Process for the preparation of esters by means of carbonylation of ethers
The invention relates to a process comprising the process steps of: a) initially charging an ether having from 3 to 30 carbon atoms; b) adding a phosphine ligand and a compound comprising Pd, or adding a comprising Pd and a phosphine ligand; c) feeding in CO; d) heating the reaction mixture, with conversion of the ether; wherein 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, —(C 3 -C 20 )-heteroaryl; at least one of the R 1 , R 2 , R 3 , R 4 radicals is a —(C 3 -C 20 )-heteroaryl radical; 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 or —(C 3 -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 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, —SO 3 H, —NH 2 , halogen; and wherein no alcohol is added to the reaction mixture.
1. Process for preparing esters from ether precursor comprising:
a) forming a reaction mixture by initially charging an ether having from 3 to 30 carbon atoms;
b) adding a phosphine ligand and a compound comprising Pd, or adding a complex comprising Pd and a phosphine ligand;
c) feeding in CO;
d) heating the reaction mixture, formed by steps a)-c), performed in any order, with conversion of the ether; wherein 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, —(C 3 -C 20 )-heteroaryl;
at least one of the R 1 , R 2 , R 3 , R 4 radicals is a —(C 3 -C 20 )-heteroaryl radical;
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 or —(C 3 -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 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, —SO 3 H, —NH 2 , halogen; and wherein no alcohol is added to the reaction mixture.
2. The process according to claim 1 ,
wherein the phosphine ligand is a compound of one of the formulae (II) and (III)
3. The process according to claim 1 ,
wherein 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 ,
wherein the R 1 and R 3 radicals are each a —(C 3 -C 20 )-heteroaryl radical.
5. The process according to claim 1 ,
wherein 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 )-cycloalky , —(C 3 -C 12 )-heterocycloalkyl, —(C 6 -C 20 )-aryl.
6. The process according to claim 1 ,
wherein 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 ,
wherein 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, isoindolyl, benzimidazolyl, quinolyl, isoquinolyl.
8. The process according to claim 1 ,
wherein the phosphine ligand is a compound of formula (1)
9. The process according to claim 1 ,
wherein the ether 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, —(C 6 -C 20 )-aryl;
R 6 and R 7 each independently are selected from —H, —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, —(C 6 -C 20 )-aryl;
and R 8 is selected from —(C 1 -C 12 )-alkyl, —(C 3 -C 12 )-cycloalkyl, —(C 6 -C 20 )-aryl.
10. The process according to claim 9 ,
wherein R 5 and R 8 are each —(C 1 -C 12 )-alkyl.
11. The process according to claim 9 ,
wherein R 6 and R 7 each independently are selected from —H, —( 1 -C 12 -alkyl, —(C 6 -C 20 )-aryl.
12. The process according to claim 9 ,
wherein not more than one of the radicals R 6 and R 7 is —H.
13. 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)palladium(II), bis(dibenzylideneacetone)palladium, bis(acetonitrile)dichloropalladium(II), palladium(cinnamyl) dichloride.