RU2479563C1 - Method of producing alkylbenzenes - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing alkylbenzenes of general formula

,where R₁=H; R₂=Et, i-Pr or R₁R₂=CH₂-CH₂-CH₂-, which involves hydrogenation of styrene with hydrogen gas in the presence of a catalyst, followed by separation of end products, which is characterised by that styrene or derivatives thereof selected from α-methylstyrene or indene are subjected to hydrogenation, and the catalyst used is nickel nanoparticles which are obtained by reducing nickel (II) chloride with lithium aluminium hydride in situ and the process is carried out at atmospheric pressure of hydrogen in a tetrahydrofuran medium at temperature of 50-60°C for 5-6 hours.

EFFECT: use of the invention simplifies the method of producing compounds of the disclosed structural formula.

1 cl, 3 ex

Description

The invention relates to a method for producing alkylbenzenes, in particular to a new method for the hydrogenation of styrene and its derivatives, which is applicable in the laboratory and allows to obtain alkylbenzenes with a saturated hydrocarbon chain of the general formula

where R ₁ = H: R ₂ = Et, i-Pr

or R ₁ R ₂ = —CH ₂ —CH ₂ —CH ₂ -,

which are used in organic synthesis as intermediates and solvents.

A known method of producing ethylbenzene by hydrogenation of styrene with hydrogen at atmospheric pressure in the presence of a specially prepared catalyst, the catalyst obtained by reducing nickel diacetate with sodium metal, zinc dust, lithium aluminum hydride or sodium borohydride [ACTIVATION OF REDUCING AGENTS. SODIUM HYDRIDE CONTAINING COWLEX REDUCING AGENTS.VII. NiC, A NEW HETEROGENEOUNS Ni HYDROGENATION CATALYST / J.J. BRUNET, P. GALLOIS, P. CAUBERE // Tetrahedron Letters 1977, - No. 45, p. 3955-3958].

The disadvantage of this method is the stage of neutralizing the excess of a flammable reducing agent, leading to the loss of quite expensive reagents, as well as the use of flammable and explosive hydrogen in a laboratory. The reaction products were determined by gas-liquid chromatography without isolation.

A known method for producing ethylbenzene by hydrogenation of styrene on nickel nanoparticles with hydrogen gas under mild conditions (temperature 35 ° C and pressure 2 atm) [Formation, nature of activity, and hydrogenation catalysis by nickel bis (acetylacetonate) -lithium tetrahydroaluminate systems. // L.B.Belykh, Yu.Yu. Titova, A.V. Rokhin, F.K.Shmidt // Inorganic Synthesis And Industrial Inorganic Chemistry. - Vol. 83, No. 11, 2010. - p. 1778-1786].

The disadvantage of this method is the use of a significant amount of relatively expensive lithium aluminum hydride as a hydrogenating agent, which significantly increases its consumption.

A known method of producing ethylbenzene by heterogeneous catalytic hydrogenation of styrene derivatives on iron nanoparticles [At the frontier between heterogeneous and homogeneous catalysis: hydrogenation of olefins and alkynes with soluble iron nanoparticles / C. Rangheard, C. de Julian Fernandez, Pim-Huat Phua, J. Hoorn, L. Lefort, JGde Vries // Dalton Trans., 2010, 39, 8464-8471].

The disadvantage of this method is the need to use an autoclave to create the required hydrogen pressure (20 atm). There are also certain difficulties with the preparation of a catalyst solution, which is prepared in a box with a nitrogen atmosphere for half an hour. In this way, compounds of the claimed structural formula were not obtained.

The closest analogue of the invention is a method for producing ethylbenzene by hydrogenation of styrene on a nickel-based bimetallic nanocatalyst with gaseous hydrogen [Nanosized bimetallic Ni-Sn and Ni-Zr catalysts prepared by SOMC / M route. Characterization and catalytic properties in styrene selective hydrogenation. // L. Deghedi, J.-M. Basset, J.-P. Candy, J.-A. Dalmon, A.-C. Dubreuil, L. Fischer // Chemical Ingineering Transactions. - 2009. - Vol.17, p.31-36].

The disadvantage of this method is the need to use a relatively high temperature (130 ° C) and a pressure of about 30 atm.

The objective of the proposed method is to develop a technologically advanced method for producing ethylbenzene or its derivatives by hydrogenation of styrene or its derivatives with gaseous hydrogen, which does not require the use of expensive catalysts and difficult technological conditions, which will allow to achieve high yield values for the initial olefin or its derivative in a chemical laboratory using available reagents. The technical result is a simplification of the method for producing compounds of the claimed structural formula.

The set result is achieved in a new method for producing alkylbenzenes of the General formula

where R ₁ = H: R ₂ = Et, i-Pr

or R ₁ —R ₂ = —CH ₂ —CH ₂ —CH ₂ -,

consisting in hydrogenation of styrene with hydrogen gas in the presence of a catalyst followed by isolation of the desired products, characterized in that styrene or its derivatives from the α-methylstyrene or indene series are hydrogenated, and nickel nanoparticles obtained by reduction of nickel (II) chloride with lithium aluminum hydride are used as a catalyst in situ, and the process is carried out at atmospheric pressure of hydrogen in tetrahydrofuran medium at a temperature of 50-60 ° C for 5-6 hours.

The essence of the method is the hydrogenation of styrene or its derivatives from the series: α-methylstyrene, indenase-hydrogen in tetrahydrofuran medium in the presence of nickel nanoparticles.

In the present invention, the entire synthesis is carried out in one stage: the preparation of the catalyst and hydrogenation proceed in situ. Also the advantage of the invention is the use of hydrogen at atmospheric pressure, which allows to simplify and reduce the cost of the method of obtaining the target products.

The method is as follows.

In a flat-bottomed flask, lithium aluminum hydride, tetrahydrofuran and anhydrous nickel (II) chloride are loaded in a molar ratio of lithium aluminum hydride: nickel (II) chloride equal to 1: 2, and a catalyst is obtained by the reaction

2NiCl ₂ + LiAlH ₄ = 2Ni ⁰ + LiCl + AlCl ₃ + 2H ₂ .

The amount of aluminum hydride is calculated based on the amount of catalyst obtained with a slight excess and, therefore, olefin hydroalumination does not occur. After obtaining a black, transparent in a thin layer of a colloidal metal solution, a hydrogenated substrate is loaded and hydrogen gas is bubbled through the reaction mass, which is previously passed through a layer of concentrated sulfuric acid to remove any traces of moisture at atmospheric pressure for 5-6 hours at a temperature of 50-60 ° C. The catalyst during the reaction coagulates and agglomerates of particles are formed, which can then be separated by filtration. If necessary, a few drops of water are added to the reaction mixture to coagulate the catalyst particles. The desired product is isolated from the filtrate by distillation at atmospheric pressure or in vacuum.

The properties of the synthesized ethylbenzene, isopropylbenzene and indane are consistent with published data.

Since stabilization of colloidal solutions of nickel nanoparticles is not required, this greatly simplifies and reduces the cost of the proposed method of hydrogenation. The resulting suspensions can be used as a reduction catalyst without isolation of nanoparticles, but the activity of the return catalyst is less. Since the same conditions are used in the synthesis of the catalyst and the reduction of the claimed compounds, the whole process is reduced to a one-step synthesis, in which the catalyst is formed in situ from nickel (II) chloride.

The invention is illustrated by the following examples:

Example 1

Ethylbenzene.

In a flat-bottomed flask equipped with a bubbler and reflux condenser, a suspension of 0.5 g (0.13 mol) of lithium aluminum hydride in 50 ml of dried tetrahydrofuran is charged, after which 3.5 g (0.028 mol) of anhydrous nickel (II) chloride are gradually added to this observed the formation of a black colloidal solution. After that, hydrogen bubbling is started and 50 g (0.48 mol) of styrene are added. The reaction is carried out by heating to 50 ° C for 5 hours. Upon completion of the reaction, the mixture is cooled, add 10 ml of water to accelerate the coagulation of the catalyst. The precipitated precipitate is filtered off, the organic layer of the filtrate is separated and tetrahydrofuran is distilled off. The residue was distilled at atmospheric pressure to obtain 38.7 g (0.365 mol, 76%) of ethylbenzene, a colorless liquid with a characteristic odor, because 133-135 ° C. ¹ H NMR spectrum, δ, ppm: 1.18 t (3H, CH ₃ ); 2.56 q (2H, CH ₂ ); 7.02-7.21 m (5H, C ₆ H ₅ ).

Example 2

Isopropylbenzene.

In a flat-bottomed flask equipped with a bubbler and reflux condenser, a suspension of 0.48 g (0.0125 mol) of lithium aluminum hydride in 50 ml of dried tetrahydrofuran was charged, after which 0.5 g (0.003 mol) of anhydrous nickel (II) chloride was added and 0 5 g (0.002 mol) of anhydrous chromium (III) chloride, while the formation of a black colloidal solution is observed. After that, hydrogen bubbling is started and 30 g (0.25 mol) of α-methylstyrene are added. The reaction is carried out by heating to 50 ° C for 6 hours. Upon completion of the reaction, the mixture is cooled, 5 ml of water are added to accelerate the coagulation of the catalyst. The precipitated precipitate is filtered off, the organic layer of the filtrate is separated and tetrahydrofuran is distilled off. The residue was distilled at atmospheric pressure to obtain 23.4 g (0.195 mol, 78%) of isopropylbenzene, a colorless liquid with a characteristic odor, because 152-155 ° C. ¹ H NMR spectrum, δ, ppm: 1.17 t (6H, 2CH ₃ ); 2.79 m (1H, CH); 6.97-7.12 m (5H, C ₆ H ₅ ).

Example 3

Indan.

In a flat-bottomed flask equipped with a bubbler and reflux condenser, a suspension of 1 g (0.026 mol) of lithium aluminum hydride in 20 ml of dried tetrahydrofuran is charged, after which 4 g (0.031 mol) of anhydrous nickel (II) chloride are gradually sprinkled, and a black colloidal solution is formed. After that, hydrogen bubbling is started and 24.2 g (0.21 mol) of indene are added. The reaction is carried out by heating to 60 ° C for 6 hours. At the end of the reaction, the mixture is cooled, add 3 ml of water to accelerate the coagulation of the catalyst. The precipitated precipitate is filtered off, the organic layer of the filtrate is separated and tetrahydrofuran is distilled off. The residue was distilled at atmospheric pressure to obtain 20.3 g (0.172 mol, 82%) of indane, a colorless liquid with a characteristic odor, because 176-177 ° C. ¹ H NMR spectrum, δ, ppm: 1.90 m (2H, CH ₂ ); 2.74 t (4H, 2CH ₂ ); 6.90-7.01 m (4H, C ₆ H ₄ ).

Thus, the above information indicates the fulfillment of the following set of conditions when using the claimed invention:

- a tool embodying the claimed invention in its implementation, is intended for use in laboratory conditions;

- for the claimed invention in the form described in the independent clause of the claims below, the possibility of its implementation using the means and methods described above or known prior to the priority date is confirmed;

- a tool embodying the claimed invention in its implementation, is able to ensure the achievement of a technical result.

findings

A new method has been developed for the production of alkylbenzenes by hydrogenation of styrene and its derivatives with hydrogen at atmospheric pressure in the presence of nickel nanoparticles, which proceeds with high yields of the initial olefins. The properties of the synthesized compounds correspond to published data.

Claims (1)

The method of producing alkylbenzenes of the General formula

where R ₁ is H: R ₂ is Et, i-Pr or
R ₁ R ₂ - -CH ₂ -CH ₂ -CH ₂ -,
consisting in hydrogenation of styrene with hydrogen gas in the presence of a catalyst followed by isolation of the desired products, characterized in that styrene or its derivatives from the α-methylstyrene or indene series are subjected to hydrogenation, and nickel nanoparticles obtained by reduction of nickel (II) chloride by lithium aluminum hydride are used as a catalyst in situ, and the process is carried out at atmospheric pressure of hydrogen in tetrahydrofuran medium at a temperature of 50-60 ° C for 5-6 hours