Process for alkoxycarbonylation of olefins using synthesis gas

Abstract

To provide a process for alkoxycarbonylation of olefins using synthesis gas.SOLUTION: There is provided a process comprising the steps of: a) initially charging an olefin; b) adding a ligand of the following formula (I); c) adding a compound comprising Pd; d) adding an alcohol; e) supplying CO and H2, where the pressure with which H2 is supplied is at least 0.6 MPa (6 bar); and f) heating the reaction mixture from steps a) to e), to convert the olefin to an ester.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a process for the alkoxycarbonylation of olefins using synthesis gas (a mixture of CO and H2). [Background technology]

[0002] Alkoxycarbonylation of ethylenically unsaturated compounds is a process that is becoming increasingly important. Alkoxycarbonylation involves the reaction of an ethylenically unsaturated compound (olefin) with carbon monoxide and an alcohol in the presence of a metal-ligand complex to give the corresponding ester. The metal typically used is palladium. The diagram below shows the general reaction scheme for alkoxycarbonylation.

[0003] [ka]

[0004] Traditionally, alkoxycarbonylation processes are operated using CO. One is described in EP 4001256. The addition of H2 has been purposely avoided because it was believed to promote side reactions (e.g., hydroformylation) and reduce conversion to the desired end product. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] European Patent Application Publication No. 4001256 Summary of the Invention [Problem to be solved by the invention]

[0006] The technical object of the present invention is to provide a novel process that results in improved yields. [Means for solving the problem]

[0007] This object is achieved by the method according to claim 1.

[0008] a) initially charging an olefin; b) Formula (I):

[0009] [ka]

[0010] (In the formula, R 1 and R 3 are -(C3-C 20 )-heteroaryl group, R 2 and R 4 are -(C1-C 12 )-alkyl. adding a ligand of c) adding a compound containing Pd; d) adding alcohol; e) feeding CO and H2, the pressure of the H2 feed being at least 6 bar; f) heating the reaction mixture of steps a) to e) and converting the olefin into an ester A method comprising:

[0011] Expression (C1~C 12 ) Alkyl includes straight-chain and branched-chain alkyl groups having 1 to 12 carbon atoms, which are preferably (C1-C8) alkyl groups, more preferably (C1-C6) alkyl groups, and most preferably (C1-C4) alkyl groups.

[0012] Expression (C3~C 20 ) Heteroaryl includes monocyclic or polycyclic aromatic hydrocarbon groups having 3 to 20 carbon atoms, wherein one or more carbon atoms are replaced by a heteroatom. Preferred heteroatoms are N, O, and S. (C3 to C 20) Heteroaryl groups have 3 to 20, preferably 6 to 14, particularly preferably 6 to 10 ring atoms. Thus, for example, in the context of this specification, pyridyl is a C6-heteroaryl group and furyl is a C5-heteroaryl group.

[0013] In one variation of the method, CO is supplied at a pressure in the range of 1 MPa (10 bar) to 3 MPa (30 bar).

[0014] In one variation of the method, CO is supplied at a pressure in the range of 1.5 MPa (15 bar) to 2.5 MPa (25 bar).

[0015] In one variation of the method, CO is supplied at a pressure of 2 MPa (20 bar).

[0016] In one variation of the method, H2 is supplied at a pressure in the range of 0.6 MPa (6 bar) to 2.9 MPa (29 bar).

[0017] In one variation of the method, H2 is supplied at a pressure in the range of 0.9 MPa (9 bar) to 2.1 MPa (21 bar).

[0018] In one variation of the method, H2 is supplied at a pressure in the range of 1 MPa (10 bar) to 2 MPa (20 bar).

[0019] In one variation of the method, the pressure ratio at which CO and H2 are supplied ranges from 1:0.3 to 1:1.4.

[0020] In one variation of this method, R 1 , R 3 are each selected from furyl, thienyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, pyrazolyl, furazanyl, tetrazolyl, pyridyl, pyridazinyl, pyrimidyl, pyrazinyl, benzofuranyl, indolyl, isoindolyl, benzimidazolyl, quinolyl, and isoquinolyl.

[0021] In one variation of this method, R 2 and R 4 teeth, ter It's Bu.

[0022] In one variation of the method, the ligand in step b) is of formula (1):

[0023] [ka]

[0024] It has.

[0025] In one variation of the method, the Pd-containing compound in step c) is selected from palladium dichloride, palladium(II) acetylacetonate, palladium(II) acetate, dichloro(1,5-cyclooctadiene)palladium(II), bis(dibenzylideneacetone)palladium, bis(acetonitrile)dichloropalladium(II), and (cinnamyl)palladium dichloride.

[0026] In one variation of the method, the Pd-containing compound in step c) is Pd(acac)2.

[0027] In one variant of the process, the alcohol of step d) is selected from methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, tert-butanol, 3-pentanol, cyclohexanol, phenol, or mixtures thereof.

[0028] In one variant of the process, the alcohol in step d) is methanol.

[0029] In one variation of the method, the method comprises: d') an additional step of adding an acid selected from aluminum triflate, sulfuric acid, methylsulfonic acid (MSA), and paratoluenesulfonic acid (p-TSA). Includes:

[0030] In one variant of the process, aluminum triflate is added in step d').

[0031] In one variation of the method, the acid:ligand ratio ranges from 1 molar:1 molar to 15 molar:1 molar.

[0032] In one variation of this method, the aluminum triflate:ligand ratio ranges from 1 mol:1 mol to 15 mol:1 mol.

[0033] In order to convert the olefin into the ester, in step f) of the process according to the invention the reaction mixture is preferably heated to a temperature in the range of from 30°C to 150°C, preferably from 40°C to 140°C, more preferably from 50°C to 120°C.

[0034] The invention is explained in detail below with reference to examples. [Example]

[0035] Experimental Example 1

[0036] [ka]

[0037] Pd(acac)2: 0.04 mol% (1): 0.12 mol% Al(OTf)3: 0.6 mol% One experiment was carried out with syngas and one with pure CO as a control experiment. The syngas was a mixture of CO and H2. In both experiments, CO was fed at a pressure of 20 bar. In the experiment with syngas, H2 was also fed at 20 bar, giving a total pressure of 40 bar. Ester yield: CO: 47% CO+H2:67%

[0038] Experimental example 2 (Variation of H2 pressure)

[0039] [ka]

[0040] Pd(acac)2: 0.04 mol% (1): 0.12 mol% Al(OTf)3: 0.6 mol% A series of experiments was carried out at a constant CO pressure of 20 bar. The H pressure was varied according to the table below.

[0041] [Table 1]

[0042] As shown in the experiments carried out, the use of synthesis gas resulted in improved yields.

Claims

1. a) initially charging an olefin; b) Formula (1): 【Chemistry 2】 adding a ligand of c) adding Pd(acac)2; d) adding methanol; e) CO and H ２ and H ２ to a pressure of between 0.9 MPa (9 bar) and 2.1 MPa (21 bar), f) heating the reaction mixture of steps a) to e) to convert the olefin to an ester. Including, the olefin is 2,2,4-trimethylpent-2-ene, The method wherein in step e) above, the ratio of pressures at which CO and H 2 are supplied is in the range of 1:0.3 to 1:1.

4.

2. 10. The method of claim 1, comprising the additional step of d') adding an acid selected from aluminum triflate, sulfuric acid, methyl sulfonic acid (MSA), and paratoluene sulfonic acid (p-TSA).

3. 3. The method of claim 2, wherein the ratio of said acid to said ligand ranges from 1 mole:1 mole to 15 mole:1 mole.

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