Process for the alkoxycarbonylation of alcohols

1. A process for forming an ester mixture product having n- and iso-ester components from a corresponding first alcohol substrate and CO and a second alcohol comprising the following process steps:

a) introducing the first alcohol selected from a secondary or tertiary alcohol, having 2 to 30 carbon atoms, to form a reaction mixture;

b) adding a phosphine ligand and a compound which comprises Pd, or adding a complex comprising Pd and the phosphine ligand;

c) adding the second alcohol;

d) supplying CO;

e) heating the reaction mixture, the first alcohol reacting with CO and then the second alcohol to form the ester mixture with the iso- and n-products;

where the phosphine ligand is a compound of formula (I)

where m and n are each independently 0 or 1;

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, where each is substituted or unsubstituted; and

at least one of the R 1 , R 2 , R 3 , R 4 radicals is a —(C 3 -C 20 )-heteroaryl radical; wherein

the substituents are 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 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 or halogen.

2. The process according to claim 1 , where the phosphine ligand is a compound of one of the formulae (II) and (III)

3. The process according to claim 1 , where at least two of the R 1 , R 2 , R 3 , R 4 radicals are a —(C 3 -C 20 )-heteroaryl radical.

4. The process according to claim 1 ,

where the R 1 and R 3 radicals are each a —(C 3 -C 20 )-heteroaryl radical.

5. The process according to claim 1 ,

where the R 1 and R 3 radicals are each a —(C 3 -C 20 )-heteroaryl radical;

and R 2 and R 4 are each independently 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 ,

where the R 1 and R 3 radicals are each a —(C 3 -C 20 )-heteroaryl radical;

and R 2 and R 4 are each independently selected from —(C 1 -C 12 )-alkyl.

7. The process according to claim 1 ,

where R 1 , R 2 , R 3 , R 4 , if they are a heteroaryl radical, are each independently selected from furyl, thienyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, pyrazolyl, furazanyl, tetrazolyl, pyridyl, pyridazinyl, pyrimidyl, pyrazinyl, benzofuranyl, indolyl, isoindolyl, benzimidazolyl, quinolyl or isoquinolyl.

8. The process according to claim 1 ,

wherein the first alcohol in process step a) is a compound of formula (IV)

where R 5 is selected from —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl or —(C 6 -C 20 )-aryl;

and R 6 and R 7 are each independently selected from —H, —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl or —(C 6 -C 20 )-aryl and wherein not more than one of the radicals R 6 and R 7 .

9. The process according to claim 8 ,

wherein R 5 is —(C 1 -C 12 )-alkyl.

10. The process according to claim 8 ,

where R 6 and R 7 are each independently selected from —H, —(C 1 -C 12 )-alkyl or —(C 6 -C 20 )-aryl.

11. The process according to claim 1 ,

wherein the compound comprising Pd in process step b) is selected from palladium dichloride, palladium(II) acetylacetonate, palladium(II) acetate, dichloro(1,5-cyclooctadiene)palla dium(II), bis(dibenzylideneacetone)palladium, bis(acetonitrile)dichloropalladium(II) or palladium(cinnamyl) dichloride.

12. The process according to claim 1 ,

wherein the second alcohol in process step c) is selected from the group consisting of methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, tert-butanol, 3-pentanol, cyclohexanol, and mixtures thereof.

13. The process according to claim 1 ,

wherein the second alcohol in process step c) is a primary alcohol.

14. A process for forming an ester mixture product having n- and iso-ester components from a corresponding first alcohol substrate and CO and a second alcohol comprising the following process steps:

a) introducing the first alcohol selected from a secondary or tertiary alcohol, having 2 to 30 carbon atoms, to form a reaction mixture;

b) adding a phosphine ligand and a compound which comprises Pd, or adding a complex comprising Pd and the phosphine ligand;

c) adding the second alcohol;

d) supplying CO;

e) heating the reaction mixture, the first alcohol reacting with CO and then the second alcohol to form the ester mixture with the iso- and n-products;

where the phosphine ligand is a compound of formula (1)

15. A process for forming an ester mixture product having n- and iso-ester components from a corresponding first alcohol substrate and CO and a second alcohol comprising the following process steps:

a) introducing the first alcohol selected from a secondary or tertiary alcohol, having 2 to 30 carbon atoms, to form a reaction mixture;

b) adding a phosphine ligand and a compound which comprises Pd, or adding a complex comprising Pd and the phosphine ligand;

c) adding the second alcohol;

d) supplying CO;

e) heating the reaction mixture, the first alcohol reacting with CO and then the second alcohol to form the ester mixture with the iso- and n-products; where the phosphine ligand is (α, α′-bis(2-pyridyl)(t-butyl)phosphino)o-xylene and the first alcohol is 3,3-dimethylbutan-2-ol.