Method for producing ammoniacal nitrogen

Abstract

The present invention relates to a process for the production of ammoniacal nitrogen, which comprises carrying out dinitrogen reduction in the presence of a compound of formula (I) containing at least one element of group 13 of the periodic table and a reducing agent, and to the use of a compound of formula (I) for the dinitrogen reduction.

Description

[Technical field]

[0001] The present invention relates to a method for producing ammoniacal nitrogen by carrying out dinitrogen reduction in the presence of compound (I) containing at least one element of group 13 of the periodic table and a reducing agent, and to the use of said compound (I) for dinitrogen reduction. [Background technology]

[0002] Nitrogen (N) plays an essential role in the composition of living organisms. It is one of the main components of proteins, including amino acids, enzymes, and nucleic acids, which make up DNA and RNA. It is also an essential nutrient for crop growth. However, while nitrogen is very abundant on the Earth's surface (there is more nitrogen than combined carbon, hydrogen, and phosphorus throughout the biosphere, hydrosphere, and atmosphere), it exists primarily in the form of dinitrogen (N2), a very stable gas. Humans can only benefit to a small extent from this abundance. Only microorganisms, such as rhizobia involved in symbiotic nitrogen fixation by legume plants, can utilize this form of nitrogen and convert it into ammoniacal nitrogen and then organic nitrogen. This organic nitrogen can then be utilized by other organisms and converted into other forms of reactive nitrogen.

[0003] Since the Industrial Revolution at the end of the 19th century, two major processes have dramatically changed the reactive nitrogen landscape to meet the growing demand for reactive nitrogen for food production. Firstly, the increasing use of fossil fuels (coal, oil, natural gas, etc.) for energy production, transportation, industrial and domestic activities has greatly increased the amount of nitric oxide present in the environment. The second most important process is the Haber-Bosch process. This process allows the synthesis of ammonia on an industrial scale from dinitrogen and dihydrogen (H2) in the presence of solid, especially iron-based, catalysts. Since the end of the 20th century, this process has produced about 200 million tons / year of ammonia NH3 on a global scale, which is more than symbiotic nitrogen fixation and is still used today. However, the Haber-Bosch process has the following disadvantages: That is, the process is carried out at high pressure and temperature, for example, pressures between 100 bar and 300 bar, and temperatures between 300°C and 550°C, which makes the process energy intensive, requires a centralized and highly secure production, and incurs high operating and transportation costs. Moreover, such a process generates a very large amount of carbon dioxide (about 1.5% of the total CO2 production), which causes environmental problems, and the yield of the process is still low.

[0004] Milder methods of ammonia production, such as electrochemical reduction, are being investigated. Electrochemical reduction involves applying an electric potential to an electrocatalyst based on a noble metal, such as gold or ruthenium. However, the yields remain low and the raw materials are scarce and very expensive. Other methods have been developed using organometallic complexes or compounds of transition metals. In particular, US Patent 6,037,459 discloses a method comprising contacting nitrogen with a compound corresponding to the formula M(NR1R2)3, where M is a transition metal (e.g., molybdenum) and R1R2 is selected from tertiary alkyl, phenyl and substituted phenyl groups, to produce a metal complex containing a nitrido ligand, and reducing the metal complex in the presence of a hydrogen source to produce ammonia. The method is carried out under ambient temperature and pressure conditions. However, US Patent 6,037,459 describes low yields and does not disclose any demonstration of ammonia production. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent No. 6037459 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to eliminate the shortcomings of the prior art, and in particular to provide a method for producing ammoniacal nitrogen which is simple, economical, can be industrialized, uses abundant raw materials, is recyclable, and can reduce carbon dioxide emissions. [Means for solving the problem]

[0007] A first aspect of the present invention is a method for producing ammoniacal nitrogen, comprising at least the following steps: i) Formula (I): R 1 R 2contacting a composition comprising a compound corresponding to MY(I), a reducing agent, and an organic solvent with dinitrogen (N2); In the formula (I), M is an element of group 13 of the periodic table, preferably selected from boron, aluminum and mixtures thereof; - R 1 and R 2 are the same or different and are selected from alkyl groups, aryl groups, aryl-alkyl groups, -OR groups, and -SR groups, where R is an alkyl group, an aryl group, or an aryl-alkyl group; - Y is halogen -X, -OR 3 Group, -SR 3 R is selected from the group consisting of an aryl group, a triflate group, a mesylate group, and a triflimidate group; 3 is an alkyl group, an aryl group, or an aryl-alkyl group; and ii) a hydrolysis step in an acidic medium.

[0008] The process of the present invention is simple, easy to carry out, economical and allows to obtain ammoniacal nitrogen under relatively mild conditions. In particular, by using the compound of formula (I) defined above, the triple bond of dinitrogen can be activated in a reducing medium to produce an intermediate which then gives ammoniacal nitrogen by hydrolysis. Finally, the process can be industrialized, utilizes abundant raw materials which can be recycled and reduces the impact on the environment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Step i) Formula (I)R 1 R 2 The compound of MY

[0010] According to the invention, as element M, boron is particularly preferred.

[0011] Formula (I)R 1 R 2 The compounds of MY are not radical compounds.

[0012] In the compound of formula (I), R 1 forms one covalent bond with element M, and R 2 forms one covalent bond with element M.

[0013] R 1 Groups and R 2 base R 1 and R 2 are the same or different and are selected from alkyl groups, aryl groups, aryl-alkyl groups, -OR groups, and -SR groups, where R is an alkyl group, an aryl group, or an aryl-alkyl group.

[0014] R 1 Group and / or R 2 The alkyl group as a group may be linear or branched, cyclic or acyclic. The alkyl group may contain 1 to 14 carbon atoms, preferably 2 to 10 carbon atoms. The alkyl group is preferably selected from ethyl, propyl, isopropyl, cyclohexyl, bicyclo[2.2.1]-2-heptyl and isopinocamphenyl. Of these groups, in particular any one of cyclohexyl, bicyclo[2.2.1]-2-heptyl or isopinocamphenyl is preferred.

[0015] R 1 Group and / or R 2 An alkyl group, as a group, may contain one or more heteroatoms, such as oxygen or sulfur atoms, with it being understood that a carbon atom of the alkyl group is directly bonded to element M of formula (I) above, and that the heteroatoms present in the alkyl group are not directly covalently bonded to other heteroatoms.

[0016] R 1 Group and / or R 2The aryl group as a group may be substituted or unsubstituted. The aryl group may contain 6 to 30 carbon atoms, preferably 6 to 18 carbon atoms. The aryl group is preferably selected from the group consisting of a phenyl group, a -CF group, a 2,4,6-(Me)3-CH group, and a 2,4,6-(iPr)3-CH group. Of these groups, in particular, any one of the 2,4,6-(Me)3-CH group or the 2,4,6-(iPr)3-CH group is preferred.

[0017] R 1 Group and / or R 2 The aryl group as a group may contain one or more heteroatoms, such as oxygen or nitrogen atoms, if the aryl group is substituted (i.e. in a substituent of said aryl group), it being understood that a carbon atom of the aryl group is directly bonded to element M of formula (I) above.

[0018] R 1 Group and / or R 2 An aryl-alkyl group is a group that contains at least one alkyl group and at least one aryl group that are bonded directly by a carbon-carbon (of the aryl group)-carbon (of the alkyl group) covalent bond or via an oxygen atom or a nitrogen atom, and the aryl group and the alkyl group are represented by R 1 Groups and R 2 As defined above for the alkyl-aryl group, the alkyl-aryl group may be bonded directly to element M of formula (I) above via a carbon atom of the aryl group or via a carbon atom of the alkyl group.

[0019] The R alkyl group of said -OR or -SR group may be linear or branched, cyclic or acyclic. The R alkyl group may contain from 1 to 10 carbon atoms, preferably from 1 to 4 carbon atoms.

[0020] The R aryl group of said -OR or -SR group may be substituted or unsubstituted. The R aryl group may contain from 6 to 30 carbon atoms, preferably from 6 to 18 carbon atoms. The R aryl group is preferably selected from a phenyl group, a naphthyl group, an anthracenyl group, or a pyrenyl group.

[0021] The R aryl-alkyl group of the -OR or -SR group is a group that contains at least one alkyl group and at least one aryl group bonded directly by a carbon (of the aryl group)-carbon (of the alkyl group) covalent bond or via an oxygen or sulfur atom, the aryl and alkyl groups being as defined above for the R group.

[0022] R 1 Groups and R 2 The groups may be covalently linked together, in particular via carbon-carbon bonds, to form a divalent group, as defined above in R 1 Groups and R 2 The radicals are as defined above. In this embodiment, the divalent radical does not form a planar ring with the element M.

[0023] According to an embodiment, the divalent group is an alkyl group (i.e., R 1 and R 2 is an alkyl group), preferably a 9-bicyclo[3.3.1]nonane group.

[0024] According to one embodiment of the present invention, R 1 and R 2 are the same or different and are selected from alkyl groups, aryl groups, and aryl-alkyl groups.

[0025] According to a preferred embodiment of the present invention, R 1 Groups and R 2 At least one of the groups is an alkyl group, particularly preferably R 1 Groups and R 2 Both of the groups are alkyl groups.

[0026] According to a particularly preferred embodiment of the present invention, R 1 and R 2 are identical.

[0027] R of compound (I) 1 Groups and R 2In other words, their function is not affected by the R groups generated during the process. 1 R 2 M 〇 The aim is not to stabilize the radical, but to make it more reactive towards nitrogen N2 as a result.

[0028] The Y group Y is halogen -X, -OR 3 Group, -SR 3 R is selected from the group consisting of a triflate (-OSO2CF3) group, a mesylate (-OSO2CH3) group, and a triflimidate (NTf2 or N(SO2CF3)2) group; 3 is an alkyl group, an aryl group, or an aryl-alkyl group.

[0029] X is preferably a chlorine atom or a bromine atom, and particularly preferably a chlorine atom.

[0030] R 3 The alkyl group can be linear or branched, cyclic or acyclic. 3 The alkyl group can contain from 1 to 10 carbon atoms, preferably from 1 to 4 carbon atoms.

[0031] R 3 The aryl group can be substituted or unsubstituted. R 3 The aryl group may contain 6 to 30 carbon atoms, preferably 6 to 18 carbon atoms. 3 The aryl group is preferably selected from the phenyl group, the 2,4,6-(Me)3-C6H2 group, and the 2,4,6-(iPr)3-C6H2 group, and the naphthyl group.

[0032] R 3 An aryl-alkyl group is a group that contains at least one alkyl group and at least one aryl group bonded directly by a carbon-carbon (of the aryl group)-carbon (of the alkyl group) covalent bond or via an oxygen atom or a sulfur atom, and the aryl group and the alkyl group are represented by R 3 As defined above for the radicals.

[0033] Y is preferably a halogen X.

[0034] The Y group of compound (I) is a group that has nucleofugal properties. In other words, its function is 1 R 2 M 〇 The aim is to facilitate the formation of radicals.

[0035] According to a particularly preferred embodiment of the invention, the compound of formula (I) is selected from dialkylchloroboranes, dialkylbromoboranes, dialkylchloroaluminum compounds and dialkylbromoaluminum compounds, such as diisopinocampheylborane, dicyclohexylborane or halides of bis(bicyclo[2.2.1]-2-heptyl)borane or haloboranes based on 9-borabicyclo[3.3.1]nonane.

[0036] The compounds of formula (I) have the advantage that they are readily available commercially or can be readily synthesized.

[0037] Said compounds of formula (I) have the properties of a Lewis acid, ie a chemical compound in which one of the constituent elements of the chemical compound has an empty electron orbital.

[0038] The reducing agent may be selected from potassium, sodium, mercury-based and sodium-based amalgams, lithium, and mixtures thereof, preferably potassium.

[0039] The use of an amalgam makes it easier to measure the amount of reducing agent used in step i).

[0040] The organic solvent may be a conventional organic solvent, an ionic liquid, or a mixture.

[0041] Ionic liquids are well known to those of skill in the art and are considered to be molten salts at room temperature (e.g., 18-25° C.) Ionic liquids contain organic cation moieties and function as solvents in the present invention in the same manner as conventional organic solvents.

[0042] In the present invention, conventional organic solvent means a salt-free organic solvent or an organic solvent that is not in the form of a salt.

[0043] Said organic solvent in step i) is preferably selected from aprotic organic solvents.

[0044] According to one embodiment of the invention, said organic solvent in step i) is selected from non-polar aprotic organic solvents (such as conventional organic solvents), ionic liquids, and mixtures thereof.

[0045] According to a first alternative of this embodiment, said organic solvent in step i) is chosen from non-polar aprotic organic solvents.

[0046] According to a second alternative of this embodiment, said organic solvent in step i) is chosen from ionic liquids.

[0047] Said non-polar aprotic organic solvent in step i) is preferably selected from THF (tetrahydrofuran) and methyl-THF.

[0048] The ionic liquid in step i) is preferably selected from ammonium salts, imidazolium salts, phosphonium salts, pyrrolidinium salts and piperidinium salts, particularly preferably alkylammonium salts, alkylimidazolium salts, alkylphosphonium salts, alkylpyrrolidinium salts and alkylpiperidinium salts.

[0049] Said ionic liquid in step i) preferably comprises an anionic moiety of the bis(trifluoromethanesulfonyl)imidate type.

[0050] Examples of the ionic liquid include triethylbutylammonium bis(trifluoromethanesulfonyl)imidate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imidate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imidate, trimethylbutylammonium bis(trifluoromethanesulfonyl)imidate, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imidate, N-propyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imidate, and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imidate.

[0051] The ionic liquid is preferably immiscible with water, which facilitates subsequent purification processes.

[0052] During step i), a composition comprising said compound of formula (I), said reducing agent and said organic solvent is contacted with dinitrogen (N2).

[0053] Step i) is carried out in a dry or anhydrous medium, in other words, step i) is preferably carried out in a glove box or in an apparatus suitable to avoid contact with air and / or moisture.

[0054] In fact, contact with air and / or moisture can result in the formation of H2 and / or R 1 R 2 M.O.M.R. 1 R 2 This results in the formation of by-products such as

[0055] Step i) may last for about 1 hour to 20 hours, preferably for about 2 hours to 12 hours.

[0056] Step i) can be carried out at a temperature preferably in the range of about -80°C to 60°C, particularly preferably about 0°C to 30°C.

[0057] Step i) is preferably carried out under stirring, for example using a mechanical or magnetic stirrer, which makes it possible to promote contact between the composition and the dinitrogen and thus promote the reaction.

[0058] To effect the reaction between dinitrogen and compound (I), the reaction is preferably carried out under a dinitrogen atmosphere, in particular under a dry dinitrogen atmosphere.

[0059] Step i) can be carried out at a pressure ranging from about 0.1 bar to 200 bar, preferably from 1 bar to 100 bar. A pressure of at least 20 bar, preferably at least 40 bar, is advantageous for improving the yield of ammoniacal nitrogen. A pressure of 1 bar is advantageous from an industrial point of view.

[0060] The reducing agent used in step i) may represent from 0.1% to 20% by weight, preferably from 0.1% to 10% by weight, of the total weight of the composition.

[0061] The compound of formula (I) used in step i) may represent from 0.1% to 10% by weight, preferably from 2% to 6% by weight, of the total weight of the composition.

[0062] During step i), the compound (I) reacts with dinitrogen to give one or more species based on nitrogen and the element M, in particular of the following formula (II): N(MR 1 R 2 ) 3-x H x where x is an integer ranging from 0 to 3.

[0063] The formation of one or more chemical species based on nitrogen and on the element M as defined above is particularly illustrated by the implementation of a radical chain reaction using one or more radicals based at least on the element M that are sufficiently unstable to react with the nitrogen of dinitrogen.

[0064] Surprisingly, the compound of formula (I), i.e., Y, M, R 1 , R2 Compound (I) according to the definition has the ability to activate the dinitrogen triple bond in a reducing medium, minimizing or even avoiding the dimerization of said radical.

[0065] Step ii) During step ii), the species based on nitrogen and on the element M are hydrolyzed in an acidic medium to form ammoniacal nitrogen.

[0066] In the present invention, ammoniacal nitrogen is the two most reduced forms of nitrogen: ammonium (NH4 + ) and ammonia (NH3). Therefore, ammonia nitrogen includes ammonium (NH4 + ), ammonia (NH3) and mixtures thereof. Generally, depending on the conditions of step ii), in particular the amount of acid, ammonium (excess acid), or ammonia (N(MR 1 R 2 ) 3-x H x (stoichiometric amount for

[0067] Step ii) of hydrolysis in an acidic medium can be carried out by contacting the reaction crude product obtained in the preceding step i) with an acidic solution or with a gaseous acid (in the form of gas).

[0068] The acidic solution can include an aqueous solvent (e.g., water) and at least one acid (hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, etc.), or an aprotic organic solvent and at least one acid (hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, etc.).

[0069] The aprotic organic solvent may be selected from ethers such as diethyl ether or dioxane, and alkanes such as hexane or heptane.

[0070] The gaseous acid may be hydrochloric acid gas.

[0071] Step ii) advantageously yields ammonium, especially when the acid is used in excess relative to the compound of formula (I).

[0072] The aqueous solvent is preferably water.

[0073] The acidic solution may have a pH in the range of 0-6.

[0074] Step ii) can last for about 1 minute to 30 minutes, preferably about 2 minutes to 10 minutes. Step ii) is a very fast, almost instantaneous step.

[0075] Step ii) is preferably carried out at a temperature in the range of about -20°C to 40°C, particularly preferably about 0°C to 20°C.

[0076] Step ii) is preferably carried out with stirring.

[0077] Step ii) is preferably carried out at atmospheric pressure.

[0078] Step ii) is the reaction of ammonia NH3 and / or ammonium NH4 + This makes it possible to bring about

[0079] Other steps of the method The method may further comprise the step i') after step i) and before step ii) of removing said organic solvent.

[0080] This embodiment is particularly employed when said organic solvent is a conventional organic solvent.

[0081] Step i') can be carried out by evaporating conventional organic solvents.

[0082] Said method may comprise, after step i) or, if present, step i′), a purification step i”) which makes it possible to remove at least some of the by-products (for example salts) which may be formed in step i). In other words, step i”) makes it possible to separate the species based on nitrogen and on the element M formed in step i) from the salts.

[0083] Step i”) can be carried out by extraction of the reaction mixture formed in step i) or, if present, in step i′), in particular with a non-polar organic solvent. Said species or species based on nitrogen and on element M formed in step i) are soluble in said non-polar organic solvent and can be separated from said salt by filtration.

[0084] The non-polar organic solvent may be selected from an alkane such as hexane, pentane or heptane.

[0085] The preferred non-polar organic solvent is pentane.

[0086] When said organic solvent of step i) is a conventional organic solvent, a purification step i") can be carried out after step i) or step i'), in particular by filtering the reaction mixture formed in step i) or step i'), as explained above.

[0087] When said organic solvent of step i) is an ionic liquid, as explained above, a purification step i") can be carried out after step i), in particular by filtering the reaction mixture formed in step i).

[0088] The method may further comprise, prior to step i), a step i0) of preparing said compound of formula (I).

[0089] The compounds of formula (I) can be prepared by double hydroboration or hydroalumination protocols as described in the following articles: H.C. Brown, N. Ravindran, J.Am.Chem.Soc. 1976, 98, 1798-1806 and H.C. Brown, N. Ravindran, J.Am.Chem.Soc. 1976, 98, 1785-1798, or by reaction of two equivalents of an alkene with one equivalent of a monohaloborane (e.g., corresponding to the formula YBH2, where Y is as defined herein) in THF or diethyl ether at room temperature.

[0090] In general, one equivalent of the compound MH2Y is 2 equivalents of the alkene R'CH=CH2. to form the compound (R'CH2CH2)2MY.

[0091] The process of the present invention preferably does not use gaseous species other than dinitrogen (N2) as an initiator.

[0092] The process may further comprise a step iii) of recycling compound (I). In this embodiment, step ii) is preferably carried out by contacting the reaction crude product obtained in the preceding step i), i') or i"), under an inert atmosphere, with an acidic solution comprising an aprotic organic solvent and at least one acid or with a gaseous acid, said acidic solution and said gaseous acid being as defined above.

[0093] Thus, step iii) can be performed after step ii) as follows. - When said organic solvent is a conventional organic solvent, for example from step i), i") or ii), if present, said solvent is removed, preferably by evaporation, and NH4 is added using a non-polar solvent. + and isolating / recovering compound (I); or - when said organic solvent is an ionic liquid, for example using a distillation system to remove said solvent from step i"), or ii), if present, and recover NH3 and separate / recover compound (I).

[0094] The non-polar solvent can be as described above.

[0095] A second aspect of the present invention is the use of a compound of formula (I) as defined in the present invention for the reduction of dinitrogen. EXAMPLES

[0096] Example 1: Method for producing ammoniacal nitrogen from dinitrogen using dicyclohexylchloroborane as the compound of formula (I) 120 mg of a solution of dicyclohexylchloroborane (1M in hexane), sold by Sigma-Aldrich under the reference number 411124, was added to 4 mL of anhydrous tetrahydrofuran, followed by the addition of 15 mg of potassium. The resulting composition was placed under an atmosphere of pure dry dinitrogen and stirred for 12 hours. At the end of the reaction, the mixture was brown. An excess of HCl (2M) in Et2O was added under an inert atmosphere, and the mixture was stirred for 12 hours. x -N(BCy2) 3-x NH4 + The solvent and volatile compounds were removed by evaporation to leave a solid residue. This solid was extracted with hexane and NH + Separate Cy2BCl from NH4 + is obtained as a white solid in 38% yield based on the initially charged Cy2BCl.

[0097] Example 2: Method for producing ammoniacal nitrogen from dinitrogen using (+)-B-chlorodiisopinocampheylborane as the compound of formula (I) 48 mg of (+)-B-chlorodiisopinocampheylborane (Ipc2BCl), sold by Sigma-Aldrich under the reference number 317012, were added to 4 mL of anhydrous tetrahydrofuran, followed by the addition of 15 mg of potassium. The resulting composition was placed under an atmosphere of pure dry dinitrogen and stirred for 12 hours. At the end of the reaction, the mixture was brown. An excess of HCI (2M) in Et2O was added under an inert atmosphere, and H x-N(BIpc2) 3-x NH4 + The solvent and volatile compounds were removed by evaporation to leave a solid residue. This solid was extracted with hexane and NH + Ipc2BCl is isolated from NH4 + is obtained as a white solid in 15% yield based on the initial Ipc2BCl input.

[0098] Example 3: Control Method (not part of this invention) 120 mg of a solution of dicyclohexylchloroborane (1M in hexane), sold by Sigma-Aldrich under the reference number 411124, was added to 4 mL of anhydrous tetrahydrofuran, followed by the addition of 15 mg of potassium. The resulting composition was placed under a pure, dry argon atmosphere and stirred for 12 hours. An excess of HCI (2M) in Et2O was added under an inert atmosphere. NH4 + No formation was observed.

[0099] Example 4: Control Method (not part of this invention) A suspension of 15 mg of potassium in 4 mL of anhydrous tetrahydrofuran was stirred for 12 h under an atmosphere of pure dry dinitrogen. An excess of HCI (2M) in Et2O was added under an inert atmosphere. NH4 + No formation was observed.

[0100] Example 5: Method for producing ammoniacal nitrogen from dinitrogen using bis(bicyclo[2.2.1]-2-heptyl)chloroborane as the compound of formula (I) 38 mg of a solution of bis(bicyclo[2.2.1]-2-heptyl)chloroborane, sold by Sigma-Aldrich under the reference number 771880, was added to 4 mL of anhydrous tetrahydrofuran, followed by the addition of 15 mg of potassium. The resulting composition was placed under an atmosphere of pure dry dinitrogen and stirred for 12 hours. At the end of the reaction, the mixture was brown. An excess of HCl (2M) in Et2O was added under an inert atmosphere, and the mixture was stirred for 12 hours. x -N(BBCH2) 3-x NH4 +The solvent and volatile compounds were removed by evaporation to leave a solid residue. This solid was extracted with hexane and NH + Isolate BCH2BCl from NH4 + is obtained as a white solid in 43% yield based on the initially introduced bis(bicyclo[2.2.1]-2-heptyl)chloroborane.

[0101] Example 6: Method for producing ammoniacal nitrogen from dinitrogen using dicyclohexylchloroborane as the compound of formula (I) In an autoclave, 120 mg of a solution of dicyclohexylchloroborane (1M in hexane), sold by Sigma-Aldrich under the reference number 41124, was added to 4 mL of anhydrous tetrahydrofuran, followed by the addition of 15 mg of potassium. The autoclave was then sealed. The resulting composition was pressurized with pure dry dinitrogen under stirring for 12 hours (20 bar: Example 6-1, 40 bar: Example 6-2, 80 bar: Example 6-3). At the end of the reaction, the mixture is brown. An excess of HCl (2M) in Et2O solution was added under an inert atmosphere, and H x -N(BCy2) 3-x NH4 + The solvent and volatile compounds were removed by evaporation to leave a solid residue. This solid was extracted with hexane and NH + Separate Cy2BCl from NH4 + is obtained as a white solid. The yields based on the initially introduced Cy2BCl are as follows: - 60% for a pressure of 20 bar (Example 6-1) - 76% at 40 bar pressure (Example 6-2) - 94% at 80 bar pressure (Example 6-3)

Claims

1. A method for producing ammoniacal nitrogen, the ammoniacal nitrogen being ammonium (NH ４ ＋ ), ammonia (NH ３ ), and mixtures thereof, comprising at least the following steps: i) Formula (I): R １ R ２ A composition containing a compound corresponding to MY(I), a reducing agent, and an organic solvent is added to a dinitrogen (N ２ ) contacting the In the formula (I), - M is an element of group 13 of the periodic table, - R １ and R ２ are the same or different and are selected from alkyl groups, aryl groups, aryl-alkyl groups, -OR groups, and -SR groups, where R is an alkyl group, an aryl group, or an aryl-alkyl group; - Y is halogen -X, -OR ３ Group, -SR ３ R is selected from the group consisting of a triflate group, a mesylate group, and a triflimidate group; ３ is an alkyl group, an aryl group, or an aryl-alkyl group; and ii) a hydrolysis step in an acidic medium; A method comprising:

2. 2. The method of claim 1, wherein the element M is selected from boron, aluminum, and mixtures thereof.

3. The two groups R １ and R ２ The method of claim 1 , wherein is an alkyl group.

4. 2. The method of claim 1, wherein Y is a halogen X.

5. 2. The method of claim 1, wherein the reducing agent is selected from potassium, sodium, mercury-based and sodium-based amalgams, lithium, and mixtures thereof.

6. 2. The method according to claim 1, characterized in that step i) is carried out at a temperature ranging from -80°C to 60°C.

7. 2. The method according to claim 1, characterized in that the reducing agent used in step i) represents between 0.1% and 20% by weight of the total weight of the composition.

8. 2. The method according to claim 1, characterized in that the compound of formula (I) used in step i) represents between 0.1% and 10% by weight of the total weight of the composition.

9. 2. The process according to claim 1, characterized in that step ii) of hydrolysis in an acidic medium is carried out by contacting the reaction crude product obtained in the preceding step i) with an acidic solution or with a gaseous acid.

10. The method of claim 9, wherein the acidic solution has a pH in the range of 0 to 6.

11. 2. The method according to claim 1, characterized in that the organic solvent in step i) is selected from non-polar aprotic organic solvents.

12. 2. The method according to claim 1, further comprising the step i') of evaporating said organic solvent after step i) and before step ii).

13. 2. The method according to claim 1, characterized in that the organic solvent of step i) is selected from ionic liquids.

14. 2. The process according to claim 1, characterized in that after step i) or, if present, step i'), it comprises a purification step i") by extraction of the reaction mixture formed in step i) or, if present, step i') with a non-polar organic solvent.

15. 2. Use of a compound of formula (I) as defined in claim 1 for dinitrogen reduction.