ] (n−2)+ (L) m (Z − ) n-2 , wherein:
M is a transition metal selected from the group consisting of Co, Ni, Cu, Rh, Ru, Ir and Pt,
n is 2 or 3,
(O˜N˜O) 2− is a tridentate, dianionic chelating ligand coordinating with M via two oxygen atoms and one nitrogen atom, which is derived by deprotonation of all the OH groups of a neutral chelating ligand selected from the group consisting of:
and combinations thereof,
L is a neutral ligand selected from the group consisting of water, azaaromatics, cyclic amines, acyclic amines, cyclic carboxamides, acyclic carboxamides, cyclic carboxylic acid esters, acyclic carboxylic acid esters, cyclic ketones, acyclic ketones, cyclic ketimines, acyclic ketimines, aliphatic ethers, aliphatic alcohols, aromatic alcohols, sulfoxides, formamides, cyclic organocarbonates, acyclic organocarbonates and nitriles,
m is 0, 1, 2 or 3 and
Z − is a monoanionic ligand selected from the group consisting of sulfonates, carboxylates, pseudohalides, [BF 4 ] − , [PF 6 ] − , [SbF 6 ] − , nitrate, hydrogensulfate, fluorosulfate and methylsulfate,
and
carrying out the process under halogen-free reaction conditions.
2. The process according to claim 1 wherein Z − is tosylate, mesylate, acetate, benzoate, cyanide, cyanate, thiocyanate, azide, nitrate, hydrogensulfate or methylsulfate.
3. The process according to claim 1 wherein the transition metal M is cobalt.
4. The process according to claim 1 wherein the catalyst is present in a concentration of 0.01 mol % to 10 mol %, based on one mol of primary amino groups.
5. The process according to claim 1 wherein the oxidative carbonylation is carried out at temperatures of 20° C. to 260° C., at an absolute carbon monoxide partial pressure of 1.0 bar to 150 bar and at an absolute oxygen partial pressure of 0.10 bar to 20 bar.
6. The process according to claim 1 wherein the oxidative carbonylation of organic amines is carried out in the presence of organic compounds carrying hydroxyl groups and leads to the preparation of urethanes or mixtures of urethanes and ureas.
7. The process according to claim 6 wherein the organic compounds carrying hydroxyl groups are:
methanol, ethanol, n-butanol, isobutanol, sec-butanol, n-propanol or isopropanol.
8. The process according to claim 1 wherein the organic amines are aliphatic, cycloaliphatic, araliphatic and/or aromatic mono- or diamines.
9. Process according to claim 8 wherein the aromatic amines are aniline or toluylenediamine.