WO2014083223A1 - Method for obtaining secondary amines from nitrobenzene in a single reactor - Google Patents

Abstract

The invention relates to a method for directly obtaining secondary amines, such as, for example, cyclohexylaniline or dicyclohexylaniline and substituted derivatives thereof, from nitrobenzene and derivatives in a single reactor, characterised in that: a nitrobenzene derivative, a solid catalyst, a solvent, an acid and hydrogen are introduced into the reactor, and it comprises a single step (one pot).

Description

 DESCRIPTION

PROCESS OF OBTAINING SECONDARY AMINES FROM NITROBENZENE IN

ONE REACTOR ONLY

Technical field

The present invention relates to obtaining products of high industrial interest such as cyclohexylaniline and dicyclohexylamine, and substituted derivatives thereof, under mild reaction conditions using the industrial compound nitrobenzene and substituted derivatives thereof as the sole organic starting material. For this, it is necessary to prepare a supported palladium catalyst that allows the direct catalytic hydrogenation of nitrobenzene to the desired product depending on the quantity and dilution of the added aqueous acid, the hydrogen pressure, the amount of catalyst and the temperature of reaction.

Background

The synthetic strategy described here is based on the use of a solid palladium catalyst that allows the cross-amination reaction between the aniline that is formed after the catalytic reduction of nitrobenzene and the cyclohexylamine that is formed after the reduction of the ring thereof, all under the same conditions of catalytic hydrogenation, resulting in the intermediate cyclohexylaniline, a product with industrial value (Xinhuan Yan; Fang Yang 2012, CN102531912, summary), in high yields. An increase in hydrogen pressure or reaction temperature allows the production of diclohexylamine, another product with industrial value (Uhlar, Jan, I.; Macack, Ivan; Stefanko, Michan; Kralik, Milan; Horak, Jaroslav; Chovanec, Stefan ; Biro, Pavel; Prezny, Branislav 2012, WO2012-018310) (Lundgren Rylan J; Stradiotto Mark; 2012 WO2012068335), also in high performance. These two secondary amines have been observed in small quantities as by-products during the obtaining of aniline by hydrogenation of nitrobenzene on platinum supported in alumina or Raney nickel at high temperatures and pressures (Naramoto, I.; Kyuma, T., 1990, 3565921). In the present invention patent, cyclohexylaniline is produced with palladium or palladium-gold catalysts, under hydrogenating conditions and in the presence of an acidic function. This new preparation strategy allows the process to be carried out in a single reactor, covering at least three synthetic elemental stages without the need to add or evacuate reagents during the process to selectively obtain secondary amines at the end of the process, for example cyclohexylaniline or dicyclohexylamine and its derivatives.

Description of the invention

The present invention describes the direct obtaining of secondary amines, such as cyclohexylaniline, dicyclohexylamine and substituted derivatives thereof, starting with nitrobenzenes. Throughout the description we refer to nitrobenzenes generically referring to both the nitrobenzene compound and its derivatives. Sometimes we will also refer to nitrobenzene and its derivatives as nitro derivatives.

 The synthetic strategy described here is summarized in Scheme 1 and is based on the use of a solid metallic catalyst, for example palladium or palladium-gold that allows the cross-amination reaction between the aniline that is formed after the catalytic reduction of nitrobenzene and the cyclohexylamine that is formed after the reduction of the ring thereof, all under the same conditions of catalytic hydrogenation, giving rise to cyclohexylaniline in high yields.

Scheme 1. Reaction described in the present invention.

For example, if desired, dicyclohexylamine can be obtained in high yield, after an increase in hydrogen pressure or reaction temperature. In addition, the remaining aniline is recycled in the Synthesis reactor itself to form more cyclohexylaniline by coupled amination. Therefore, the entire process occurs in the same reactor, covering at least three synthetic elemental stages without the need to add or evacuate reagents during the process to selectively obtain secondary amines, for example cyclohexylaniline or dicyclohexylamine and derivatives thereof at the end of the process. This requires the introduction of a catalyst with at least one supported metal that allows the direct catalytic hydrogenation of nitrobenzene to the desired product based on the amount and dilution of the added aqueous acid, the hydrogen pressure, the amount of catalyst and of the reaction temperature among others.

Thus, the present invention relates to a process for obtaining secondary amines from nitrobenzene and derivatives in a single reactor which may comprise introducing at least one nitrobenzene derivative, a solid catalyst, a solvent, an acid into a reactor. and hydrogen and that takes place in a single stage.

According to a particular embodiment of the present invention, the nitrobenzene derivatives (s) used as the starting compound correspond to the formula.

R _x -C ₆ H _y - (N0 ₂ ) _z where

 R is selected from the group of linear or branched alkyls, the group of the esters, the group of the ethers and combinations thereof;

 x the number of substituents on the aromatic ring,

 + z = 6 - - x;

 It has a value between 0 and 2

it has a value between 1 and 5, preferably between 4 and 5 it has a value between 1 and 3, preferably between 1 and 2 The catalyst used in the process described in accordance with the present invention is a catalyst comprising at least one support that can be selected from alumina, silica, carbon, amorphous aluminosilicates, crystalline aluminosilicates and combinations thereof, preferably carbon, and nanoparticles of at least one metal. The nanoparticles can be nanoparticles of Pd, Ru, Pt, Rh, Ir, Pd-Au and combinations thereof.

According to a particular embodiment, the metal nanoparticles are preferably Pd nanoparticles, and more preferably Pd nanoparticles with an orientation {100}.

According to another particular embodiment, the metal nanoparticles are preferably Pd-Au nanoparticles.

In general, it can be said that the catalyst used in the process of the present invention responds to the following general formula:

MetalI _m -Metal2 _n -Support where

 m can be in a range between 1-20%, preferably between 1-5% by weight, and

 n may be in a range between 0-20%, preferably between 0-5% by weight.

According to this general formula, in a particular embodiment of the present invention the metal 1 could be Pd and the metal 2 could be Au, the catalyst formula being as follows:

Palladium _m- Gold _n -Support where

m can be in a range between 1-20%, preferably between 1-5% by weight, and n may be in a range between 0-20%, preferably between 0-5% by weight,

According to a particular embodiment of the present invention, the catalyst used can be a supported palladium catalyst. For the preparation of this catalyst, on a support, the palladium precursor is deposited, for example by impregnation with a solution of a palladium compound in a polar solvent, preferably ethanol. As a palladium precursor, salts such as palladium ammonium nitrate, palladium chloride or palladium complexes such as palladium acetylacetonate or palladium acetate, among others, can be used. The solution is prepared with the required amount and deposited on a solid support. As a method of deposition, impregnation, precipitation or anchoring of the palladium precursor is used. As supports, different types of alumina (preferably γ-alumina), silica, carbons, amorphous or crystalline aluminosilicates and combinations thereof can be used. After deposition of the palladium precursor, the precursor is reduced or calcined-reduced in order to obtain the supported palladium nanocrystals. As reducing agents, H ₂ , phenylethanol, sodium borohydride or any other reducer capable of reducing palladium at temperatures below 400 ° C can be used. Of the different possible crystallographic orientations in palladium nanocrystals, the orientation {100} is preferred. The amount of Pd in the catalyst can be between 1-20% by weight.

According to another particular embodiment, the catalyst is a supported catalyst of palladium and gold. In this case, on a support, the palladium and gold precursors are deposited, for example by impregnation with a solution of a palladium compound in a polar solvent, preferably ethanol. As a palladium precursor, salts such as palladium ammonium nitrate, palladium chloride or palladium complexes such as palladium acetylacetonate or palladium acetate can be used. As a gold precursor, salts such as gold chloride, gold bromide or sodium aurothiomalate can be used. The solution is prepared with the required quantities and deposited on a solid support. As a method of deposition, impregnation, precipitation or anchoring of the palladium precursor is used. As supports, different types of alumina (preferably γ-alumina), silica, carbons, amorphous or crystalline aluminosilicates and combinations thereof can be used. After the deposition of the palladium and gold precursor, the precursors are reduced or calcined-reduced in order to obtain the supported palladium and gold nanocrystals. As reducing agents, H ₂ , phenylethanol, borohydride, or any other reducer capable of reducing palladium at temperatures below 400 ° C can be used. Of the different possible crystallographic orientations in palladium nanocrystals, the orientation {100} is preferred. The amount of Pd in the catalyst can be between 1-20% by weight and between 0-20% by weight for gold.

According to another particular embodiment, the catalyst used in the present invention is a carbon supported palladium and gold catalyst that responds to formula (II)

Palladium _m- Gold _n- Carbon (II) where m and n correspond to the percentage by weight of the metals in the solid catalyst, typically in the range between 1-20%, and preferably in the range between 1-5% for m and 1 -5% for n.

According to this particular embodiment, the solid catalyst is produced after the co-hydrogenation of palladium and gold salts previously impregnated on the active carbon in aqueous solution. This co-hydrogenation occurs by heating a gram of impregnated solid at 200 ° C for one hour under a flow of hydrogen of between 1 and 100 milliliters per minute, preferably between 5 and 10 milliliters per minute, diluted in nitrogen with a flow between 10 and 150 milliliters per minute, preferably between 90 and 120 milliliters per minute, and with a ramp of previous rise of between 5 and 20 ° C per minute until reaching the final temperature from ambient temperature. As described above, the process of the present invention also includes the use of a solvent. Preferably this solvent is selected from hexane, tetrahydrofuran, ether, dichloromethane, dioxane and combinations thereof, and more preferably from hexane, dichloromethane and combinations thereof. Preferably said solvent is in an amount between 0.1-20 milliliters per millimol of nitro-derivative, and more preferably it is 10 milliliters per millimol of nitro-derivative.

According to a particular embodiment, those solvents that are not miscible with water are preferably used since they allow a good separation between solid catalyst and acid further favor the formation of secondary amines, for example cyclohexylaniline, dicyclohexylamine and derivatives, as is the preferred case of hexane and dichloromethane.

According to a particular embodiment of the present invention, the acid used in the described process may be selected from hydrochloric acid, methanesulfonic acid, acetic acid, paratoluenesulfonic acid, an acid function forming part of the support and combinations thereof, and preferably is methanesulfonic acid. .

The reaction conditions according to the process of the present invention may vary. According to a particular embodiment, the reaction described is carried out at a temperature between 10 and 80 ° C, at a pressure between 5 and 20 atmospheres and for a time that can vary between one hour and five days (varying the time according to substrate) . By varying these reaction conditions it is possible to selectively obtain one product or another.

According to a particular embodiment, the process of the present invention is carried out in a batch reactor. According to a particular embodiment, the product obtained is cyclohexylaniline and the reaction can be carried out at a temperature between 10 and 80 ° C, preferably between 14 and 60, and more preferably between 20-30 ° C, at a pressure between 5 and 20 atmospheres, preferably between 8-12 atmospheres, which is equivalent to an excess of between two and three times the amount required for the entire hydrogenation process.

According to another particular embodiment, the product obtained is dicyclohexylamine and the reaction can be carried out at a temperature between 10 and 80 ° C, preferably between 30 and 80, and more preferably between 50-80 ° C, at a pressure between 5 and 20 atmospheres, preferably between 10-15 atmospheres, which is equivalent to an excess of between two and three times the amount required for the entire hydrogenation process.

According to a particular embodiment, the representative molar ratio between nitrobenzene (starting material): catalyst: hydrogen: acid may vary in the range 100: 20-1: 800-200: 200-100, the preferred range being 100: 5: 600: 100. Starting material means each molecule that contains a nitro group and a benzene ring, in the case of containing more than one of these groups the amounts should be recalculated accordingly.

According to a particular embodiment, the method described herein can also be used to couple two different nitro derivatives by adding in excess of the least reactive of them to favor heterocoupling instead of homocoupling in case the nitro derivatives are equal.

According to a particular embodiment, the product can be recovered after solid filtration and removal of volatile compounds from the rotary evaporator. The solid thus recovered can be recycled for a second reaction. Throughout the description and the claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will be derived partly from the description and partly from the practice of the invention. The following examples are provided by way of illustration, and are not intended to be limiting of the present invention.

EXAMPLES

Non-limiting examples of the present invention will be described below.

Example 1: Preparation of palladium-gold on support.

49 mg (0.12 mmol) of sodium tetrachloroaurate and 143 mg (0.47 mmol) of palladium acetylacetonate are dissolved in 1.6 ml of ethanol, and impregnated in 1 g of activated carbon (Norit, GSX, steam activated, acid washed). The mixture is left in an oven at 80 ° C one night. The next day, it is reduced in a reduction oven, under a flow of 10% of H ₂ and 90% of N ₂ , with a ramp of 10 ° C / min until reaching 360 ° C, temperature at which keep lh.

Example 2: Preparation of palladium on support.

143 mg (0.47 mmol) of palladium acetylacetonate are dissolved in 1.6 ml of ethanol, and impregnated in 1 g of activated carbon (Norit, GSX, steam activated, acid washed). The mixture is left in an oven at 80 ° C one night. The next day, it is reduced in a reduction oven, under a flow of 10% of H ₂ and 90% of N ₂ , with a ramp of 10 ° C / min until reaching 360 ° C, temperature at which keep lh.

Example 3: Preparation of palladium on support.

143 mg (0.47 mmol) of palladium acetylacetonate are dissolved in toluene, and stir with 1 g of MgO for 12 h. After this time, the mixture is left in vacuo to evaporate toluene, then at 80 ° C under vacuum overnight and then calcined under a nitrogen atmosphere at 580 ° C (with a ramp of 5 ° / min) for 3.5h (Climent, MJ; Corma, A .; Iborra, S .; Mifsud, M .; J. Catal. 2007; 247, 223-230).

Example 4: Preparation of cyclohexylaniline by hydrogen reduction of a solution of nitrobenzene in hexane using supported palladium and methanesulfonic acid.

In a reinforced glass reactor equipped with a pressure and temperature control, 21 μΐ (0.2 mmol) of nitrobenzene are dissolved in 1 ml of hexane, in 10 μΐ (0.22 mmol) of methanesulfonic acid in the presence of 21 mg of palladium on carbon active (5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar, 6 eq.) and stirred at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 days the conversion is 92%.

Example 5: Preparation of dicyclohexylamine by hydrogen reduction of a solution of nitrobenzene in hexane using supported palladium and methanesulfonic acid.

In a reinforced glass reactor equipped with a pressure and temperature control, 21 μΐ (0.2 mmol) of nitrobenzene are dissolved in 1 ml of hexane, in 10 μΐ (0.22 mmol) of methanesulfonic acid in the presence of 21 mg of RuPt-C ( 5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar, 6eq.) And stirred at 60 ° C. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 hours the conversion is 93%. Example 6: Preparation of N, Np-methylcyclohexyl-p-toluidine by hydrogen reduction of a solution of p-methylnitrobenzene in hexane using supported palladium and methanesulfonic acid.

In a reinforced glass reactor equipped with a pressure and temperature control, 27.4 mg of p-methylnitrobenzene is dissolved in 1 ml of hexane, in the presence of 10 μΐ (0.22 mmol) of methanesulfonic acid and 21 mg of palladium on activated carbon ( 5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar, 6 eq.) And stirred at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 days the conversion is 82%.

Example 7: Preparation of N, N-p-tertbutylcyclohexyl p-terbutylaniline by hydrogen reduction of a solution of p-terbutyl nitrobenzene in hexane using supported palladium and methanesulfonic acid.

In a reinforced glass reactor equipped with a pressure and temperature control, 27.4 mg (0.2 mmol) of ptertbutylnitrobenzene is dissolved in 1 ml of hexane, in the presence of 10 μΐ (0.22 mmol) of methanesulfonic acid and 21 mg of palladium on activated carbon (5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar, 6 eq.) and stirred at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 days the conversion is 79%.

Example 8: Preparation of Np-ethylcyclohexyl-p-ethylaniline by hydrogen reduction of a solution of p-ethylnitrobenzene in hexane using supported palladium and methanesulfonic acid. In a reinforced glass reactor equipped with a pressure and temperature control, 30.5 mg (0.2 mmol) mg of p-ethylnitrobenzene is dissolved in 1 ml of hexane, in the presence of 10 μΐ (0.22 mmol) of methanesulfonic acid and 21 mg of Palladium on activated carbon (5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar) and stirred at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 hours the conversion is 88%.

Example 9: Preparation of ethyl 4- (4- ((N- (p-methoxy-4-oxoethyl) cyclohexyl) amino) phenyl) butanoate by hydrogen reduction of a solution of ethyl p-nitrophenyl acetate in hexane using palladium supported and methanesulfonic acid.

In a reinforced glass reactor, equipped with a pressure and temperature control, 44.6 mg (0.2 mmol) of ethyl p-nitrophenyl butanoate is dissolved in 1 ml of hexane, in the presence of 10 μΐ (0.22 mmol) of Methanesulfonic acid and 21 mg of palladium on activated carbon (5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar) and stirred at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 hours the conversion is 90%.

Example 10: Preparation of 4- (4- ((N- (p-ethoxy-4-oxoethyl) cyclohexyl) amino) phenyl) ethyl acetate by hydrogen reduction of a solution of ethyl p-nitrophenyl acetate in hexane using palladium supported and methanesulfonic acid.

In a reinforced glass reactor equipped by a pressure control and at temperature 41.8 mg (0.2 mmol) of p-nitrophenyl ethyl acetate is dissolved in 1 ml of hexane, in the presence of 10 μΐ (0.22 mmol) of methanesulfonic acid and 21 mg of palladium on activated carbon (5 mol% ), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar) and stirred at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 hours the conversion is 90%.

Example 11: Preparation of diphenethylamine ethyl acetate by hydrogen reduction of a solution of nitro-styrene in hexane using supported palladium and methanesulfonic acid.

In a reinforced glass reactor equipped with a pressure and temperature control, 29.8 mg (0.2 mmol) of p-nitrophenyl ethyl acetate is dissolved in 1 ml of hexane, in the presence of 10 μΐ (0.22 mmol) of methanesulfonic acid and 21 mg of palladium on activated carbon (5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar) and stirred at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 hours the conversion is 57%.

Example 12: Preparation of bis- (4-methoxyphenethyl) amine by hydrogen reduction of a solution of p-methoxy-3-nitrostyrene in hexane using supported palladium and methanesulfonic acid.

In a reinforced glass reactor equipped with a pressure and temperature control, 35.8 mg (0.2 mmol) of p-methoxy- / 3- nitrostyrene is dissolved in 1 ml of hexane, in the presence of 10 μΐ (0.22 mmol) of methanesulfonic acid and 21 mg of palladium on activated carbon (5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then fill with the desired pressure of H ₂ (10 bar) and stir at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 hours the conversion is 50%.

Example 13: Preparation of N- (4-methoxyphenethyl) aniline by hydrogen reduction of a solution of p-methoxy-β-nitrostyrene and nitrobenzene in hexane using supported palladium and methanesulfonic acid.

In a reinforced glass reactor, equipped with a pressure and temperature control, 18 mg (0.1 mmol) of p-methoxy- / 3- nitrostyrene and 15 μΐ (0.15 mmol) of nitrobenzene are dissolved in 1 ml of hexane, in the presence 10 μΐ (0.22 mmol) of methanesulfonic acid and 21 mg of palladium on activated carbon (5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar) and stir at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 hours the conversion is 72%.

Example 14: Preparation of 2- (4- (p-tolylamino) phenyl) ethyl acetate by hydrogen reduction of a solution of ethyl p-nitrophenyl acetate in hexane using supported palladium and methanesulfonic acid.

In a reinforced glass reactor, equipped with a pressure and temperature control, 21 mg (0.2 mmol) of p-nitrophenyl ethyl acetate is dissolved in the presence of 10 μΐ (0.22 mmol) of methanesulfonic acid and 21 mg of palladium on carbon active (5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar) and stirred at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, they are centrifuged to remove the catalyst particles and the product is analyzed with GC-MS. After 24 hours the conversion is 78%. Example 15: Preparation of bis (3,5-dimethylcyclohexyl) amine by hydrogen reduction of a solution of 1,3-dimethyl-5- nitrobenzene in hexane using supported palladium and methanesulfonic acid. In a reinforced glass reactor, equipped with a pressure and temperature control, 30.5 mg (0.2 mmol) of 1,3-dimethyl-5- nitrobenzene is dissolved in the presence of 10 μΐ (0.22 mmol) of methanesulfonic acid and 21 mg ( 5 mol%) of palladium on activated carbon, the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar) and stirred at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 hours the conversion is 72%.

Example 16: Preparation of bis ((p-ethoxy-2-oxoethyl) cyclohexyl) amine by hydrogen reduction of a solution of ethyl p-nitrophenylacetate in hexane using supported palladium and methanesulfonic acid. In a reinforced glass reactor equipped with a pressure and temperature control, 41.8 mg (0.2 mmol) of ethyl p-nitrophenylacetate is dissolved in the presence of 10 μΐ (0.22 mmol) of methanesulfonic acid and 21 mg of palladium on carbon active (5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar) and stirred at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 hours the conversion is 72%.

Example 17: Preparation of indoline by hydrogen reduction of a Dissolution of β, 2-dinitro-styrene in hexane using supported palladium and methanesulfonic acid.

In a reinforced glass reactor equipped with a pressure and temperature control, 38.8 mg (0.2 mmol) of β, 2-dinitroestirene is dissolved in the presence of 10 μΐ (0.22 mmol) of methanesulfonic acid and 21 mg of palladium on carbon active (5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar) and stirred at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 hours the conversion is 64%.

Example 18: Preparation of cyclohexylaniline by hydrogen reduction of a solution of nitrobenzene in hexane using supported palladium and acetic acid.

In a reinforced glass reactor, equipped with a pressure and temperature control, 21μ1 (0.2 mmol) of nitrobenzene are dissolved in 1 ml of hexane, in 13 μΐ (0.22 mmol) of acetic acid in the presence of 21 mg of palladium on carbon active (5 mol%), the reactor is purged 5 times with 10 bar of hydrogen, then filled with the desired pressure of H ₂ (10 bar, 6 eq.) and stirred at room temperature. During the experiment the pressure of H ₂ is reduced. Aliquots are taken from the reactor at different times that are diluted in ethanol, centrifuged to remove catalyst particles and the product is analyzed with GC-MS. After 24 days the conversion is 92%.

Claims

1. Procedure for obtaining secondary amines from nitrobenzene and derivatives in a single reactor characterized in that it comprises introducing into a reactor at least one nitrobenzene derivative, a solid catalyst, a solvent, an acid and hydrogen and which takes place in single stage 2. Procedure for obtaining secondary amines in a single reactor according to claim 1, characterized in that the nitrobenzene derivative corresponds to the formula R _x -C ₆ H _y - (N0 ₂ where  R is selected from the group of linear or branched alkyls, the group of the esters, the group of the ethers and combinations thereof;  X the number  y + z = 6 - x; X has a ^■ and has a ^■ z has a ^■ 3. Method for obtaining secondary amines in a single reactor according to claim 1, characterized in that the catalyst is a catalyst comprising at least one support and nanoparticles of at least one metal. . Method of obtaining secondary amines in a single reactor according to claim 3, characterized in that the nanoparticles are selected from nanoparticles of Pd, Ru, Pt, Rh, Ir, Pd-Au and combinations thereof. 5. Procedure for obtaining secondary amines in a single reactor according to claim 4, characterized in that the nanoparticles are Pd. Method for obtaining secondary amines in a single reactor according to claim 5, characterized in that the palladium nanoparticles have an orientation {100}. 7. Method for obtaining secondary amines in a single reactor according to claim 4, characterized in that the nanoparticles are Pd-Au. 8. Method for obtaining secondary amines in a single reactor according to claim 3, characterized in that the support is selected from alumina, silica, carbon, amorphous aluminosilicates, crystalline aluminosilicates and combinations thereof. Method of obtaining secondary amines in a single reactor according to claim 8, characterized in that the support is carbon. 10. Process for obtaining secondary amines in a single reactor according to claim 3, characterized in that the catalyst has the following general formula: MetalI _m -Metal2 _n -Support where  m is in a range between 1-20% by weight, and  n is in a range between 0-20% by weight. 11. Method for obtaining secondary amines in a single reactor according to claim 10, characterized in that m is in a range between 1-5% by weight, and n is in a range between 0-5% by weight. 12. Procedure for obtaining secondary amines in a single reactor according to claims 10 and 11, characterized in that the metal 1 is palladium and the metal 2 is gold. 13. Method for obtaining secondary amines in a single reactor according to claim 1, characterized in that the solvent is selected from hexane, tetrahydrofuran, ether, dichloromethane, dioxane and combinations thereof. 14. Method for obtaining secondary amines in a single reactor according to claim 13, characterized in that the solvent is selected from hexane, dichloromethane and combinations thereof. 15. Method of obtaining secondary amines in a single reactor according to claim 1, characterized in that the acid is selected from hydrochloric acid, methanesulfonic acid, acetic acid, paratoluenesulfonic acid, an acid function forming part of the support and combinations thereof. 16. Method of obtaining secondary amines in a single reactor according to claim 15, characterized in that the acid is methanesulfonic acid. 17. Method of obtaining secondary amines in a single reactor according to claim 1, characterized in that it is carried out at a temperature between 10 and 80 ° C, at a pressure between 5 and 20 atmospheres and during a reaction time between a hour and five days 18. Method of obtaining secondary amines in a single reactor according to claim 1, characterized in that the amount of solvent is 0.1-20 milliliters per millimol of nitroderivative. 19. Method of obtaining secondary amines in a single reactor according to claim 18, characterized in that the amount of solvent is 10 milliliters per millimol of nitro-derivative. 20. Method of obtaining secondary amines in a single reactor according to claim 1, characterized in that the molar ratio between the nitrobenzene derivative: catalyst: hydrogen: acid is between 100: 20-1: 800-200: 200-100. 21. Method of obtaining secondary amines in a single reactor according to claim 20, characterized in that the molar ratio between the nitrobenzene derivative: catalyst: hydrogen: acid is 100: 5: 600: 100. 22. Method of obtaining secondary amines in a single reactor according to claim 1, characterized in that the product obtained is cyclohexylaniline. 23. Method of obtaining secondary amines in a single reactor according to claim 22, characterized in that it is carried out at a temperature between 14 and 60 and at a pressure between 8 and 12 atmospheres. 24. Method of obtaining secondary amines in a single reactor according to claim 1, characterized in that the product obtained is dicyclohexylamine. 25. Method of obtaining secondary amines in a single reactor according to claim 24, characterized in that it is carried out at a temperature between 30 and 80 and at a pressure between 10 and 15 atmospheres.