Methoxypyridyl ligands and their use in alkoxycarbonylation
Patent Information
- Application Number
- EP2023798922
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-11-04
- Filing Date
- 2023-10-27
- Publication Date
- 2025-09-10
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Current alkoxycarbonylation processes for ethylenically unsaturated compounds face limitations in increasing yield and efficiency, particularly in the selection of effective ligands and reaction conditions.
The use of methoxypyridyl ligands, specifically compounds with certain R1 and R2 radicals, in combination with palladium compounds and co-catalysts like aluminum triflate, under controlled conditions such as temperature and CO partial pressure, to enhance the alkoxycarbonylation of ethylenically unsaturated compounds into esters.
Significantly improves the yield and efficiency of the alkoxycarbonylation process, as demonstrated by increased conversion of ethylenically unsaturated compounds into esters, with specific examples showing enhanced production of methyl esters from di-iso-butene and trimethylpentene isomers.
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Abstract
Description
[0001] Methoxypyridyl ligands and their use in alkoxycarbonylation
[0002] The invention relates to methoxypyridyl ligands and their use in alkoxycarbonylation.
[0003] The alkoxycarbonylation of ethylenically unsaturated compounds is a process of increasing importance. Alkoxycarbonylation is the reaction of ethylenically unsaturated compounds (olefins) with carbon monoxide and alcohols in the presence of a metal-ligand complex to form the corresponding esters. Palladium is typically used as the metal. The following scheme shows the general reaction equation for an alkoxycarbonylation:
[0004] ligand
[0005] The technical object of the invention is to provide a new ligand / process with which the conversion can be increased.
[0006] The problem is solved by a connection according to claim 1.
[0007] Compound according to formula (I): where one of the two residues R 1 , R 2 stands for -O-(Ci-C4)-alkyl and the other radical stands for -H.
[0008] In one embodiment, one of the two radicals R 1 , R 2 represents -O-CHs, and the other radical represents -H. In one embodiment, the compound has the structure (1):
[0009] In one embodiment, the compound has the structure (2):
[0010] In addition to the compounds themselves, a process is also claimed in which the compounds are used. A process comprising the process steps: a) initially charging an ethylenically unsaturated compound; b) adding a previously described compound according to formula (I); c) adding a Pd compound; d) adding a co-catalyst selected from: aluminum triflate, H2SO4, MA, pTSA, TFA; e) adding an alcohol; f) adding CO; g) heating the reaction mixture from a) to f), whereby the ethylenically unsaturated compound is converted to an ester. The substances can be added in any order. However, the CO is usually added after the reactants have been initially charged in steps a) to e). Furthermore, CO can also be added in several steps, so that, for example, part of the CO is added first, then heated, and subsequently another part of CO is added.
[0011] In a variant of the process, the Pd compound is selected from: palladium dichloride, palladium(II) acetylacetonate, palladium(II) acetate, dichloro(1,5-cyclooctadiene)palladium(II), bis(dibenzylideneacetone)palladium, bis(acetonitrile)dichloropalladium(II),
[0012] Palladium(cinnamyl)dichloride.
[0013] In a variant of the process, the Pd compound is selected from: Pd(dba)2, Pd(acac)2 or Pd(OAc)2.
[0014] In a variant of the process, the Pd compound is Pd(acac)2.
[0015] In a variant of the process, the alcohol in process step e) is selected from: methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, tert-butanol, 3-pentanol, cyclohexanol, phenol, or mixtures thereof.
[0016] In a variant of the process, the alcohol in process step e) is methanol.
[0017] In a variant of the process, the alcohol is used in excess in process step e).
[0018] In a variant of the process, the alcohol is simultaneously used as a solvent in process step e).
[0019] In a variant of the process, CO is added in process step f) at a CO partial pressure in the range of 1 to 5 MPa (10 to 50 bar).
[0020] In a variant of the process, CO is added in process step f) at a CO partial pressure in the range of 1 to 5 MPa (10 to 40 bar).
[0021] In one variant of the process, the reaction mixture in process step g) is heated to a temperature in the range of 40 °C to 140 °C. In one variant of the process, the reaction mixture in process step g) is heated to a temperature in the range of 80 °C to 140 °C.
[0022] In a variant of the process, di-iso-butene is used as the ethylenically unsaturated compound.
[0023] In a variant of the process, a mixture of 2,4,4-trimethylpent-1-ene (TMP1) and 2,4,4-trimethylpent-2-ene (TMP2) is used as the ethylenically unsaturated compound.
[0024] In one variant of the process, the co-catalyst is aluminum triflate.
[0025] In the following, the invention will be explained in more detail using exemplary embodiments.
[0026] General working regulations
[0027] The reaction is carried out under an argon atmosphere. Reaction vessels are previously dried under the influence of temperature (80 °C) and oil pump vacuum. Liquid substances are degassed for at least 15 minutes by bubbling with argon. Aluminum trifluoromethanesulfonic acid (Al(OTf)s) is used as the acid. The ligands used are (1), (2) and the reference ligand (3), (4). Palladium(II)bis(acetylacetonate) (Pd(acac)2) is used as the precursor. Diisobutene, a mixture of the two C8 isomers 2,4,4-trimethylpent-1-ene (TMP1) and 2,4,4-trimethylpent-2-ene (TMP2) in a ratio of 79:21, is used as the substrate. , mn
[0028] 3,5,5-T rimethylhexanoic acid-
[0029] 1 mol / L DiB (TMP1:TMP2 = 79:21) methyl ester (TMH methyl ester)
[0030] Precursor stock solution:
[0031] Pd(acac)2 (10 mg, 33 pmol) is weighed into a 20 mL vial, sealed hermetically with a crimped septum and dissolved in methanol (10 mL).
[0032] The reaction is carried out in 20 mL glass vessels equipped with magnetic stirrers. First, Al(OTf)s (0.8 mol%) and the ligand (0.2 mol%) are weighed into the glass vessel and then sealed hermetically with a crimped septum. A pierced cannula connected to an argon distribution station ensures an argon atmosphere in the following steps, while simultaneously allowing pressure equalization (adding solutions). The required amount of precursor stock solution (1.5 mL) is added via a pL syringe, resulting in a sample weight of Pd(acac)2 (0.05 mol%). Finally, methanol is added via a pL syringe to achieve a total volume of 8.4 mL. The autoclave is sealed, purged three times with nitrogen, and checked for density at 20 bar nitrogen. After determining the density, the same procedure is followed with CO. The reaction solutions are then heated to the required temperature of 120 °C.After 20 minutes at constant temperature, the substrate is transferred to the reaction vessels using an HPLC pump. After 15 minutes, a sample is drawn from each via the substrate line.
[0033] The sales are listed in the following table:
[0034] * embodiment according to the invention
[0035] The tests carried out prove that the task is solved by a compound according to the invention.
Claims
Claims 1. Compound according to formula (I): where one of the two residues R 1 , R 2 represents -O-(Ci-C4)-alkyl and the other radical represents -H.
2. A compound according to claim 1, wherein one of the two radicals R 1 , R 2 stands for -O-CH3, and the other residue stands for -H.
3. A compound according to any one of claims 1 or 2, wherein the compound has the structure (1):
4. A compound according to any one of claims 1 or 2, wherein the compound has the structure (2):
5. A process comprising the process steps: a) introducing an ethylenically unsaturated compound; b) adding a compound according to any one of claims 1 to 4; c) adding a Pd compound; d) adding a co-catalyst selected from: aluminum triflate, H2SO4, MSA, pTSA, TFA; e) adding an alcohol; f) adding CO; g) heating the reaction mixture from a) to f), whereby the ethylenically unsaturated compound is converted to an ester.
6. The process according to claim 5, wherein the Pd compound 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.
7. The process according to claim 5 or 6, wherein the alcohol in process step e) is selected from: methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, tert-butanol, 3-pentanol, cyclohexanol, phenol, or mixtures thereof.
8. A process according to any one of claims 5 to 7, wherein the alcohol in process step e) is methanol.
9. The process according to any one of claims 5 to 8, wherein CO is introduced in process step f) at a CO partial pressure in the range of 1 to 5 MPa (10 to 50 bar).
10. The process according to any one of claims 5 to 9, wherein the reaction mixture in process step g) is heated to a temperature in the range of 40°C to 140°C.
11. Process according to one of claims 5 to 10, wherein diisobutene is used as the ethylenically unsaturated compound.
12. A process according to any one of claims 6 to 11, wherein the co-catalyst is aluminum triflate.