A method for preparing sodium dihydrogen bis(2-methoxyethoxy)aluminate

Abstract

This application discloses a method for preparing sodium dihydrobis(2-methoxyethoxy)aluminate, belonging to the field of organic synthesis technology. The method uses aluminum powder, ethylene glycol monomethyl ether, and metallic sodium as main raw materials, and carries out a hydrogenation reaction under the action of a Raney nickel catalyst to generate the target product, sodium dihydrobis(2-methoxyethoxy)aluminate. The sodium dihydrobis(2-methoxyethoxy)aluminate prepared by this process uses inexpensive and readily available raw materials, is simple to operate, and has a yield of over 98.5%. It boasts high yield, low cost, and a short process route, reducing production costs compared to existing technologies and making it suitable for industrial production.

Description

Technical Field

[0001] This application belongs to the field of organic synthesis technology, and in particular relates to a method for preparing sodium dihydrobis(2-methoxyethoxy)aluminate. Background Technology

[0002] Red aluminum, chemically known as sodium dihydrobis(2-methoxyethoxy)aluminate, has strong reducing properties, good safety, and wide applicability. It has broad development prospects in industries such as pharmaceuticals, liquid crystals, and polymer synthesis, and is the best alternative to active reducing agents such as lithium aluminum hydride, sodium borohydride, and borane.

[0003] Patent US005112991A mentions that aluminum alloy powder is used as raw material, and a large amount of hydrogen gas is generated during the reaction of aluminum alloy powder with ethylene glycol monomethyl ether. After the reaction is completed, the hydrogen gas needs to be discharged before the next reaction can be carried out. After cooling to room temperature, metallic sodium is added, and then hydrogen is added at 150 °C with a hydrogenation pressure of 5-10 MPa. This method has high equipment cost and production risk, and aluminum-titanium alloy has high cost.

[0004] Patent CN114437123A mentions placing NaH and aluminum methoxyethoxy in a reaction vessel, adding toluene and stirring, then adding aluminum trichloride / THF complex dropwise. After the addition is complete, stirring is continued for 0.5-2 hours, followed by solid-liquid separation to obtain the supernatant. Concentration yields a 70% toluene solution of sodium dihydrobis(2-methoxyethoxy)aluminate. This method involves a long reaction process and uses expensive raw materials.

[0005] Patent CN117447317A mentions that a 70% toluene solution of sodium dihydrobis(2-methoxyethoxy)aluminate is prepared by preparing an aluminum hydride suspension and a sodium alkoxide solution; however, this method involves a long reaction process and uses expensive raw materials.

[0006] In existing technologies, the production process of red aluminum is costly and complex. Developing a new process to reduce the price of red aluminum has become a research hotspot. Summary of the Invention

[0007] The purpose of this application is to provide a method for preparing sodium dihydrobis(2-methoxyethoxy)aluminate, so as to solve the technical problems of expensive raw materials, complicated reaction routes, high production costs and low yield in the existing red aluminum synthesis process.

[0008] To achieve the above objectives, the technical solution adopted in this application is: to provide a method for preparing sodium dihydrobis(2-methoxyethoxy)aluminate, specifically including the following steps:

[0009] (a) Add metallic sodium, aluminum powder, toluene and Raney nickel to the reaction vessel, ventilate in a closed environment, heat up and start stirring;

[0010] (ii) Continue to add ethylene glycol monomethyl ether dropwise to the reaction vessel to carry out the reaction; during the reaction, pressurize and maintain pressure; cool down and separate the solid and liquid to obtain sodium dihydrobis(2-methoxyethoxy)aluminate.

[0011] In one embodiment,

[0012] In step (i), the molar ratio of metallic sodium to aluminum powder is 1-1.1 : 1.2-1.5, the molar ratio of metallic sodium to toluene is 1-1.1 : 0.66-0.7, and the molar ratio of metallic sodium to Raney nickel is 1-1.1 : 0.01-0.015.

[0013] In one embodiment,

[0014] The specific operation of the gas exchange in step (1) is as follows: use nitrogen and hydrogen to replace the gas 3 times each.

[0015] In one embodiment,

[0016] The temperature for heating in step (1) is 90-130 ℃.

[0017] In one embodiment,

[0018] The stirring speed in step (1) is 400-800 rpm.

[0019] In one embodiment,

[0020] The molar ratio of metallic sodium to ethylene glycol monomethyl ether is 1-1.1 : 2-2.3.

[0021] In one embodiment,

[0022] The ethylene glycol monomethyl ether is added in step (ii) over a period of 3-6 hours.

[0023] In one embodiment,

[0024] The gas used for filling in step (ii) is hydrogen.

[0025] In one embodiment,

[0026] The pressure for holding pressure in step (ii) is 5-8 MPa.

[0027] In one embodiment,

[0028] The temperature for cooling in step (ii) is room temperature.

[0029] This application provides a method for preparing sodium dihydrobis(2-methoxyethoxy)aluminate. The method uses aluminum powder, ethylene glycol monomethyl ether, and metallic sodium as main raw materials, and a hydrogenation reaction is carried out under the action of a Raney nickel catalyst to generate the target product, sodium dihydrobis(2-methoxyethoxy)aluminate. The reaction mechanism is as follows: the intermediate of the reaction between metallic sodium and the alcohol ether is hydrogenated on the surface of Raney nickel to generate sodium dihydrobis(2-methoxyethoxy)aluminate. The sodium dihydrobis(2-methoxyethoxy)aluminate prepared by this process uses inexpensive and readily available raw materials, is simple to operate, and has a yield of over 98.5%. It boasts high yield, low cost, and a short process route, reducing production costs compared to existing technologies and making it suitable for industrial production. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The NMR spectrum of sodium dihydrobis(2-methoxyethoxy)aluminate in Example 1 is shown. Detailed Implementation

[0032] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, this application will be further described in detail. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.

[0033] Example 1

[0034] (a) Add 24.01 g of metallic sodium, 37.27 g of aluminum powder, 62.01 g of toluene and 0.60 g of Raney nickel to the reactor, combine the reactors, and purge with nitrogen and hydrogen three times respectively; heat the reactor to 90 ℃ and stir at 400 rpm.

[0035] (II) 152.20 g of ethylene glycol monomethyl ether was added dropwise to the reaction vessel and the reaction was completed over 3 hours. Then, hydrogen gas was introduced to a pressure of 6.91 MPa and maintained until the reaction was terminated. After cooling to room temperature, solid-liquid separation was performed to obtain the final product, sodium dihydrobis(2-methoxyethoxy)aluminate, with a hydrogen yield of 98.1%. The NMR spectrum of sodium dihydrobis(2-methoxyethoxy)aluminate is shown below. Figure 1 As shown.

[0036] Example 2

[0037] (a) Add 26.01 g of metallic sodium, 45.27 g of aluminum powder, 64.01 g of toluene and 0.84 g of Raney nickel to the reactor, combine the reactors, and purge with nitrogen and hydrogen three times respectively; heat the reactor to 130 ℃ and stir at 600 rpm;

[0038] (ii) 172.20 g of ethylene glycol monomethyl ether was added dropwise to the reaction vessel and the reaction was completed in 4 h; then hydrogen gas was introduced to 7.96 MPa and the pressure was maintained until the reaction was terminated; after cooling to room temperature, solid-liquid separation was performed to obtain the product sodium dihydrobis(2-methoxyethoxy)aluminate with a hydrogen yield of 98.7%.

[0039] Example 3

[0040] (a) Add 25.01 g of metallic sodium, 39.27 g of aluminum powder, 63.01 g of toluene and 0.75 g of Raney nickel to the reactor, combine the reactors, and purge with nitrogen and hydrogen three times respectively; heat the reactor to 100 ℃ and stir at 800 rpm;

[0041] (ii) 162.20 g of ethylene glycol monomethyl ether was added dropwise to the reaction vessel and the reaction was completed in 5 h; then hydrogen gas was introduced to 7.97 MPa and the pressure was maintained until the reaction was terminated; after cooling to room temperature, solid-liquid separation was performed to obtain the product sodium dihydrobis(2-methoxyethoxy)aluminate with a hydrogen yield of 98.9%.

[0042] Example 4

[0043] (a) Add 24.34 g of metallic sodium, 38.37 g of aluminum powder, 62.01 g of toluene and 0.71 g of Raney nickel to the reactor, combine the reactors, and purge with nitrogen and hydrogen three times respectively; heat the reactor to 110 ℃ and stir at 700 rpm;

[0044] (ii) 156.20 g of ethylene glycol monomethyl ether was added dropwise to the reaction vessel and the reaction was completed in 4 h. Then, hydrogen gas was introduced to 4.95 MPa and the pressure was maintained until the reaction was terminated. After cooling to room temperature, solid-liquid separation was performed to obtain the product sodium dihydrobis(2-methoxyethoxy)aluminate with a hydrogen yield of 98.5%.

[0045] Example 5

[0046] (a) Add 25.44 g of metallic sodium, 39.77 g of aluminum powder, 63.21 g of toluene and 0.61 g of Raney nickel to the reactor, combine the reactors, and purge with nitrogen and hydrogen three times respectively; heat the reactor to 120 ℃ and stir at 700 rpm;

[0047] (ii) 166.20 g of ethylene glycol monomethyl ether was added dropwise to the reaction vessel and the reaction was completed in 6 h; then hydrogen gas was introduced to 6.95 MPa and the pressure was maintained until the reaction was terminated; after cooling to room temperature, solid-liquid separation was performed to obtain the product sodium dihydrobis(2-methoxyethoxy)aluminate with a hydrogen yield of 98.6%.

[0048] Example 6

[0049] (a) Add 24.44 g of metallic sodium, 37.77 g of aluminum powder, 61.23 g of toluene and 0.81 g of Raney nickel to the reactor, combine the reactors, and purge with nitrogen and hydrogen three times respectively; heat the reactor to 120 ℃ and stir at 800 rpm;

[0050] (ii) 156.23 g of ethylene glycol monomethyl ether was added dropwise to the reaction vessel and the reaction was completed in 5 h. Then, hydrogen gas was introduced to 7.98 MPa and the pressure was maintained until the reaction was terminated. After cooling to room temperature, solid-liquid separation was performed to obtain the product sodium dihydrobis(2-methoxyethoxy)aluminate with a hydrogen yield of 99.1%.

[0051] Comparative Example 1

[0052] (a) Add 27.44 g of metallic sodium, 47.77 g of aluminum powder, 64.21 g of toluene and 0.72 g of Raney nickel to the reactor, combine the reactors, and purge with nitrogen and hydrogen three times respectively; heat the reactor to 80 ℃ and stir at 800 rpm.

[0053] (ii) 176.23 g of ethylene glycol monomethyl ether was added dropwise to the reaction vessel and the reaction was completed in 2 h. Then, hydrogen gas was introduced to 3.88 MPa and the pressure was maintained until the reaction was terminated. After cooling to room temperature, solid-liquid separation was performed to obtain the product sodium dihydrobis(2-methoxyethoxy)aluminate with a hydrogen yield of 92.1%.

[0054] Comparative Example 2

[0055] (a) Add 23.44 g of metallic sodium, 30.77 g of aluminum powder, 64.24 g of toluene and 0.71 g of Raney nickel to the reactor, combine the reactors, and purge with nitrogen and hydrogen three times respectively; heat the reactor to 140 ℃ and stir at 800 rpm.

[0056] (ii) 151.23 g of ethylene glycol monomethyl ether was added dropwise to the reaction vessel and the reaction was completed in 2.5 h. Then, hydrogen gas was introduced to 4.78 MPa and the pressure was maintained until the reaction was terminated. After cooling to room temperature, solid-liquid separation was performed to obtain the product sodium dihydrobis(2-methoxyethoxy)aluminate with a hydrogen yield of 93.1%.

[0057] As can be seen from Examples 1-6 and Comparative Examples 1-2, the yield will decrease slightly if the reaction conditions deviate from the range of this process.

[0058] This application provides a method for preparing sodium dihydrobis(2-methoxyethoxy)aluminate, comprising the following steps: adding metallic sodium, aluminum powder, toluene, and Raney nickel to a reaction vessel, ventilating under a closed environment, heating, and stirring; continuing to add ethylene glycol monomethyl ether dropwise to the reaction vessel to carry out the reaction; maintaining pressure during the reaction; cooling and solid-liquid separation to obtain sodium dihydrobis(2-methoxyethoxy)aluminate. This method, through process optimization, shortens the reaction route and selects the cheaper and more efficient Raney nickel as a catalyst, which can reduce production costs and has industrial application value.

[0059] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing sodium dihydrobis(2-methoxyethoxy)aluminate, characterized in that, Specifically, the following steps are included: (i) Add metallic sodium, aluminum powder, toluene and Raney nickel to the reaction vessel, ventilate in a closed environment, heat up and start stirring; (ii) Continue to add ethylene glycol monomethyl ether dropwise to the reaction vessel to carry out the reaction; during the reaction, pressurize and maintain pressure; cool down and separate the solid and liquid to obtain sodium dihydrobis(2-methoxyethoxy)aluminate; In step (i), the molar ratio of metallic sodium to aluminum powder is 1-1.1 : 1.2-1.5, the molar ratio of metallic sodium to toluene is 1-1.1 : 0.66-0.7, and the molar ratio of metallic sodium to Raney nickel is 1-1.1 : 0.01-0.015; the heating temperature is 90-130 ℃; the specific operation of the gas exchange is: purging with nitrogen and hydrogen three times each. In step (ii), the molar ratio of sodium metal to ethylene glycol monomethyl ether is 1-1.1: 2-2.3; the holding pressure is 5-8 MPa; and the gas used for filling is hydrogen.

2. The method for preparing sodium dihydrobis(2-methoxyethoxy)aluminate according to claim 1, characterized in that, The stirring speed in step (1) is 400-800 rpm.

3. The method for preparing sodium dihydrobis(2-methoxyethoxy)aluminate according to claim 1, characterized in that, The ethylene glycol monomethyl ether is added in step (ii) over a period of 3-6 hours.

4. The method for preparing sodium dihydrobis(2-methoxyethoxy)aluminate according to claim 1, characterized in that, The temperature for cooling in step (ii) is room temperature.

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