PLATINUM COMPLEXES HAVING FERROCENE LIGANDS FOR THE CATALYSIS OF THE ALKOXYCARBONYLATION OF ETHYLENICALLY UNSATURATED COMPOUNDS

Abstract

Platinum complexes having ferrocene ligands for the catalysis of the alkoxycarbonylation of ethylenically unsaturated compounds.

Claims

1. Complex comprising Pt and a compound of formula (I) ##STR00010## where R.sup.1, R.sup.2, R.sup.3, R.sup.4 are each independently selected from —(C.sub.1-C.sub.12)-alkyl, —(C.sub.3-C.sub.12)-cycloalkyl, —(C.sub.3-C.sub.12)-heterocycloalkyl, —(C.sub.6-C.sub.2)-aryl, —(C.sub.6-C.sub.20)-heteroaryl; at least one of the R.sup.1, R.sup.2, R.sup.3, R.sup.4 radicals is a —(C.sub.6-C.sub.20)-heteroaryl radical having at least six ring atoms; and R.sup.1, R.sup.2, R.sup.3, R.sup.4, if they are —(C.sub.1-C.sub.12)-alkyl, —(C.sub.3-C.sub.12)-cycloalkyl, —(C.sub.3-C.sub.12)-heterocycloalkyl, —(C.sub.6-C.sub.20)-aryl or —(C.sub.6-C.sub.20)-heteroaryl, may each independently be substituted by one or more substituents selected from: —(C.sub.1-C.sub.12)-alkyl, —O—(C.sub.1-C.sub.12)-alkyl, —OH, —NH.sub.2, halogen.

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

3. Complex according to claim 1, wherein the R.sup.1 and R.sup.3 radicals are each a —(C.sub.6-C.sub.20)-heteroaryl radical having at least six ring atoms.

4. Complex according to claim 1, wherein the R.sup.1 and R.sup.3 radicals are each 2-pyridyl.

5. Complex according to claim 1, wherein R.sup.2 and R.sup.4 are —(C.sub.1-C.sub.12)-alkyl.

6. Complex according to claim 1, wherein R.sup.2 and R.sup.4 are tent-butyl.

7. Complex according to claim 1, wherein the compound (I) has the structure (1): ##STR00011##

8. Process comprising the process steps of: a) initially charging an ethylenically unsaturated compound: b) adding a complex according to claim 1, or a compound of formula (I) ##STR00012## where R.sup.1, R.sup.2, R.sup.3, R.sup.4 are each independently selected from —(C.sub.1-C.sub.12)-alkyl, —(C.sub.3-C.sub.12)-cycloalkyl, —(C.sub.3-C.sub.12)-heterocycloalkyl, —(C.sub.6-C.sub.20)-aryl, —(C.sub.6-C.sub.20)-heteroaryl; at least one of the R.sup.1, R.sup.2, R.sup.3, R.sup.4 radicals is a —(C.sub.6-C.sub.20)-heteroaryl radical having at least six ring atoms; and R.sup.1, R.sup.2, R.sup.3, R.sup.4, if they are —(C.sub.1-C.sub.12)-alkyl, —(C.sub.3-C.sub.12)-cycloalkyl, —(C.sub.3-C.sub.12)-heterocycloalkyl, —(C.sub.6-C.sub.20)-aryl or —(C.sub.6-C.sub.20)-heteroaryl, may each independently be substituted by one or more substituents selected from: —(C.sub.1-C.sub.12)-alkyl, —O—(C.sub.1-C.sub.12)-alkyl, —OH, —NH.sub.2, halogen, and a substance comprising Pt; c) adding an alcohol; d) feeding in CO; e) heating the reaction mixture from a) to d), with conversion of the ethylenically unsaturated compound to an ester.

9. Process according to claim 8, wherein the ethylenically unsaturated compound is selected from: ethene, propene, 1-butene, cis- and/or trans-2-butene, isobutene, 1,3-butadiene, 1-pentene, cis- and/or trans-2-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, hexene, tetramethylethylene, heptene, 1-octene, 2-octene, di-n-butene, or mixtures thereof.

10. Process according to claim 8, wherein the alcohol in process step c) is selected from: methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, Pert-butanol, 3-pentanol, cyclohexanol, phenol.

11. Process according to claim 8, wherein the alcohol in process step c) is methanol.

12. Process according to claim 8, wherein the substance comprising Pt is selected from: platinum dichloride (PtCl.sub.2), platinum(II) acetylacetonate [Pt(acac).sub.2], platinum(II) acetate [Pt(OAc).sub.2], dichloro(1,5-cyclooctadiene)platinum(II) [Pt(cod).sub.2Cl.sub.2], bis(dibenzylideneacetone)platinum [Pt(dba).sub.2], bis(acetonitrile)dichloroplatinum(II) [Pt(CH.sub.3CN).sub.2Cl.sub.2], cinnamyl)platinum dichloride [Pt(cinnamyl)Cl.sub.2].

13. Process according to claim 8, wherein the substance comprising Pt is selected from: platinum dichloride (PtCl.sub.2), platinum(II) acetylacetonate [Pt(acac).sub.2], platinum(II) acetate [Pt(OAc).sub.2].

Description

[0025] The invention further relates to the use of a complex according to the invention for catalysis of an alkoxycarbonylation reaction.

[0026] Process comprising the process steps of: [0027] a) initially charging an ethylenically unsaturated compound; [0028] b) adding an above-described complex, or  a compound of formula (I)

##STR00004##

where [0029] R.sup.1, R.sup.2, R.sup.3, R.sup.4 are each independently selected from —(C.sub.1-C.sub.12)-alkyl, —(C.sub.3-C.sub.12)-cycloalkyl, —(C.sub.3-C.sub.12)-heterocycloalkyl, —(C.sub.6-C.sub.20)-aryl, —(C.sub.6-C.sub.20)-heteroaryl; [0030] at least one of the R.sup.1, R.sup.2, R.sup.3, R.sup.4 radicals is a —(C.sub.6-C.sub.20)-heteroaryl radical having at least six ring atoms; and [0031] R.sup.1, R.sup.2, R.sup.3, R.sup.4, if they are —(C.sub.1-C.sub.12)-alkyl, —(C.sub.3-C.sub.12)-cycloalkyl, —(C.sub.3-C.sub.12)-heterocycloalkyl, —(C.sub.6-C.sub.20)-aryl or —(C.sub.6-C.sub.20)-heteroaryl, [0032] may each independently be substituted by one or more substituents selected from: —(C.sub.1-C.sub.12)-alkyl, —O—(C.sub.1-C.sub.12)-alkyl, —OH, —NH.sub.2, halogen, and [0033] a substance comprising Pt; [0034] c) adding an alcohol; [0035] d) feeding in CO; [0036] e) heating the reaction mixture from a) to d), with conversion of the ethylenically unsaturated compound to an ester.

[0037] In this process, process steps a), b), c) and d) can be effected in any desired sequence. Typically, however, the addition of CO is effected after the co-reactants have been initially charged in steps a) to c). Steps d) and e) can be effected simultaneously or successively. In addition, CO can also be fed in in two or more steps, in such a way that, for example, a portion of the CO is first fed in, then the mixture is heated, and then a further portion of CO is fed in.

[0038] The ethylenically unsaturated compounds used as reactant in the process according to the invention contain one or more carbon-carbon double bonds. These compounds are also referred to hereinafter as olefins for simplification. The double bonds may be terminal or internal.

[0039] The ethylenically unsaturated compounds may, in addition to the one or more double bonds, contain further functional groups. At the same time, the ethylenically unsaturated compound preferably comprises a total of 2 to 30 carbon atoms, preferably 2 to 22 carbon atoms, more preferably 2 to 12 carbon atoms.

[0040] In one variant of the process, the ethylenically unsaturated compound does not comprise any further functional groups apart from carbon-carbon double bonds.

[0041] In one variant of the process, the ethylenically unsaturated compound is selected from: ethene, propene, 1-butene, cis- and/or trans-2-butene, isobutene, 1,3-butadiene, 1-pentene, cis- and/or trans-2-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, hexene, tetramethylethylene, heptene, 1-octene, 2-octene, di-n-butene, or mixtures thereof.

[0042] In one variant of the process, the ethylenically unsaturated compound is selected from: propene, 1-butene, cis-2-butene, trans-2-butene, or mixtures thereof.

[0043] In one variant of the process, the ethylenically unsaturated compound is selected from: 1-pentene, cis-2-pentene, trans-2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-butene, or mixtures thereof.

[0044] Suitable mixtures of ethylenically unsaturated compounds are those called raffinates I to III. Raffinate I comprises 40% to 50% isobutene, 20% to 30% 1-butene, 10% to 20% cis- and trans-2-butene, up to 1% 1,3-butadiene and 10% to 20% n-butane and isobutane. Raffinate II is a portion of the C.sub.4 fraction which arises in naphtha cracking and consists essentially of the isomeric n-butenes, isobutane and n-butane after removal of isobutene from raffinate I. Raffinate III is a portion of the C.sub.4 fraction which arises in naphtha cracking and consists essentially of the isomeric n-butenes and n-butane.

[0045] In one variant, a mixture comprising isobutene, 1-butene, cis- and trans-2-butene is used. Preferably, the mixture comprises 1-butene, cis- and trans-2-butene.

[0046] In one variant of the process, the alcohol in process step c) is selected from: methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, test-butanol, 3-pentanol, cyclohexanol, phenol.

[0047] In one variant of the process, the alcohol in process step c) is methanol.

[0048] In one variant of the process, the substance comprising Pt is selected from: platinum dichloride (PtCl.sub.2), platinum(II) acetylacetonate [Pt(acac).sub.2], platinum(II) acetate [Pt(OAc).sub.2], dichloro(1,5-cyclooctadiene)platinum(II) [Pt(cod).sub.2Cl.sub.2], bis(dibenzylideneacetone)platinum [Pt(dba).sub.2], bis(acetonitrile)dichloroplatinum(II) [Pt(CH.sub.3CN).sub.2Cl.sub.2], (cinnamyl)platinum dichloride [Pt(cinnamyl)Cl.sub.2].

[0049] In one variant of the process, the substance comprising Pt is selected from: platinum dichloride (PtCl.sub.2), platinum(II) acetylacetonate [Pt(acac).sub.2], platinum(II) acetate [Pt(OAc).sub.2].

[0050] CO is fed in in step d) preferably at a partial CO pressure between 0.1 and 10 MPa (1 to 100 bar), preferably between 1 and 8 MPa (10 to 80 bar), more preferably between 2 and 6 MPa (20 to 60 bar).

[0051] The reaction mixture is heated in step e) of the process according to the invention preferably to a temperature in the range from 60° C. to 160° C., preferably in the range from 80 to 140° C., more preferably in the range from 100 to 140° C., in order to convert the ethylenically unsaturated compound to an ester.

[0052] The invention is to be ted in detail hereinafter by a working example.

Conversion of 1-Octene to the Methyl Ester

[0053] ##STR00005##

[0054] Reaction conditions: 1-Octene (1.0 mmol), PtCl.sub.2 (0.01 mmol, 1.0 mol %), ligand: monodentate phosphine ligand (0.04 mmol, 4.0 mol %), bidentate phosphine ligand (0.02 mmol, 2.0 mol %), PTSA.H.sub.2O (monohydrate of p-toluenesulfonic acid) (5.0 mol %), MeOH (2.0 ml), pressure (CO): 40 bar, temperature: 120° C., reaction time: 20 h.

[0055] The reaction was conducted with the following ligands:

Monodentate Phosphine Ligands

[0056] ##STR00006## ##STR00007##

Bidentate Phosphine Ligands

[0057] ##STR00008## ##STR00009##

[0058] The respective yield and n/iso selectivity are stated below the ligand. Selectivities and yields were determined by gas chromatography with mesitylene as internal standard.

[0059] Of the 16 ligands used, 11 did not give any conversion (0%). Only with one ligand (L12=(1)) was it possible to achieve a conversion of more than 60%. As shown by the series experiments, the greatest conversion is achieved with the inventive complex of Pt and (1).

[0060] The cost of Pt is below that of Pd. The object is thus achieved by a complex according to the invention.