Hydroformylation catalyst system with synthesis gas alternative

Abstract

Described herein are hydroformylation catalyst systems and methods that can be used to produce aldehydes from olefin substrates without the use of carbon monoxide gas. The hydroformylation catalyst system includes: a hydroformylation catalyst complex comprising a Group 9 metal complexed with a phosphine-based ligand; a syngas substitute comprising formic acid and anhydride compounds, which forms carbon monoxide in situ; and hydrogen, which may or may not be derived from the syngas substitute. The method involves reacting an olefin substrate with a syngas substitute in the presence of a hydroformylation catalyst complex, wherein the syngas substitute forms carbon monoxide and optionally hydrogen in situ, and then separating the aldehyde compound from the reaction mixture.

Description

Technical Field

[0001] The present invention relates to the preparation of aldehydes from olefins and more particularly to the preparation of aldehydes from olefins using a synthesis gas substitute in the presence of a Group 9 metal catalyst. Background Art

[0002] Carbonylation generally refers to a group of closely linked reactions in which molecules of carbon monoxide (CO) are incorporated into a substrate. Hydroformylation, which is a type of carbonylation reaction, was discovered unexpectedly by Otto Roelen in 1938. The conventional reaction process for the hydroformylation of terminal olefins is characterized by the use of a mixture of elemental hydrogen (H2) and carbon monoxide (CO), commonly referred to as synthesis gas or syngas, at elevated pressure in the presence of a transition metal (e.g., Group 7-10) catalyst to form aldehydes. Hydrogen ("hydro") and formyl (HC=O) are added to the olefin in an atom-economical manner (Scheme 1). Unless ethylene is used as a substrate, the reaction may result in a mixture of isomeric products, normal aldehydes (straight chain) and isoaldehydes (branched chain). Since double bond isomerization of the substrate (usually depending on the type of catalyst) may occur prior to hydroformylation, different branched chain aldehydes may be formed even when a single terminal olefin has undergone the reaction. Therefore, in addition to the reaction rate, the ratio of the isomers (regioselectivity) is an important parameter in every hydroformylation.

[0003] Scenario 1:

[0004]

[0005] Traditionally, industrial carbonylation processes use highly toxic and flammable gaseous carbon monoxide. Indeed, these properties (toxicity / flammability) have hampered the wider use of carbonylation reactions in industry and academia. Therefore, it is extremely desirable to perform carbonylation without the use of gaseous CO.

[0006] Over the past 30 years, carbon monoxide (CO) substitutes in olefin carbonylation reactions have been reported intermittently. Syngas substitutes include carbon dioxide, methanol, formaldehyde, formic acid, formate, formamide, and biomass (see Beller et al., Angew. Chem. Int. Ed. 2014, 53, 2-13). However, some of these syngas substitutes require separate reaction chambers or conversion catalysts, and / or the catalyst systems that call these syngas substitutes produce undesirable linear / branched selectivity, require higher catalyst loadings, or result in different functional groups (e.g., alcohols, carboxylic acids).

[0007] Recently, a palladium-catalyzed hydroformylation of olefins using a synthesis gas surrogate containing 2 equivalents of formic acid and 1 equivalent of acetic anhydride was reported to produce a mixture of linear / branched aldehydes and the corresponding carboxylic acids (see Ren et al., J. Am. Chem. Soc. 2016, 138, 14864-14867). Optimized conditions using 1,3-bis(diphenylphosphino)propane (dppp) ligand and tetrabutylammonium iodide (TBAI) additive in dichloroethane (DCE) solvent provided the corresponding linear aldehydes in moderate yields and selectivities. In addition to the use of potentially carcinogenic dichloroethane, the high catalyst loading (5 mol% Pd) is also economically prohibitive on an industrial scale, as attempts to use recycled palladium catalysts for subsequent hydroformylation provide reduced yields and / or selectivities.

[0008] In view of the above, there is a need for new hydroformylation catalyst systems and methods for hydroformylating olefins to form aldehydes. Summary of the invention

[0009] The present invention is based on the recognition that aldehyde compounds can be synthesized from olefinic substrates without using a gaseous carbon monoxide source, but rather using a synthesis gas substitute comprising formic acid and anhydride compounds and hydrogen in the presence of a hydroformylation catalyst complex comprising a Group 9 metal. The hydrogen is either derived from the synthesis gas substitute or not.

[0010] Thus, according to an embodiment of the present invention, there is provided a hydroformylation catalyst system useful for converting an olefin substrate to an aldehyde compound. The hydroformylation catalyst system comprises (or consists essentially of): a hydroformylation catalyst complex comprising a Group 9 metal complexed with a phosphine-based ligand; and a synthesis gas substitute comprising formic acid and anhydride compounds, which in situ form carbon monoxide in the presence of the hydroformylation catalyst complex, and hydrogen, which is either in situ derived from the synthesis gas substitute or is not derived from the synthesis gas substitute.

[0011] According to another embodiment of the present invention, a method for preparing an aldehyde compound is provided. The method includes mixing an olefin substrate in a hydroformylation catalyst system to form a reaction mixture, wherein the hydroformylation catalyst system comprises (or is substantially composed of): a hydroformylation catalyst complex, and a synthesis gas substitute comprising formic acid and anhydride compounds, which forms carbon monoxide in situ in the presence of the hydroformylation catalyst complex, and hydrogen, which is either in situ derived from the synthesis gas substitute or not derived from the synthesis gas substitute. The hydroformylation catalyst complex comprises a Group 9 metal complexed with a phosphine-based ligand. The Group 9 metal is selected from cobalt, rhodium and iridium, preferably rhodium. The method may further include separating the aldehyde compound from the reaction mixture to provide an aldehyde product and a hydroformylation catalyst residue comprising the hydroformylation catalyst complex.

[0012] The objects and advantages of the present invention will be further understood in conjunction with the following detailed description and examples. DETAILED DESCRIPTION

[0013] Therefore, keeping in mind the above problems arising in the prior art, an object of the present invention is to provide a hydroformylation catalyst system comprising a hydroformylation catalyst complex and a synthesis gas substitute, characterized by excellent catalytic activity and stability, and capable of controlling the linear-branched (l / b) selectivity in the aldehyde product. A further object is to provide a hydroformylation process using the same.

[0014] Accordingly, the present invention relates to a hydroformylation catalyst system and a hydroformylation process for producing aldehydes from olefin substrates using the same. More particularly, the hydroformylation catalyst system comprises: a hydroformylation catalyst complex comprising a Group 9 metal complexed with a phosphine-based ligand, and a synthesis gas substitute comprising formic acid and anhydride compounds, which in situ forms carbon monoxide in the presence of the hydroformylation catalyst complex, and hydrogen, which is either in situ derived from the synthesis gas substitute or not derived from the synthesis gas substitute. The synthesis gas substitute eliminates the need to supply gaseous carbon monoxide to the hydroformylation catalyst system, but does not exclude the optional addition of hydrogen. In the presence of the synthesis gas substitute, the application of the hydroformylation catalyst system comprising the hydroformylation catalyst complex to the olefin substrate provides a desired aldehyde product having excellent catalytic activity and stability and good linear / branched (l / b) selectivity.

[0015] According to an embodiment of the present invention, the hydroformylation catalyst complex comprises a Group 9 transition metal selected from the group consisting of cobalt, rhodium and iridium.

[0016] In one embodiment, the Group 9 transition metal comprises cobalt. Exemplary forms of acceptable cobalt compounds include, but are not limited to, dicobalt octacarbonyl Co2(CO)8, cobalt oxide Co2O3, cobalt carbonate CoCO3, cobalt carboxylates Co(RCOO)2, Co2(CO)6(PnBu3)2, Co2(CO)6(P(OPh)3)2, or combinations thereof, more particularly Co2(CO)8. In another embodiment, the Group 9 transition metal comprises iridium. Exemplary forms of acceptable iridium compounds include, but are not limited to, Ir(acac)(COD), HIr(CO)(PPh3)3, [Ir(COD)Cl]2, Ir(COD)2BF4, and Ir2(CO)6(PPh3)2, more particularly Ir(acac)(COD).

[0017] In yet another embodiment, the Group 9 transition metal comprises rhodium. Exemplary forms of acceptable rhodium compounds include, but are not limited to, rhodium complexes or rhodium salts of carboxylic acids, rhodium carbonyl species, rhodium halide species, rhodium alkoxide species, and / or rhodium organophosphine complexes. Examples of rhodium carboxylates include rhodium ethylhexanoate. Some examples of rhodium carbonyl species include (acetylacetonato) dicarbonyl rhodium (Rh(acac)(CO)2), Rh4(CO) 12 and Rh6(CO) 16 . Examples of rhodium halide species include chloro(1,5-cyclooctadiene)rhodium dimer [Rh(COD)Cl]2. Examples of rhodium alkoxide species include methoxy(cyclooctadiene)rhodium dimer [(MeO)Rh(COD)]2. An example of a rhodium organophosphine complex is tris(triphenylphosphine)carbonyl hydride rhodium [RhH(CO)(PPh3)3] (wherein Ph=C6H5). In one embodiment, a suitable rhodium compound is selected from Rh(acac)(CO)2, [Rh(COD)Cl]2 and [(MeO)Rh(COD)]2, more particularly Rh(acac)(CO)2. In one embodiment, the hydroformylation catalyst may be selected from Rh(acac)(CO)2, [Rh(COD)Cl]2 and [(MeO)Rh(COD)]2, Ir(acac)(COD) and Co2(CO)8.

[0018] Preferably, the content of the Group 9 metal is in the range of 0.00001 to 0.5 mole (0.001 mol% to 50 mol%) based on 1 mole of the olefin substrate; more preferably in the range of 0.0001 to 0.1 (0.01 mol% to 10 mol%); and more preferably in the range of 0.0005 to 0.01 mole (0.05 mol% to 1 mol%) relative to 1 mole of the olefin substrate. For example, the molar percentage of the Group 9 metal based on the olefin substrate may be 0.001 mol%, 0.005 mol%, 0.01 mol%, 0.05 mol%, 0.1 mol%, 0.5 mol%, 1 mol%, 5 mol%, 10 mol%, 50 mol%, or 100 mol%, or in the range between any two of the foregoing.

[0019] In one embodiment, the Group 9 metal comprises cobalt. Preferably, the content of cobalt is in the range of 0.00001 to 0.5 moles (0.001 mol% to 50 mol%) based on 1 mole of the olefin substrate, and more preferably in the range of 0.0005 to 0.05 moles (0.05 mol% to 5 mol%) relative to 1 mole of the olefin substrate. In another embodiment, the Group 9 metal comprises iridium. Preferably, the content of iridium is in the range of 0.00001 to 0.5 moles (0.001 mol% to 50 mol%) based on 1 mole of the olefin substrate, and more preferably in the range of 0.0005 to 0.01 moles (0.05 mol% to 1 mol%) relative to 1 mole of the olefin substrate. Preferably, in another embodiment, the Group 9 metal comprises rhodium. Preferably, the content of rhodium is in the range of 0.00001 to 0.5 mol (0.001 mol% to 50 mol%) based on 1 mol of the olefin substrate, and more preferably in the range of 0.0005 to 0.01 mol (0.05 mol% to 1 mol%) relative to 1 mol of the olefin substrate.

[0020] According to an embodiment of the present invention, the hydroformylation catalyst complex comprises a phosphine-based ligand that forms a complex with a Group 9 metal. In one aspect, the phosphine-based ligand can be monodentate or bidentate, more particularly monodentate.

[0021] In one embodiment, the phosphine-based ligand is of the general formula (1) PR 1 R 2 R 3 At least one compound wherein R 1 , R 2 and R 3 Each is independently selected from a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms; a substituted or unsubstituted cycloalkyl or cycloalkenyl group having 5 to 20 carbon atoms; a substituted or unsubstituted aryl group having 6 to 36 carbon atoms; a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms; a substituted or unsubstituted heteroaryl group having 4 to 36 carbon atoms; or a substituted or unsubstituted heterocyclic group having 4 to 36 carbon atoms, wherein the heteroalkyl group, heteroaryl group and heterocyclic group include one or more atoms selected from N, O and S, and the substituent is a nitro group (-NO2), a fluorine group (-F), a chlorine group (-Cl), a bromine group (-Br) or an alkyl group having 1 to 4 carbon atoms, when R 1 , R 2 and R 3 When substituted with a substituent. More particularly, R 1 , R 2 and R 3Each independently selected from a substituted or unsubstituted aryl group having 6 to 36 carbon atoms. It is preferred that the monodentate phosphine ligand represented by the above formula 1 is selected from one or more of the following: triphenylphosphine (TPP or PPh3), tri(m-tolyl)phosphine (TMTP), diphenyl(p-tolyl)phosphine (DPPTP), tri(2,6-dimethoxyphenyl)phosphine (TDMPP), tri(4-methoxyphenyl)phosphine (TMPP), tri-s-tritolylphosphine (TMSTP), tri-3,5-xylylphosphine (TXP), tricyclohexylphosphine (TCHP), tribenzylphosphine (TBP), benzyldiphenylphosphine (BDPP), and diphenyl(2-methoxyphenyl)phosphine (DPMPP). More particularly, the monodentate ligand represented by the above formula 1 is triphenylphosphine (TPP or PPh3).

[0022] In another embodiment, the phosphine-based ligand is of the general formula (2): R 1 R 2 PR 4 -PR 5 R 6 At least one compound wherein R 4 is a hydrocarbon group having 2 to 20 carbon atoms, and R 5 and R 6 Each is independently selected and compared with the above R 1 and R 2 Same definition. It is preferred that the bidentate phosphine ligand represented by the above formula 2 is one or more selected from the following: 1,2-bis(diphenylphosphine)ethane (dppe); 1,2-bis(dimethylphosphine)ethane (dmpe); 1,3-bis(diphenylphosphine)propane (dppp); 1,4-bis(diphenylphosphine)butane (dppb); 1,5-bis(diphenylphosphine)pentane (dpppe); 1,6-bis(diphenylphosphine)hexane (dpph); 2,2′-bis(diphenylphosphine)-1,1′-binaphthyl (binap); and combinations thereof. More particularly, the bidentate phosphine ligand represented by the above formula 2 is 1,2-bis(diphenylphosphine)ethane (dppe).

[0023] Preferably, the content of the phosphine-based ligand in the hydroformylation catalyst system is in the range of 0.001 to 10 mol (ie, 0.1 mol% to 1,000 mol%), for example, 0.01 to 5 mol (ie, 1 mol% to 500 mol%) based on 1 mol of the olefin substrate.

[0024] Alternatively, the content of the phosphine-based ligand can be expressed as a molar equivalent relative to the moles of the Group 9 metal present in the catalyst system, and thus is in the range of 1 to 500 moles, such as 2 to 250, 5 to 200, or 10 to 150, based on 1 mole of the Group 9 metal. Thus, the molar equivalent of the phosphine-based ligand can be 1, 2, 5, 10, 15, 25, 35, 50, 75, 100, 150, 200, 300, 400, 500, or in the range between any two of the foregoing, based on the Group 9 metal present in the catalyst complex. Non-limiting examples of molar ratios of phosphine-based ligands to Group 9 metals include, but are not limited to, 1:1 to 500:1, 1:1 to 300:1, 1:1 to 200:1, 1:1 to 150:1, 1:1 to 100:1, 1:1 to 75:1, or 1:1 to 50:1.

[0025] Phosphine-based ligands can be easily oxidized to their corresponding phosphine oxides, which appear to be ineffective ligands for hydroformylation catalysts based on Group 9 metals. Oxidants such as molecular oxygen or peroxides are particularly effective in oxidizing phosphine to phosphine oxides. Accordingly, it is preferred to minimize the presence of adventitious oxygen in the hydroformylation reaction system. However, even if the hydroformylation reaction system is completely free of any exogenous oxygen, oxidation of phosphine ligands to inactive phosphine oxides has been observed. Without being bound by any particular theory, it is believed that perhaps phosphine ligands can also act as oxygen acceptors in the conversion of carbon dioxide (CO2) to ligand carbon monoxide (CO), wherein carbon dioxide (CO2) is from formic acid (HCO2H) acid to carbon dioxide (CO2) and hydrogen (H2) of the Group 9 metal-catalyzed dehydrogenation reaction.

[0026] Peroxides may be present in one or more of the hydroformylation reaction system components (e.g., olefin substrate or solvent) as impurities in the hydroformylation reaction system. Accordingly, pretreatment of the olefin and / or solvent with an antioxidant (e.g., a saturated aqueous solution of sodium metabisulfite (Na2S2O5)) followed by distillation may be useful to significantly reduce or eliminate peroxide impurities. In one embodiment, the olefin substrate may be washed with a saturated aqueous solution of sodium metabisulfite, separated from the aqueous layer, and optionally distilled to remove any traces of water.

[0027] However, conversion of the phosphine ligand to its inactive phosphine oxide can be counteracted by adding more of the appropriate phosphine ligand (same or different) during the reaction. Alternatively, the reaction can be initiated with an abundant phosphine-based ligand in the hydroformylation catalyst system to ensure that a sufficient amount of the phosphine-based ligand is present throughout the conversion of the olefin to the aldehyde, thereby maintaining the desired level of catalyst complex activity and selectivity.

[0028] In a preferred embodiment, the hydroformylation catalyst complex comprises rhodium and a phosphine-based ligand. Preferably, the rhodium is provided as a rhodium compound selected from the group consisting of Rh(acac)(CO)2, [Rh(COD)Cl]2, and [(MeO)Rh(COD)]2, more particularly Rh(acac)(CO)2.; and the phosphine-based ligand is a monodentate triarylphosphine, such as triphenylphosphine (TPP), or a bidentate diarylalkylphosphine, for example 1,2-bis(diphenylphosphino)ethane (dppe). In connection with this, reduced conversion and / or selectivity is observed when the total content of monodentate phosphine-based ligands is less than 10 moles based on 1 mole of rhodium at the start of the reaction and its slow oxidation is not offset by the addition of more phosphine-based ligands. Accordingly, in one embodiment, the initial molar ratio of monodentate phosphine ligand to rhodium is at least 10: 1, e.g., at least 15: 1, at least 20: 1, at least 25: 1, at least 30: 1, at least 35: 1, at least 40: 1, at least 50: 1, at least 75: 1, at least 100: 1, or at least 200: 1 or within a range between any two of the foregoing. If the above total molar ratio of phosphine-based ligand to rhodium is greater than 500, costs are increased without significant additional benefits.

[0029] The preparation of the hydroformylation catalyst complex employed in the practice of the present invention requires no special provisions, although it is preferred that all manipulations of the Group 9 metal and phosphine-based ligand components be carried out under an inert atmosphere (e.g., N2, Ar, etc.) for high catalyst activity. The desired amounts of the appropriate Group 9 metal compound and the phosphine-based ligand are charged to the reactor in a suitable solvent. The order in which the various catalyst components are charged to the reactor is not critical. Thus, the Group 9 metal compound may be added to the reactor followed by the phosphine-based ligand; or conversely, the phosphine-based ligand may be added to the reactor followed by the Group 9 metal compound; or, alternatively, a preformed Group 9 metal-phosphine-based ligand complex may be charged to the reactor.

[0030] Embodiments of the present invention further provide a synthesis gas substitute comprising formic acid and anhydride, which in situ forms carbon monoxide in the presence of a hydroformylation catalyst complex, and hydrogen, which is either in situ derived from the synthesis gas substitute or not derived from the synthesis gas substitute. The formic acid and anhydride should be sufficiently pure and do not contain any impurities that may poison the active catalytic species. Advantageously, the formic acid and anhydride can be distilled before use.

[0031] Formic acid is hygroscopic, and thus the moisture content should be minimized to avoid hydrolysis of the anhydride compound.For example, the formic acid may be characterized as having a moisture content of less than 5 wt %, such as 2 wt % or less.

[0032] Acid anhydrides are selected from the group consisting of 7C=O)-O-(O=CR 8 ) wherein R 7 and R 8 are independently selected from substituted or unsubstituted alkyl or substituted or unsubstituted aryl, wherein the substituent may be nitro (-NO2), fluorine (-F), chlorine (-Cl), bromine (-Br) or an alkyl group having 1 to 4 carbon atoms. Symmetric anhydrides (wherein R 7 and R 8 Non-limiting examples of the anhydride (are the same) include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, pentanoic (valeric) anhydride, 3-methylbutyric (isovaleric) anhydride and caproic anhydride. In one embodiment, the anhydride is selected from acetic anhydride, propionic anhydride, isovaleric anhydride and combinations thereof. In a preferred embodiment, the anhydride comprises acetic anhydride.

[0033] Based on the olefin substrate, the amount of formic acid in the reaction mixture may be between 1 and 10 equivalents, preferably between 1.1 and 3 equivalents; and the amount of acetic anhydride may be between 1 and 5 equivalents, preferably between 1.1 and 1.5 equivalents. In one embodiment, the molar ratio between formic acid and anhydride is in the range of 1:1 to 4:1, preferably between 1:1 to 5:2.

[0034] Without being bound by any particular theory, it is believed that formic acid and anhydride react to form a mixed anhydride, which decomposes in situ under the hydroformylation reaction conditions to form the desired carbon monoxide reactant and carboxylic acid for the hydroformylation reaction. In the case where the anhydride is acetic anhydride, the mixed anhydride is formic acetic anhydride. The carbon monoxide generated in situ binds to the Group 9 metal center of the active catalyst complex and is ultimately incorporated into the olefin substrate to form the desired aldehyde.

[0035] When a stoichiometric excess of formic acid relative to anhydride (i.e., a molar ratio of formic acid to anhydride greater than one) is present in the syngas substitute, the required hydrogen (H2) reactant for the hydroformylation reaction is also generated in situ with carbon dioxide (CO2), presumably from a Group 9-catalyzed dehydrogenation of formic acid. If the stoichiometric excess of formic acid is at least equimolar to the olefin substrate (e.g., 2 equivalents of formic acid and 1 equivalent of anhydride based on the olefin substrate), then a separate supply of hydrogen is not required to achieve complete or substantially complete conversion of the olefin substrate. However, if the amount of formic acid is insufficient to generate the necessary hydrogen (H2) reactant, then hydrogen pressure should be supplied to the reaction vessel. Excessive hydrogen pressure (e.g., >100 bar) can increase hydrogenation side reaction pathways before carbon monoxide is generated. In one embodiment, the molar ratio of formic acid to anhydride in the syngas substitute is one or less, so hydrogen pressure is applied to the reaction vessel. Therefore, the reaction vessel can be charged with hydrogen pressure to 25 bar or less, such as 20 bar, 15 bar, 10 bar, 4 bar, or 1 bar. For example, in one embodiment, each of formic acid and anhydride is present in the hydroformylation catalyst system at 1.1 equivalents based on the olefin substrate, and an external supply of hydrogen (e.g., in the range of 1 to 20 bar, preferably in the range of 4 to 10 bar) is applied to the sealed reaction vessel prior to heating.

[0036] In the above hydroformylation process, it is preferred that the above olefin substrate is a monosubstituted or disubstituted olefin substrate. In one embodiment, the olefin substrate is a monosubstituted olefin substrate (i.e., α-olefin). In one embodiment, the olefin substrate is a disubstituted olefin substrate. In another embodiment, the olefin substrate is represented by the following formula (4):

[0037]

[0038] Where R 9 , R 10 and R 11 Each is independently selected from: hydrogen, substituted or unsubstituted alkyl having 1 to 20 carbon atoms; substituted or unsubstituted alkenyl having 1 to 20 carbon atoms, wherein the alkyl substituent or alkenyl substituent is selected from fluorine (F), chlorine (Cl), bromine (Br), trifluoromethyl (CF3); and substituted or unsubstituted aryl having 6 to 20 carbon atoms, wherein the aryl substituent of the aryl can be selected from nitro (NO2), fluorine (F), chlorine (Cl), bromine (Br), methyl, ethyl, propyl and butyl, wherein R 9 , R 10 or R 11 In another embodiment, at least one of R 9 , R 10 or R 11In another embodiment, at least one of R is not hydrogen. 11 is hydrogen, and R 9 and R 10 In yet another embodiment, R 10 and R 11 is hydrogen, and R 9 In yet another embodiment, R 9 or R 10 is hydrogen, and R 11 Not hydrogen.

[0039] Non-limiting examples of suitable olefin substrates include one or more compounds selected from the following: 1,4-dimethyl-4-vinylcyclohexene; cyclohexene; 1-hexene; cis-hex-3-enoic acid ethyl ester; 3,3-dimethyl-1-butene; 7-octenal; 10-undecenoic acid methyl ester; 4-tert-butyl-styrene; 5,7-dimethylocta-1,6-diene; and limonene. In one embodiment, the olefin substrate is selected from: 1,4-dimethyl-4-vinylcyclohexene; cyclohexene; cis-hex-3-enoic acid ethyl ester; 3,3-dimethyl-1-butene; 7-octenal; 10-undecenoic acid methyl ester; 5,7-dimethylocta-1,6-diene, and limonene.

[0040] In the above hydroformylation process, the reaction mixture may be run neat (i.e., in the absence of any solvent) or in the presence of an organic solvent such that the concentration of the olefin substrate in the reaction mixture is greater than about 0.1 molar (M), for example, in the range of about 1 M to about 4 M. Examples of suitable organic solvents include, but are not limited to, ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, anisole, dimethoxyethane, and / or dioxane; aldehydes such as propionaldehyde, butyraldehyde, pentylaldehyde, and / or valeraldehyde; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, and / or cyclohexanone; aromatic compounds such as benzene, toluene, and / or xylene; carboxylic acids such as acetic acid; amides such as dimethylformamide, dimethylacetimidide, or n-methyl-2-pyrrolidone; halogenated aromatics such as n-dichlorobenzene; halogenated paraffins such as dichloromethane; and / or paraffins such as cyclohexane and / or heptane. Preferably, the solvent comprises an ether, such as 2-methyltetrahydrofuran (2-MeTHF).

[0041] In the hydroformylation process, preferred reaction temperature and reaction pressure may include those known in the art. For example, the present hydroformylation process may be carried out in a sealed container at a reaction temperature preferably in the range of about 20°C to 200°C, more preferably about 50°C to 150°C and most preferably about 60°C to 130°C. If the hydroformylation catalyst system further comprises hydrogen not derived from a syngas substitute, hydrogen may be charged into the container to a desired pressure before the reaction mixture is heated to the desired reaction temperature. For example, the hydrogen charged into the reaction vessel may be in the range of about atmospheric pressure to less than 100 bar, preferably between 1 bar and 25 bar. Hydrogen may be supplied during the reaction process to maintain a desired pressure.

[0042] In order to carry out the above hydroformylation reaction, the desired amount of hydroformylation catalyst system components (i.e., Group 9 metal compound, phosphine-based ligand, olefin substrate, anhydride compound, formic acid, and optionally hydrogen and / or organic solvent) is introduced into a sealable reaction vessel (e.g., autoclave), which is then sealed, agitated, and heated to carry out the hydroformylation reaction. When heated to a sufficient temperature to initiate the generation of CO and optionally H2 from the synthesis gas substitute, the pressure in the hydroformylation reaction system initially increases, and then the system pressure decreases as the reaction gas (CO / H2) reacts with the olefin substrate to form the desired aldehyde compound.

[0043] According to one aspect of the invention, the hydroformylation catalyst complex is recyclable and maintains satisfactory conversion and selectivity through multiple batch runs. These properties are derived from maintaining an appropriate ratio of phosphine ligand to Group 9 metal during the hydroformylation reaction. The slow conversion of the phosphine ligand to its inactive phosphine oxide can be offset by adding more suitable phosphine ligand (same or different) during the reaction or by starting the reaction with a significant excess of phosphine ligand. In one embodiment, the molar ratio of phosphine-based ligand to Group 9 metal is at least 1:1, such as 2:1, 5:1, 10:1, 20:1 or greater, 40:1 or greater, 50:1 or greater, or 100:1 or greater. In one embodiment, the Group 9 metal is rhodium and the molar ratio of phosphine-based ligand to rhodium is in the range of 2:1 to 20:1.

[0044] In one embodiment, the amount of phosphine ligand remaining in the hydroformylation reaction mixture at the end of the reaction is quantified. Quantification can be achieved by various analytical techniques (e.g., GC, HPLC, NMR, etc.) using appropriate standards. In order to ensure that a sufficient amount of phosphine ligand is present in the recycled hydroformylation catalyst mixture, the amount of phosphine ligand lost due to conversion of the phosphine ligand to phosphine oxide can be added to the reaction mixture before separating the aldehyde product from the catalyst.

[0045] For example, in one embodiment, the phosphine ligand of the desired amount is added to the reaction end mixture, and then the reaction mixture is distilled to recover the solvent, the starting olefin substrate (if any), the aldehyde product and / or impurities. For example, the solvent can be recovered by distillation under a first temperature / pressure condition, followed by the aldehyde product being recovered under a second temperature / pressure condition. Then, the distillation residue remaining after the recovery of the solvent / aldehyde can be mixed with a second batch of olefin substrates, formic acid, anhydride compounds and optionally solvent and / or hydrogen to carry out another batch of hydroformylation operations.

[0046] Advantageously, the hydroformylation catalyst systems and methods described herein can be applied to the production of one or more valuable aldehyde compounds, which can themselves be useful compounds, such as aromatic molecules. According to one embodiment, a product comprising an aldehyde is provided, wherein the aldehyde is formed by hydroformylating an olefin using the hydroformylation catalyst system described herein, wherein the olefin is selected from: 1,4-dimethyl-4-vinyl-cyclohexene; cyclohexene; 1-hexene; cis-hex-3-enoic acid ethyl ester; 3,3-dimethyl-1-butene; 7-octenal; 10-undecenoic acid methyl ester; 5,7-dimethyloct-1,6- diene; 4-tert-butyl-styrene; and limonene; and wherein the aldehyde is selected from: 3-(1,4-dimethyl-3-cyclohexen-1-yl)propanal; cyclohexanecarboxaldehyde; ethyl 3-formylhexanoate and / or ethyl 4-formylhexanoate; 4,4-dimethylpentanal; nonanedialdehyde; methyl 11-formylundecanoate; 6,8-dimethyl-7-nonenal; 3-[p-(tert-butyl)phenyl]propanal; and p-ment-1-ene-9-carboxaldehyde.

[0047] The aldehydes derived from the hydroformylation catalyst systems and methods described herein can also be useful chemical intermediates for making other valuable molecules, such as pharmaceuticals, flavors, or fragrances. For example, the perfume compound 6,8-dimethyl-non-7-enal described by Jaunky et al. in WO2006077305 is prepared in good yield by hydroformylating 5,7-dimethyl-octa-1,6-diene using a hydroformylation catalyst system. According to an embodiment of the present invention, the hydroformylation of DMVCH provides the aldehyde 3-(1,4-dimethyl-3-cyclohexen-1-yl)propanal, which can be further converted into various aromatic chemicals, such as 6-(1,4-dimethylcyclohexyl-1-en-4-yl)hex-3-en-2-one; 2,5-dimethylbicyclo[3,3,1]non-2-en-8-yl)acetone; 6-(1,4-dimethylcyclohex-1-en-4-yl)hex-4-en-2-one; or (2,6-dimethylbicyclo-[3,3,1]non-2-en-8-yl)acetone, as described in GB1471856A to Aalderht Johannes de Jong. According to another embodiment of the present invention, there is provided a method for preparing 6,8-dimethyl-non-7-enal comprising treating an olefin substrate 5,7-dimethyl-octa-1,6-diene with a hydroformylation catalyst complex and a synthesis gas substitute.

[0048] Thus, according to an embodiment of the present invention, there is provided a hydroformylation catalyst system useful for converting an olefin substrate into an aldehyde compound, the system comprising: a hydroformylation catalyst complex comprising a Group 9 metal complexed with a phosphine-based ligand, wherein the Group 9 metal is selected from the group consisting of cobalt, rhodium and iridium, preferably rhodium; and a synthesis gas substitute comprising formic acid and anhydride compounds, which in situ forms carbon monoxide in the presence of the hydroformylation catalyst complex, and optionally hydrogen.

[0049] In another embodiment, the catalyst system is as described above, wherein the Group 9 metal comprises rhodium. In another embodiment, the catalyst system is as described in any of the above systems, wherein the Group 9 metal comprises rhodium provided in a rhodium compound selected from the group consisting of Rh(acac)(CO)2, [Rh(COD)Cl]2, and [(MeO)Rh(COD)]2. In another embodiment, the catalyst system is as described in any of the above systems, wherein the phosphine-based ligand is selected from a monodentate phosphine ligand, a bidentate phosphine ligand, or a combination thereof. In another embodiment, the catalyst system is as described in any of the above systems, wherein the phosphine-based ligand is a monodentate phosphine ligand comprising at least one compound of formula (1):

[0050] PR 1 R 2 R 3(1)

[0051] Where R 1 , R 2 and R 3 are each independently selected from a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms;

[0052] a substituted or unsubstituted cycloalkyl or cycloalkenyl group having 5 to 20 carbon atoms;

[0053] a substituted or unsubstituted aryl group having 6 to 36 carbon atoms;

[0054] a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms;

[0055] a substituted or unsubstituted heteroaryl group having 4 to 36 carbon atoms; or

[0056] a substituted or unsubstituted heterocyclic group having 4 to 36 carbon atoms, wherein the heteroalkyl, heteroaryl and heterocyclic groups include one or more atoms selected from N, O and S;

[0057] wherein the substituent is selected from nitro (-NO2), fluorine (-F), chlorine (-Cl), bromine (-Br) and an alkyl group having 1 to 4 carbon atoms, when R 1 , R 2 and R 3 When substituted by a substituent.

[0058] In another embodiment, the catalyst system is as described in any of the above systems, wherein the phosphine-based ligand is a bidentate phosphine ligand comprising at least one compound of formula (2):

[0059] R 1 R 2 PR 4 -PR 5 R 6 (2)

[0060] Where R 1 , R 2 , R 5 and R 6 are each independently selected from a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms;

[0061] a substituted or unsubstituted cycloalkyl or cycloalkenyl group having 5 to 20 carbon atoms;

[0062] a substituted or unsubstituted aryl group having 6 to 36 carbon atoms;

[0063] a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms;

[0064] a substituted or unsubstituted heteroaryl group having 4 to 36 carbon atoms; or

[0065] a substituted or unsubstituted heterocyclic group having 4 to 36 carbon atoms, wherein the heteroalkyl, heteroaryl and heterocyclic groups include one or more atoms selected from N, O and S;

[0066] wherein the substituent is selected from nitro (-NO2), fluorine (-F), chlorine (-Cl), bromine (-Br) and an alkyl group having 1 to 4 carbon atoms, when R 1 , R 2 , R 4 and R 6 When substituted with a substituent; and

[0067] Where R 4 is a hydrocarbon group having 2 to 20 carbon atoms.

[0068] In another embodiment, the catalyst system is as described above, wherein the anhydride compound comprises a compound having the general formula (3):

[0069] (R 7 C=O)-O-(O=CR 8 ) (3)

[0070] Where R 7 and R 8 Independently selected from substituted or unsubstituted alkyl or substituted or unsubstituted aryl, wherein the substituent may be nitro (-NO2), fluorine (-F), chlorine (-Cl), bromine (-Br) or an alkyl group having 1 to 4 carbon atoms.

[0071] In another embodiment, the catalyst system is as described in any of the above systems, wherein the molar ratio of formic acid to anhydride is in the range of 1: 1 to 4: 1. In another embodiment, the catalyst system is as described in any of the above systems, further comprising hydrogen that is not derived from the syngas substitute.

[0072] In another embodiment, the catalyst system is as described in any of the above systems, wherein the Group 9 metal comprises rhodium, and wherein the molar ratio of rhodium to phosphine-based ligand is in the range of 1:1 to 1:500. One or more of the foregoing hydroformylation catalyst systems can be used in a process for preparing aldehyde compounds from olefinic substrates.

[0073] Therefore, according to yet another embodiment of the present invention, there is provided a method for preparing an aldehyde compound, comprising: mixing an olefin substrate in a hydroformylation catalyst system to form a reaction mixture, wherein the hydroformylation catalyst system comprises a hydroformylation catalyst complex and a synthesis gas substitute, wherein the hydroformylation catalyst complex comprises a Group 9 metal complexed with a phosphine-based ligand, wherein the synthesis gas substitute comprises formic acid and anhydride compounds, and wherein the Group 9 metal is selected from cobalt, rhodium and iridium, preferably rhodium; and separating the aldehyde compound from the reaction mixture to provide an aldehyde product and a hydroformylation catalyst residue comprising the hydroformylation catalyst complex.

[0074] In another embodiment, the method is as described above, wherein separating the aldehyde compound comprises distilling the aldehyde compound from the reaction mixture and providing an aldehyde product and an undistilled fraction comprising hydroformylation catalyst residues. In another embodiment, the method is as described in any of the above methods, further comprising: mixing a second olefin substrate with the hydroformylation catalyst residue and the synthesis gas substitute to form a second reaction mixture. In another embodiment, the method is as described in any of the above methods, wherein a portion of the phosphine-based ligand is converted to its corresponding phosphine oxide, the method further comprising adding an amount of the phosphine-based ligand to the second reaction mixture to offset at least a portion of the phosphine oxide that is converted to the corresponding phosphine oxide.

[0075] In yet another embodiment, the method is as described in any of the methods above, wherein the molar ratio of formic acid to anhydride is in the range of 1: 1 to 4: 1. In yet another embodiment, the method is as described in any of the methods above, further comprising providing hydrogen that is not derived from a syngas substitute.

[0076] In yet another embodiment of the present invention, the catalyst system as described in any of the above embodiments is used in any of the above methods for preparing aldehyde compounds, comprising: mixing the hydroformylation catalyst system of the present invention with an olefin substrate to form a reaction mixture in a sealed reaction vessel; and reacting the olefin substrate with carbon monoxide and hydrogen in the presence of the hydroformylation catalyst complex.

[0077] In another embodiment of the present invention, in any of the above methods for preparing aldehyde compounds, the step of separating the aldehyde compounds from the reaction mixture to provide an aldehyde product and a hydroformylation catalyst residue is included. In another embodiment of the present invention, in any of the above methods for preparing aldehyde compounds, the step of separating the aldehyde compounds comprises distilling the aldehyde compounds from the above reaction mixture (hereinafter referred to as the "first reaction mixture") to provide an aldehyde product and an undistilled fraction containing a hydroformylation catalyst residue.

[0078] In yet another embodiment of the present invention, in any of the above methods for preparing aldehyde compounds, comprising: recycling the hydroformylation catalyst residue by combining with an additional amount of a second olefin substrate and a synthesis gas substitute comprising formic acid and anhydride compounds, and optionally hydrogen to form a second reaction mixture; and reacting the second olefin substrate with carbon monoxide and hydrogen produced from the synthesis gas substitute (which either originates from the synthesis gas substitute or does not originate from the synthesis gas substitute) in the presence of the hydroformylation catalyst residue to form the aldehyde compound in the second reaction mixture.

[0079] In yet another embodiment of the present invention, in any of the above methods for preparing an aldehyde compound, wherein a portion of the phosphine-based ligand is converted to its corresponding phosphine oxide, the method further comprises quantifying the phosphine-based ligand and / or the corresponding phosphine oxide, and determining the molar ratio of the Group 9 metal to the phosphine-based ligand before and / or after separating the aldehyde compound from the first and / or second reaction mixture.

[0080] In another embodiment of the present invention, in any of the above methods for preparing an aldehyde product, further comprising adding a sufficient amount of a phosphine-based ligand to the hydroformylation catalyst system before and / or after separating the aldehyde compound from the first reaction mixture to adjust the molar ratio of the Group 9 metal to the phosphine-based ligand to be in the range of 1:5 to 1:500.

[0081] In yet another embodiment of the present invention, the catalyst system as described in any of the above embodiments is used in any of the above methods for preparing an aroma product comprising an aldehyde compound or a derivative thereof, the use comprising: mixing the hydroformylation catalyst system of the present invention with an olefin substrate in a sealed reaction vessel; and reacting the olefin substrate with carbon monoxide and hydrogen produced from a synthesis gas substitute (which either originates from the synthesis gas substitute or does not originate from the synthesis gas substitute) in the presence of a hydroformylation catalyst complex to form an aldehyde compound; separating the aldehyde compound; and optionally further reacting the aldehyde compound to form a derivative thereof; and combining the separated aldehyde compound or its derivative with one or more aroma compounds to obtain an aroma product.

[0082] Hereinafter, embodiments of the present invention will be described in detail by way of example. However, the present invention can be embodied in many different forms and should not be construed as being limited to the examples set forth herein. On the contrary, these examples are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the present invention to those skilled in the art.

[0083] Example:

[0084] Example 1: Various reaction conditions for the hydroformylation of 1,4-dimethyl-4-vinylcyclohexene (DMVCH) using a syngas substitute containing formic acid and anhydride compounds were investigated. A summary of the reaction details and results is shown in Table 1. The mole percentages (mol%) of the catalyst and ligand and the equivalents (eq. or equiv.) of the reactants are based on moles relative to the olefin substrate.

[0085] Table 1: Hydroformylation reaction systems using syngas alternatives.

[0086]

[0087] a1) DMVCH (5g), 2.5 mol% TBAI, DCE, 80°C, 24h; a2) DMVCH (5g), 0.05mol% TBAI, DCE, 80°C, 22h; bc) DMVCH (7g), 2-MeTHF, 90°C, 22h and then 130°C 2h; d) DMVCH (7g), 2-MeTHF, 90°C, 22h; e) DMVCH (7g), 2-MeTHF, 90°C, 3h; f) DMVCH (7g), 2-MeTHF, 90°C, 24h; g) DMVCH (30g), 2-MeTHF, 90°C, 24h; hj) DMVCH (7g), 2-MeTHF, 90°C, 24h; k) DMVCH (7g), 2-MeTHF, 130°C, 19h; l) DMVCH (7g), 2-MeTHF, 130°C, 16h; m) DMVCH (7g), 2-MeTHF, 130°C, 22h.

[0088] Comparative Example (No. a1) utilizes palladium acetate to realize the hydroformylation of 1,4-dimethyl-4-vinylcyclohexene (DMVCH) under the optimized conditions (Table 1, No. 15, for example, 5mol% Pd, dichloroethane solvent, tetrabutylammonium iodide additive) reported in the prior art publication Ren et al., J.Am.Chem.Soc.2016, 138, 14864-14867. Reducing the catalyst loading to 0.1mol% (based on DMVCH substrate) resulted in almost no conversion after 22 hours (No. a2). Attempts to realize the hydroformylation of DMVCH with two different ruthenium compounds (Comparative Examples No. b and c) failed to form any corresponding aldehyde.

[0089] In numbers d to j, various rhodium-containing hydroformylation catalyst complexes were studied for the hydroformylation of 1,4-dimethyl-4-vinylcyclohexene (DMVCH). In numbers g to j, various anhydride compounds were studied in rhodium-based hydroformylation catalyst systems. In numbers k to m, iridium-based and cobalt-based hydroformylation catalyst complexes were studied for the hydroformylation of DMVCH. In these examples, a Group 9 metal compound, a phosphine-based ligand, DMVCH, a solvent (2-MeTHF, 1M DMVCH), formic acid and anhydride compounds were added to an autoclave, which was purged with nitrogen, sealed, and then stirred while heated to an elevated temperature. At the end of the reaction period, the reaction mixture was cooled, vented, and an aliquot was analyzed by GC-FID (HP-DB1 (30 m, 0.25 mm, 0.25 μm), H2 1.4 mL / min, 50°C to 250°C, at 50°C / min, and 250°C for 10 min). Conversion, selectivity, and linear: branched (l:b) ratio were determined by GC area percent (GC%). Overall, the Group 9 metal-based hydroformylation catalyst systems proved to be acceptable in terms of conversion and selectivity, while the ruthenium-based catalysts failed to achieve the desired hydroformylation.

[0090] Due to the high cost of noble metal catalysts, the recyclability of various hydroformylation catalyst complexes was further studied (see Table 2). At the end of the initial reaction, the solvent, any unreacted starting materials and reaction products were removed by distillation under reduced pressure. The undistilled fraction containing the hydroformylation catalyst residue was combined with DMVCH, solvent (2-MeTHF, 1M DMVCH), formic acid (2.2 equiv) and anhydride compound (1.1 equiv) in an autoclave, which was purged with nitrogen, sealed, and then stirred while heated to the desired reaction temperature. At the end of the reaction period, the reaction mixture was cooled, vented, and an aliquot was analyzed by GC. The recycling process can be repeated with or without adding more phosphine-based ligands to offset any observed oxidation.

[0091] While comparative experiments using fresh palladium catalyst at relatively high loadings (5 mol%) provided good conversions in the initial reactions, selectivity to the aldehyde product was modest (76%), and the yield of the recycled catalyst decreased in subsequent reactions. In contrast, the recycled rhodium catalyst maintained its high conversion (>90%) and selectivity (94%) (see Table 2). Unoptimized experiments run with other Group 9 metals (i.e., iridium and cobalt) showed good conversions with modest selectivity to the desired aldehyde. However, in these Ir and Co examples, excellent linear:branched (l:b) selectivities were achieved.

[0092] Table 2: Recycle operation of various hydroformylation catalysts.

[0093]

[0094] a DMVCH (5g), Pd(OAc)2 (5mol%), dppp (10mol%), TBAI (2.5mol%), HCOOH (4eq.), Ac2O (3eq.), DCE (1M), 80°C, 24h; b DMVCH (30g), Rh(acac)(CO)2 (0.1mol%), PPh3 (10mol%), HCOOH (2.2eq.), Ac2O (1.1eq.), 2-MeTHF (1M), 90°C, 24h; c Ir(acac)(COD) (0.5mol%), dppe (0.5mol%), HCOOH (2.2eq.), Ac2O (1.1eq.), 2-MeTHF (1M), 130°C, 19h; d Co2(CO)8 (5mol%), PPh3 (10mol%), HCOOH (2.2eq.), Ac2O (1.1eq.), 2-MeTHF (1M), 130°C, 22h; e Co2(CO)8 (5mol%), dppe (10mol%), HCOOH (2.2eq.), Ac2O (1.1eq.), 2-MeTHF (1M), 130°C, 22h; f The crude reaction mixture also contained 33% of the hydrogenated product; and g The crude reaction mixture also contained 26% of the hydrogenated product.

[0095] Embodiment 2: Rh (acac) (CO) 2 (0.057g, 0.220mmol), triphenylphosphine (5.78g, 22.0mmol), 2-methyltetrahydrofuran (2-MeTHF) (220ml), dimethylvinylcyclohexene (DMVCH, 30g, 220mmol), formic acid (18.58ml, 484mmol) and acetic anhydride (22.85ml, 242mmol) were introduced into a 600mL autoclave. The mixture was heated at 90°C for 24h. The pressure reached a maximum at 16bar, and the final pressure was 12bar. The pressure was then released and the mixture was transferred to a distillation apparatus. An aliquot was analyzed by GC to check the degree of conversion, selectivity (GC%) and oxidation of the phosphine ligand. Distillation was started to collect the solvent and separate the aldehyde from the reaction mixture (see Table 3).

[0096] Table 3: Distillation of the reaction mixture of Example 2 from the first run with fresh catalyst.

[0097]

[0098] Embodiment 3:Then the distillation residue from embodiment 2 is diluted with 2-MeTHF (220ml), dimethylvinylcyclohexene (DMVCH, 30g, 220mmol) and transferred back to 600mL autoclave.Add formic acid (18.58ml, 484mmol) and acetic anhydride (22.85ml, 242mmol) and the mixture is heated at 90 ℃ for 24h.The pressure reaches the maximum value at 16bar, and the final pressure is 12bar.Then release the pressure and transfer the mixture to the distillation apparatus.Analyze aliquots by GC to check the degree of conversion, selectivity (GC%) and oxidation of phosphine ligands.Add triphenylphosphine (2.022g, 7.71mmol).The collection of solvent from the reaction mixture and the separation of aldehyde are again carried out by distillation under reduced pressure (see Table 4).

[0099] Table 4: Distillation of the reaction mixture of Example 3 from the second run with recycled catalyst.

[0100]

[0101] Example 4: The distillation residue from Example 3 was then diluted with 2-MeTHF (220 ml), dimethylvinylcyclohexene (DMVCH, 30 g, 220 mmol) and transferred back to a 600 mL autoclave. Formic acid (18.58 ml, 484 mmol) and acetic anhydride (22.85 ml, 242 mmol) were added and the mixture was heated at 90° C. for 24 h. The pressure reached a maximum at 16 bar and the final pressure was 12 bar. The pressure was then released and the mixture was transferred to a distillation apparatus. An aliquot was analyzed by GC and a conversion of 94% was obtained with a selectivity of 94% to aldehydes.

[0102] To demonstrate the general applicability of the hydroformylation catalyst system, the conditions of Example 2 were applied to various olefin substrates (see Examples 5-15, Table 5). Conversion, selectivity and linear:branched (1:b) ratio were determined by GC area percentage.

[0103] Table 5: Hydroformylation of various olefinic substrates a .

[0104]

[0105] aOlefin (1 equiv); Rh(acac)(CO)2 (0.1 mol%); PPh3 (10 mol%); Ac2O (1.1 equiv); HCO2H (2.2 equiv); 2-methyltetrahydrofuran (1M olefin); 90°C, 13-19h. b 130℃, 4h. c Combined into 2 possible aldehyde positional isomers (regioisomers); d cComparative Example.

[0106] Under typical non-optimized conditions, excellent conversions were observed for monosubstituted alpha olefin substrates, while moderate to good conversions were observed for disubstituted olefins (1,1- or 1,2-substituted). However, trisubstituted olefins (Comparative Example 8) showed very little reactivity (<1%).

[0107] Example 16: Synthesis gas alternative and external hydrogen. A synthesis gas alternative containing equimolar amounts of formic acid and acetic anhydride and externally supplied hydrogen was used to screen the model olefin substrate 1,4-dimethyl-4-vinylcyclohexene (DMVCH) to evaluate the conversion and selectivity to the corresponding aldehyde, as well as the extent of oxidation of the phosphine-based ligand. A rhodium-containing compound (0.1 mol% Rh), a monodentate phosphine-based ligand (10 mol%), DMVCH (1 equiv), a solvent (2-MeTHF, 1 MDM VCH), formic acid (1.1 equiv) and anhydride (1.1 equiv) were added to an autoclave, which was purged with nitrogen, sealed, evacuated, and external hydrogen (H2) gas pressure was supplied to the system. At the end of the reaction period, the reaction mixture was cooled, vented, and an aliquot was analyzed by GC-FID (HP-DB1 (30 m, 0.25 mm, 0.25 μm), H2 1.4 mL / min, 50° C. to 250° C., at 50° C. / min, and 250° C. for 10 min). Conversion, selectivity, amount of hydrogenated product, and extent of phosphine oxidation were determined by GC area percentage.

[0108] Table 6: Hydroformylation using equimolar formic acid / anhydride and external H2.

[0109]

[0110] a DMVCH (1 equiv), Rh(acac)(CO)2 (0.1 mol%), PPh3 (10 mol%), HCOOH (1.1 eq.), Ac2O (1.1 eq.), 2-MeTHF (1 M), H2 pressure, 90 °C, 24 h; b15 h, 90 °C, no H2 pressure, then add about 5 bar H2 pressure; 90 °C, 5 h.

[0111] In Examples 16a and 16b, the autoclave was pressurized to 4 bar and 10 bar, respectively, with externally applied hydrogen before heating to 90° C. Excellent conversion and selectivity to the desired aldehyde were achieved, with minimal (<5%) hydrogenation by-products produced. Under these conditions, the extent of oxidation of the phosphine-based ligand was less than 10%.

[0112] In Example 16c, the autoclave was sealed after nitrogen purging, but no hydrogen was introduced before heating. The pressure increased to 20 bar when heated to 90° C. and remained unchanged, and no conversion of the starting DMVCH was observed; the observed pressure increase was partly due to thermal expansion, but also due to the formation of carbon monoxide. After 15 hours at 90° C., external hydrogen was applied until the system pressure increased to 25 bar, and the sealed system was then allowed to react for a further 5 hours. After 5 hours, the internal pressure dropped to 10 bar, and a conversion of 63% was achieved, with a selectivity of about 90% for the desired aldehyde and only 0.3% for the hydrogenated product. Under these conditions, the extent of oxidation of the phosphine-based ligand was less than 10%.

[0113] Although the present invention is illustrated by the description of one or more embodiments thereof, and although the embodiments have been described in considerable detail, they are not intended to limit or in any way restrict the scope of the appended claims. Additional advantages and modifications will be readily apparent to those skilled in the art. Therefore, the present invention in its broader aspects is not limited to the specific details, representative products and methods, and illustrative examples shown and described. Accordingly, these details may be deviated from without departing from the scope of the general inventive concept covered by the following claims.

Claims

1. A hydroformylation catalyst system for converting an olefin substrate into an aldehyde compound, the system comprising: A hydroformylation catalyst complex comprising a Group 9 metal complexed with a phosphine-based ligand, wherein the Group 9 metal comprises rhodium and the phosphine-based ligand is selected from a monodentate phosphine ligand, 1,2-bis(diphenylphosphino)ethane, or a combination thereof; A synthesis gas substitute comprising formic acid and anhydride compounds which form carbon monoxide in situ in the presence of a hydroformylation catalyst complex, and optionally hydrogen; and optionally hydrogen, It is understood that if the synthesis gas substitute does not form hydrogen in situ in the presence of the hydroformylation catalyst complex, the system contains hydrogen.

2. The catalyst system of claim 1, wherein the rhodium is rhodium provided in a rhodium compound selected from the group consisting of Rh(acac)(CO)2, [Rh(COD)Cl]2 and [(MeO)Rh(COD)]2.

3. The catalyst system according to claim 1, wherein the phosphine-based ligand is a monodentate phosphine ligand comprising at least one compound of the general formula (1): PR 1 R 2 R 3 (1) Where R 1 , R 2 and R 3 are each independently selected from a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms; a substituted or unsubstituted cycloalkyl or cycloalkenyl group having 5 to 20 carbon atoms; a substituted or unsubstituted aryl group having 6 to 36 carbon atoms; a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms; a substituted or unsubstituted heteroaryl group having 4 to 36 carbon atoms; or a substituted or unsubstituted heterocyclic group having 4 to 36 carbon atoms, wherein the heteroalkyl, heteroaryl and heterocyclic groups include one or more atoms selected from N, O and S; wherein the substituent is selected from nitro (-NO2), fluorine (-F), chlorine (-Cl), bromine (-Br) and an alkyl group having 1 to 4 carbon atoms, when R 1 , R 2 and R 3 When substituted by a substituent.

4. The catalyst system according to claim 1, wherein the anhydride compound comprises a compound having the general formula (3): (R 7 C=O)-O-(O=CR 8 ) (3) Where R 7 and R 8 are independently selected from substituted or unsubstituted alkyl or substituted or unsubstituted aryl.

5. The catalyst system according to claim 4, wherein R 7 and R 8 Independently selected from substituted or unsubstituted alkyl or substituted or unsubstituted aryl, wherein the substituent is nitro (-NO2), fluorine (-F), chlorine (-Cl), bromine (-Br) or an alkyl group having 1 to 4 carbon atoms.

6. The catalyst system of claim 1, wherein the molar ratio of formic acid to anhydride is in the range of 1:1 to 4:

1.

7. The catalyst system of claim 1, further comprising hydrogen that is not derived from the syngas substitute.

8. The catalyst system of claim 1, wherein the Group 9 metal comprises rhodium, and wherein the molar ratio of rhodium to phosphine-based ligand is in the range of 1:1 to 1:

500.

9. A method for preparing an aldehyde compound using a catalyst system as described in any one of claims 1 to 8, the method comprising the steps of: mixing the hydroformylation catalyst system of any preceding claim with an olefin substrate to form a reaction mixture in a sealed reaction vessel; and An olefin substrate is reacted with carbon monoxide produced from a syngas substitute and hydrogen either derived from the syngas substitute or not derived from the syngas substitute in the presence of a hydroformylation catalyst complex in a reaction mixture to form an aldehyde compound.

10. The method according to claim 9, further comprising: The aldehyde compound is separated from the reaction mixture to provide an aldehyde product and a hydroformylation catalyst residue.

11. The process of claim 10, wherein separating the aldehyde compound comprises distilling the aldehyde compound from the reaction mixture to provide an aldehyde product and an undistilled fraction comprising hydroformylation catalyst residues.

12. The method according to claim 10, wherein the reaction mixture is a first reaction mixture, the method further comprising recycling the hydroformylation catalyst residue by combining the hydroformylation catalyst residue with a second olefin substrate and a synthesis gas substitute comprising formic acid and anhydride compounds and optionally hydrogen to form a second reaction mixture; and In the second reaction mixture, the second olefin substrate is reacted with carbon monoxide produced from the syngas substitute and hydrogen either derived from the syngas substitute or not derived from the syngas substitute in the presence of the hydroformylation catalyst residue to form an aldehyde compound in the second reaction mixture.

13. The method of claim 10, wherein the reaction mixture is a first reaction mixture and wherein a portion of the phosphine-based ligand is converted to its corresponding phosphine oxide, the method further comprising: The phosphine-based ligand and / or the corresponding phosphine oxide are quantified and the molar ratio of the Group 9 metal to the phosphine-based ligand is determined before and / or after separating the aldehyde compound from the first and / or second reaction mixture.

14. The method according to claim 10, wherein the reaction mixture is a first reaction mixture, the method further comprising: A sufficient amount of phosphine-based ligand is added to the hydroformylation catalyst system to adjust the molar ratio of Group 9 metal to phosphine-based ligand to be in the range of 1:5 to 1:500 before and / or after separating the aldehyde compound from the first reaction mixture.

15. A method for preparing a fragrance product comprising an aldehyde compound obtained using a catalyst system as claimed in any one of claims 1 to 8, the method comprising the steps of: mixing the hydroformylation catalyst system of any of the preceding claims 1 to 8 with an olefin substrate in a sealed reaction vessel; and reacting an olefin substrate with carbon monoxide produced from a syngas substitute and hydrogen either derived from the syngas substitute or not derived from the syngas substitute in the presence of a hydroformylation catalyst complex to form an aldehyde compound; separation of aldehyde compounds; and optionally further reacting the aldehyde compound to form a derivative thereof, and The isolated aldehyde compound or its derivative is combined with one or more aroma compounds to obtain a fragrance product.

16. The catalyst system according to any one of claims 1 to 8, The phosphine-based ligand is a monodentate phosphine ligand selected from triphenylphosphine, tri(m-tolyl)phosphine, diphenyl(p-tolyl)phosphine, tri(2,6-dimethoxyphenyl)phosphine, tri(4-methoxyphenyl)phosphine, tri-mesitylphosphine, tri-3,5-xylylphosphine, tricyclohexylphosphine, tribenzylphosphine, benzyldiphenylphosphine, diphenyl(2-methoxyphenyl)phosphine, and combinations thereof.

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