Picolyl ligands and their use in alkoxycarbonylation
Patent Information
- Application Number
- EP2023800342
- 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 yields, particularly in the use of traditional ligands and metal-ligand complexes with palladium, which restrict the efficiency of forming esters from olefins, carbon monoxide, and alcohols.
The development of picolyl ligands, specifically compounds with certain alkyl and hydrogen residues, and a process involving the introduction of an ethylenically unsaturated compound, a picolyl ligand, a Pd compound, a co-catalyst, an alcohol, and carbon monoxide, followed by heating, to enhance the alkoxycarbonylation reaction and increase ester formation efficiency.
The use of picolyl ligands and the described process significantly improves the yield of ester formation by optimizing the reaction conditions, including the choice of Pd compounds, co-catalysts, and reaction parameters, thereby enhancing the overall efficiency of the alkoxycarbonylation process.
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Abstract
Description
[0001] Picolyl ligands and their use in alkoxycarbonylation
[0002] The invention relates to picolyl 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 three residues R 1 , R 2 , R 3 represents -(Ci-C4)-alkyl, and the other two radicals represent -H. In one embodiment, one of the three radicals R 1 , R 2 , R 3 stands for -CHs, and the other two residues stand for -H.
[0008] In one embodiment, the compound has the structure (1):
[0009] In one embodiment, the compound has the structure (2): In one embodiment, the compound has the structure (3): In addition to the compounds themselves, a process is also claimed in which the compounds are used.
[0010] Process comprising the process steps: a) introducing 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, 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.
[0011] The substances can be added in any order. Typically, however, CO is added after the reactants have been introduced in steps a) to e). Furthermore, CO can also be added in multiple steps, so that, for example, a portion of the CO is added first, then heated, and then another portion of CO is added.
[0012] 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),
[0013] Palladium(cinnamyl)dichloride.
[0014] In a variant of the process, the Pd compound is selected from: Pd(dba)2, Pd(acac)2 or Pd(OAc)2.
[0015] In a variant of the process, the Pd compound is Pd(acac)2.
[0016] 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.
[0017] In one variant of the process, the alcohol in process step e) is methanol. In one 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 a 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.
[0022] In a 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.
[0023] In a variant of the process, di-iso-butene is used as the ethylenically unsaturated compound.
[0024] 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.
[0025] In one variant of the process, the co-catalyst is aluminum triflate.
[0026] In the following, the invention will be explained in more detail using exemplary embodiments.
[0027] General working regulations
[0028] 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), (3), and (4) as a reference ligand. 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
[0029] 3,5,5-T rimethylhexanoic acid-
[0030] 1 mol / L DiB (TMP1:TMP2 = 79:21) methyl ester (TMH methyl ester)
[0031] Precursor stock solution:
[0032] 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).
[0033] 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.
[0034] The sales are listed in the following table:
[0035] * embodiment according to the invention
[0036] 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 three residues R 1 , R 2 , R 3 represents -(Ci-C4)-alkyl, and the other two radicals represent -H.
2. A compound according to claim 1, wherein one of the three radicals R 1 , R 2 , R 3 stands for -CH3, and the other two residues stand 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 compound according to any one of claims 1 or 2, wherein the compound has the structure (3):
6. A process comprising the process steps: a) introducing an ethylenically unsaturated compound; b) adding a compound according to any one of claims 1 to 5; 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.
7. The process according to claim 6, 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.
8. The process according to claim 6 or 7, 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.
9. A process according to any one of claims 6 to 8, wherein the alcohol in process step e) is methanol.
10. Process according to one of claims 6 to 9, wherein CO is supplied in process step f) at a CO partial pressure in the range of 1 to 5 MPa (10 to 50 bar).
11. The process according to any one of claims 6 to 10, wherein the reaction mixture in process step g) is heated to a temperature in the range from 40 °C to 140 °C.
12. Process according to one of claims 6 to 11, wherein di-isobutene is used as the ethylenically unsaturated compound.
13. A process according to any one of claims 6 to 12, wherein the co-catalyst is aluminum triflate.