Alkyl picolyl ligands and their use in alkoxycarbonylation

Abstract

The invention relates to an alkyl picocol-based ligand and application of the alkyl picocol-based ligand in alkoxycarbonylation.

Description

Technical Field

[0001] The present invention relates to alkyl picolyl ligands and their use in alkoxycarbonylation. Background Art

[0002] The alkoxycarbonylation of olefinically unsaturated compounds is an increasingly important process. Alkoxycarbonylation is understood to mean the reaction of an olefinically unsaturated compound (olefin) with carbon monoxide and an alcohol in the presence of a metal ligand complex to obtain the corresponding ester. Generally, the metal used is palladium. The following scheme shows the general reaction equation for alkoxycarbonylation:

[0003] Summary of the Invention

[0004] The technical object of the present invention is to provide novel ligands and new methods which make it possible to increase the yield of esters.

[0005] The object is achieved by the compound according to claim 1.

[0006] Compound having structure (1) or (2):

[0007]

[0008] In one embodiment, the compound has structure (1):

[0009]

[0010] In one embodiment, the compound has structure (2):

[0011]

[0012] In addition to the compound itself, a method using the compound is also claimed. Method comprising the following method steps:

[0013] a) preloading an olefinically unsaturated compound or a mixture of olefinically unsaturated compounds; b) adding a compound having structure (1) or (2):

[0014]

[0015] c) adding a Pd compound;

[0016] d) adding a cocatalyst selected from: aluminum trifluoromethanesulfonate, H2SO4, MSA, pTSA, TFA;

[0017] e) adding an alcohol;

[0018] f) supplying CO;

[0019] g) Heat the reaction mixture from a) to f) to convert the ethylenically unsaturated compound into an ester.

[0020] In one variant of the method, 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), dichloro(cinnamyl)palladium.

[0021] In one variant of the method, the Pd compound is Pd(acac)2.

[0022] In one variant of the method, the cocatalyst is aluminum trifluoromethanesulfonate.

[0023] In one variant of the method, 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.

[0024] In one variant of the method, the alcohol in process step e) is methanol.

[0025] In one variant of the method, CO is supplied in process step f) at a pressure of 1 to 5 MPa (10 to 50 bar).

[0026] In one variant of the method, CO is supplied in process step f) at a pressure of 1 to 3 MPa (10 to 30 bar).

[0027] In one variant of the method, the reaction mixture is heated to a temperature of 80 °C to 160 °C in process step g).

[0028] In one variant of the method, the reaction mixture is heated to a temperature of 100 °C to 140 °C in process step g).

[0029] In one variant of the method, a mixture of ethylenically unsaturated compounds is pre-loaded in process step a).

[0030] In one variant of the method, a mixture of 1-octene is pre-loaded in process step a). Detailed Description

[0031] The present invention will now be described in more detail with reference to the embodiments.

[0032] The reaction was carried out in a 20 mL glass vessel equipped with a magnetic stir bar. First, Al(OTf)3 (9.5 mg, 0.2 mol%) and the ligand (0.1 mol%) were weighed into the glass vessel and then hermetically sealed using a crimped septum. An argon atmosphere was ensured in the following steps through a cannula connected to an argon distributor passing through it, while allowing pressure equalization. The required amount of the precursor mother liquor (0.8 ml) was added via a μL syringe, thereby weighing in Pd(acac)2 (0.8 mg, 0.025 mol%). Subsequently, 0.3 ml of ethylbenzene was added as an internal standard. Then, methanol was added using a μL syringe to make the total volume 8.4 ml. The autoclave was sealed and purged three times with nitrogen. Then, CO was supplied at a pressure of 20 bar. Then, the reaction solution was heated to the desired temperature of 120 °C. The substrate (n-octene mixture) was metered in. Samples were taken after 15 minutes.

[0033] The n-octene mixture used consisted of C8 isomers: 1-octene, cis-2-octene, trans-2-octene, cis-3-octene, trans-3-octene, cis-4-octene, and trans-4-octene.

[0034] The reaction was carried out with ligands (1), (2), and (3). The experiment using ligand (3) was used as a comparative experiment.

[0035]

[0036] Reaction conditions:

[0037] Pd(acac)2, ligand (X), Al(OTf)3, MeOH, CO: 20 bar, 120 °C, 15 minutes.

[0038] The yields of the esters are listed in the table below.

[0039] Ligand Yield (1)* 62％ (2)* 57％ (3) 55％

[0040] *Examples of the present invention

[0041] The experiments conducted showed that the object was achieved by the compounds according to the present invention.

Claims

1. A compound having structure (1) or (2):

2. The compound according to claim 1, having structural formula (1):

3. The compound according to claim 1, having structural formula (2):

4. A method comprising the following method steps: a) Preloading an ethylenically unsaturated compound or a mixture of ethylenically unsaturated compounds; b) Adding a compound having structure (1) or (2); c) Adding a Pd compound; d) Adding a cocatalyst selected from: aluminum trifluoromethanesulfonate, H2SO4, MSA, pTSA, TFA; e) Adding an alcohol; f) Supplying CO; g) Heating the reaction mixture from a) to f) to convert the ethylenically unsaturated compound into an ester.

5. The method according to claim 4, wherein the Pd compound is selected from: palladium dichloride, palladium(II) acetylacetonate, palladium(II) acetate, palladium(II) dichloride (1,5-cyclooctadiene), bis(dibenzylideneacetone)palladium, bis(acetonitrile)palladium(II) dichloride, palladium(II) dichloride (cinnamyl).

6. The method according to any one of claims 4 or 5, wherein the Pd compound is Pd(acac)2.

7. The method according to any one of claims 4 to 6, wherein the cocatalyst is aluminum trifluoromethanesulfonate.

8. The method according to any one of claims 4 to 7, wherein the alcohol in method step e) is selected from: methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, tert-butanol, 3-pentanol, cyclohexanol, phenol or a mixture thereof.

9. The method according to any one of claims 4 to 8, wherein the alcohol in method step e) is methanol.

10. The method according to any one of claims 4 to 9, wherein CO is supplied in method step f) at a pressure of 1 to 5 MPa (10 to 50 bar).

11. The method according to any one of claims 4 to 10, wherein the reaction mixture is heated to a temperature of 80 °C to 160 °C in method step g).

12. The method according to any one of claims 4 to 11, wherein a mixture of ethylenically unsaturated compounds is preloaded in method step a).

13. The method according to any one of claims 4 to 12, wherein a mixture of 1-octene is preloaded in method step a).

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