Process for the direct conversion of diisobutene to a carboxylic acid

1. A process for preparing a carboxylic acid comprising:

adding diisobutene,

adding a complex, comprising a compound of general formula (I) and also Pd,

or a compound according to general formula (I) and a substance comprising Pd

wherein

R 1 , R 2 , R 3 , R 4 are each independently selected from —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, —(C 3 -C 12 )-heterocycloalkyl, —(C 6 -C 20 )-aryl or —(C 3 -C 20 )-heteroaryl; wherein

at least one of the R 1 , R 2 , R 3 , R 4 radicals is a —(C 6 -C 20 )-heteroaryl radical having at least six ring atoms;

and

R 1 , R 2 , R 3 , and R 4 are optionally substituted by one or more substituents selected from —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, —(C 3 -C 12 )-heterocycloalkyl, —O—(C 1 -C 12 )-alkyl, —O—(C 1 -C 12 )-alkyl-(C 6 -C 20 )-aryl, —O—(C 3 -C 12 )-cycloalkyl, —S—(C 1 -C 12 )-alkyl, —S—(C 3 -C 12 )-cycloalkyl, —COO—(C 1 -C 12 )-alkyl, —COO—(C 3 -C 12 )-cycloalkyl, —CONH—(C 1 -C 12 )-alkyl, —CONH—(C 3 -C 12 )-cycloalkyl, —CO—(C 1 -C 12 )-alkyl, —CO—(C 3 -C 12 )-cycloalkyl, —N—[(C 1 -C 12 )-alkyl] 2 , —(C 6 -C 20 )-aryl, —(C 6 -C 20 )-aryl-(C 1 -C 2 )-alkyl, —(C 6 -C 20 )-aryl-O—(C 1 -C 12 )-alkyl, —(C 3 -C 20 )-heteroaryl, —(C 3 -C 20 )-heteroaryl-(C 1 -C 12 )-alkyl, —(C 3 -C 20 )-heteroaryl-O—(C 1 -C 12 )-alkyl, —COOH, —OH, —SO 3 H, —NH 2 or halogen;

feeding in CO;

heating the reaction mixture such that the diisobutene is directly converted to the carboxylic acid.

2. The process according to claim 1 ,

wherein at least two of the R 1 , R 2 , R 3 , R 4 radicals are a —(C 6 -C 20 )-heteroaryl radical having at least six ring atoms.

3. The process according to claim 1 ,

wherein the R 1 and R 3 radicals are each a —(C 6 -C 20 )-heteroaryl radical having at least ring atoms.

4. The process according to claim 1 ,

wherein the R 1 and R 3 radicals are each a —(C 6 -C 20 )-heteroaryl radical having at least six ring atoms;

R 2 is —(C 6 -C 20 )-heteroaryl having at least six ring atoms or is selected from —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, —(C 3 -C 12 )-heterocycloalkyl or —(C 6 -C 20 )-aryl;

and R 4 is selected from —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, —(C 3 -C 12 )-heterocycloalkyl or —(C 6 -C 20 )-aryl.

5. The process according to claim 1 ,

wherein the R 1 and R 3 radicals are each a —(C 6 -C 20 )-heteroaryl radical having at least six ring atoms;

and R 2 and R 4 are selected from —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, —(C 3 -C 12 )-heterocycloalkyl or —(C 6 -C 20 )-aryl.

6. The process according to claim 1 ,

wherein the R 1 and R 3 radicals are each a —(C 6 -C 20 )-heteroaryl radical having at least six ring atoms;

and R 2 and R 4 are —(C 1 -C 12 )-alkyl.

7. The process according to claim 1 ,

wherein R 1 , R 2 , R 3 , R 4 , are each independently selected from pyridyl, pyridazinyl, pyrimidyl, pyrazinyl, benzofuranyl, indolyl, isoindolyl, benzimidazolyl, quinolyl or isoquinolyl.

8. The process according to claim 1 ,

wherein the compound (I) has the structure (1):

9. The process according to claim 1 ,

wherein the substance in process step b) is selected from:

PdCl 2 , PdBr 2 , Pd(acac) 2 , Pd(dba) 2 (dba=dibenzylideneacetone) or PdCl 2 (CH 3 CN) 2 .

10. The process according to claim 1 ,

wherein the process comprises

prior to heating the reaction mixture adding acetic acid.

11. The process according to claim 1 ,

wherein the process comprises

prior to heating the reaction mixture adding water.

12. The process according to claim 1 ,

wherein the process comprises

prior to heating the reaction mixture adding p-toluenesulfonic acid.

13. The process according to claim 1 ,

wherein the reaction mixture is heated to a temperature in the range from 80° C. to 160° C.

14. The process according to claim 1 ,

wherein the CO is fed in under pressure in the range from 20 bar to 60 bar.

15. The process according to claim 1 ,

wherein the diisobutene is converted to the compound P1: