NEW PROCESS FOR THE CATALYTIC PRODUCTION OF OXALATE AND OXAMIDE COMPOUNDS

Description

[0001] The present invention relates to a novel process for the preparation of oxalate and oxamide compounds by catalytic means. CONTEXT OF THE INVENTION

[0002] Oxalates and oxamides are important raw materials in the organic chemical industry, which are widely used to produce various dyes, medicines, important solvents, extractants and various intermediates in the fine chemical industry.

[0003] For example, the hydrogenation of oxalates and oxamides can produce ethylene glycol, which is an important raw material in the chemical industry.

[0004] A traditional method of producing oxalates uses the esterification of oxalic acid with alcohols. This production technique is expensive, energy-intensive, polluting, and results in an unreasonable use of raw materials.

[0005] A traditional method for producing oxamides relies on the reaction of oxalic acid, or a derivative thereof, with an amine. However, this method has drawbacks, as it involves the use of expensive or toxic and corrosive reagents. The use of such highly reactive starting compounds easily leads to unwanted side reactions, lowering the reaction selectivity and yields.

[0006] Oxalate and oxamide compounds can be synthesized directly by oxidative carbonylation of an alcohol or an amine respectively, in the presence of a palladium (Pd) or platinum (Pt) catalyst.

[0007] A crucial step in the industrial oxidative reaction catalyzed by palladium or platinum is the efficient regeneration of the metal atom in oxidation state +2 from the metal atom in oxidation state 0 that is reduced in the reaction. In general, it is quite difficult to directly reoxidize Pd(0) to Pd(II) or Pt(0) to Pt(II) by molecular oxygen, so an additional oxidant is usually used.

[0008] Reoxidation of Pd(0) or Pt(0) can be achieved by metal redox couples or by benzoquinones. The main disadvantages are: (1) the use of excess metals which leads to corrosive damage to the installations and (2) the difficulty of separating the reaction product from the oxidant (for example when benzoquinone is used as an oxidant, hydroquinone is formed as a by-product). In addition, the prior art processes for the preparation of oxalates are carried out under anhydrous conditions and possibly with a dehydrating agent, since the production of an oxalate is prevented by the water formed in situ when oxygen is used as an oxidant or when water is present in the reactants or solvents. Indeed, water deactivates the catalyst.

[0009] Another approach to oxalate synthesis is based on the use of alkyl nitrites (RONO), explosive compounds, which on the one hand act as effective reoxidizing agents for Pd(0) and on the other hand act through their alkoxy function (RO) as good nucleophiles for CO. However, side reactions occur, in particular the production of nitric acid.

[0010] The methods of the prior art disclose the use of organometallic complexes of palladium or platinum as homogeneous catalysts for the oxidative carbonylation of alcohols to oxalates and of amines to oxamides. Pd(II) salts such as PdCl 2 , PdBr 2 , Pd(acac) 2 , Pd(OAc) 2 , PdSO 4 , Pd(NO 3 ) 2 alone or in combination with a phosphine such as Ph 2 EtP, PhEt 2 P, (PhO) 3 P, Ph 3 P or with other ligands or Pt(II) salts such as PtCl 2 have in particular been used. US 4,005,129 A and US 4,614,832 A describe oxidative carbonylation processes for the preparation of oxalates in the presence of Pd or Pt based catalysts with phosphite type ligands.

[0011] However, although the presence of ligands in palladium catalysts has been shown to improve catalyst performance, when operating with strong oxidants such as O2 and RONO, the phosphorus donor ligands, the P-donors, can be easily oxidized, leading to the degradation of the catalyst into toxic products, which must be removed in particular by an additional purification step.

[0012] For many years, a low-cost and environmentally friendly way of preparing oxalates and oxamides has been sought.

[0013] One of the aims of the invention is the use of a palladium-(carbene) catalyst N- heterocyclic) or a platinum-(carbene) catalyst N -heterocyclic) allowing the preparation of oxalates or oxamides.

[0014] Another object of the present invention is the use of a palladium-(carbene) catalyst N-heterocyclic) or a platinum-(carbene) catalyst N -heterocyclic) allowing operation under oxidation conditions with a strong oxidant such as oxygen.

[0015] Another object of the present invention is the use of a palladium-(carbene) catalyst N- heterocyclic) or a platinum-(carbene) catalyst N -heterocyclic) which is stable during the oxidative carbonylation reaction allowing the preparation of oxalate and oxamide and which can be recovered and reused.

[0016] Another object of the invention is the use of a palladium-(N-heterocyclic carbene) catalyst or a platinum-(N-heterocyclic carbene) catalyst. N -heterocyclic), advantageously immobilized on a support, making it possible to obtain a catalyst in recyclable and efficient supported form.

[0017] One of the aims of the invention in the particular case of the preparation of oxalates, concerns the use of a palladium-(carbene) catalyst N -heterocyclic) or a platinum-(carbene) catalyst N -heterocyclic) in an oxidative carbonylation process, under specific conditions, which can avoid the use of: harmful and toxic reagents such as nitric oxide (NO), dehydrating agents, transition metal co-catalysts, or P-donor ligands.

[0018] Another object of the invention is the use of a palladium-(carbene) catalyst N- heterocyclic) or a platinum-(carbene) catalyst N -heterocyclic), in an oxidative carbonylation process of an alcohol or an amine leading to an efficient yield.

[0019] Another object of the invention is the use of a palladium-(carbene) catalyst N-heterocyclic) or a platinum-(carbene) catalyst N -heterocyclic), in an oxidative carbonylation process, the selectivity of which is greater than 80% in oxalates or oxamides. Another object of the invention is a process for the preparation of oxalates and oxamides, in the presence of a palladium-(carbene) catalyst N -heterocyclic) or a platinum-(carbene) catalyst N -heterocyclic). Use

[0020] A first object of the present invention is the use of an M-NHC catalyst, wherein M represents Pd or Pt and NHC represents a carbene group N -heterocyclic, comprising at least one atom M linked to at least one carbene ligand N-heterocyclic, in the implementation of a process for the selective preparation of oxalates or oxamides, from carbon monoxide, an oxidant, in particular molecular oxygen or air, and an alcohol or an amine respectively, optionally in the presence of a promoter.

[0021] For the purposes of the present invention, the term “oxalate” means the dialkyloxalate corresponding to the alcohol used.

[0022] The term "oxamide" means the oxamide derivative 1,1'-oxalyl diamine corresponding to the amine used.

[0023] The term M-NHC catalyst means an organometallic complex comprising at least one metal center M consisting of a palladium or platinum atom as a catalytic site, said metal center being linked to at least one carbene ligand. N -heterocyclic.

[0024] By "carbene" we mean N-heterocyclic" or NHC, a molecular species having a divalent carbon with 6 valence electrons included in a heterocycle containing at least one nitrogen atom.

[0025] By way of non-limiting examples, the following catalysts also fall within the definition according to the invention: a complex that comprises one M center bound to one NHC ligand, a complex that comprises one M center bound to two NHC ligands, a complex that comprises two M centers and two NHC ligands, a complex that comprises two M centers and 4 NHC ligands, a complex that comprises n M centers and n NHC ligands, n being an integer from 1 to 1000, in particular from 1 to 10, and a complex which includes n center M and 2n NHC ligands, n being an integer from 1 to 1000, especially from 1 to 10.

[0026] We understand from the value of the whole number n , that the catalyst according to the invention can be a polymer.

[0027] According to a particular embodiment, the invention relates to the use of an M-NHC catalyst in the implementation of a process for the selective preparation of oxalates or oxamides, from carbon monoxide, an oxidant, and an alcohol or an amine respectively. According to a particular embodiment, the invention relates to the use of an M-NHC catalyst in the implementation of a process for the selective preparation of oxalates, from carbon monoxide, an oxidant and an alcohol.

[0028] According to a particular embodiment, the invention relates to the use of an M-NHC catalyst, in the implementation of a process for the selective preparation of oxamides, from carbon monoxide, an oxidant, and an amine.

[0029] Advantageously, the invention relates to the use of a palladium catalyst Pd-NHC.

[0030] According to a particular embodiment, the invention relates to the use of a Pd-NHC catalyst in the implementation of a process for the selective preparation of oxalates or oxamides, from carbon monoxide, an oxidant and an alcohol or an amine respectively. According to a particular embodiment, the invention relates to the use of a Pd-NHC catalyst in the implementation of a process for the selective preparation of oxalates, from carbon monoxide, an oxidant and an alcohol.

[0031] According to a particular embodiment, the invention relates to the use of a Pd-NHC catalyst, in the implementation of a process for the selective preparation of oxamides, from carbon monoxide, an oxidant and an amine.

[0032] Advantageously, the invention relates to the use of a Pt-NHC platinum catalyst.

[0033] According to a particular embodiment, the invention relates to the use of a Pt-NHC catalyst in the implementation of a process for the selective preparation of oxalates or oxamides, from carbon monoxide, an oxidant and an alcohol or an amine respectively. According to a particular embodiment, the invention relates to the use of a Pt-NHC catalyst in the implementation of a process for the selective preparation of oxalates, from carbon monoxide, an oxidant and an alcohol.

[0034] According to a particular embodiment, the invention relates to the use of a Pt-NHC catalyst, in the implementation of a process for the selective preparation of oxamides, from carbon monoxide, an oxidant and an amine.

[0035] According to a particular embodiment, the invention relates to the use as defined above in which the oxidant is chosen from: molecular oxygen (O 2 ), air, a dione, in particular 1,4-benzoquinone, 1,4-dichloro-2-butene and CuCl 2 .

[0036] For the purposes of the present invention, air is defined as an oxidant. Air is a gas composition comprising in molar fraction approximately 78% nitrogen (N 2 ), 21% oxygen O 2 and approximately less than 1% of other gases including carbon dioxide (CO 2 ), methane (CH 4 ) and rare gases including argon, helium, neon, krypton and xenon. Since nitrogen is an inert gas, it is understood that the oxidative reactivity of air is governed by that of oxygen. Oxygen is also called molecular oxygen or oxygen in the present invention. Advantageously, the invention relates to the use as defined above in which molecular oxygen or air is used as an oxidant.

[0037] According to a particular embodiment, the invention relates to the use of an M-NHC catalyst, in the implementation of a process for the selective preparation of oxalates or oxamides, from carbon monoxide, molecular oxygen or air and an alcohol or an amine respectively.

[0038] According to a particular embodiment, the invention relates to the use of an M-NHC catalyst, in the implementation of a process for the selective preparation of oxalates, from carbon monoxide, molecular oxygen or air and an alcohol.

[0039] According to a particular embodiment, the invention relates to the use of an M-NHC catalyst, in the implementation of a process for the selective preparation of oxamides, from carbon monoxide, molecular oxygen or air and an amine.

[0040] Advantageously, the invention relates to the use as defined above of a Pd-NHC catalyst in which molecular oxygen or air is used as oxidant.

[0041] According to a particular embodiment, the invention relates to the use of a Pd-NHC catalyst, in the implementation of a process for the selective preparation of oxalates or oxamides, from carbon monoxide, molecular oxygen or air and an alcohol or an amine respectively.

[0042] According to a particular embodiment, the invention relates to the use of a Pd-NHC catalyst in the implementation of a process for the selective preparation of oxalates from carbon monoxide, molecular oxygen or air and an alcohol.

[0043] According to a particular embodiment, the invention relates to the use of a Pd-NHC catalyst in the implementation of a process for the selective preparation of oxamides, from carbon monoxide, molecular oxygen or air and an amine.

[0044] Advantageously, the invention relates to the use as defined above of a Pt-NHC catalyst in which molecular oxygen or air is used as oxidant.

[0045] According to a particular embodiment, the invention relates to the use of a Pt-NHC catalyst, in the implementation of a process for the selective preparation of oxalates or oxamides, from carbon monoxide, molecular oxygen or air and an alcohol or an amine respectively.

[0046] According to a particular embodiment, the invention relates to the use of a Pt-NHC catalyst in the implementation of a process for the selective preparation of oxalates from carbon monoxide, molecular oxygen or air and an alcohol.

[0047] According to a particular embodiment, the invention relates to the use of a Pt-NHC catalyst in the implementation of a process for the selective preparation of oxamides, from carbon monoxide, molecular oxygen or air and an amine.

[0048] Advantageously, the invention relates to the use as defined above of a Pd-NHC catalyst, in the presence of a promoter.

[0049] According to a particular embodiment, the invention relates to the use of a Pd-NHC catalyst in the implementation of a process for the selective preparation of oxalates or oxamides, from carbon monoxide, an oxidant and an alcohol or an amine respectively, in the presence of a promoter.

[0050] According to a particular embodiment, the invention relates to the use of a Pd-NHC catalyst in the implementation of a process for the selective preparation of oxalates, from carbon monoxide, an oxidant and an alcohol, in the presence of a promoter.

[0051] According to a particular embodiment, the invention relates to the use of a Pd-NHC catalyst in the implementation of a process for the selective preparation of oxamides, from carbon monoxide, an oxidant and an amine, in the presence of a promoter.

[0052] Advantageously, the invention relates to the use as defined above of a Pd-NHC catalyst, in which molecular oxygen or air is used as oxidant, in the presence of a promoter.

[0053] According to a particular embodiment, the invention relates to the use of a Pd-NHC catalyst in the implementation of a process for the selective preparation of oxalates or oxamides, from carbon monoxide, molecular oxygen or air and an alcohol or an amine respectively, in the presence of a promoter.

[0054] According to a particular embodiment, the invention relates to the use of a Pd-NHC catalyst in the implementation of a process for the selective preparation of oxalates, from carbon monoxide, molecular oxygen or air and an alcohol, in the presence of a promoter.

[0055] According to a particular embodiment, the invention relates to the use of a Pd-NHC catalyst in the implementation of a process for the selective preparation of oxamides, from carbon monoxide, molecular oxygen or air and an amine, in the presence of a promoter.

[0056] Advantageously, the catalyst for use according to the invention can be chosen so as not to comprise any phosphorus ligand.

[0057] According to a particular embodiment, the invention relates to the use of an M-NHC catalyst not having phosphorus ligands, in particular phosphine groups.

[0058] Unlike M-Phosphine complexes in which the P-donor phosphine ligands oxidize leading to the formation of degradation products during catalysis, the stability of M-NHC catalysts allows catalyst reuse and catalyst stability in an oxidizing reaction medium. Supported catalyst

[0059] Advantageously, it is possible to bind the M-NHC catalyst to a support.

[0060] According to an advantageous embodiment, the invention relates to the use as defined above of a supported M-NHC catalyst in the implementation of a process for the selective preparation of oxalates or oxamides respectively from carbon monoxide, an oxidant and an alcohol or an amine respectively.

[0061] According to a particular embodiment, the invention relates to the use as defined above of a supported M-NHC catalyst in the implementation of a process for the selective preparation of oxalates from carbon monoxide, an oxidant and an alcohol.

[0062] According to a particular embodiment, the invention relates to the use as defined above of a supported M-NHC catalyst in the implementation of a process for the selective preparation of oxamides from carbon monoxide, an oxidant and an amine.

[0063] By "supported M-NHC catalyst" we mean that the M-NHC catalyst is bound to a support. The association between the organometallic complex and the support can be achieved in different ways.

[0064] The association between the catalyst and the support may be by chemical bonding, including covalent bonds, ionic bonds and / or intermolecular interactions such as hydrogen bonds. Preferably, the catalyst is covalently bonded to the support. According to a particular embodiment, the catalyst is bonded to said support by at least one of its ligands, thus allowing accessibility to the metal center.

[0065] According to a particular embodiment, the catalyst is linked to said support through the carbene group N -heterocyclic.

[0066] In one embodiment, the support is an oxide, particularly silica, a polymer, a carbon material such as carbon nanotubes and graphene oxide, or magnetic nanoparticles, preferably a polymer or silica.

[0067] In one embodiment, the support is in the form of beads.

[0068] By way of non-limiting examples, the support consists of polystyrene beads or silica beads, for example in the form of silica gel.

[0069] The use of a supported catalyst has the advantage of facilitating the separation of the catalyst from the reaction medium, making it easy to recover and reuse the catalyst. The use of a supported catalyst also has the advantage of allowing the catalyst to be fixed in the reactor in an enclosure such as a cartridge, when operating under continuous flow and thus obtaining products at the outlet of the reactor free of catalyst. M-NHC catalyst

[0070] Advantageously, without limitation, the use according to the invention as defined above can be implemented with M-NHC catalysts of specific formulas, defined below.

[0071] M-(N-heterocyclic carbene) catalyst comprising a metal center M bound to an NHC ligand.

[0072] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula I: in which: M represents Pd or Pt, R 1 and R 2 independently of each other represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, C 6 to C 20 aryl or C 3 to C 20 heteroaryl, and C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, L 1 represents a halogen atom chosen from Cl, Br and I, and either L 2 and L 3 are linked and together represent a bidentate ligand, or L 2 represents a halogen atom chosen from Cl, Br and I, and L 3 represents a monodentate ligand, said compound of Formula I being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0073] According to a particular embodiment, the invention relates to the use as defined above, said compound of Formula I being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0074] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula I, in which: L 1 represents an iodine atom, and either L 2 and L 3 are linked and together represent a bidentate ligand, or L 2 represents a halogen atom chosen from Cl, Br and I and L 3 represents a monodentate ligand.

[0075] The inventors have surprisingly discovered that the use of a catalyst carrying an iodinated ligand has the advantage of avoiding the presence of a promoter, in particular an iodinated promoter such as tetrabutylammonium iodide (Bu 4 Nl).

[0076] For the purposes of the present invention, the term "C 1 to C 10 alkyl, linear or branched" means a saturated, linear or branched, acyclic carbon chain comprising 1 to 10 carbon atoms. These are the methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl groups. The definition of propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl includes all possible isomers. For example, the term butyl includes n- butyl, iso -butyl, dry -butyl and ter -butyl. One or more hydrogen atoms may be replaced in the alkyl chain.

[0077] “C 3 -C 10 cycloalkyl” means: a C 3 cyclopropyl group, a C 4 cyclobutyl group, a C 5 cyclopentyl group, a C 6 cyclohexyl group, a C 7 cycloheptyl group, a C 8 cyclooctyl group, a C 9 cyclononyl group, or a C 10 cyclodecyl group, and fused cycloalkane rings such as adamantyl.

[0078] The term "C 6 to C 20 aryl" denotes an aromatic group comprising 6 to 20 carbon atoms within the aromatic ring, in particular from 6 to 12 carbon atoms, in particular comprising 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms. The aryl groups according to the present invention may also be substituted, in particular by one or more substituents chosen from a linear or branched C 1 to C 10 alkyl group.

[0079] Phenyl, toluyl, anisyl and naphthyl o -tolyl, m -tolyl, p -tolyl, o -xylyl,m -xylyl, p -xylyl, are examples of aryl groups.

[0080] The term "heteroaryl » denotes an aryl group as defined above, comprising atoms other than carbon atoms, in particular N, O or S within the aromatic ring. Pyridyl, imidazoyl, furfuryl or furanyl are examples of heteroaryl groups according to the present invention.

[0081] The term “C 7 to C 20 alkyl-aryl” designates a linear alkyl chain of formula -(CH 2 ) m -, m varying from 1 to 14, linked to an aryl group as defined above, the alkyl-aryl group consisting of 7 to 20 carbon atoms.

[0082] The term “C 4 to C 20 alkyl-heteroaryl” denotes a linear alkyl chain of formula -(CH 2 ) m -, m varying from 1 to 16, linked to a heteroaryl group as defined above, the alkyl-heteroaryl group consisting of 4 to 20 carbon atoms.

[0083] Advantageously, the groups R 1 and R 2 can be chosen independently of one another from the following groups: methyl, iso -propyl, tert -butyl, cyclohexyl, adamantyl, mesityl (2,4,6-trimethylphenyl) and diisopropylphenyl.

[0084] In one embodiment, the groups R 1 and R 2 are identical. In another embodiment, the groups R 1 and R 2 are different.

[0085] The term "bidentate ligand" means a molecular group, charged or neutral, forming two bonds with the metal center M, in particular through two atoms of the molecular group.

[0086] The term "monodentate ligand" means a molecular group, charged or neutral, forming a bond with the metal center M, in particular through an atom of the molecular group.

[0087] In one embodiment, the ligands L 1 , L 2 and L 3 do not contain phosphorus. Advantageously, the catalyst does not contain a phosphine ligand.

[0088] The R 1 or R 2 groups can be used to link the catalyst to a support in order to form a supported catalyst.

[0089] In a particular embodiment, at least one of the R 1 and R 2 groups of the catalyst is linked to a support, preferably by covalent bonding. The catalyst used is a supported catalyst.

[0090] In a particular embodiment, the support is a polymer, in particular polystyrene (PS).

[0091] In a particular embodiment, the support is silica, in particular a silica gel.

[0092] In a particular embodiment, the R 1 and R 2 groups of the catalyst are not linked to a support. The catalyst used is a homogeneous catalyst.

[0093] Palladium-(N-heterocyclic carbene) catalyst comprising a Pd bound to an NHC ligand.

[0094] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula II: in which: R 1 and R 2 independently represent a group selected from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, C 6 to C 20 aryl or C 3 to C 20 heteroaryl, and C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, L 1 represents a halogen atom selected from Cl, Br and I, and either L 2 and L 3 are linked and together represent a bidentate ligand, or L 2 represents a halogen atom selected from Cl, Br and I, and L 3 represents a monodentate ligand, said compound of Formula II being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0095] According to a particular embodiment, the invention relates to the use as defined above, said compound of Formula II being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0096] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula II, in which: L 1 represents an iodine atom, and either L 2 and L 3 are linked and together represent a bidentate ligand, or L 2 represents a halogen atom chosen from Cl, Br and I and L 3 represents a monodentate ligand,

[0097] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula II, in which: L 1 and L 2 each represent an iodine atom, and L 3 represents a monodentate ligand,

[0098] According to a particular embodiment, the invention relates to the use as defined above, in which the bidentate ligand is chosen from: acetylacetonate (acac), allyl, cinnamyl and acetate, the bidentate ligand being in particular acetylacetonate.

[0099] According to a particular embodiment, the invention relates to the use as defined above, in which the monodentate ligand is chosen from: pyridine, 3-chloropyridine, acetonitrile, triethylamine, or a phosphine-based ligand, in particular triphenylphosphine. Preferably, the monodentate ligand is in particular 3-chloropyridine.

[0100] According to a particular embodiment, the invention relates to the use as defined above, in which the monodentate ligand is chosen from: pyridine, 3-chloropyridine, acetonitrile, triethylamine. Preferably the monodentate ligand is 3-chloropyridine.

[0101] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula II: in which: R 1 and R 2 represent, independently of each other, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, L 1 represents a halogen atom chosen from Cl, Br and I, and either L 2 and L 3 represent a bidentate ligand, in particular chosen from acetylacetonate (acac), allyl, cinnamyl and acetate, preferably acetylacetonate, or L 2 represents a halogen atom chosen from Cl, Br and I, and L 3 represents a monodentate ligand, in particular chosen from: pyridine, 3-chloropyridine, acetonitrile, triethylamine, or a phosphine-based ligand, in particular triphenylphosphine, preferably 3-chloropyridine, said compound of Formula II being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0102] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula II: in which: R 1 and R 2 represent, independently of one another, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, L 1 represents an iodine atom, and either L 2 and L 3 represent a bidentate ligand, in particular chosen from acetylacetonate (acac), allyl, cinnamyl and acetate, preferably acetylacetonate, or L 2 represents a halogen atom chosen from Cl, Br and I and L 3 represents a monodentate ligand, in particular chosen from: pyridine, 3-chloropyridine, acetonitrile, triethylamine, or a phosphine-based ligand, in particular triphenylphosphine, preferably 3-chloropyridine, said compound of Formula II being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0103] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula II-4: in which: R 1 and R 2 independently of each other represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkylaryl or C 4 to C 20 alkylheteroaryl, in which either L 2 and L 3 represent a bidentate ligand, in particular chosen from acetylacetonate (acac), allyl, cinnamyl and acetate, preferably acetylacetonate, or L 2 represents a halogen atom chosen from Cl, Br and I and L 3 represents a monodentate ligand, in particular chosen from: pyridine, 3-chloropyridine, acetonitrile, triethylamine, or a ligand based on of phosphine, in particular triphenylphosphine, preferably 3-chloropyridine, said compound of Formula II-4 being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0104] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula II: in which: R 1 and R 2 represent, independently of one another, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, L 1 and L 2 each represent an iodine atom, and L 3 represents a monodentate ligand, in particular chosen from: pyridine, 3-chloropyridine, acetonitrile, triethylamine, or a phosphine-based ligand, in particular triphenylphosphine, preferably 3-chloropyridine, said compound of Formula II being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0105] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula II-5: in which: R 1 and R 2 represent, independently of each other, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, L 3 represents a monodentate ligand, in particular chosen from: pyridine, 3-chloropyridine, acetonitrile, triethylamine, or a phosphine-based ligand, in particular triphenylphosphine, preferably 3-chloropyridine, said compound of Formula II-5 being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0106] According to a particular embodiment, the invention relates to the use as defined above, said compound of Formula II being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0107] According to a particular embodiment, the invention relates to the use as defined above, said compound of Formula II-4 being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0108] According to a particular embodiment, the invention relates to the use as defined above, said compound of Formula II-5 being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0109] Palladium-(N-heterocyclic carbene) catalyst comprising a bound Pd and two NHC ligands.According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst comprises two N-heterocyclic carbene groups linked to palladium.

[0110] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula III: in which: R 1 , R 2 , R 3 and R 4 independently of each other represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, or L 1 and L 2 independently of each other represent: a halogen atom chosen from Cl, Br and I, or a monodentate ligand, or L 1 and L 2 are linked and represent a bidentate ligand, said compound of Formula III being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 , optionally one of the groups R 1 or R 2 may be linked to R 3 or R 4 and together represent a bidentate group comprising two N-heterocyclic carbene groups.

[0111] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst of Formula III comprises one of the groups R 1 or R 2 linked to R 3 or R 4 and together represent a bidentate group comprising two N-heterocyclic carbene groups.

[0112] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula III in which at least one of the groups L 1 and L 2 represents an iodine atom.

[0113] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to the following Formula III-2: in which: R 1 , R 2 , R 3 and R 4 independently represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, in which L 1 represents: a halogen atom chosen from Cl, Br and I, or a monodentate ligand, said compound of Formula III-2 being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 , optionally one of the groups R 1 or R 2 can be linked to R 3 or R 4 and together represents a bidentate group comprising two groups N-heterocyclic carbene.

[0114] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula III in which the groups L 1 and L 2 each represent an iodine atom.

[0115] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to the following Formula III-3: in which: R 1 , R 2 , R 3 and R 4 independently represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, said compound of Formula III-3 being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 , optionally one of the groups R 1 or R 2 can be linked to R 3 or R 4 and together represents a bidentate group comprising two N-heterocyclic carbene groups.

[0116] According to a particular embodiment, the invention relates to the use as defined above, said compound of Formula III being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 .

[0117] According to a particular embodiment, the invention relates to the use as defined above, said compound of Formula III-2 being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 .

[0118] According to a particular embodiment, the invention relates to the use as defined above, said compound of Formula III-3 being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 .

[0119] Dimer: Palladium-(N-heterocyclic carbene) catalyst comprising two Pd and two NHC ligands.

[0120] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula IV: in which: R 1 and R 2 represent, independently of each other, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, L 1 and L 2 represent a halogen atom chosen from Cl, Br and I.

[0121] It is understood from formula IV that the Pd---L 2 bonds are dative and that the complex formed is a dimer of symmetrical structure.

[0122] Specific formulas of palladium-(N-heterocyclic carbene) catalyst comprising a Pd bound to an NHC ligand.

[0123] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula II-1: in which: R 1 and R 2 represent, independently of one another, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, said compound of Formula II-1 being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0124] In one embodiment, the R 1 and R 2 groups of the catalyst of Formula II-1 are identical. In another embodiment, the R 1 and R 2 groups of the catalyst of Formula II-1 are different.

[0125] In one embodiment, the R 1 and R 2 groups of the catalyst of Formula II-1 are not linked to a support.

[0126] In another embodiment at least one of the groups R 1 and R 2 of the catalyst of Formula II-1 is linked to a support, in particular a polymer or silica.

[0127] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula II-2: In which : R 1 and R 2 represent, independently of one another, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, said compound of Formula II-2 being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0128] In one embodiment, the R 1 and R 2 groups of the catalyst of Formula II-2 are identical. In another embodiment, the R 1 and R 2 groups of the catalyst of Formula II-2 are different.

[0129] In one embodiment, the R 1 and R 2 groups of the catalyst of Formula II-2 are not linked to a support.

[0130] In another embodiment at least one of the groups R 1 and R 2 of the catalyst of Formula II-2 is linked to a support, in particular a polymer or silica.

[0131] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula II-3: in which: R 1 and R 2 represent, independently of one another, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, said compound of Formula II-3 being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0132] In one embodiment, the R 1 and R 2 groups of the catalyst of Formula II-3 are identical. In another embodiment, the R 1 and R 2 groups of the catalyst of Formula II-3 are different.

[0133] In one embodiment, the R 1 and R 2 groups of the catalyst of Formula II-3 are not linked to a support.

[0134] In another embodiment at least one of the groups R 1 and R 2 of the catalyst of Formula II-3 is linked to a support, in particular a polymer or silica.

[0135] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst is linked to polystyrene.

[0136] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst is chosen from: or in which the catalyst, bound to a support, is chosen from:

[0137] According to a particular embodiment, the invention relates to the use defined above, in which the catalyst corresponds to Formula II-1 or to Formula II-2 or to Formula II-3: In which : R 1 and R 2 represent, independently of one another, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, said catalyst being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 , in particular said catalyst is chosen from: or in which the catalyst, bound to a support (PS) is chosen from:

[0138] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula III-1: in which: R 1 , R 2 , R 3 and R 4 independently represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, said compound of Formula III-1 being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 , optionally one of the groups R 1 or R 2 can be linked to R 3 or R 4 and together represents a bidentate group comprising two N-heterocyclic carbene groups.

[0139] In one embodiment the groups R 1 , R 2 , R 3 and R 4 of the catalyst of Formula III-1 are not linked to a support.

[0140] According to a particular embodiment, the invention relates to the use as defined above, said compound of Formula III-1 being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 .

[0141] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst of Formula III-1, bound to a support, is chosen from:

[0142] Platinum-(N-heterocyclic carbene) catalyst comprising a Pt bound to an NHC ligand.

[0143] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula V: in which: R 1 and R 2 independently represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, C 6 to C 20 aryl or C 3 to C 20 heteroaryl, and C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, L 1 represents a halogen atom chosen from Cl, Br and I, and either L 2 and L 3 are linked and together represent a bidentate ligand, or L 2 represents a halogen atom chosen from Cl, Br and I, and L 3 represents a monodentate ligand, or L 1 , L 2 and L 3 are linked and together represent a tridentate ligand, said compound of Formula V being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0144] According to a particular embodiment, the invention relates to the use as defined above, in which the bidentate ligand is ethylenediamine.

[0145] According to a particular embodiment, the invention relates to the use as defined above, in which the monodentate ligand is chosen from: pyridine, 3-chloropyridine, cyclohexylamine, morpholine and dimethylsulfide, a phosphine in particular triphenylphosphine (PPh 3 ), ammonia (NH 3 ) and dimethylsulfoxide (DMSO).

[0146] According to a particular embodiment, the invention relates to the use as defined above, in which the tridentate ligand is chosen from terpyridine and diethylenetriamine.

[0147] Platinum-(N-heterocyclic carbene) catalyst comprising a Pt bound to 2 NHC ligands.

[0148] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula VI: in which: R 1 , R 2 , R 3 and R 4 independently of each other represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, or L 1 and L 2 independently of each other represent: a halogen atom chosen from Cl, Br and I, or a monodentate ligand, or L 1 and L 2 are linked and represent a bidentate ligand, said compound of Formula VI being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 , optionally one of the groups R 1 or R 2 may be linked to R 3 or R 4 and together represent a bidentate group comprising two N-heterocyclic carbene groups. Process

[0149] A second objectof the present invention is a process for preparing an oxalate compound or an oxamide compound, from carbon monoxide (CO), an oxidant in particular molecular oxygen or air, an alcohol or an amine respectively, catalyzed by an M-NHC catalyst, in which M represents the palladium atom (Pd) or the platinum atom (Pt) and NHC represents an N-heterocyclic carbene ligand.

[0150] Advantageously, under particular conditions, the presence of a promoter, a base, a solvent or a heating step is optional.

[0151] The reaction balance of the oxidative carbonylation of an alcohol or an amine for the process for preparing oxalates or oxamides according to the invention is written as follows:

[0152] According to a particular embodiment, the invention relates to a process for preparing an oxalate compound or an oxamide compound comprising: a step A of bringing an alcohol or an amine into contact, respectively, with: ▪ carbon monoxide, ▪ an oxidant, ▪ an M-NHC catalyst, in which M represents Pd or Pt and NHC represents an N-heterocyclic carbene group, comprising at least one atom M linked to at least one N-heterocyclic carbene ligand, and ▪ optionally a promoter ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxatate compound or the oxamide compound.

[0153] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact, respectively, with: ▪ carbon monoxide, ▪ an oxidant, ▪ an M-NHC catalyst, and ▪ optionally a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxatate compound.

[0154] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact, respectively, with: ▪ carbon monoxide, ▪ an oxidant, ▪ an M-NHC catalyst, and ▪ optionally a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxamide compound.

[0155] Advantageously, the invention relates to a process for preparing an oxalate compound or an oxamide compound, using a palladium Pd-NHC catalyst.

[0156] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound or an oxamide compound comprising: a step A of bringing an alcohol or an amine into contact, respectively, with: ▪ carbon monoxide, ▪ an oxidant, ▪ a Pd-NHC catalyst, and ▪ optionally a promoter ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxatate compound or the oxamide compound.

[0157] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact, respectively, with: ▪ carbon monoxide, ▪ an oxidant, ▪ a Pd-NHC catalyst, and ▪ optionally a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxatate compound.

[0158] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact, respectively, with: ▪ carbon monoxide, ▪ an oxidant, ▪ a Pd-NHC catalyst, and ▪ optionally a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxamide compound.

[0159] Advantageously, the invention relates to a process for preparing an oxalate compound or an oxamide compound, using a platinum Pt-NHC catalyst.

[0160] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound or an oxamide compound comprising: a step A of bringing an alcohol or an amine into contact, respectively, with: ▪ carbon monoxide, ▪ an oxidant, ▪ a Pt-NHC catalyst, and ▪ optionally a promoter ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxatate compound or the oxamide compound.

[0161] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact, respectively, with: ▪ carbon monoxide, ▪ an oxidant, ▪ a Pt-NHC catalyst, and ▪ optionally a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxatate compound.

[0162] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact, respectively, with: ▪ carbon monoxide, ▪ an oxidant, ▪ a Pt-NHC catalyst, and ▪ optionally a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxamide compound.

[0163] According to a particular embodiment, the invention relates to a process as defined above, of an oxalate compound or of an oxamide compound, in which the oxidant is chosen from: molecular oxygen (O 2 ), air, a dione, in particular 1,4-benzoquinone, 1,4-dichloro-2-butene and CuCl 2 .

[0164] Advantageously, the oxidant is molecular oxygen or air.

[0165] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound or an oxamide compound comprising: a step A of bringing an alcohol or an amine into contact, respectively, with: ▪ carbon monoxide, ▪ oxygen or air, ▪ an M-NHC catalyst, and ▪ a promoter ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxatate compound or the oxamide compound.

[0166] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact, respectively, with: ▪ carbon monoxide, ▪ oxygen or air, ▪ an M-NHC catalyst, and ▪ a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxatate compound.

[0167] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact, respectively, with: ▪ carbon monoxide, ▪ oxygen or air, ▪ an M-NHC catalyst, and ▪ a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxamide compound.

[0168] Advantageously, the invention relates to a process for preparing an oxalate compound or an oxamide compound, using a palladium Pd-NHC catalyst, in the presence of oxygen or air as oxidant.

[0169] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound or an oxamide compound comprising: a step A of bringing an alcohol or an amine into contact, respectively, with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a Pd-NHC catalyst, and ▪ a promoter ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxatate compound or the oxamide compound.

[0170] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact, respectively, with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a Pd-NHC catalyst, and ▪ a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxatate compound.

[0171] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact, respectively, with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a Pd-NHC catalyst, and ▪ a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxamide compound.

[0172] Advantageously, the invention relates to a process for preparing an oxalate compound or an oxamide compound, using a platinum Pt-NHC catalyst, in the presence of oxygen or air as oxidant.

[0173] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound or an oxamide compound comprising: a step A of bringing an alcohol or an amine into contact, respectively, with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a Pt-NHC catalyst, and ▪ a promoter ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxatate compound or the oxamide compound.

[0174] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact, respectively, with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a Pt-NHC catalyst, and ▪ a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxatate compound.

[0175] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact, respectively, with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a Pt-NHC catalyst, and ▪ a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxamide compound.

[0176] A "promoter" means a substance that can improve the properties of a catalyst such as catalytic activity, selectivity, anti-toxicity, stability, lifetime or prevent catalyst deactivation.

[0177] According to a particular embodiment, the promoter is chosen from iodinated derivatives and ammonium salts. The group of iodinated derivatives includes I 2 , Kl, LiI, Hl, NaI and tetrabutylammonium iodide (Bu 4 Nl). Iodinated derivatives have the advantage of being soluble in the reaction medium and can thus be advantageously used in the preparation process without causing excessive formation of solid products. Preferably tetrabutylammonium iodide (Bu 4 Nl) is used as promoter, the latter being soluble at 25°C and not precipitating during the preparation process.

[0178] In Pd(II)-catalyzed reactions, promoters are known to allow in-situ reoxidation of the generated Pd(0) to Pd(II) and thus ensure the catalytic cycle. The promoter can also protect the Palladium catalyst from water present in the system and thus prevent catalyst deactivation, avoid the addition of dehydrating agent in the system.

[0179] According to a particular embodiment, the process according to the invention is carried out under oxidative carbonylation conditions in the presence of oxygen and the promoter acts as an additional oxidant. The promoter can thus promote the oxidative carbonylation process by allowing the oxidation of M(0) to M(II) of the M-NHC catalyst during the reaction. Indeed, it is quite difficult to directly reoxidize Pd(0) to Pd(II) by molecular oxygen, so an additional oxidant is generally used.

[0180] The term "reaction medium" refers to all the species brought together during a chemical reaction. It includes in particular the reactants in liquid or gaseous form, the catalyst, and possibly a solvent, additives or promoters. Process for the preparation of oxalates in the presence of a Pd-NHC catalyst. Heating stage

[0181] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxalate compound.

[0182] According to a particular embodiment, the invention relates to a process for the preparation as defined above of an oxalate compound, in which step B of heating is carried out at a temperature of from 25 to 200°C, in particular from 60 to 110°C, preferably approximately 90°C.

[0183] The expression "from 25 to 200°C" corresponds to the ranges: from 25 to 40°C; from 40 to 60°C; from 60 to 80°C; from 80 to 100°C; from 100 to 120°C; from 120 to 140°C; from 140 to 160°C; from 160 to 180°C; from 180 to 200°C.

[0184] The expression "from 60 to 110°C" corresponds to the ranges: from 60 to 70°C; from 70 to 80°C; from 80 to 90°C; from 90 to 100°C; from 100 to 110°C.

[0185] According to a particular embodiment, the invention relates to a preparation process according to the invention defined above of an oxalate compound comprising: a step A of bringing an alcohol into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxalate compound, in particular carried out at a temperature of from 25 to 200°C, in particular from 60 to 110°C, preferably approximately 90°C. Base in the reaction medium

[0186] The process according to the invention for preparing oxalates can be carried out with or without base in the reaction medium. Presence of a base

[0187] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a base, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ optionally a solvent, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxalate compound.

[0188] According to a particular embodiment, the invention relates to a process as defined above for preparing an oxalate compound, in which said reaction medium comprises a base.

[0189] The presence of a base, advantageously chosen in the reaction medium, allows an increase in the yield of the reaction.

[0190] According to a particular embodiment, the invention relates to a process for the preparation as defined above, of an oxalate compound, in which the base is chosen from potassium carbonate (K 2 CO 3 ), sodium carbonate (Na 2 CO 3 ), potassium tert-butoxide (KOtBu), potassium phosphate (K 3 PO 4 ) and triethylamine (Et 3 N).

[0191] According to a particular embodiment, the invention relates to a preparation process as defined above, of an oxalate compound, in which the base is triethylamine.

[0192] Advantageously, the use of triethylamine (Et 3 N) allows its easy evaporation during the isolation of the product and its presence does not induce problems of recycling of the catalyst like the solid bases K 2 CO 3 and Na 2 CO 3 which precipitates at room temperature while the triethylamine remains in liquid phase. Absence of an added base

[0193] Advantageously, the process according to the invention for preparing an oxalate compound can be carried out without the use of a base.

[0194] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ optionally a solvent, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxalate compound.

[0195] The absence of base in the reaction medium makes it possible to limit the reagents to be introduced into the process and to limit the formation of degradation products. Solvent in the reaction medium

[0196] The process according to the invention for preparing oxalates can be carried out with or without solvent in the reaction medium. Presence of a solvent

[0197] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound, in which said reaction medium comprises a solvent.

[0198] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ optionally a base, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxalate compound.

[0199] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a base, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxalate compound.

[0200] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxalate compound. Without solvent added to the reaction medium

[0201] According to a particular embodiment, the invention relates to a method for preparing, as defined above, an oxalate compound, in which the method is carried out in the absence of solvent, the alcohol from which the oxalate is prepared acting as solvent. The method for preparing an oxalate compound according to the invention can be carried out without the use of solvent. This makes it possible to limit the preparation steps and the presence of degradation products to be treated and to limit the solvent treatment steps. For example, the use of alcohol as a reagent and solvent can simplify the recycling of the alcohol, in the event of incomplete conversion thereof. Thus, there is no need to separate solvents such as acetonitrile from alcohol.

[0202] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ optionally a base, ▪ a promoter, and ▪ a Pd-NHC catalyst, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxalate compound.

[0203] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a base, ▪ a promoter, and ▪ a Pd-NHC catalyst, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxalate compound.

[0204] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxalate compound comprising: a step A of bringing an alcohol into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a promoter, and ▪ a Pd-NHC catalyst, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxalate compound. Presence of water

[0205] Water formed in situ or present in the reactants can be harmful and in particular deactivate palladium catalysts in oxidative carbonylation during an oxalate preparation process.

[0206] Unlike other catalysts of the prior art such as described in US3,393,136, US4,005,130, US4,005,129 and US4,005,128, where the presence of water is detrimental during the process of preparing oxalates, the use of palladium-(N-heterocyclic carbene) catalysts under conditions according to the invention makes it possible to dispense with the use of a dehydrating agent or a step of dehydration of the reactants in the preparation of an oxalate compound.

[0207] Advantageously, the process according to the invention using the palladium-(N-heterocyclic carbene) catalyst in the presence of oxygen or air and a promoter allows selective preparation of oxalates in the presence of water in the reaction medium.

[0208] According to a particular embodiment, the invention relates to the use of a palladium-(N-heterocyclic carbene) catalyst in the implementation of a process for the selective preparation of oxalates from carbon monoxide, molecular oxygen or air, a promoter and an alcohol, not requiring anhydrous preparation conditions. Alcohol used as substrate

[0209] According to a particular embodiment, the invention relates to a process for the preparation as defined above, of an oxalate compound of Formula 2, in which step A comprises bringing into contact an alcohol of Formula 1: in which R a represents a group chosen from: C 1 to C 10 alkyl, straight or branched, and C 3 to C 10 cycloalkyl.

[0210] According to a particular embodiment, the invention relates to a process for preparing an oxalate compound as defined above, in which step A comprises bringing into contact an alcohol chosen from methanol, ethanol and isopropanol.

[0211] The oxalates prepared with methanol, ethanol, and isopropanol are dimethyloxalate, diethyloxalate, and diisopropyloxalate, respectively, shown below:

[0212] According to a particular embodiment, the invention relates to a preparation process according to the invention as defined above, of an oxalate compound of Formula 2, in which step A comprises bringing into contact an alcohol of Formula 1: in which R a represents a group chosen from: C 1 to C 10 alkyl, linear or branched, and C 3 to C 10 cycloalkyl, in particular the alcohol is chosen from methanol, ethanol and isopropanol. Process for the preparation of oxamides in the presence of a Pd-NHC catalyst.

[0213] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ optionally a base, ▪ optionally a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxamide compound.

[0214] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ optionally a base, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxamide compound.

[0215] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ optionally a base, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxamide compound. Base in the reaction medium

[0216] The process according to the invention for preparing oxamides can be carried out with or without base in the reaction medium. Without base added to the reaction medium

[0217] According to a particular embodiment, the invention relates to a process as defined above for preparing an oxamide compound, in which the base is the amine from which said oxamide compound is prepared.

[0218] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxamide compound. Presence of a base added to the reaction medium

[0219] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a base, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxamide compound.

[0220] According to a particular embodiment, the invention relates to a process for the preparation as defined above, of an oxamide compound, in which the base is chosen from potassium carbonate (K 2 CO 3 ), sodium carbonate (Na 2 CO 3 ), potassium tert-butoxide (KOtBu), potassium phosphate (K 3 PO 4 ) and triethylamine (Et 3 N).

[0221] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound, in which said base is an inorganic base, in particular K 2 CO 3 .

[0222] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound, in which said base is an organic base, in particular triethylamine.

[0223] The process for preparing an oxamide compound of the invention can be carried out with the addition of an inorganic base as well as with the addition of an organic base. It has been found that the inorganic base K 2 CO 3 is as effective as the organic base, triethylamine. Process with a heating step

[0224] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ optionally a base, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxamide compound.

[0225] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a base, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxamide compound.

[0226] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium, a step B of heating said reaction medium, to obtain the oxamide compound.

[0227] According to one embodiment, the process as defined above for preparing an oxamide compound comprises a step B of heating to a temperature of 25 to 110°C. Process without heating step

[0228] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound, in which said reaction medium is maintained at an ambient temperature of 20 to 25°C.

[0229] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ optionally a base, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium comprising the oxamide compound.

[0230] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a base, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium comprising the oxamide compound.

[0231] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a promoter, ▪ a Pd-NHC catalyst, and ▪ a solvent, to obtain a reaction medium comprising the oxamide compound.

[0232] The process for preparing oxamides according to the invention by oxidative carbonylation can advantageously be carried out at room temperature of 20 to 25°C.

[0233] Indeed, it was observed that the process for preparing oxamides according to the invention in the presence of a base and solvent made it possible to obtain oxamides in the reaction medium without a heating step.

[0234] Consequently, a heating step of the reaction medium is optional, which represents an industrial advantage in terms of cost and safety.

[0235] According to a particular embodiment, the invention relates to a process as defined above for the preparation of an oxamide compound comprising: a step A of bringing an amine into contact with: ▪ carbon monoxide, ▪ oxygen or air, ▪ a promoter, ▪ a Pd-NHC type catalyst, and ▪ a solvent, ▪ optionally a base, in particular chosen from K 2 CO 3 or Et 3 N, to obtain a reaction medium comprising oxamide. The amine used as a substrate

[0236] According to a particular embodiment, the invention relates to a process for the preparation as defined above, of an oxamide compound of Formula 4 in which step A comprises bringing into contact an amine of Formula 3: in which R b and R c represent, independently of one another: a hydrogen atom, a linear or branched C 1 to C 20 alkyl group, a linear or branched C 2 to C 20 alkenyl group, a linear or branched C 1 to C 20 heteroalkyl group, the heteroatom being in particular O or N, at least one of the R b or R c groups being other than hydrogen, R b and R c being able to form a cycle.

[0237] The term “straight or branched heteroalkyl” means a straight or branched alkyl group, as defined above, comprising atoms other than carbon atoms, in particular N, O or S within the alkyl chain.

[0238] The term “alkenyl, linear or branched” means an alkyl group, linear or branched, as defined above having a C=C double bond.

[0239] According to a particular embodiment, the invention relates to a preparation process as defined above, of an oxamide compound, in which step A comprises bringing into contact an amine chosen from: diethylamine, piperidine, pyrrolidine and morpholine.

[0240] The oxamides prepared with diethylamine, piperidine, pyrrolidine and morpholine are respectively represented below:

[0241] According to a particular embodiment, the invention relates to a process for the preparation as defined above, of an oxamide compound of Formula 4, in which the groups R b and R c are linked and form a cycle.

[0242] According to a particular embodiment, the invention relates to a process for the preparation as defined above, of an oxamide compound of Formula 4, in which step A comprises bringing into contact an amine of Formula 3: in which R b and R c represent, independently of one another: a hydrogen atom, a linear or branched C 1 to C 20 alkyl group, a linear or branched C 2 to C 20 alkenyl group, a linear or branched C 1 to C 20 heteroalkyl group, the heteroatom being in particular O or N, at least one of the R b or R c groups being other than hydrogen, R b and R c being able to form a cycle, in particular the amine is chosen from: diethylamine, piperidine, morpholine, pyrrolidine. Common characteristics of the process for the preparation of oxalates and oxamides. Catalysts

[0243] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the catalyst corresponds to Formula II-B: in which: R 1 and R 2 independently represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, L 1< represents a halogen atom chosen from Cl, Br and I, and either L 2< and L 3< represent a bidentate ligand, or L 2< represents a halogen atom chosen from Cl, Br and I, and L 3< represents a monodentate ligand, said compound of Formula II-B being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0244] According to a particular embodiment, the invention relates to the preparation process as defined above, in which the catalyst corresponds to Formula II-B, in which: L 1 represents an iodine atom, and either L 2 and L 3 are linked and together represent a bidentate ligand, or L 2 represents a halogen atom chosen from Cl, Br and I and L 3 represents a monodentate ligand,

[0245] According to a particular embodiment, the invention relates to the preparation process as defined above, in which the catalyst corresponds to Formula II-4B: in which: R 1 and R 2 independently of each other represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkylaryl or C 4 to C 20 alkylheteroaryl, in which either L 2 and L 3 represent a bidentate ligand, in particular chosen from acetylacetonate (acac), allyl, cinnamyl and acetate, preferably acetylacetonate, or L 2 represents a halogen atom chosen from Cl, Br and I and L 3 represents a monodentate ligand, in particular chosen from: pyridine, 3-chloropyridine, acetonitrile, triethylamine, or a ligand based on of phosphine, in particular triphenylphosphine, preferably 3-chloropyridine, said compound of Formula II-4B being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0246] According to a particular embodiment, the invention relates to the preparation process as defined above, in which the catalyst corresponds to Formula II-B, in which: L 1 and L 2 each represent an iodine atom, and L 3 represents a monodentate ligand.

[0247] According to a particular embodiment, the invention relates to the preparation process as defined above, in which the catalyst corresponds to Formula II-5B: in which: R 1 and R 2 represent, independently of each other, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, L 3 represents a monodentate ligand, in particular chosen from: pyridine, 3-chloropyridine, acetonitrile, triethylamine, or a phosphine-based ligand, in particular triphenylphosphine, preferably 3-chloropyridine, said compound of Formula II-5B being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0248] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the bidentate ligand is chosen from: acetylacetonate (acac), allyl, cinnamyl and acetate, the bidentate ligand being in particular acetylacetonate.

[0249] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the monodentate ligand is chosen from: pyridine, 3-chloropyridine, acetonitrile, triethylamine, or a phosphine-based ligand, in particular triphenylphosphine. Preferably, the monodentate ligand is in particular 3-chloropyridine.

[0250] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the monodentate ligand is chosen from: pyridine, 3-chloropyridine, acetonitrile, triethylamine, preferably the monodentate ligand being in particular 3-chloropyridine.

[0251] According to a particular embodiment, the invention relates to the preparation process as defined above, said compound of Formula II-B not being bound to a support.

[0252] According to a particular embodiment, the invention relates to the preparation process as defined above, said compound of Formula II-B being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0253] According to a particular embodiment, the invention relates to the preparation process as defined above, said compound of Formula II-4B being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0254] According to a particular embodiment, the invention relates to the preparation process as defined above, said compound of Formula II-5B being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0255] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the catalyst corresponds to Formula II-1B: in which: R 1 and R 2 represent, independently of one another, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, said compound of Formula II-1B being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0256] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the catalyst corresponds to Formula II-2B: in which: R 1 and R 2 represent, independently of one another, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, said compound of Formula II-2B being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0257] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the catalyst corresponds to Formula II-3B: in which: R 1 and R 2 represent, independently of each other, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, said compound of Formula II-3B being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0258] According to a particular embodiment, the invention relates to the preparation process as defined above, said compound of Formula II-3B being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 or R 2 .

[0259] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the support is polystyrene or silica gel, said catalyst being bound to said polystyrene or said silica gel.

[0260] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the catalyst is chosen from: or in which the catalyst, bound to a support, is chosen from:

[0261] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the catalyst corresponds to Formula III-B: in which: R 1 , R 2 , R 3 and R 4 independently of each other represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, or L 1 and L 2 independently of each other represent: a halogen atom chosen from Cl, Br and I, or a monodentate ligand, or L 1 and L 2 are linked and represent a bidentate ligand, said compound of Formula III-B being able to be linked to a support, in particular a polymer, by at least one of the groups R 1 , R 2 , R 3 or R 4 , optionally one of the groups R 1 or R 2 can be linked to R 3 or R 4 and together represents a bidentate group comprising two N-heterocyclic carbene groups.

[0262] According to a particular embodiment, the invention relates to the preparation process as defined above, said compound of Formula III-B being linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 .

[0263] According to a particular embodiment, the invention relates to the use as defined above, in which the catalyst corresponds to Formula III-B in which at least one of the groups L 1 and L 2 represents an iodine atom.

[0264] According to a particular embodiment, the invention relates to the preparation process as defined above, in which the catalyst corresponds to Formula III-1B: in which: R 1 , R 2 , R 3 and R 4 independently of each other represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, said compound of Formula III-1B being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 , optionally one of the groups R 1 or R 2 can be linked to R 3 or R 4 and together represents a bidentate group comprising two N-heterocyclic carbene groups.

[0265] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the catalyst of Formula III-1B bound to a support is chosen from:

[0266] According to a particular embodiment, the invention relates to the preparation process as defined above, in which the catalyst corresponds to Formula III-2B: in which: R 1 , R 2 , R 3 and R 4 independently of one another represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, in which L 1 represents: a halogen atom chosen from Cl, Br and I, or a monodentate ligand, said compound of Formula III-2B being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 , optionally one of the groups R 1 or R 2 can be linked to R 3 or R 4 and together represents a bidentate group comprising two N-heterocyclic carbene groups.

[0267] According to a particular embodiment, the invention relates to the preparation process as defined above, in which the catalyst corresponds to Formula III-3B: in which: R 1 , R 2 , R 3 and R 4 independently of each other represent a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, and C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, said compound of Formula III-3B being able to be linked to a support, in particular a polymer or silica, by at least one of the groups R 1 , R 2 , R 3 or R 4 , optionally one of the groups R 1 or R 2 can be linked to R 3 or R 4 and together represents a bidentate group comprising two N-heterocyclic carbene groups.

[0268] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the catalyst corresponds to Formula IV-B: in which: R 1 and R 2 represent, independently of each other, a group chosen from: linear or branched C 1 to C 10 alkyl, C 3 to C 10 cycloalkyl, C 6 to C 20 aryl or C 3 to C 20 heteroaryl, C 7 to C 20 alkyl-aryl or C 4 to C 20 alkyl-heteroaryl, L 1< and L 2< represent a halogen atom chosen from Cl, Br and I. Other settings

[0269] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the promoter is chosen from: tetrabutylammonium iodide (Bu 4 NI), sodium iodide (Nal) and potassium iodide (KI), the promoter being in particular tetrabutylammonium iodide.

[0270] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the solvent is chosen from: acetonitrile, toluene, 1,4-dioxane, tetrahydrofuran, ethanol, methanol and ethyl acetate, the solvent being in particular acetonitrile or tetrahydrofuran.

[0271] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the oxidant is oxygen or air, the oxygen being used at a rate of 0.5 to 2.5 MPa (5 to 25 bars).

[0272] Advantageously, oxygen is used at a rate of 1.5 MPa for the oxalate preparation process.

[0273] Advantageously, oxygen is used at a rate of 1.0 MPa for the process of preparing oxamides.

[0274] The expression MPa corresponds to 10 6< Pascal and is equivalent to 10 bars.

[0275] The expression "from 0.5 to 2.5 MPa" corresponds to the ranges: from 0.5 to 1.0 MPa; from 1.0 to 1.5 MPa; from 1.5 to 2.0 MPa; from 2.0 to 2.5 MPa.

[0276] According to a particular embodiment, the invention relates to a preparation process as defined above, in which carbon monoxide is used at a rate of 1.0 to 10.0 MPa (10 to 100 bars), in particular at 6.5 MPa (65 bars).

[0277] The expression "from 1.0 to 10.0 MPa" corresponds to the ranges: from 1.0 to 1.5 MPa; from 1.5 to 2.0 MPa; from 2.0 to 2.5 MPa; from 2.5 to 3.0 MPa; from 3.0 to 3.5 MPa; from 3.5 to 4.0 MPa; from 4.0 to 4.5 MPa; from 4.5 to 5.0 MPa; from 5.0 to 5.5 MPa; from 5.5 to 6.0 MPa; from 6.0 to 6.5 MPa; from 6.5 to 7.0 MPa; from 7.0 to 7.5 MPa; from 7.5 to 8.0 MPa; from 8.0 to 8.5 MPa; from 8.5 to 9.0 MPa; from 9.0 to 9.5 MPa; from 9.5 to 10 MPa.

[0278] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the carbon monoxide / oxygen pressure ratio used is from 3 to 10, in particular approximately 4.

[0279] The expression "from 3 to 10" corresponds to the scales: from 3 to 4; from 4 to 5; from 5 to 6; from 6 to 7; from 7 to 8; from 8 to 9; from 9 to 10.

[0280] Advantageously, the CO / O 2 pressure ratio is approximately 4 for the oxalate preparation process.

[0281] Advantageously, the CO / O 2 pressure ratio is approximately 6.5 for the oxamide preparation process.

[0282] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the catalyst is used in a proportion of 0.001 to 10 mol% relative to the alcohol or the amine.

[0283] The expression "from 0.001 to 10%" corresponds to the ranges: from 0.001 to 0.005%; from 0.005 to 0.01%; from 0.01 to 0.05%; from 0.05 to 0.1%; from 0.1 to 0.15%; from 0.15 to 0.2%; from 0.2 to 0.5%; from 0.5 to 1%; from 1 to 2%; from 2 to 3%; from 3 to 4%; from 4 to 5%; from 5 to 6%; from 6 to 7%; from 7 to 8%; from 8 to 9%; from 9 to 10%.

[0284] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the promoter is used in an amount of 2 to 100 molar equivalents relative to the catalyst.

[0285] Advantageously, the promoter is used at a rate of 5 molar equivalents relative to the catalyst for the process of preparing oxalates.

[0286] Advantageously, the promoter is used at a rate of 62.5 molar equivalents relative to the catalyst for the process of preparing oxamides.

[0287] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the base is used in an amount of 2 to 150 molar equivalents relative to the catalyst.

[0288] Advantageously, the base is used at a rate of 5 molar equivalents relative to the catalyst for the process of preparing oxalates.

[0289] Advantageously, the base is used at a rate of 125 molar equivalents relative to the catalyst for the process of preparing oxamides.

[0290] According to a particular embodiment, the invention relates to a preparation process as defined above, of an oxalate compound or an oxamide compound comprising: a step A of bringing an alcohol or an amine into contact, respectively, with: ▪ carbon monoxide, in particular used at a rate of 1.0 to 10.0 MPa, in particular at 6.5 MPa, ▪ an oxidant, in particular oxygen or air, preferably oxygen used at a rate of 0.5 to 2.5 MPa, ▪ an M-NHC catalyst, in which M represents Pd or Pt and NHC represents a carbene group N -heterocyclic, comprising at least one atom M linked to at least one carbene ligand N -heterocyclic, and ▪ optionally a promoter, in particular chosen from: tetrabutylammonium iodide (Bu 4 NI), sodium iodide (Nal) and potassium iodide (KI), preferably tetrabutylammonium iodide, ▪ optionally a base, in particular chosen from potassium carbonate (K 2 CO 3 ), sodium carbonate (Na 2 CO 3 ), tert-potassium butoxide (KOtBu), potassium phosphate (K 3 PO 4 ) and triethylamine (Et 3 N), ▪ optionally a solvent, in particular acetonitrile, toluene, 1,4-dioxane, tetrahydrofuran, ethanol, methanol and ethyl acetate, preferably acetonitrile and tetrahydrofuran, to obtain a reaction medium, optionally a step B of heating said reaction medium, to obtain the oxalate compound, or the oxamide compound.

[0291] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the process further comprises, after step B of heating, a step C of filtration of the reaction medium to obtain a recovered catalyst, and a filtrate free of catalyst, said catalyst being a supported catalyst as defined above.

[0292] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the catalyst used in contacting step A is a catalyst recovered at the end of a filtration step C.

[0293] Advantageously, the catalyst recovered after the process of the invention is not degraded and is stable, and it can be reused in another catalytic reaction process. Thus it is possible to repeat the process according to the invention with the same recovered catalyst. According to a particular embodiment, the invention relates to a process for the preparation as defined above, of an oxalate compound or an oxamide compound, in which the catalyst is stable at the end of the reaction and can be reused in another catalytic reaction process.

[0294] According to a particular embodiment, the invention relates to a preparation process as defined above, in which steps A, B and C are repeated at least 5 times, without substantial loss of the catalytic activity of the catalyst.

[0295] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the process is carried out in continuous flow, the catalyst being a supported catalyst as defined above.

[0296] According to a particular embodiment, the invention relates to a process for preparing oxalates or oxamides as defined above, carried out in continuous flow, wherein the catalyst is a supported catalyst introduced into a column or cartridge, or wherein the catalyst is suspended in the reaction mixture.

[0297] As a non-limiting example, the continuous flow process is carried out in a reactor of the following type: a continuously stirred tank reactor (CSTR), a flow reactor or tubular reactor, a fixed or packed bed reactor.

[0298] Without limitation, the method according to the invention can be implemented in a flow chemistry apparatus, for example in commercial reactors such as "H-Cube Pro ®<" or "Phoenix ®<" from the company ThalesNano INC. (7 Zahony Street, Graphisoft Park, Building D, H-1031 Budapest, Hungary) or such as the "E-Series" or "R-Series flow chemistry systems" reactors from the company Vapourtec Ltd (Unit 21 / Park Farm Business Centre / Fornham Pk, Bury Saint Edmunds IP28 6TS, United Kingdom).

[0299] Advantageously, the continuous flow process is carried out at a temperature of 25°C to 200°C. Advantageously, the continuous flow process is carried out at a pressure of 0.1 MPa to 4 MPa. The expression “0.1 to 4 MPa” corresponds to the following ranges: from 0.1 to 0.5 MPa; from 0.5 to 1.0 MPa; from 1.0 to 1.5 MPa; from 1.5 to 2.0 MPa; from 2.0 to 2.5 MPa; from 2.5 to 3.0 MPa; from 3.0 to 3.5 MPa; from 3.5 to 4.0 MPa.

[0300] According to a particular embodiment, the continuous flow process is carried out in a reactor in which the gases represent 10 to 90% of the volume of the reactor.

[0301] The expression "10 to 90%" corresponds to the following ranges: 10 to 20%; 20 to 30%; 30 to 40%; 40 to 50%; 50 to 60%; 60 to 70%; 70 to 80%; 80 to 90%.

[0302] According to a particular embodiment, the continuous flow process is carried out by means allowing a contact time between the reagents of 1 second to 2 hours, in particular of 1 second to 2 minutes.

[0303] The expression "1 second to 2 hours" corresponds to the ranges: from 1 to 15 seconds; from 15 to 30 seconds; from 30 seconds to 1 minute; from 1 to 2 minutes; from 2 to 15 minutes; from 15 to 30 minutes; from 30 minutes to 1 hour; from 1 to 2 hours.

[0304] According to a particular embodiment, the continuous flow process comprises means for introducing into the reactor the flow of CO in contact with the substrate (the alcohol or the amine) and the flow of oxygen or air individually or as a mixture.

[0305] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the oxalate product, or the oxamide product, is isolated in the absence of carbonate products or urea products respectively, the oxalate / carbonate ratio being greater than 98%, the oxamide / urea ratio being greater than 98%.

[0306] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the oxalate product is isolated in the absence of carbonate products, the oxalate / carbonate ratio being greater than 98%.

[0307] According to a particular embodiment, the invention relates to a preparation process as defined above, in which the oxamide product is isolated in the absence of urea products, the oxamide / urea ratio being greater than 98%.

[0308] As non-limiting examples, the oxalate product or the oxamide product may be isolated by distillation or by extraction and recrystallization.

[0309] According to a particular embodiment, the invention relates to a preparation process as defined above, of an oxalate compound or an oxamide compound, in which the yield obtained is greater than 100 mmol of the oxalate compound or of the oxamide compound per mmol of Pd.

[0310] According to a particular embodiment, the invention relates to a preparation process as defined above, of an oxalate compound, in which the yield obtained is greater than 100 mmol of the oxalate compound per mmol of Pd.

[0311] According to a particular embodiment, the invention relates to a preparation process as defined above, of an oxamide compound, in which the yield obtained is greater than 200 mmol of the oxamide compound per mmol of Pd.

[0312] Advantageously, the process for preparing oxamides according to the invention makes it possible to achieve yields of more than 90%, in particular of the order of 97%.

[0313] The yields of the process for preparing oxalates or oxamides according to the invention can be described in terms of “Number of Catalytic Cycles (NCC)”

[0314] In particular, the catalytic activity under given conditions of temperature, pressure and concentrations of solutes and time of the process for preparing oxalates or oxamides according to the invention can be described in terms of NCC.

[0315] The “Number of Catalytic Cycles (NCC)” is defined as the ratio between the number of moles of product formed (n prod ) and the number of moles of metal (Pd or Pt) of the catalyst (n cat ): NCC = n prod n cat

[0316] Unlike the "Turnover Number (TON)" which represents the maximum number of catalytic cycles that a catalyst can reach before its total and irreversible degradation, the Catalytic Cycle Number represents a total number of catalytic cycles carried out by the catalyst under given reaction conditions. At the end of the reaction, the catalyst used would not necessarily be degraded and could therefore be reused. Thus the NCC is not a measure of the lifetime of a catalyst, but allows to measure the productivity of the catalyst under given conditions of the catalyzed reaction.

[0317] According to a particular embodiment, the invention relates to a preparation process as defined above, of an oxalate compound, in which the NCC obtained is greater than 100. According to a particular embodiment, the invention relates to a preparation process as defined above, of an oxamide compound, in which the NCC is greater than 200.

[0318] According to a particular embodiment, the invention relates to a process for the preparation as defined above, of an oxalate compound or an oxamide compound, in which the selectivity towards the oxalate product, or the oxamide product, is greater than 70%, in particular approximately 80%.

[0319] According to a particular embodiment, the invention relates to a process for the preparation as defined above, of an oxalate compound in which the selectivity towards the oxalate product is greater than 75%, in particular approximately 80%.

[0320] According to a particular embodiment, the invention relates to a process for the preparation as defined above of an oxamide compound, in which the selectivity towards the oxamide product is greater than 95%, in particular approximately 98%.

[0321] The following examples illustrate the invention, without limiting its scope. EXAMPLES Example 1: Catalysts

[0322]

[0323] PEPPSI™<-IPr catalyst can be commercially obtained from Sigma Aldrich.

[0324] The catalysts [(IPr)Pd(acac)Cl], [(IMes)Pd(acac)Cl] were prepared according to the literature described in N. Marion et al. (Adv. Synth. Catal. 2007, 349, 2380-2384).

[0325] The 1-(mesityl)imidazolium-loaded polymeric support (PS-IMes-HCl), was prepared according to the literature described in D.-H. Lee, et al. (Org. Lett. 2008, 10, 1609-1612).

[0326] The amount of imidazolium on the imidazolium-loaded polymer support (PS-IMes-HCl) was determined by evaluating the nitrogen content N by elemental analysis (N 0.89%, i.e. a catalyst amount of: 0.32 mmol / g).

[0327] The support (PS-IMes-HCl) is used for the preparation of the catalyst [(PS-IMes)Pd(acac)Cl] described in Example 2. Example 2 - Preparation of the catalyst [(PS-IMes)Pd(acac)Cl]

[0328] In a flask equipped with a magnetic stir bar and a condenser, Pd(acac) 2 (456 mg, 1.5 mmol), an imidazolium-loaded polymer support (PS-IMes-HCl) (2 g, 0.32 mmol / g), and 1,4-dioxane (30 mL) were introduced, and the formed reaction mixture was heated at 100 °C for 16 h. Then, the reaction mixture was cooled to room temperature, filtered, and the polymer support was washed vigorously with distilled water (5 x 10 mL), methanol (5 x 10 mL), and dried under reduced pressure to obtain [(PS-IMes)Pd(acac)Cl] (2.1 g).

[0329] The amount of Pd loaded on the polymer support was determined using ICP-AES analysis. The polymer-supported palladium-N-heterocyclic complex (50 mg) was treated with a mixture (25 mL) of hydrochloric acid and nitric acid (1:1, v / v) at room temperature for 30 min. The orange solution formed was filtered and washed with distilled water. The filtrate and the washing solution were combined to determine the amount of Pd by inductively coupled plasma atomic emission spectrometry (ICP-AES). The calculated amount of Pd was evaluated to be 0.29 mmol / g of support. Example 3: Representative procedure for comparative tests with Pd-phosphine catalysts Test A:

[0330] In a general procedure, a 450 mL Parr autoclave equipped with a stirring bar was charged with palladium(II) acetylacetonate (91.3 mg, 0.3 mmol), triphenylphosphine (236.1 mg, 0.9 mmol), tetrabutylammonium iodide (0.5 g, 1.5 mmol), triethylamine (0.2 mL, 1.5 mmol), acetonitrile (100 mL), and absolute ethanol (50 mL). The reactor was sealed, the mixture was purged three times with nitrogen (5 bar), then twice with oxygen (5 bar). The autoclave was then pressurized with 15 bar of oxygen and then 65 bar of carbon monoxide to obtain a total pressure of 80 bar; and the reaction medium was stirred at 90°C for 14 h. The autoclave was then allowed to cool to room temperature before being slowly depressurized and purged three times with nitrogen (5 bar).The reactor contents were transferred to a round-bottom flask and excess ethanol and solvent were removed by rotary evaporator and diethyl oxalate DEO (9.3 g) was recovered by vacuum distillation (boiling point = 120 °C / 30-15 mbar).

[0331] For reactions with alcohols, the results are indicated in terms of mass of oxalate product obtained and described in number of catalytic cycles NCC as defined above. Test B

[0332] Test B was carried out under the same operating conditions as Test A but in the absence of tetrabutylammonium iodide. Traces of diethyl oxalate were observed by quantitative analysis by gas chromatography. Test C

[0333] Test C was carried out under the same operating conditions as Test A but in the absence of triethylamine. Traces of diethyl oxalate were observed by quantitative analysis by gas chromatography.

[0334] Table 1 reports the operating conditions and results (obtained mass of oxalate and NCC) of the tests carried out with a palladium-phosphine catalyst. Table 1: Operating conditions of the tests carried out with a palladium-phosphine catalyst and the yield results (obtained mass of oxalate and NCC) Ex n (EtOH), mmol [Pd]cat, mol% n For Figure 4 NI, mol% base, mol% solvent, ml O2 / CO, bar T, °C Duration, h m (DEO) g NCC A 856 Pd(acac) 2 : PPh 3 = 1:3 0.04 0.18 NEt 3, 0.18 CH 3 CN, 100 15 / 65 90 14 9,3 212 B 856 Pd(acac) 2 : PPh 3 = 1:3 0.04 - NEt 3, 0.18 CH 3 CN, 100 15 / 65 90 14 traces - C 856 Pd(acac) 2 : PPh 3 = 1:3 0.04 0.18 - CH 3 CN, 100 15 / 65 90 14 traces - Example 4: Representative procedure for the catalytic oxidative carbonylation of aliphatic alcohols to oxalates using homogeneous palladium catalysts

[0335] In a general procedure, a 450 mL Parr autoclave equipped with a stir bar was charged with homogeneous Pd-NHC complex (0.3 mmol), tetrabutylammonium iodide (0.5 g, 1.5 mmol), triethylamine (0.2 mL, 1.5 mmol), acetonitrile (100 mL), and aliphatic alcohol (50 mL). The reactor was sealed, the mixture was purged three times with nitrogen (5 bar), then twice with oxygen (5 bar). The autoclave was then pressurized with 15 bar of oxygen followed by 65 bar of carbon monoxide to bring the total pressure to 80 bar; and the reaction mixture was stirred at 90 °C for 14 h. The autoclave was then allowed to cool to room temperature before being slowly depressurized and purged three times with nitrogen (5 bar).The reactor contents were transferred to a round bottom flask and excess aliphatic alcohol and solvent were removed by rotary evaporator and dialkyl oxalate (DEO) was recovered by vacuum distillation (boiling point = 120 °C / 50-15 mbar). The reported dialkyl oxalate yield was calculated on the isolated yield by mass and a Catalytic Cycle Number NCC was calculated as defined above.

[0336] Table 2 reports the operating conditions and the results (obtained mass of oxalate and NCC) of the tests carried out with a homogeneous Pd-NHC catalyst according to the invention. Table 2: Operating conditions of the tests carried out with a homogeneous Pd-NHC catalyst and the yield results (obtained mass of oxalate) and NCC. Ex n (EtOH), mmol [Pd]cat, mol% n For Figure 4 NI, mol% base, mol% solvent, ml O2 / CO, bar T, °C Duration, h m (DEO) g NCC 1 856 0.18 NEt 3, 0.18 CH 3 CN, 100 15 / 65 90 14 8 182 2 856 0.18 NEt 3, 0.18 CH 3 CN, 100 15 / 65 90 14 10 228 3 856 0.18 NEt 3, 0.18 CH 3 CN, 100 15 / 65 90 14 9,5 216 Example 5: Influence of promoter and base on the oxidative carbonylation reaction of alcohol

[0337] Test A1 - presence of water:Test A1 is carried out under the same operating conditions as test 1 in example 4 but in the presence of water (1 mol%). The reaction yield is equivalent to test 1 in example 4.

[0338] Test A2- without base And 3 N:

[0339] Test A3- without n Bu 4 NI:

[0340] Table 3 reports the operating conditions and the results (obtained mass of oxalate and NCC) of the tests carried out. Table 3 reports the operating conditions of the tests carried out with Pd-NHC and the results of yield (obtained mass of oxalate) and NCC. # n (EtOH), mmol [Pd]cat, mol% n For Figure 4 NI, mol% And 3 N, mol% CH 3 CN, ml O 2 / CO, Bar T, °C Duration, h m (DEO), g NCC 1 856 0.18 0.18 100 15 / 65 90 14 8 182 A1 856 0.18 0.18 100 et H 2 O (1 mol%) 15 / 65 90 14 7.8 178 A2 856 0.18 - 100 15 / 65 90 14 <1.0 - A3 856 - 0.18 100 15 / 65 90 14 <0.1 - Example 6: Representative Procedure for the Catalytic Oxidative Carbonylation of Aliphatic Alcohols to Oxalates Using a Heterogeneous Pd-NHC Catalyst According to the Invention

[0341] In a general procedure, a 450 mL Parr autoclave equipped with a stir bar was charged with heterogeneous Pd-NHC complex (1.2 g, 0.29 mmol Pd / g, 0.35 mmol Pd), tetrabutylammonium iodide (0.5 g, 1.5 mmol), triethylamine (0.2 mL, 1.5 mmol), acetonitrile (100 mL), and aliphatic alcohol (50 mL). The reactor was sealed, the reaction mixture was purged three times with nitrogen (5 bar), then twice with oxygen (5 bar). The autoclave was then pressurized with 15 bar of oxygen followed by 65 bar of carbon monoxide to bring the total pressure to 80 bar; and the reaction mixture was stirred at 90 °C for 14 h. The autoclave was then allowed to cool to room temperature before being slowly depressurized and purged three times with nitrogen (5 bar). The reactor contents were filtered to recover the catalyst.The filtrate was transferred to a round-bottom flask and excess aliphatic alcohol and solvent were removed by rotary evaporator and the dialkyl oxalate was recovered by vacuum distillation (boiling point = 120 °C / 50-15 mbar).

[0342] The reported dialkyl oxalate yield was calculated on the isolated mass yield and a Catalytic Cycle Number NCC was calculated as defined above.

[0343] Table 4 reports the operating conditions and results (obtained mass of oxalate and NCC) of a test carried out with a heterogeneous Pd-NHC catalyst according to the invention. Table 4: Operating conditions of the test with the catalyst [(PS-IMes)Pd(acac)Cl] and the yield results (obtained mass of oxalate) and NCC. # n (EtOH), mmol [Pd]cat, mol%, n For Figure 4 NI, mol% base, mol % solvent, ml O 2 / CO, bar T, °C Duration, h m (DEO) g NCC 4 856 0.18 NEt 3 , 0.18 CH 3 CN, 100 15 / 65 90 14 8 182 Example 7: Representative procedure for the recyclability study of the complex [(PS-IMes)Pd(acac)Cl]

[0344] The reaction was carried out as mentioned in Example 6 above in a typical experimental procedure. However, after the reaction was completed, vented and purged with nitrogen, the catalyst was filtered and washed vigorously with distilled water (5 × 10 mL) and methanol (5 × 10 mL) to remove any traces of product or reactants present. The filtered catalyst was then dried under reduced pressure before the next recycling. The dried catalyst was then used for a catalyst recyclability experiment, and it was observed that the recovered catalyst could be reused at least up to five consecutive cycles giving a good to appreciable yield of the desired product.

[0345] The recyclability study demonstrates a possible application of the heterogeneous catalyst in a continuous flow reactor.

[0346] Table 5 reports the conditions and results of the recyclability tests of the [(PS-IMes)Pd(acac)Cl] complex. Table 5: Recyclability test conditions of the [(PS-IMes)Pd(acac)Cl] complex and performance results. exp Cycle N n[Pd], mmol Carbonylation conditions m (DEO), g NCC Total NCC C1 1 0.3 856 mmol (50 mL) EtOH; 1.5 mmol NEt 3 ; 1.5 mmol n Bu 4 NI ; CH 3 CN 100 mL ; CO / O 2 = 65 / 15, 90 °C, 14h 8 182 1096 C2 2 0.24 6 171 C3 3 0.198 6 207 C4 4 0.15 6 274 C5 5 0.1125 4.3 262

[0347] The results of these manual recycling experiments demonstrate that the Pd-NHC catalyst is stable. Indeed, the recovered catalyst is not or only slightly sensitive to water and oxygen. In addition, there is no loss of NCC efficiency during catalyst recycling in several successive catalytic reactions.

[0348] By switching to flow, manual recycling is no longer necessary, preventing catalyst loss during washes, and efficiency should be maintained during the reaction since reaction conditions will be stable. Oxamide Example 8: Representative procedure for the catalytic oxidative carbonylation of amines to oxamides

[0349] PEPPSI™<-IPr, tetrabutylammonium iodide, base, solvent, and piperidine were added to a 450 mL Parr autoclave equipped with a stir bar. The reactor was sealed, the mixture was purged three times with nitrogen (5 bar), then twice with oxygen (5 bar). The autoclave was then pressurized with 10 bar of oxygen and then 65 bar of carbon monoxide to a total pressure of 75 bar; and the reaction mixture was stirred at room temperature for 18 h. Then, the pressure was carefully released, and the autoclave was purged three times with nitrogen (5 bar). The contents of the reactor were transferred to a round-bottomed flask, and the volatiles were removed under reduced pressure. Then the residue was extracted into toluene, filtered through silica gel (2-3 cm) and the solution was evaporated to dryness to give 1,1'-oxalyl dipiperidine as an off-white powder.

[0350] The yield of oxamide is indicated in mass of isolated product and a Catalytic Cycle Number NCC was calculated as defined above. Example 9: Influence of solvent on the catalytic oxidative carbonylation of amine to oxamide. M1-THF test

[0351] PEPPSI™<-IPr catalyst (62.5 mg, 0.092 mmol), tetrabutylammonium iodide (2.12 g, 5.75 mmol), potassium carbonate (1.59 g, 11.5 mmol), THF (200 ml), and piperidine (22.7 ml, 230 mmol) were added to a 450 ml Parr autoclave equipped with a stirring bar. The reactor was sealed, the mixture was purged three times with nitrogen (5 bar), then twice with oxygen (5 bar). The autoclave was then pressurized with 10 bar of oxygen and then 65 bar of carbon monoxide to obtain a total pressure of 75 bar; and the reaction mixture was stirred at room temperature for 18 h. After this time, the pressure was carefully released and the autoclave was purged three times with nitrogen (5 bar). The contents of the reactor were transferred to a round-bottomed flask and the volatiles were removed under reduced pressure.Then the residue was extracted into toluene, filtered through silica gel (2-3 cm) and the solution was evaporated to dryness to give 1,1'-oxalyl dipiperidine as an off-white powder (9.5 g; 42 mmol). Test M2 - Acetonitrile

[0352] Test M2 was performed under the same conditions as test M1, except that 200 mL of acetonitrile was used instead of THF.

[0353] Result: 9.5 g of oxamide 2 were isolated. M3 test - solvent-free

[0354] Test M3 was carried out under the same conditions as test M1, in the absence of solvent. Result: 4.2 g of oxamide 2 were isolated.

[0355] Table 6 reports the conditions on the nature and presence of the solvent and the results of the catalytic oxidative carbonylation tests of amines to oxamides with homogeneous Pd-NHC catalysts according to the invention. Table 6: Operating conditions with different solvents of the tests with piperidine with Pd-NHC catalysts and the yield results. Ex n (piperidine), mmol [Pd]cat, mol% n For Figure 4 NI, mol% base, mol% solvent, ml O 2 / CO, bar T, °C Duration, h Yield (oxamide) M1 230 2.5 K 2 CO 3 5 THF, 200 10 / 65 25 18 9.5 g NCC = 460 M2 230 2.5 K 2 CO 3 5 CH 3 CN, 200 10 / 65 25 18 9.5 g NCC = 460 M3 230 2.5 K 2 CO 3 5 - 10 / 65 25 18 4.2 g NCC = 203

[0356] The reaction occurs in the presence of both THF and CH 3 CN with the same efficiency as demonstrated by tests M1 and M2.

[0357] The reaction takes place in the absence of solvent as demonstrated by test M3.

[0358] Example 10: Influence of base on the catalytic oxidative carbonylation of amine to oxamide. M4 Test

[0359] Test M4 was carried out under the same conditions as test M1, except that the base used was triethylamine (5 mol %). M5 Test

[0360] Test M5 was carried out under the same conditions as test M1, without added base.

[0361] Table 7 reports the conditions on the nature and presence of the added base and the results of the catalytic oxidative carbonylation tests of amines to oxamides with homogeneous Pd-NHC catalysts according to the invention. Table 7: Operating conditions with different bases of tests with piperidine with Pd-NHC catalysts and the yield results. Ex n (piperidine), mmol [Pd]cat, mol% n For Figure 4 NI, mol% base, mol% solvent, ml O 2 / CO, bar T, °C Duration, h Yield (oxamide) M1 230 2.5 K 2 CO 3 5 THF, 200 10 / 65 25 18 9.5 g NCC = 460 M4 230 2.5 NEt 3 5 THF, 200 10 / 65 25 18 9.3 g NCC = 450 M5 230 2.5 - THF, 200 10 / 65 25 18 17.0 g NCC = 823

[0362] Organic and inorganic bases have comparable effects on the reaction as demonstrated by the results of M1 and M4.

[0363] The reaction is more efficient in the absence of an added base in the reaction mixture as demonstrated by test M5. Example 11: Use of catalyst [(PS-IMes)Pd(acac)Cl] for the catalytic oxidative carbonylation of amines to oxamides using heterogeneous catalyst Pd-NHC: M6 test

[0364] Into a 450 ml Parr autoclave equipped with a stirring bar were introduced catalyst [(PS-Imes)Pd(acac)Cl] (317 mg, 0.29 mmol Pd / g, 0.092 mmol Pd), tetrabutylammonium iodide (2.12 g, 5.75 mmol), THF (200 ml) and piperidine (22.7 ml, 230 mmol). The reactor was sealed, the mixture was purged three times with nitrogen (5 bar), then twice with oxygen (5 bar). The autoclave was then pressurized with 10 bar of oxygen and then 65 bar of carbon monoxide to obtain a total pressure of 75 bar; and the reaction mixture was stirred at room temperature for 18 h. Then, the pressure was carefully released and the autoclave was purged three times with nitrogen (5 bar). The reactor contents were filtered to recover the catalyst. The filtrate was transferred to a round-bottomed flask and the volatiles were removed under reduced pressure.Then the residue was extracted into toluene, filtered through silica gel (2-3 cm) and the solution was evaporated to dryness to give 1,1'-oxalyl dipiperidine as an off-white powder.

[0365] Table 8 reports the operating conditions of a test with a homogeneous catalyst and a test with a supported catalyst for catalytic oxidative carbonylation of amines, piperidine, to oxamide, 1,1'-oxalyl dipiperidine, and the yield results. Table 8: Operating conditions with a homogeneous catalyst and with a supported catalyst for oxidative carbonylation with piperidine and the yield results. Ex n (piperidine), mmol [Pd]cat, mol% n For Figure 4 NI, mol% base, mol% solvent, ml O 2 / CO, bar T, °C Duration, h Yield (oxamide) M5 230 2.5 - THF, 200 10 / 65 25 18 17.0 g NCC = 823 66% M6 230 2.5 - THF, 200 10 / 65 25 18 18.0 g NCC = 872 70% Example 12: Influence of the introduction of CO and O 2 M7 Test

[0366] Test M7 was carried out under the same conditions as test M5, except that after 18 hours of stirring at room temperature, the reactor was purged and pressurized a second time with 10 bars of oxygen and 65 bars of CO; and the reaction medium was stirred at room temperature for an additional 18 hours.

[0367] Table 9 shows the operating conditions. Table 9: Operating conditions on the influence of pressure and duration conditions. Ex n (piperidine), mmol [Pd]cat, mol% n For Figure 4 NI, mol% base, mol% solvent, ml O 2 / CO, bar T, °C Duration, H Yield (oxamide) M5 230 2.5 - THF, 200 10 / 65 25 18 17.0g NCC = 823 66% M7 230 2.5 - THF, 200 10 / 65 for 18h + 10 / 65 for 18h 25 36 25.0 g NCC = 1211 97%

[0368] Test M7 shows that re-pressurizing the reactor with additional CO and O2 during the reaction allows full efficiency to be achieved. Example 13: Representative procedure for the catalytic oxidative carbonylation of aliphatic alcohols to oxalates using Pt-NHC catalysts.

[0369] In a general procedure, a 450 mL Parr autoclave equipped with a stir bar is charged with homogeneous Pt-NHC complex (0.6 mmol), tetrabutylammonium iodide (1.1 g, 3.0 mmol), triethylamine (0.4 mL, 3.0 mmol), acetonitrile (100 mL), and aliphatic alcohol (50 mL). The reactor is sealed, the mixture is purged three times with nitrogen (5 bar), then twice with oxygen (5 bar). The autoclave is then pressurized with 15 bar of oxygen followed by 65 bar of carbon monoxide to bring the total pressure to 80 bar; and the reaction mixture is stirred at 90 °C for 14 h. The autoclave is then allowed to cool to room temperature before being slowly depressurized and purged three times with nitrogen (5 bar).The reactor contents are transferred to a round bottom flask and excess aliphatic alcohol and solvent are removed by rotary evaporator and dialkyl oxalate (DEO) is recovered by vacuum distillation (boiling point = 120 °C / 50-15 mbar). The reported dialkyl oxalate yield is calculated on the isolated yield by mass and a Catalytic Cycle Number NCC was calculated as defined above. Example 14: Representative procedure for the catalytic oxidative carbonylation of amines to oxamides using Pt-NHC catalysts:

[0370] Pt-NHC catalyst (1.0 mmol), tetrabutylammonium iodide (2.12 g, 5.75 mmol), THF (200 ml), and piperidine (22.7 ml, 230 mmol) were added to a 450 ml Parr autoclave equipped with a stirring bar. The reactor was sealed, the mixture was purged three times with nitrogen (5 bar), then twice with oxygen (5 bar). The autoclave was then pressurized with 10 bar of oxygen followed by 65 bar of carbon monoxide to obtain a total pressure of 75 bar; and the reaction mixture was stirred at 90 °C for 14 h. The autoclave was then allowed to cool to room temperature before being slowly depressurized and purged three times with nitrogen (5 bar). The contents of the reactor were transferred to a round-bottomed flask, and the volatiles were removed under reduced pressure. Then the residue was extracted into toluene, filtered through silica gel (2-3 cm) and the solution was evaporated to dryness to give 1,1'-oxalyl dipiperidine. Example 15: Synthesis of a Pd-NHC catalyst supported on silica gel (PdCl 2 NHC / Si) with the following formula:

[0371]

[0372] The catalyst was prepared according to the following steps: A) Synthesis of 1-methyl-3-(trimethoxysilylpropyl)-imidazolium chloride according to the following reaction scheme:

[0373]

[0374] In a flask equipped with a magnetic stir bar and a condenser, the mixture of N-methyl imidazole (freshly distilled) (10.3160 g, 0.1258 mol) and 3-chloropropyl trimethoxysilane (25 g, 0.1258 mol) was refluxed at 95 °C for 24 hours. After cooling to room temperature, the reaction mixture was washed with diethyl ether and dried under vacuum to obtain the desired product. B) Immobilization of 1-methyl-3-(trimethoxysilylpropyl)-imidazolium chloride on the surface of silica gel according to the following reaction scheme:

[0375]

[0376] To a solution of 1-methyl-3-(trimethoxysilylpropyl)-imidazolium chloride (0.70 g, 2.2 mmol) in toluene silica gel was added. The mixture was stirred at 105 °C for 12 hours. After cooling, the reaction mixture was filtered and washed with CH 2 Cl 2 (3 * 10 mL), and dried at 60 °C under vacuum to give the silica-supported ionic liquid (2.39 g). Elemental analysis showed the presence of 0.89 mmol of ligand on 1.0 g of support. C) Preparation of an NHC-Pd complex supported on silica gel according to the following reaction scheme

[0377]

[0378] To a solution of silica-supported ligand (1.0 g, 0.89 mmol) in THF (5 mL) was added Pd(OAc) 2 (101 mg, 0.45 mmol). The mixture was stirred for 4 h at 60 °C and then for an additional 30 min at 100 °C. The silica-supported NHC-Pd complex was filtered through a frit and washed with water and then with CH 2 Cl 2 (3 x 10 mL). Once washed, the catalyst was dried. ICP analysis showed the presence of 0.35 mmol of Pd on 1 g of support.

[0379] With an amount of 0.35 mmol of Pd on 1 g of support, a better complexation of palladium on this supported ligand is observed compared to the catalyst [(PS-IMes)Pd(acac)Cl] of example 2 which comprises an amount of 0.29 mmol / g. Example 16: Recyclability study of the PdCl 2 NHC / Si catalyst Protocol

[0380] In a general procedure, a 450 mL Parr autoclave equipped with a stirring bar was charged with heterogeneous Pd-NHC complex (1.0 g, 0.35 mmol Pd / g), tetrabutylammonium iodide (0.5 g, 1.5 mmol), triethylamine (0.2 mL, 1.5 mmol), acetonitrile (100 mL), and aliphatic alcohol (50 mL). The reactor was sealed, the reaction mixture was purged three times with nitrogen (5 bar), then twice with oxygen (5 bar). The autoclave was then pressurized with 15 bar of oxygen followed by 65 bar of carbon monoxide to bring the total pressure to 80 bar, and the reaction mixture was stirred at 90 °C for 14 h. The autoclave was then allowed to cool to room temperature before being slowly depressurized and purged three times with nitrogen (5 bar). The reactor contents were filtered to recover the catalyst.The filtrate was transferred to a round bottom flask and excess aliphatic alcohol and solvent were removed by rotary evaporation and the dialkyl oxalate was recovered by vacuum distillation (boiling point = 120 °C / 50-15 mbar). The reported yield of dialkyl oxalate was calculated on the isolated yield by mass and a Catalytic Cycle Number NCC was calculated as defined above.

[0381] Table 10 reports the conditions and results of the recyclability tests with the PdCl 2 NHC / Si catalyst. Table 10: Recyclability test conditions with PdCl 2 NHC / Si catalyst and yield and NCC results. Exp Cycle n[Pd], mmol Carbonylation conditions m(DEO), 8 NCC Total NCC A 1 0.35 856 mmol (50 mL) EtOH ; 1.5 mmol Net 3 ; 1.5 mmol n Bu 4 NI ; CH 3 CN 100 mL ;CO / O 2 = 65 / 15, 90 °C, 14h 11 215 561 B 2 0.3 8 182 C 3 0.25 6 164 Example 17: Preparation of the palladium catalyst with an NHC group supported with iodinated ligands, PdI 2 NHC / PS of the following formula:

[0382]

[0383] In a flask equipped with a magnetic stir bar and a condenser, PdCl 2 (266 mg, 1.5 mmol), imidazolium-loaded polymer support (PS-IMes-HCl) (1 g, 1.6 mmol / g), potassium iodide (1.2 g, 7.5 mmol), potassium carbonate (1.03 g, 7.5 mmol) and pyridine (7 mL) were introduced and the reaction mixture formed was heated at 80°C for 16 h. Then, the reaction mixture was cooled to room temperature, filtered and the polymer support was washed vigorously with distilled water (5 x 10 mL), methanol (5 x 10 mL) and dried under reduced pressure to obtain (1.6 g) of the desired product.

[0384] The amount of Pd loaded on the polymer support was determined using ICP-AES analysis. The palladium- NPolymer-supported heterocyclic phosphate (50 mg) was treated with a mixture (25 mL) of hydrochloric acid and nitric acid (1:1, v / v) at room temperature for 30 min. The orange solution formed was filtered and washed with distilled water. The filtrate and the washing solution were combined to determine the amount of Pd by inductively coupled plasma atomic emission spectrometry (ICP-AES). The amount of calculated Pd was estimated to be 0.9 mmol / g of support. Example 18: Carbonylation procedure without added iodine salt

[0385] The inventors have succeeded in avoiding the addition of iodine salt. Indeed, iodine is directly incorporated into the catalyst such as PdI 2 NHC / PS prepared in example 17 and makes it possible to maintain efficient reoxidation of the catalyst while avoiding having to manage the addition of additional iodine salt. Protocol

[0386] A 450 mL Parr autoclave equipped with a stir bar was charged with heterogeneous Pd-NHC complex (1.0 g, 0.35 mmol Pd / g), triethylamine (0.2 mL, 1.5 mmol), acetonitrile (100 mL), and ethanol (50 mL). The reactor was sealed, the reaction mixture was purged three times with nitrogen (5 bar), then twice with oxygen (5 bar). The autoclave was then pressurized with 15 bar of oxygen followed by 65 bar of carbon monoxide to bring the total pressure to 80 bar, and the reaction mixture was stirred at 90 °C for 14 h. The autoclave was cooled to room temperature before being slowly depressurized and purged three times with nitrogen (5 bar). The reactor contents were filtered to recover the catalyst. The filtrate was transferred to a round-bottomed flask and residual ethanol and acetonitrile were removed using a rotary evaporator.The purified dialkyl oxalate was recovered by vacuum distillation (boiling point = 120 °C / 50-15 mbar). The reported dialkyl oxalate yield was calculated on the isolated yield by mass and a Catalytic Cycle Number NCC was calculated as defined above.

[0387] Table 11 reports the operating conditions and the results obtained. Table 11: Operating conditions for carbonylation with the PdI 2 NHC / PS catalyst without adding an iodine salt as promoter and the yield and NCC results. React Cat Ethanol MeCN T, (°C) CO (Bar) O 2 (Bar) Time, (h) Quantity (g) NCC 1 PdI 2 NHC / PS 0.9 mmol (1g) 50 mL 100 mL 90 65 15 16 8,5 g 64 Example 19: Representative procedure for the catalytic oxidative carbonylation of amines to oxamides no added iodine salt

[0388] A 450 mL Parr autoclave equipped with a stir bar was charged with heterogeneous PdI 2 NHC / PS complex prepared according to Example 17 (1.0 g, 0.9 mmol Pd / g), THF (200 mL), and piperidine (22.7 mL, 230 mmol). The reactor was sealed, the mixture was purged three times with nitrogen (5 bar), then twice with oxygen (5 bar). The autoclave was then pressurized with 10 bar of oxygen followed by 65 bar of carbon monoxide to obtain a total pressure of 75 bar; and the reaction mixture was stirred at room temperature for 18 h. Then, the pressure was carefully released, and the autoclave was purged three times with nitrogen (5 bar). The reactor contents were filtered to recover the catalyst. The filtrate was transferred to a round-bottom flask and the volatiles were removed under reduced pressure.Then the residue was extracted into toluene, filtered through silica gel (2-3 cm) and the solution was evaporated to dryness to give 1,1'-oxalyl dipiperidine as an off-white powder.

Claims

1. Use of an M-NHC catalyst, in which M represents Pd or Pt and NHC represents an N-heterocyclic carbene group, comprising at least one M atom linked to at least one N-heterocyclic carbene ligand, in the implementation of a method for selectively preparing oxalates or oxamides, from carbon monoxide, an oxidant, in particular molecular oxygen or air, and an alcohol or an amine respectively, optionally in the presence of a promoter.

2. Use according to claim 1, in which the catalyst corresponds to Formula II : in which : R1 and R2 independently of one another represent a group chosen from : • C1 to C10 linear or branched alkyl, • C3 to C10 cycloalkyl, • C6 to C20 aryl or C3 to C20 heteroaryl, and • C7 to C20 alkyl-aryl or C4 to C20 alkyl-heteroaryl, L1 represents a halogen atom chosen from CI, Br and I, and • either L2 and L3 represent a bidentate ligand, in particular chosen from acetylacetonate (acac), allyl, cinnamyl and acetate, preferably acetylacetonate, • or L2 represents a halogen atom chosen from CI, Br and I, and L3 represents a monodentate ligand, in particular selected from: pyridine, 3-chloropyridine, acetonitrile, triethylamine, or a phosphine-based ligand, in particular triphenylphosphine, preferably 3-chloropyridine, said compound of Formula II may be bonded to a support, in particular a polymer or silica, by at least one of the groups R1 or R2.

3. Use according to claim 2, in which the catalyst corresponds to Formula II , in which : L1 represents an iodine atom, and • either L2 and L3 are linked and together represent a bidentate ligand, • or L2 represents a halogen atom chosen from Cl, Br and I and L3 represents a monodentate ligand.

4. Use according to one of claims 2 or 3, in which the catalyst corresponds to Formula II , in which : L1 and L2 each represent an iodine atom and L3 represents a monodentate ligand.

5. Use according to claim 1, in which the catalyst corresponds to Formula III : in which : R1, R2, R3 and R4 independently of one another represent a group selected from : • C1 to C10 linear or branched alkyl • C3 to C10 cycloalkyl • C6 to C20 aryl or C3 to C20 heteroaryl, and • C7 to C20 alkyl-aryl or C4 to C20 alkyl-heteroaryl, either L1 and L2 represent each other independently: - a halogen atom selected from CI, Br and I, or - a monodentate ligand, or L1 and L2 are linked and represent a bidentate ligand, said compound of Formula II can be bonded to a support in particular a polymer or silica, by at least one of the groups R1, R2, R3 or R4, optionally one of the groups R1 or R2 can be linked to R3 or R4 and together represent a bidentate group comprising two N-heterocyclic carbene groups.

6. Use according to claim 5, in which the catalyst corresponds to Formula III in which at least one of the groups L1 and L2 represents an iodine atom.

7. Use according to one of claims 5 or 6, in which the catalyst corresponds to Formula III in which the groups L1 and L2 each represent an iodine atom.

8. Use according to claim 1, in which the catalyst corresponds to Formula IV : in which : R1 and R2 independently of one another represent a group chosen from : • C1 to C10 linear or branched alkyl, • C3 to C10 cycloalkyl, • C6 to C20 aryl or C3 to C20 heteroaryl, and • C7 to C20 alkyl-aryl or C4 to C20 alkyl-heteroaryl, L1 and L2 represent a halogen atom chosen from CI, Br and I.

9. Use according to one of claims 1 or 2, in which the catalyst corresponds to Formula II-1 or Formula II-2 or Formula II-3 : in which : R1 and R2 independently of one another represent a group chosen from : • C1 to C10 linear or branched alkyl, • C3 to C10 cycloalkyl, • C6 to C20 aryl or C3 to C20 heteroaryl, and • C7 to C20 alkyl-aryl or C4 to C20 alkyl-heteroaryl, said catalyst may be bonded to a support, in particular a polymer or silica, by at least one of the groups R1 or R2 , in particular said catalyst is selected from : or in which the catalyst, bound to a support (PS), is chosen from:

10. Use according to one of claims 1 or 5, wherein the catalyst corresponds to Formula III-1 : in which : R1, R2, R3 and R4 independently of one another represent a group selected from : • C1 to C10 linear or branched alkyl, • C3 to C10 cycloalkyl, • C6 to C20 aryl or C3 to C20 heteroaryl, and • C7 to C20 alkyl-aryl or C4 to C20 alkyl-heteroaryl, said compound of Formula III-1 may be bonded to a support, in particular a polymer or silica, by at least one of the groups R1 , R2 , R3 or R4, optionally one of the groups R1 or R2 can be linked to R3 or R4 and together represent a bidentate group comprising two N-heterocyclic carbene groups, in particular said supported catalyst of Formula III-1 is selected from :

11. Use according to claim 1 of a Pt-NHC catalyst in a method for selectively preparing oxalates or oxamides from carbon monoxide, an oxidant, in particular molecular oxygen or air, and an alcohol or an amine respectively.

12. A method for preparing an oxalate compound or an oxamide compound comprising : • a step A of contacting an alcohol or an amine, respectively, with : ▪ carbon monoxide, in particular used from 1.0 to 10.0 MPa, in particular 6.5 MPa, ▪ an oxidant, in particular oxygen or air, preferably oxygen used at 0.5 to 2.5 MPa, ▪ an M-NHC catalyst, in which M represents Pd or Pt and NHC represents an N-heterocyclic carbene group, comprising at least one M atom linked to at least one N-heterocyclic carbene ligand, and ▪ optionally a promoter, in particular selected from: tetrabutylammonium iodide (Bu4NI), sodium iodide (Nal) and potassium iodide (KI), preferably tetrabutylammonium iodide, ▪ optionally a base, in particular selected from potassium carbonate (K2CO3), sodium carbonate (Na2CO3), potassium tert-butylate (KotBu), potassium phosphate (K3PO4) and triethylamine (Et3N), ▪ optionally a solvent, in particular acetonitrile, toluene, 1,4-dioxane, tetrahydrofuran, ethanol, methanol and ethyl acetate, preferably acetonitrile and tetrahydrofuran, to obtain a reaction medium, • optionally a step B of heating said reaction medium, to obtain the oxalate compound or the oxamide compound, in particular comprising : • a step A of contacting an alcohol or an amine, respectively, with : ▪ carbon monoxide, ▪ oxygen or air, ▪ a Pd-NHC catalyst, ▪ optionally a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, • optionally a step B of heating said reaction medium, to obtain the oxalate compound or the oxamide compound.

13. A method for the preparation according to claim 12 of an oxalate compound comprising : • a step A of contacting an alcohol with : ▪ carbon monoxide, ▪ oxygen or air, ▪ a Pd-NHC catalyst, and ▪ optionally a promoter, ▪ optionally a base, ▪ optionally a solvent, to obtain a reaction medium, • a step B of heating said reaction medium, to obtain the oxalate compound, in particular at a temperature from 25 to 200°C, in particular from 60 to 110°C, preferably about 90°C.

14. A method for the preparation according to any of claims 12 or 13, of an oxalate compound of Formula 2, wherein step A comprises contacting an alcohol of Formula 1 : in which Ra represents a group chosen from : • C1 to C10 linear or branched alkyl, and • C3 to C10 cycloalkyl in particular the alcohol is chosen from methanol, ethanol and isopropanol.

15. A method for the preparation according to claim 12 of an oxamide compound comprising : • a step A of contacting an amine with : ▪ carbon monoxide, ▪ oxygen or air, ▪ optionally a promoter, ▪ a Pd-NHC type catalyst, • a solvent, and ▪ optionally a base, in particular selected from K2CO3 or Et3N, to obtain a reaction medium comprising the oxamide, in particular for the preparation of an oxamide compound of Formula 4, wherein step A comprises contacting an amine of Formula 3 : in which Rb and Rc independently of one another represent : • a hydrogen atom, • C1 to C20 linear or branched alkyl group • C2 to C20 linear or branched alkenyl group • C1 to C20 linear or branched heteroalkyl group, the heteroatom being in particular O or N, at least one of the groups Rb or Rc being other than hydrogen, Rb and Rc can form a cycle, in particular the amine is chosen from: diethylamine, piperidine, pyrrolidine and morpholine.