Process comprising the process steps of: a) addition of diisobutene; b) addition of a complex, comprising a compound of general formula and also Pd, or a compound according to general formula 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, -(C 3 -C 20)-heteroaryl; 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, R 4, if they are -(C 1 -C 12)-alkyl, -(C 3 -C 12)-cycloalkyl, -(C 3 -C 12) -heterocycloalkyl, -(C 6 -C 20)-aryl, -(C 3 -C 20) -heteroaryl or -(C 6 -C 20)-heteroaryl, may each independently be 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 r C 12)-cycloalkyl, -N-[(C 1 -C 12) -alkyl] 2, -(C 6 -C 20)-aryl, -(C 6 -C 20) -aryl-(C 1 -C 12) -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, halogen; c) feeding in CO; d) heating the reaction mixture such that the diisobutene is converted to a carboxylic acid, wherein the diisobutene is directly converted to the carboxylic acid. a) addition of diisobutene; b) addition of a complex, comprising a compound of general formula and also Pd, or a compound according to general formula 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, -(C 3 -C 20)-heteroaryl; 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, R 4, if they are -(C 1 -C 12)-alkyl, -(C 3 -C 12)-cycloalkyl, -(C 3 -C 12) -heterocycloalkyl, -(C 6 -C 20)-aryl, -(C 3 -C 20) -heteroaryl or -(C 6 -C 20)-heteroaryl, may each independently be 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 r C 12)-cycloalkyl, -N-[(C 1 -C 12) -alkyl] 2, -(C 6 -C 20)-aryl, -(C 6 -C 20) -aryl-(C 1 -C 12) -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, halogen; 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, -(C 3 -C 20)-heteroaryl; 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, R 4, if they are -(C 1 -C 12)-alkyl, -(C 3 -C 12)-cycloalkyl, -(C 3 -C 12) -heterocycloalkyl, -(C 6 -C 20)-aryl, -(C 3 -C 20) -heteroaryl or -(C 6 -C 20)-heteroaryl, may each independently be 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 r C 12)-cycloalkyl, -N-[(C 1 -C 12) -alkyl] 2, -(C 6 -C 20)-aryl, -(C 6 -C 20) -aryl-(C 1 -C 12) -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, halogen; c) feeding in CO; d) heating the reaction mixture such that the diisobutene is converted to a carboxylic acid, wherein the diisobutene is directly converted to the carboxylic acid.