Method for selective catalytic hydrogenation and application thereof

Abstract

Disclosed in the present invention are a method for selective catalytic hydrogenation and an application thereof. The present invention relates to the regulation of product selectivity in a catalytic hydrogenation reaction and an application of an iridium-based hydrogenation coupling catalyst, and particularly relates to using an iridium-based multidentate ligand compound to perform a catalytic hydrogenation reaction on urea or a derivative thereof, or carbamate compounds. Moreover, the present invention is the first to propose the precise regulation of the product selectivity in the catalytic hydrogenation reaction of urea or the derivative thereof, or the carbamate compounds without an acid or base additive to prepare amide compounds, methanol, or methylamine compounds.

Description

A method for selective catalytic hydrogenation and its application Technical Field

[0001] This invention belongs to the field of fine chemicals and relates to a method for preparing amide compounds, methanol or methylamine compounds by selective catalytic hydrogenation. In particular, it relates to a method for the controllable synthesis of the amide compounds, methanol or methylamine compounds by catalytic hydrogenation using an iridium-based hydrogenation coupling catalyst. It also relates to a new application of the iridium-based hydrogenation coupling catalyst. Background Technology

[0002] Currently, atmospheric carbon dioxide concentrations have exceeded 400 ppm, making the search for technologies to reduce CO2 emissions essential. Converting CO2 into chemicals may offer suitable applications in the short term because the end products have added value, offsetting the costs of CO2 capture and conversion. To date, only a few CO2 conversion processes have been industrialized, primarily for urea (Bosch-Meiser process) and carbamate production. The range of chemicals directly derived from CO2 remains very narrow compared to currently available petrochemical products. Further improvements in the application of urea or its derivatives, or carbamate compounds, would significantly accelerate the carbon neutrality process. In this context, further converting urea or its derivatives, or carbamate compounds, into fuels and chemicals is an ideal approach to achieving a CO2 chemical cycle.

[0003] Amides, methanol, and methylamine compounds are widely used chemicals in industry, serving as solvents and raw materials for the further synthesis of other chemicals. Additionally, methanol can be used directly as a fuel or as a fuel additive.

[0004] While the conversion of amines and CO2 in a H2 atmosphere can provide an efficient alternative route for the production of fine chemicals such as formamide, methylamine, and methanol, these methods mostly require high reaction temperatures (>200°C) and high hydrogen pressures. Notably, the reaction of CO2 with the corresponding amines, or with amines and alcohols, to form C–N and C–O bonds to generate urea derivatives and carbamates, can lower the activation energy of CO2 reduction. Therefore, the catalytic hydrogenation of CO2-derived urea derivatives and carbamates may offer a milder synthetic strategy for the indirect reduction of CO2 to two-electron reduction products (amides) and six-electron reduction products (methylamines and methanol).

[0005] In the reported catalytic systems for the hydrogenation of urea derivatives, only methanol or formamide products can be obtained. Furthermore, it is known that in the current literature on amide hydrogenation (Yuan, ML; Xie, JH; Zhu, SF; Zhou, QLD Deoxygenative hydrogenation of amides catalyzed by a well-defined iridium pincer complex. ACS Catal. 2016, 6(6), 3665-3669; Zou, YQ; Chakraborty, S.; Nerush, A.; Oren, D.; Diskin-Posner, Y.; Ben-David, Y.; Milstein, D. Highly selective, efficient deoxygenative hydrogenation of amides catalyzed by a manganese pincer complex via metal-ligand cooperation. ACS catal. 2018, 8(9), 8014-8019.), the selective regulation between C=O bond cleavage and C–N bond cleavage is mainly achieved through acid-base additives.

[0006] Furthermore, the inventors' research group (Zhu, J.; Zhang, Y.; Wen, Z.; Ma, Q.; Wang, Y.; Yao, J.; Li, H. Highly Efficient Ruthenium-Catalyzed Semihydrogenation of Urea Derivatives to Formamides. Chem. Eur. J. 2023, 29(31), e202300106.; Zhu, J.; Wang, Y.; Yao, J.; Li, H. Switching hydrogenation selectivity of urea derivatives via subtly tuning the amount and type of additive in the catalyst system. Chem. Sci. 2024, 15(6), 2089-2099.) reported the use of ruthenium-based catalysts to achieve selective control of the hydrogenation of urea derivatives to amide compounds, methanol, and methylamine compounds by adjusting the amount or type of base additive.

[0007] The applicant's earlier patent application (CN 117003663 A) disclosed a catalytic hydrogenation reaction and the application of a manganese-based catalyst. This patent application used a manganese-based polydentate ligand compound for the catalytic hydrogenation reaction, achieving selective hydrogenation of urea or its derivatives, or carbamate compounds, with high selectivity and efficiency. However, this catalytic hydrogenation reaction requires a relatively high hydrogen pressure, needing to be carried out at 60 bar to achieve high efficiency, which poses a certain degree of danger and places high demands on equipment in industrial applications. Summary of the Invention

[0008] The problem the invention aims to solve

[0009] In existing hydrogenation reactions of urea or its derivatives, or carbamate compounds, there are still problems such as the need to add additional acid or base additives, or the need for high hydrogen pressure, and the yield is not high enough.

[0010] Therefore, this invention provides a hydrogenation reaction catalyzed by an iridium-based polydentate ligand compound. This reaction is carried out using an iridium-based polydentate ligand compound as a catalyst without the presence of additional acid or base additives. Compared to conventional metal catalyst systems, this not only reduces hydrogen pressure, improves safety, and lowers the requirements for reaction equipment, but also exhibits superior catalytic selectivity and efficiency, and allows for the precise customization of various reduction products.

[0011] Furthermore, this invention also proposes for the first time a new use for the above-mentioned iridium-based polydentate ligand compounds, namely, as a catalyst for the catalytic hydrogenation reaction of compounds of general formula (1).

[0012] Based on the above, this invention also proposes a new approach to the recycling of carbon dioxide.

[0013] Solution for solving the problem

[0014] Long-term research has revealed that the above-mentioned technical problems can be solved by implementing the following technical solutions:

[0015] The present invention primarily provides a method for catalytic hydrogenation, wherein the method includes:

[0016] The step of contacting a compound of general formula (1) with hydrogen in the presence of a catalyst and a solvent,

[0017] and,

[0018] The compound of general formula (1) has the following structure:

[0019] In this context, R1, R2, and R3 may appear the same or different each time, and they independently represent monovalent organic groups; or, R1 and R2 may be linked together to form a ring; X represents a nitrogen atom or an oxygen atom; n represents 1 or 2, and when n is 2, the two R3s may be the same or different, or the two R3s may be linked together to form a ring;

[0020] The catalyst is an iridium-based polydentate ligand compound.

[0021] The iridium-based polydentate ligand compound is derived from the combination of at least an iridium-based compound and a compound having a ligand structure of the following general formula (2): (R4)2Y—LQLY(R4)2 (2)

[0022] Wherein, Q represents an organic group containing nitrogen or phosphorus atoms, and the sum of the number of nitrogen and phosphorus atoms in Q is 1 or 2;

[0023] The L may appear the same or different each time, and the independent L indicates a single bond or a divalent connecting group;

[0024] Y may appear the same or different each time it appears, and each of them independently represents a phosphorus atom or a nitrogen atom.

[0025] R4 may appear the same or different each time, and each independent R4 represents a monovalent organic group.

[0026] Preferably, the iridium-based compound comprises one or more iridium compounds containing hydrogen atoms and / or halogens and / or CO; the solvent is selected from one or more organic solvents sufficient to dissolve the catalyst.

[0027] Preferably, R1, R2 and R3 in the general formula (1) are each independently selected from hydrogen, straight chain, branched chain or cyclic hydrocarbon groups or heteroaryl groups, and optionally the hydrocarbon groups have an aromatic structure.

[0028] R1, R2, and R3 are each independently selected from hydrogen, C1 to C3. 10 Alkyl, C1-C 10 alkoxy, substituted or unsubstituted phenyl or pyridyl, wherein the substituents on the phenyl or pyridyl group are selected from C1 to C2. 10 Alkyl, C1-C 10 One or more of alkoxy, halogen, and trifluoromethyl.

[0029] Preferably, in the general formula (1), X is an oxygen atom and R3 is not hydrogen.

[0030] As a further preferred option, in the general formula (1), X is N or O.

[0031] Preferably, the iridium-based compound is one or more of an inorganic salt of iridium or an iridium complex;

[0032] The iridium complex is one or more of a mononuclear iridium complex or a polynuclear iridium complex.

[0033] Preferably, the ligand structure of the general formula (2) includes one or more of the following general formula (2-1), general formula (2-2), or general formula (2-3): 3-t (R5-)N(-LY(R4)2) t (2-1) 3-t (R5-)P(-LY(R4)2) t (2-3)

[0034] Where t represents 2 or 3; R5 represents a monovalent organic group;

[0035] In general formula (2-1), N represents a nitrogen atom;

[0036] In general formula (2-2), the ring structure A represents a ring with an aromatic structure, N represents a nitrogen atom, and all three covalent bonds of the nitrogen atom are connected to the ring structure;

[0037] In general formula (2-3), P represents a phosphorus atom.

[0038] Preferably, the ring structure A in the general formula (2-2) has more than one ring, which are connected by single bonds or share at least one carbon atom.

[0039] Preferably, in the general formula (2), L is a hydrocarbon group with 1 to 6 carbon atoms.

[0040] Preferably, in the general formula (2), Y is a phosphorus atom, R4 is a straight chain, a branched chain, or an aromatic hydrocarbon group with 1 to 12 carbon atoms, and the aromatic hydrocarbon group may also have one or more of the following substituents: halogen, trifluoromethyl, C1 to C6 alkyl, or C1 to C6 alkoxy.

[0041] Preferably, in general formulas (2-1), (2-2), and (2-3), R5 is a hydrogen atom, a straight-chain alkyl group with 1 to 10 carbon atoms, a branched alkyl group with 3 to 10 carbon atoms, or an aromatic hydrocarbon group with 6 to 10 carbon atoms;

[0042] L represents a single bond or an alkylene group having 1 to 6 carbon atoms;

[0043] Y is a phosphorus atom, R4 is a straight-chain alkyl group with 1 to 10 carbon atoms, a branched alkyl group with 3 to 10 carbon atoms, a cycloalkyl group with 5 to 10 carbon atoms, or an aromatic hydrocarbon group with 6 to 10 carbon atoms, and the aromatic hydrocarbon group may also have one or more of the following substituents: halogen, trifluoromethyl, C1 to C6 alkyl, or C1 to C6 alkoxy.

[0044] In general formula (2-2), the cyclic structure A is a pyridine ring, a pyrrole ring, a benzopyridine ring, a benzopyrrole ring, a polybenzopyridine ring, or a polybenzopyrrole ring, and these structures may also have one or more of the following substituents: halogen, trifluoromethyl, C1-C6 alkyl or C1-C6 alkoxy.

[0045] Preferably, the compound of general formula (1) is reacted with hydrogen gas at a temperature of 80 to 280°C and at a pressure of 100 bar or less.

[0046] Preferably, the amount of the catalyst, in terms of the number of moles of iridium, is less than 30 mol% of the number of moles of the compound of general formula (1).

[0047] Preferably, the compound of general formula (1) reacts with hydrogen gas, and the product of the reaction is an amide compound, methanol, methylamine compound or ester compound.

[0048] Preferably, the methylamine compound is one or more of monomethylamine, dimethylamine, or trimethylamine.

[0049] The present invention also provides a method for utilizing carbon dioxide, wherein the method includes:

[0050] (1) Using carbon dioxide to synthesize compounds with the following general formula (1-1) or general formula (1-2):

[0051] Among them, the definitions of R1, R2 and R3 are the same as those in the general formula (1) above;

[0052] (2) The compound of general formula (1-1) or general formula (1-2) is further reacted with hydrogen using the method described above.

[0053] Preferably, the carbon dioxide can be recycled carbon dioxide.

[0054] The effects of the invention

[0055] By implementing the above technical solution, the present invention can achieve the following technical effects:

[0056] 1) For compounds of general formula (1), the present invention provides a new method for chemically selective catalytic hydrogenation, which uses a new (homogeneous) catalyst system, which is a polydentate ligand compound of an iridium-based compound. Compared with the catalysts previously used in the catalytic hydrogenation of the above compounds, the present invention has more diverse controllable synthesis of reduction products and does not require additional acid or base additives.

[0057] 2) The catalytic hydrogenation method of the present invention has the advantages of high selectivity, mild reaction conditions, high atom economy, many product types that are simple and easy to adjust, and environmental friendliness.

[0058] 3) This invention provides a novel catalytic application for an iridium-based polydentate ligand compound, expanding the industrial application scope of this catalyst.

[0059] 4) This invention also provides a cheaper and more feasible method for recycling carbon dioxide. Attached Figure Description

[0060] Figure 1 shows the MS-ESI spectrum of the catalytically active component detected in the reaction solution of Example 1. Detailed Implementation

[0061] The present invention will now be described in detail. The descriptions of the technical features described below are based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0062] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0063] In this specification, the numerical range indicated by "above" or "below" refers to the numerical range that includes the stated number.

[0064] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0065] In this specification, the terms "optional" or "optional" are used to indicate the use or non-use of certain substances, components, procedures, application conditions, etc., and there are no restrictions on the manner of use.

[0066] In this specification, the term "unsaturated structure" refers to a structure formed by carbon-carbon double bonds, unless otherwise specified.

[0067] In this invention, the "monovalent organic group" includes a "hydrogen atom".

[0068] In this specification, the term "hydrocarbon group" is used to refer to the organic structure formed by the loss of a hydrogen atom in a hydrocarbon compound composed of carbon and hydrogen elements, and it can be an aromatic or non-aromatic group.

[0069] In this specification, "hydro-alkyl group" is used to refer to the organic structure formed after a hydrocarbon compound composed of carbon and hydrogen loses a hydrogen atom, and it can be an aromatic or non-aromatic group.

[0070] In this specification, "alkyl" is used to refer to the organic structure formed when a saturated hydrocarbon compound consisting of carbon and hydrogen loses a hydrogen atom.

[0071] In this specification, "alkoxy" is used to refer to the organic structure formed when a hydroxyl group on a saturated alcohol composed of carbon, hydrogen, and oxygen loses a hydrogen atom.

[0072] Among them, C1~C6, C 1～C10 The number in the figure represents the number of C atoms.

[0073] In this specification, the term "halogen" refers to fluorine, chlorine, bromine, or iodine. Fluorine, chlorine, or bromine are preferred, and bromine and chlorine are more preferred.

[0074] All unit names used in this manual are international standard unit names, and unless otherwise stated, the "%" used refers to weight or mass percentage content.

[0075] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0076] The present invention primarily provides a catalytic hydrogenation method for compounds with the following general formula (1), for example, the compound with the general formula (1) can be a urea (or its derivative) or a carbamate compound. Furthermore, this type of compound undergoes a hydrogenation reaction with hydrogen under the catalysis of an iridium-based polydentate ligand compound, without the need for additional acid or base additives, thus obtaining amide compounds in an economical, efficient, and controllable manner. 、 Products such as methanol and methylamine compounds.

[0077] This invention is mainly based on the following insights:

[0078] Although there are reports on catalytic systems for the hydrogenation of urea derivatives and carbamates, these have only yielded single methanol or amide compounds. Furthermore, it is known that in the reported literature on amide hydrogenation, the selectivity between C=O and C–N bond cleavage is mainly achieved through acid-base additives. Therefore, there are no reports on catalysts that can be used for the selective hydrogenation of urea (or its derivatives) or carbamates without acid-base additives, especially considering the requirements of additional acid-base additives on the reaction equipment and the difficulty in achieving selective control between C=O and C–N bond cleavage.

[0079] It has been unexpectedly discovered that using iridium-based polydentate ligands as catalysts to catalyze compounds of the general formula (1) exhibits good catalytic selectivity, thus improving product yield. Furthermore, the hydrogen pressure during the reaction is lower, and amide compounds can be controllably generated without the need for acid or base additives. 、 Products such as methanol and methylamine compounds are produced. This significantly improves the economy and applicability of the catalytic process.

[0080] (Reaction materials)

[0081] The reaction raw materials or catalytic hydrogenation targets of the present invention are urea or its derivatives used in the art, or carbamate compounds.

[0082] In some specific embodiments of the present invention, the reactant compound may be one or more compounds having the following general formula (1).

[0083] In this context, R1, R2, and R3 may appear the same or different each time they appear, and they independently represent monovalent organic groups. Furthermore, R1 and R2 can be linked together to form a ring.

[0084] There are no particular limitations on the monovalent organic groups mentioned above, and they can be selected based on the types of compounds already available in the art. In some specific embodiments, the monovalent organic group can be selected from hydrogen atoms, straight-chain or branched or cyclic hydrocarbon groups, or hydrocarbon groups with unsaturated (or aromatic) structures, and these hydrocarbon groups can optionally have substituents. Preferably, these substituents can be halogens or halogen-containing groups; or, the carbon atoms in the aforementioned hydrocarbon groups can be replaced by other N, O, or S atoms.

[0085] In some preferred embodiments, the monovalent organic group may be selected from hydrogen atoms, straight-chain, branched, cyclic saturated or unsaturated hydrocarbon groups having 1 to 25 carbon atoms (preferably 1 to 15), and these groups may optionally have halogenated substituents or may optionally have carbon aromatic or heteroaromatic structures.

[0086] In some preferred embodiments, the monovalent organic group may be selected from one or more of hydrogen atoms, alkyl groups (methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl), cycloalkyl (4-6 membered ring), phenyl, pyridyl, and imidazolyl, having 1 to 10 carbon atoms, and these groups optionally have alkyl groups or halogen-containing substituents, such as one or more chlorine atoms, fluorine atoms, trifluoromethyl, methyl, ethyl, isopropyl, tert-butyl, methoxy, etc.

[0087] The above-mentioned R1 and R2 can be linked into a ring, which means that R1, R2 and the N connecting R1 and R2 together form an N-containing heterocycle, and the N-containing heterocycle may also contain other heteroatoms such as O, S, etc. The N-containing heterocycle is further a 3- to 10-membered N-containing heterocycle, further a 5- to 8-membered N-containing heterocycle, and in some more preferred embodiments, the N-containing heterocycle is tetrahydropyrrolyl, piperidinyl, morpholinyl, N-methylpiperazine, etc.

[0088] For X in the general formula (1), it can represent a nitrogen atom or an oxygen atom. When X represents a nitrogen atom, the compound with the general formula (1) can be urea or its derivatives, which has the structure of the following general formula (1-1); when X represents an oxygen atom, the compound with the general formula (1) can be a carbamate compound, which has the structure of the following general formula (1-2):

[0089] The value of n can be chosen based on different cases of X; therefore, n can be 1 or 2.

[0090] In the case of general formula (1-1), the two R3s can be the same or different. In addition to the two R3s representing monovalent organic groups independently as mentioned above, the two R3s can also form an N-containing heterocycle together with the N connecting the two R3s. The N-containing heterocycle can also contain other heteroatoms such as O, S, etc. The N-containing heterocycle is further a 3- to 10-membered N-containing heterocycle, further a 5- to 8-membered N-containing heterocycle. In some more preferred embodiments, the N-containing heterocycle is tetrahydropyrrole, piperidinyl, morpholino, N-methylpiperazine, etc.

[0091] In addition, in the case of general formula (1-2), preferably, R3 is not a hydrogen atom.

[0092] Furthermore, as preferred reaction raw materials of the present invention, compounds with the following structures can be listed:

[0093] (catalyst)

[0094] The catalyst of the present invention for the catalytic hydrogenation of compounds with the above-described general formula (1) can be one or more iridium-based polydentate ligand compounds. The iridium-based polydentate ligand compound can be derived from a combination of components comprising at least an iridium-based compound and a polydentate ligand compound.

[0095] In some specific embodiments of the present invention, the iridium-based compound includes one or more iridium compounds containing hydrogen atoms and / or halogens and / or CO. In some preferred embodiments, the iridium-based compound may be selected from carbonyl dihydrotris(triphenylphosphine)iridium (I), acetylacetone dicarbonyliridium (I), carbonyl di(triphenylphosphine)chloride iridium (I), carbonyl tris(triphenylphosphine)chloride iridium (I), chlorodi(cyclooctene)iridium (I) dimer, 1,5-cyclooctadiene iridium chloride dimer, bis(ethylene)iridium (I)chloride dimer, IrCl3, preferably carbonyl dihydrotris(triphenylphosphine)iridium (I).

[0096] Furthermore, the polydentate ligand compound includes one or more compounds having a ligand structure of the following general formula (2): (R4)3Y—LQL—Y(R4)3 (2)

[0097] Wherein, the compound of general formula (2) is a tridentate or more ligand, preferably a tridentate or tetradentate ligand. Q is an organic group containing a nitrogen atom or a phosphorus atom, and the total number of nitrogen atoms and phosphorus atoms is 1 or 2. Y may be the same or different each time it appears, and independently represents a phosphorus atom or a nitrogen atom, and preferably, all Y are phosphorus atoms.

[0098] The L mentioned above represents a single bond or a divalent linking group. In principle, there are no particular restrictions on the divalent linking groups that can be used for L. Commonly used linking groups in the art can be used. In some preferred embodiments, the divalent linking group can be a hydrocarbon group with 1 to 10 carbon atoms, more preferably 1 to 6.

[0099] R4 may be the same or different each time it appears, and each R4 independently represents a monovalent organic group. In some specific embodiments, each R4 independently represents a hydrocarbon group with 1 to 20 carbon atoms, preferably 2 to 15 or 3 to 10 straight chains, 3 to 10 branched chains, or 6 to 10 aromatic structures.

[0100] In a further specific embodiment of the present invention, the ligand of the general formula (2) structure includes one or more of the following general formula (2-1), general formula (2-2), or general formula (2-3): 3-t (R5-)N(-LY(R4)2) t (2-1) 3-t (R5-)P(-LY(R4)2)t (2-3)

[0101] In the general formula (2-1) structure, R5 represents a monovalent organic group. Preferably, R5 is the same or different each time it appears, and represents a hydrocarbon group with 1 to 20 hydrogen atoms or carbon atoms, preferably 2 to 15 or 3 to 10 straight-chain, branched, or 6 to 10 aromatic structures; t represents 2 or 3; N represents nitrogen atoms.

[0102] For the general formula (2-2) structure, where the above-mentioned cyclic structure A represents a ring with an aromatic structure, and all three bonds of the nitrogen atom represented by N are connected to the cyclic structure of the ring, preferably, the ring connected by N (the smallest unit ring) is an aromatic nitrogen heterocycle.

[0103] In other specific embodiments, the cyclic structure A has 4 to 20 rings, preferably 6 to 18 rings with carbon atoms on each ring. Such a cyclic structure can consist of one or more rings connected by single bonds or sharing at least one carbon atom, for example, by forming the cyclic structure A in a fused ring configuration. In a further preferred embodiment, the cyclic structure A can be a structure derived from pyridine, pyrrole, (poly)benzopyridine, or (poly)benzopyrrole, and these structures may optionally have substituents such as alkyl groups.

[0104] For the general formula (2-3) structure, R5 represents a monovalent organic group, which is defined in the same way as general formula (2-1). Preferably, R5 represents a hydrocarbon group with 1 to 20 hydrogen atoms or carbon atoms, preferably 2 to 15 or 3 to 10 straight-chain, branched, or 6 to 10 aromatic structures; t represents 2 or 3; and P represents a phosphorus atom.

[0105] From the perspective of improving the conversion rate of the catalyst hydrogenation reaction described below, the present invention preferably uses compounds with the general formula (2-2) as ligand compounds for forming the catalyst of the present invention.

[0106] (Catalyst formation)

[0107] The catalyst of the present invention can be obtained by reacting an iridium-based compound with a polydentate ligand compound having the structure of the above general formula (2).

[0108] The main point is that, for the above catalyst, the catalyst can be added to the subsequent hydrogenation reaction system after the complete catalyst is formed, or the above iridium-based compound and the polydentate ligand compound with the above general formula (2) can be directly added to the reaction vessel, and then the hydrogenation reaction reactants can be added in situ in the vessel after the catalyst is formed.

[0109] In some specific embodiments, the molar ratio of the iridium-based compound to the ligand of the structure of the above general formula (2) can be 1.0:(0.01 to 10), preferably 1.0:(1 to 3).

[0110] Additionally, if desired, the formation of the catalyst can be carried out in the presence of a solvent, which may be the same solvent used in the catalytic hydrogenation reaction described below. The solvent is one or more of nitrogen heterocyclic solvents, oxygen heterocyclic solvents, alcohol solvents, benzene solvents, or sulfone solvents. Tetrahydrofuran and 1,4-dioxane are preferred for the preparation of amide compounds and methanol; methanol or a mixture of methanol and tetrahydrofuran is preferred for the preparation of methylamine compounds; the amount of solvent is preferably 2 to 6 mL relative to 1 mmol of a compound of general formula (1).

[0111] (Catalytic hydrogenation reaction)

[0112] The catalytic hydrogenation reaction of the present invention involves the contact of a compound of general formula (1) with hydrogen gas in the presence of a solvent to undergo catalytic hydrogenation in order to obtain the desired product.

[0113] For the catalytic hydrogenation reaction of the present invention, depending on the different X in the compound of general formula (1), it can be carried out in the following manner:

[0114] In method (a), formamide compounds, methanol, methylamine compounds, and amine compounds can be obtained. In method (b), in addition to formamide compounds, methanol, and methylamine compounds, corresponding alcohols and esters can also be obtained. In some preferred embodiments, the methylamine compounds include secondary and tertiary amines.

[0115] For methods (a) and (b), methanol and methylamine compounds can be obtained in two steps, that is, the compound of general formula (1) is first hydrogenated to generate formamide compounds or formate ester compounds, and then the obtained formamide compounds or formate ester compounds are hydrogenated to generate methanol and methylamine compounds. Alternatively, formamide compounds, methanol, methylamine compounds or ester compounds can be obtained selectively in a one-pot process.

[0116] In addition, for method (a), since the reactants have symmetrical and asymmetrical structures, one or two different formamide compounds or methylamine compounds can be obtained.

[0117] There are no particular limitations on the solvents that can be used, as long as they are sufficient to dissolve the catalyst. In some specific embodiments, the solvent may include one or more of nitrogen heterocyclic solvents, oxygen heterocyclic solvents, alcohol solvents, benzene solvents, or sulfone solvents. More specifically, the solvent may be one or more of 1,4-dioxane, toluene, tetrahydrofuran, methanol, ethanol, isopropanol, and dimethyl sulfoxide, with tetrahydrofuran being particularly preferred. For the preparation of methylamine compounds, methanol is more preferably used as a solvent or as a co-solvent with one or more of the solvents mentioned above.

[0118] The reaction can be carried out under high pressure. In some specific embodiments, the reaction pressure is below 100 bar, preferably 1-90 bar, more preferably 1-60 bar, and even more preferably 5-30 bar. Compared with other catalysts in the prior art, the present invention can obtain higher conversion and selectivity at lower pressures. In some specific embodiments, the reaction pressure is further preferably 5-10 bar, which can be controlled to obtain amide compounds in methods (a) and (b) above; or the reaction pressure is further preferably 10-30 bar, which can be further controlled to obtain methanol and methylamine compounds. Therefore, the hydrogenation reaction can be carried out in a high-pressure reactor.

[0119] In addition, there is no particular limitation on the reaction temperature in the hydrogenation reaction step. This may be related to the type of reactants. It can usually be below 250°C, preferably 80 to 200°C, and more preferably 130 to 180°C.

[0120] Furthermore, in the catalytic hydrogenation reaction, the amount of the catalyst, based on the molar amount of iridium, is less than 30 mol% of the molar amount of the compound of general formula (1), preferably 0.1 to 25 mol%, more preferably 0.5 to 15 mol%, and even more preferably 1 to 6 mol%.

[0121] In addition, there is no particular limitation on the reaction time, which can usually be 1 to 72 hours, preferably 6 to 60 hours, and more preferably 6 to 48 hours.

[0122] In some preferred embodiments of the catalytic hydrogenation reaction of the present invention, the yield can be 24% by mass or more, preferably 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, and the conversion rate can preferably be 90% by mass or more, more preferably 95% by mass or more.

[0123] (Carbon dioxide recycling)

[0124] Furthermore, the present invention also provides a method for utilizing carbon dioxide, particularly wherein the carbon dioxide may be carbon dioxide recovered from the environment by means of adsorption or the like.

[0125] The method includes:

[0126] Using the carbon dioxide described above, compounds with the following general formula (1-1) and general formula (1-2) structures were synthesized:

[0127] In this context, R1, R2, and R3 may appear the same or different each time they appear, and they represent monovalent organic groups that are independent of each other. The monovalent organic groups are defined in the same way as those in the general formula (1) above.

[0128] Furthermore, the compounds of general formula (1-1) and general formula (1-2) are further reacted with hydrogen using the catalytic hydrogenation method described above.

[0129] Example

[0130] The embodiments of the present invention will be described in detail below with reference to the examples. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0131] Example 1

[0132] In a glove box under N2 atmosphere, 0.02 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I) and 0.03 mmol of different ligands, 2,6-bis[(diphenylphosphine)methyl]pyridine, 2,6-bis((di-tert-butylphosphine)methyl)pyridine, bis(2-(dicyclohexylphosphine)ethyl)amine, tris(2-(diphenylphosphine)ethyl)phosphine, and bis(2-(di-tert-butylphosphine)ethyl)amine, were added to a 50 mL high-pressure reactor containing 4 mL of tetrahydrofuran solvent. After stirring for about 5 min, 2 mmol of 1,3-bis(4-chlorophenyl)urea was added.

[0133] Remove the sealed high-pressure reactor from the glove box and flush it with hydrogen 4-6 times (first pressurize the hydrogen to 30 bar, then release it to about 2 bar, repeating this cycle 4-6 times). Finally, pressurize to 10 bar and heat at 130°C with stirring to carry out the hydrogenation reaction. After the reaction is complete, move the reactor to an ice bath to cool it below room temperature, then slowly release the gas to atmospheric pressure and open the reactor. Add biphenyl as an internal standard, and take samples for GC analysis after filtration. The conversion and yield are shown in Table 1. MS-ESI analysis was also performed on samples of the reaction solution with 2,6-bis[(diphenylphosphine)methyl]pyridine as the ligand.

[0134] The qualitative and quantitative methods for the products in this invention are based on gas chromatography-programmed temperature detection (Chem.Eur.J.2023,29,e202300106;Chem.Sci.2024,15,2089-2099), and the instrument used is a GC-2010 (Shimadzu, Japan) with an HP-1 column.

[0135] Table 1. Conversion rate and formamide yield of 1,3-bis(4-chlorophenyl)urea with different ligands.

[0136] The formamide is N-(4-chlorophenyl)formamide.

[0137] As can be seen from the comparison of the results in Table 1, the use of various ligands can demonstrate industrial usefulness.

[0138] Example 2

[0139] In a glove box under N2 atmosphere, 0.02 mmol of the iridium compound from Table 2 (for halogen-containing iridium compounds, an equivalent amount of alkali or other methods are needed to extract the halogen ligand) and 0.03 mmol of the ligand 2,6-bis[(diphenylphosphino)methyl]pyridine were added separately to a 50 mL high-pressure reactor containing 4 mL of tetrahydrofuran solvent. After stirring for about 5 min, 2 mmol of 1,3-bis(4-chlorophenyl)urea was added.

[0140] Remove the sealed high-pressure reactor from the glove box and flush it with hydrogen 4-6 times (first pressurize to 30 bar, then release to about 2 bar, repeating this cycle 4-6 times). Finally, pressurize to 10 bar and heat at 130°C with stirring to carry out the hydrogenation reaction. After the reaction is complete, move the reactor to an ice bath to cool to below room temperature, then slowly release the gas to atmospheric pressure and open the reactor. Add biphenyl as an internal standard, and take a sample for filtration and GC analysis. The conversion and yield are shown in Table 2.

[0141] The qualitative and quantitative methods for the products in this invention are based on gas chromatography-programmed temperature detection (Chem.Eur.J.2023,29,e202300106;Chem.Sci.2024,15,2089-2099), and the instrument used is a GC-2010 (Shimadzu, Japan) with an HP-1 column.

[0142] Table 2 shows the conversion rate of 1,3-bis(4-chlorophenyl)urea and the yield of formamide when different iridium-based compounds are used.

[0143] The results in Table 2 show that the use of various mononuclear or polynuclear iridium complexes can demonstrate industrial usefulness.

[0144] Example 3

[0145] In a glove box under N2 atmosphere, 0.02 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I) and 0.03 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand were added to 50 mL high-pressure reactors containing 4 mL of tetrahydrofuran, toluene, methanol, 1,4-dioxane, and dimethyl sulfoxide solvents, respectively. After stirring for approximately 5 min, 2 mmol of 1,3-bis(4-chlorophenyl)urea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reactors were heated and stirred at 130 °C for hydrogenation. After the reaction was complete, the reactors were moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactors. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The conversion and yield are shown in Table 3.

[0146] Table 3. Conversion rate of 1,3-bis(4-chlorophenyl)urea and yield of formamide in different solvents.

[0147] As can be seen from the comparison of the results in Table 3, although the yield of formamide fluctuates to some extent when carrying out the hydrogenation reaction of 1,3-bis(4-chlorophenyl)urea in different solvents, the overall results are still satisfactory.

[0148] Example 4

[0149] In a glove box under N2 atmosphere, 0.02 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.03 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-bis(4-chlorophenyl)urea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 30 bar, and the hydrogenation reaction was carried out by stirring and heating at 120, 130, 150, and 180 °C, respectively. After the reaction was completed, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The conversion and yield are shown in Table 4.

[0150] Table 4. Conversion rate and formamide yield of 1,3-bis(4-chlorophenyl)urea at different reaction temperatures.

[0151] Example 5

[0152] In a glove box under N2 atmosphere, 0.02 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.03 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-bis(4-fluorophenyl)urea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reaction was stirred and heated at 130 °C for 24 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 5.

[0153] Example 6

[0154] In a glove box under N2 atmosphere, 0.02 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.03 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-bis(3,4-dichlorophenyl)urea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reaction was stirred and heated at 130 °C for 12 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 5.

[0155] Example 7

[0156] In a glove box under N2 atmosphere, 0.02 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.03 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-bis[3-(trifluoromethyl)phenyl]urea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reaction was stirred and heated at 130 °C for 16 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 5.

[0157] Example 8

[0158] In a glove box under N2 atmosphere, 0.04 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.06 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-bisphenylurea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reaction was stirred and heated at 130 °C for 46 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 5.

[0159] Example 9

[0160] In a glove box under N2 atmosphere, 0.04 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.06 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-dipyridin-2-ylurea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reaction was stirred and heated at 130 °C for 48 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 5.

[0161] Example 10

[0162] In a glove box under N2 atmosphere, 0.04 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.06 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-bis(4-methylphenyl)urea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reaction was stirred and heated at 130 °C for 60 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 5.

[0163] Example 11

[0164] In a glove box under N2 atmosphere, 0.08 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.12 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-dibutylurea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reaction was stirred and heated at 140 °C for 48 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 5.

[0165] Example 12

[0166] In a glove box under N2 atmosphere, 0.04 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I) and 0.06 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, along with 4 mL of tetrahydrofuran solvent, were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 3-(3,4-dichlorophenyl)-1,1-dimethylurea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reaction was stirred and heated at 130 °C for 24 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 5.

[0167] Example 13

[0168] In a glove box under N2 atmosphere, 0.06 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.09 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 1 mmol of N-phenylcarbamate was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reaction was stirred and heated at 140 °C for 24 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 5.

[0169] Example 14

[0170] In a glove box under N2 atmosphere, 0.06 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I) and 0.09 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, along with 4 mL of tetrahydrofuran solvent, were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 1 mmol of ethyl phenylcarbamate was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reactor was stirred and heated at 140 °C for 24 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 5.

[0171] Example 15

[0172] In a glove box under N2 atmosphere, 0.06 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.09 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 1 mmol of (3-chlorophenyl)carbamate was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reaction was stirred and heated at 140 °C for 24 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 5.

[0173] Example 16

[0174] In a glove box under N2 atmosphere, 0.06 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I) and 0.09 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, along with 4 mL of tetrahydrofuran solvent, were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 1 mmol of tert-butyl phenylcarbamate was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the reactor was stirred and heated at 140 °C for 24 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 5.

[0175] Table 5: Reaction conditions and yields of Examples 5-16

[0176] As shown in Table 5, the in-situ iridium-based hydrogenation coupling catalyst system has high hydrogenation efficiency for urea derivatives and carbamates and has a wide range of applications.

[0177] Example 17

[0178] In a glove box under N2 atmosphere, 0.08 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.12 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-bis(4-chlorophenyl)urea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 30 bar, and the reaction was stirred and heated at 150 °C for 48 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 6.

[0179] Example 18

[0180] In a glove box under N2 atmosphere, 0.04 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.06 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of N-(4-chlorophenyl)formamide was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 30 bar, and the reaction was stirred and heated at 150 °C for 48 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 6.

[0181] Example 19

[0182] In a glove box under N2 atmosphere, 0.04 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.06 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 4 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of N-phenylformamide was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 30 bar, and the reaction was stirred and heated at 160 °C for 24 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 6.

[0183] Example 20

[0184] In a glove box under N2 atmosphere, 0.06 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I), 0.08 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, and 3 mL of tetrahydrofuran solvent were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 1 mmol of N-phenylcarbamate was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 30 bar, and the reactor was stirred and heated at 160 °C for 24 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 6.

[0185] Table 6: Reaction conditions and yields of Examples 17-20

[0186] As shown in Table 6, the in-situ iridium-based hydrogenation coupling catalyst system has a wide range of applications for the hydrogenation of urea derivatives and carbamates to methanol.

[0187] Example 21

[0188] In a glove box under N2 atmosphere, 0.08 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I) and 0.1 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, along with 4 mL of solvent (2 mL methanol and 2 mL tetrahydrofuran), were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-bis(4-chlorophenyl)urea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 30 bar, and the reaction was stirred and heated at 180 °C for 48 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 7.

[0189] Example 22

[0190] In a glove box under N2 atmosphere, 0.04 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I) and 0.06 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, along with 4 mL of solvent (0.3 mL methanol and 3.7 mL tetrahydrofuran), were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-bisphenylurea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 30 bar, and the reactor was stirred and heated at 180 °C for 48 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 7.

[0191] Example 23

[0192] In a glove box under N2 atmosphere, 0.06 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I) and 0.08 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, along with 4 mL of solvent (0.5 mL methanol and 3.5 mL tetrahydrofuran), were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of N-phenylcarbamate was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 30 bar, and the reactor was stirred and heated at 180 °C for 48 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 7.

[0193] Example 24

[0194] In a glove box under N2 atmosphere, 0.04 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I) and 0.06 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, along with 4 mL of solvent (0.5 mL methanol and 3.5 mL tetrahydrofuran), were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-bis(4-methylphenyl)urea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 30 bar, and the reactor was stirred and heated at 180 °C for 48 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 7.

[0195] Example 25

[0196] In a glove box under N2 atmosphere, 0.04 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I) and 0.06 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, along with 4 mL of solvent (2 mL methanol and 2 mL tetrahydrofuran), were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 2 mmol of 1,3-bis(4-methoxyphenyl)urea was added. The sealed high-pressure reactor was removed from the glove box and flushed with hydrogen 4-6 times (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 30 bar, and the reactor was stirred and heated at 180 °C for 48 h. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The yields are shown in Table 7.

[0197] Table 7: Reaction conditions and yields of Examples 21-25

[0198] As shown in Table 7, the in-situ iridium-based hydrogenation coupling catalyst system has a wide range of applications for the hydrogenation of urea derivatives and carbamates to produce methylamine compounds.

[0199] Example 25

[0200] In a glove box under N2 atmosphere, 0.04 mmol of carbonyl dihydrotris(triphenylphosphine)iridium(I) and 0.06 mmol of 2,6-bis[(diphenylphosphine)methyl]pyridine ligand, along with 4 mL of tetrahydrofuran solvent, were added to a 50 mL high-pressure reactor. After stirring for approximately 5 min, 4 mmol of aniline and 0.3 mL of methanol were added. The sealed high-pressure reactor was removed from the glove box and rinsed 4-6 times with N2 (first pressurizing to 30 bar, then releasing to approximately 2 bar, repeating this cycle 4-6 times). Finally, the pressure was increased to 10 bar, and the hydrogenation reaction was carried out by stirring and heating at 130, 140, 150, and 160 °C, respectively. After the reaction was complete, the reactor was moved to an ice bath to cool to below room temperature, and then slowly vented to atmospheric pressure before opening the reactor. Biphenyl was added as an internal standard, and samples were filtered and analyzed by GC. The conversion and yield are shown in Table 8.

[0201] Table 8. Yields of N-methylaniline catalytically coupled with aniline and methanol at different reaction temperatures.

[0202] As shown in Table 8, the in-situ iridium-based catalyst system has a significant catalytic coupling effect on aniline and methanol, and the reaction conditions are mild.

[0203] See Comparative Example 1

[0204] In a glove box under N2 atmosphere, 0.02 mmol of the metal precursor from Table 9 and 0.03 mmol of 2,6-bis[(diphenylphosphino)methyl]pyridine ligand were added separately to a 50 mL high-pressure reactor containing 4 mL of tetrahydrofuran solvent. After stirring for about 5 min, 2 mmol of 1,3-bis(4-chlorophenyl)urea was added.

[0205] Remove the sealed high-pressure reactor from the glove box and flush it with hydrogen 4-6 times (first pressurize to 30 bar, then release to about 2 bar, repeating this cycle 4-6 times). Finally, pressurize to 10 bar and heat at 130°C with stirring to carry out the hydrogenation reaction. After the reaction is complete, move the reactor to an ice bath to cool to below room temperature, then slowly release the gas to atmospheric pressure and open the reactor. Add biphenyl as an internal standard, and take a sample for filtration and GC analysis. The conversion and yield are shown in Table 9.

[0206] The qualitative and quantitative methods for the products in this invention are based on gas chromatography-programmed temperature detection (Chem.Eur.J.2023,e202300106;Chem.Sci.2024,15,2089-2099), and the instrument used is a GC-2010 (Shimadzu, Japan) with an HP-1 column.

[0207] Table 9 shows the conversion rate of 1,3-bis(4-chlorophenyl)urea and the yield of N-(4-chlorophenyl)formamide when other metal precursors are used.

[0208] See Comparative Example 2

[0209] In a glove box under N2 atmosphere, 0.02 mmol of Mn(CO)5Br and 0.03 mmol of 2,6-bis[(diphenylphosphino)methyl]pyridine ligand were added separately to a 50 mL high-pressure reactor containing 4 mL of tetrahydrofuran solvent. After stirring for about 5 min, 2 mmol of 1,3-bis(4-chlorophenyl)urea was added.

[0210] Remove the sealed high-pressure reactor from the glove box and flush it with hydrogen 4-6 times (first pressurize with hydrogen to 30 bar, then release to about 2 bar, repeating this cycle 4-6 times). Finally, pressurize to 10 bar and perform the hydrogenation reaction by stirring and heating at 140℃, 160℃, and 180℃ respectively. After the reaction is complete, move the reactor to an ice bath to cool to below room temperature, then slowly release the gas to atmospheric pressure and open the reactor. Add biphenyl as an internal standard, and take a sample for filtration and GC analysis. The conversion and yield are shown in Table 10.

[0211] The qualitative and quantitative methods for the products in this invention are based on gas chromatography-programmed temperature detection (Chem.Eur.J.2023,e202300106;Chem.Sci.2024,15,2089-2099), and the instrument used is a GC-2010 (Shimadzu, Japan) with an HP-1 column.

[0212] Table 10. Conversion rate of 1,3-bis(4-chlorophenyl)urea and yields of N-(4-chlorophenyl)formamide, methanol, and methylamine at different reaction temperatures.

[0213] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0214] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for selective catalytic hydrogenation, characterized in that, The method includes: The step of contacting a compound of general formula (1) with hydrogen in the presence of a catalyst and a solvent, and, The compound of general formula (1) has the following structure: In this context, R1, R2, and R3 may appear the same or different each time, and they independently represent monovalent organic groups; or, R1 and R2 may be linked together to form a ring; X represents a nitrogen atom or an oxygen atom; n represents 1 or 2, and when n is 2, the two R3s may be the same or different, or the two R3s may be linked together to form a ring; The catalyst is an iridium-based polydentate ligand compound. The iridium-based polydentate ligand compounds are derived from the combination of iridium-based compounds and compounds having the following general formula (2): (R4)2Y-LQLY(R4)2 (2) Wherein, Q represents an organic group containing nitrogen or phosphorus atoms, and the total number of nitrogen and phosphorus atoms in Q is 1 or 2. The L may appear the same or different each time, and the independent L indicates a single bond or a divalent connecting group; Y may appear the same or different each time it appears, and each of them independently represents a phosphorus atom or a nitrogen atom. R4 may appear the same or different each time, and each independent R4 represents a monovalent organic group.

2. The method according to claim 1, characterized in that, The iridium-based compound includes one or more iridium compounds containing hydrogen atoms and / or halogens and / or CO; the solvent is selected from one or more organic solvents sufficient to dissolve the catalyst.

3. The method according to claim 1 or 2, characterized in that, The iridium-based compound is one or more of an inorganic salt of iridium or an iridium complex; The iridium complex is one or more of a mononuclear iridium complex or a polynuclear iridium complex; The solvent is one or more of nitrogen heterocyclic solvents, oxygen heterocyclic solvents, alcohol solvents, benzene solvents, or sulfone solvents.

4. The method according to claim 1, characterized in that, R1, R2 and R3 in the general formula (1) are each independently selected from hydrogen, straight-chain, branched or cyclic hydrocarbon groups, or heteroaryl groups, wherein the hydrocarbon groups may or may not have an aromatic structure.

5. The method according to claim 1, characterized in that, The ligand structure of the general formula (2) includes one or more of the following general formula (2-1), general formula (2-2), or general formula (2-3): 3-t (R5-)N(-LY(R4)2) t (2-1) 3-t (R5-)P(-LY(R4)2) t (2-3) Where t represents 2 or 3; R5 represents a monovalent organic group; In general formula (2-1), N represents a nitrogen atom; In general formula (2-2), the ring structure A represents a ring with an aromatic structure, N represents a nitrogen atom, and all three covalent bonds of the nitrogen atom are attached to the ring structure; In general formula (2-3), P represents a phosphorus atom.

6. The method according to claim 5, characterized in that, The ring structure A in the general formula (2-2) has more than one ring, which are connected by single bonds or share at least one carbon atom.

7. The method according to any one of claims 1, 5 to 6, characterized in that, In the general formulas (2), (2-1), (2-2) or (2-3), L is a hydrocarbon group having 1 to 6 carbon atoms; Y represents a phosphorus atom; R4 is a hydrocarbon group with a straight chain of 1 to 20 carbon atoms, a branched chain of 3 to 20 carbon atoms, or an aromatic structure of 6 to 20 carbon atoms.

8. The method according to claim 1, characterized in that, The compound of general formula (1) reacts with the hydrogen gas at a temperature of 80 to 280°C and a pressure of less than 100 bar. The amount of the catalyst, in terms of the number of moles of iridium, is less than 30 mol% of the number of moles of the compound of general formula (1).

9. The method according to claim 1, characterized in that, The compound of general formula (1) reacts with the hydrogen gas, and the reaction product is an amide compound, methanol, methylamine compound or ester compound; The methylamine compounds mentioned are one or more of monomethylamine compounds, dimethylamine compounds, or trimethylamine.

10. A method for utilizing carbon dioxide, characterized in that, The method includes: (1) Using carbon dioxide to synthesize compounds with the following general formula (1-1) or (1-2): Wherein, R1, R2 and R3 are as shown in any one of the general formulas (1) as claimed in claims 1 to 9; (2) The compound of general formula (1-1) or general formula (1-2) is further reacted with hydrogen using the method described in any one of claims 1 to 9.

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