阅读说明：本技术 一种芳香族偶氮化合物的合成方法 (Synthetic method of aromatic azo compound ) 是由 胡宇强 韩利民 苏鹏康 于 2021-11-05 设计创作，主要内容包括：本发明属于偶氮化合物技术领域,公开了一种芳香族偶氮化合物的合成方法。本发明将芳香胺和催化剂按摩尔比1:0.05～0.06混合,在95～110℃反应22～25h,反应结束后冷却至室温,将产物进行萃取、减压蒸发、硅胶柱层析分离,得到芳香族偶氮化合物。本发明在反应器中通过一步法即可制得芳香族偶氮化合物,与目前偶氮苯类化合物合成的主要方法相比,本发明不需要贵金属化合物作为催化剂,也不需要有机溶剂体系,且无需氧化剂、还原剂等反应助剂,反应条件温和,反应产物收率较高,芳香胺原料可回收,不会对环境产生VOCs污染,符合绿色低碳的经济发展模式。(The invention belongs to the technical field of azo compounds, and discloses a synthetic method of an aromatic azo compound. According to the invention, aromatic amine and a catalyst are mixed according to a molar ratio of 1: 0.05-0.06, the mixture is reacted at 95-110 ℃ for 22-25 h, the reaction product is cooled to room temperature after the reaction is finished, and the product is extracted, evaporated under reduced pressure and separated by silica gel column chromatography to obtain the aromatic azo compound. Compared with the existing main method for synthesizing azobenzene compounds, the method does not need a noble metal compound as a catalyst, an organic solvent system, an oxidant, a reducing agent and other reaction assistants, has mild reaction conditions, higher reaction product yield, recoverable aromatic amine raw materials, and no pollution of VOCs to the environment, and accords with the green low-carbon economic development mode.)

1. A method for synthesizing an aromatic azo compound, comprising the steps of:

mixing aromatic amine and a catalyst, placing the mixture in a closed tube reactor, reacting at 95-110 ℃ for 22-25 h, cooling to room temperature after the reaction is finished, and extracting, decompressing and evaporating a product, and separating by silica gel column chromatography to obtain an aromatic azo compound;

the structural formula of the aromatic amine is as follows:

wherein R is hydrogen, trifluoromethyl, trichloromethyl, tribromomethyl, triiodomethyl, alkoxy or nitro;

the structural formula of the aromatic azo compound is as follows:

wherein R is independently hydrogen, trifluoromethyl, trichloromethyl, tribromomethyl, triiodomethyl, alkoxy or nitro.

2. The method for synthesizing an aromatic azo compound according to claim 1, wherein the catalyst is ferrocenyl cuprous alkynyl, and the preparation method comprises the following steps:

dissolving cuprous iodide in ammonia water with the mass concentration of 22-25% to obtain a solution A; dissolving ferrocenyl acetylene in absolute ethyl alcohol to obtain a solution B; dropwise adding the solution B into the solution A, stirring for 20-40 min, filtering the product, sequentially washing with water and absolute ethyl alcohol for 3-5 times, and drying to obtain ferrocenyl cuprous alkynyl;

wherein the mass-volume ratio of the cuprous iodide to the ammonia water is 28-32 mg:1 mL; the mass-volume ratio of the ferrocene acetylene to the absolute ethyl alcohol is 8-11 mg:1 mL; the volume ratio of the solution A to the solution B is 7-8: 5-6.

3. The method for synthesizing an aromatic azo compound according to claim 1 or 2, wherein the molar ratio of the aromatic amine to the catalyst is 1:0.05 to 0.06.

4. The method for synthesizing an aromatic azo compound according to claim 3, wherein the extractant used for extraction is dichloromethane.

5. The method for synthesizing the aromatic azo compound according to claim 2 or 4, wherein the eluent obtained by the silica gel column chromatography is dichloromethane and petroleum ether in a volume ratio of 1-2: 4-6.

6. The method for synthesizing an aromatic azo compound according to claim 3, wherein the aromatic amine is one or more of aniline, 4-methoxyaniline, and 3-trifluoromethylaniline.

Technical Field

The invention relates to the technical field of azo compounds, in particular to a synthetic method of an aromatic azo compound.

Background

Azo compounds can be used for coloring fibers, paper, ink, leather, plastics and color photographic materials, certain azo compounds can also be used as acid-base indicators and metal indicators in analytical chemistry, and aromatic azo compounds are used as important compound intermediates and widely applied to a plurality of fields such as organic dyes, biological medicines, food additives, free radical initiators, liquid crystal materials, nonlinear optical materials and the like.

As the synthesis method of the aromatic azo compound, there are mainly diazo coupling method, nitro reduction method, arylhydrazine oxidation method, arylamine oxidation method and the like. However, the synthesis of the aromatic azo compound needs to be carried out in an organic solvent, which is likely to cause VOCs pollution to the environment, and at the same time, expensive noble metal compounds are needed as catalysts, and a plurality of reaction aids are needed, which is not in line with the economic development mode of green and low carbon. For example, in the prior art CN113019449A, the reaction raw materials include polyoxometallate catalyst, additive, organic solvent, aromatic amine compound and oxidant, and the product yield is high, but the organic solvent used in the method is toluene, ether solvent and the like, which easily causes environmental pollution. For another example, CN105218395A in the prior art discloses that the raw materials are reacted in an organic solvent in the presence of a catalyst, an auxiliary, a promoter, and an alkali, wherein the reaction system uses a large amount of additives, and the catalyst further contains a noble metal palladium, which increases the production cost and is not favorable for green development.

Therefore, how to provide a preparation method for preparing the aromatic azo compound by a one-step method, which has a simple preparation method and needs no organic solvent in a reaction system, has important significance for the current green economic development and environmental protection.

Disclosure of Invention

The invention aims to provide a synthetic method of an aromatic azo compound, which solves the problems that the preparation of the azo compound in the prior art needs more organic solvent systems and additives, needs noble metal catalysts, is not beneficial to environmental protection and the like.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a synthetic method of an aromatic azo compound, which comprises the following steps:

mixing aromatic amine and a catalyst, placing the mixture in a closed tube reactor, reacting at 95-110 ℃ for 22-25 h, cooling to room temperature after the reaction is finished, and extracting, decompressing and evaporating a product, and separating by silica gel column chromatography to obtain an aromatic azo compound;

the structural formula of the aromatic amine is as follows:

wherein R is hydrogen, trifluoromethyl, trichloromethyl, tribromomethyl, triiodomethyl, alkoxy or nitro;

the structural formula of the aromatic azo compound is as follows:

wherein R is independently hydrogen, trifluoromethyl, trichloromethyl, tribromomethyl, triiodomethyl, alkoxy or nitro.

Preferably, in the above method for synthesizing an aromatic azo compound, the catalyst is ferrocenyl cuprous alkynyl, and the preparation method thereof comprises the following steps:

dissolving cuprous iodide in ammonia water with the mass concentration of 22-25% to obtain a solution A; dissolving ferrocenyl acetylene in absolute ethyl alcohol to obtain a solution B; and dropwise adding the solution B into the solution A, stirring for 20-40 min, filtering the product, sequentially washing with water and absolute ethyl alcohol for 3-5 times, and drying to obtain ferrocenyl cuprous alkynyl.

Preferably, in the synthesis method of the aromatic azo compound, the mass-volume ratio of the cuprous iodide to the ammonia water is 28-32 mg:1 mL; the mass-volume ratio of the ferrocene acetylene to the absolute ethyl alcohol is 8-11 mg:1 mL; the volume ratio of the solution A to the solution B is 7-8: 5-6.

Preferably, in the above method for synthesizing an aromatic azo compound, the molar ratio of the aromatic amine to the catalyst is 1:0.05 to 0.06.

Preferably, in the above method for synthesizing an aromatic azo compound, the extractant used for extraction is dichloromethane.

Preferably, in the above method for synthesizing an aromatic azo compound, the eluent separated by silica gel column chromatography is dichloromethane and petroleum ether at a volume ratio of 1-2: 4-6.

Preferably, in the above method for synthesizing an aromatic azo compound, the aromatic amine is one or more of aniline, 4-methoxyaniline and 3-trifluoromethylaniline.

Through the technical scheme, compared with the prior art, the invention has the following beneficial effects:

the aromatic azo compound can be prepared by taking aromatic amine as a raw material and a ferrocenyl alkynyl cuprous catalyst in a reactor through a one-step method, the aromatic amine is taken as the raw material and also taken as a solvent, and the air in the reactor can play an oxidizing role in the reaction process without adding an oxidant and a protective atmosphere. Compared with the existing main method for synthesizing azobenzene compounds, the method does not need a noble metal compound as a catalyst, an organic solvent system, reaction auxiliaries such as an oxidant and a reducing agent, has mild reaction conditions, high yield of reaction products and recoverable aromatic amine raw materials, does not generate VOCs pollution to the environment, and accords with the green low-carbon economic development mode.

Detailed Description

The invention provides a synthetic method of an aromatic azo compound, which comprises the following steps:

mixing aromatic amine and a catalyst, placing the mixture in a closed tube reactor, reacting for 22-25 h at 95-110 ℃, cooling to room temperature after the reaction is finished, and extracting, decompressing and evaporating the product, and separating by silica gel column chromatography to obtain the aromatic azo compound.

In the present invention, the structural formula of the aromatic amine is preferably:

among them, R is preferably hydrogen, trifluoromethyl, trichloromethyl, tribromomethyl, triiodomethyl, alkoxy, or nitro, more preferably hydrogen, trifluoromethyl, or alkoxy, and even more preferably trifluoromethyl.

In the present invention, the structural formula of the aromatic azo compound is preferably:

among them, R is independently preferably hydrogen, trifluoromethyl, trichloromethyl, tribromomethyl, triiodomethyl, alkoxy, or nitro, more preferably hydrogen, trifluoromethyl, or alkoxy, and even more preferably trifluoromethyl.

In the invention, the catalyst is preferably ferrocenyl alkynyl cuprous, and the preparation method comprises the following steps:

dissolving cuprous iodide in ammonia water with the mass concentration of 22-25% to obtain a solution A; dissolving ferrocenyl acetylene in absolute ethyl alcohol to obtain a solution B; and dropwise adding the solution B into the solution A, stirring for 20-40 min, filtering the product, sequentially washing with water and absolute ethyl alcohol for 3-5 times, and drying to obtain ferrocenyl cuprous alkynyl.

In the invention, the mass-to-volume ratio of cuprous iodide to ammonia water is preferably 28-32 mg:1mL, more preferably 28-30 mg:1mL, and even more preferably 29mg:1 mL; the mass-volume ratio of the ferrocenyl acetylene to the absolute ethyl alcohol is preferably 8-11 mg:1mL, more preferably 8-10 mg:1mL, and even more preferably 9.6mg:1 mL; the volume ratio of the solution A to the solution B is preferably 7-8: 5-6, more preferably 7-8: 6, and even more preferably 7: 6.

In the present invention, the molar ratio of the aromatic amine to the catalyst is preferably 1:0.05 to 0.06, more preferably 1:0.051 to 0.057, and still more preferably 1: 0.053.

In the invention, the reaction temperature is preferably 95-110 ℃, more preferably 99-107 ℃, and more preferably 103 ℃; the reaction time is preferably 22 to 25 hours, more preferably 23 to 25 hours, and still more preferably 23 hours. In the present invention, the reaction temperature is too low to allow the reaction to proceed efficiently; if the reaction temperature is too high, the raw materials may be carbonized and deteriorated.

In the present invention, the extractant for extraction is preferably dichloromethane.

In the invention, the eluent for silica gel column chromatography separation is preferably a mixture of dichloromethane and petroleum ether, and further preferably the mixture of dichloromethane and petroleum ether according to the volume ratio of 1-2: 4-6, more preferably dichloromethane and petroleum ether in a volume ratio of 1: 4, and (4) mixing.

In the present invention, the aromatic amine is preferably one or more of aniline, 4-methoxyaniline, and 3-trifluoromethylaniline, more preferably aniline or 4-methoxyaniline, and even more preferably 4-methoxyaniline.

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The embodiment provides ferrocenyl alkynyl cuprous provided with the following structural formula:

the preparation method comprises the following steps:

dissolving 1048mg of cuprous iodide in 35mL of 23% ammonia water by mass concentration to obtain a solution A; 288mg of ferroceneacetylene is dissolved in 30mL of absolute ethyl alcohol to obtain a solution B; dropwise adding the solution B into the solution A, stirring for 30min, generating a large amount of orange-red precipitate, filtering the product, sequentially washing with water and absolute ethanol for 3 times, and vacuum drying to obtain 316mg of ferrocenyl alkynyl cuprous (the measured decomposition temperature is 275 ℃) and the yield is 85.1%.

Example 2

And (3) synthesizing azobenzene, wherein the structural formula is as follows:

5.1mL (55.9mmol) of aniline and 727.0mg (2.8mmol) of ferrocenyl cuprous alkynyl (prepared in example 1) are added into a 25mL closed-loop reactor, and the reaction is stirred at 100 ℃ for 24 h; after the reaction is finished, cooling to room temperature, adding 20mL of dichloromethane for extraction, and removing dichloromethane by adopting a rotary evaporator through reduced pressure evaporation to obtain a crude product; the crude product was subjected to silica gel column chromatography (200 mesh silica gel) using dichloromethane and petroleum ether as eluents (dichloromethane: petroleum ether volume ratio: 1: 4) by gradient elution to obtain 4201.8mg of azobenzene as a pale yellow solid with a purity of 99% (melting point measured 60 to 61 ℃) and an isolated yield of 82.6%.

The nuclear magnetic resonance hydrogen spectrum and carbon spectrum data of the product are as follows:

nuclear magnetic resonance data:¹H NMR(500MHz,CDCl₃):δ7.45(m,2H),7.49(m,4H),7.92(m,4H)ppm.

¹³C NMR(125MHz,CDCl₃):δ122.8,129.0,130.9,152.6.

infrared spectrum data IR (KBr) v 690,774,1377,1462,2855,2925cm^-1.

Example 3

The synthesis of 4, 4' -bis (methoxy) azobenzene has the following structural formula:

5.0mL (43.0mmol) of 4-methoxyaniline and 559.5mg (2.2mmol) of ferrocenyl alkynyl cuprous oxide (prepared in example 1) are added into a 25mL closed-loop reactor, and the reaction is stirred at 104 ℃ for 23.5 h; after the reaction is finished, cooling to room temperature, adding 20mL of dichloromethane for extraction, and removing dichloromethane by adopting a rotary evaporator through reduced pressure evaporation to obtain a crude product; the crude product was subjected to silica gel column chromatography (300 mesh silica gel) using dichloromethane and petroleum ether as an eluent (dichloromethane: petroleum ether volume ratio: 1: 5) by gradient elution to obtain 4424.5mg of 4, 4' -bismethoxyazobenzene as a red-yellow solid with a purity of 99% (melting point measured 161-162 ℃), and the isolated yield was 85.0%.

The nuclear magnetic resonance hydrogen spectrum and carbon spectrum data of the product are as follows:

nuclear magnetic resonance data:¹H NMR(500MHz,CDCl₃):δ3.89(s,6H),7.00-7.02(d,4H),7.87-7.90(d,4H).

¹³C NMR(125MHz,CDCl₃):δ55.5,114.1,125.3,147.3,162.5.

infrared spectrum data IR (KBr) v 846,1257,1474,1499,1596,2927,2981cm^-1.

Example 4

The synthesis of 3, 3' -bis (trifluoromethyl) azobenzene has the following structural formula:

5.0mL (39.8mmol) of 3-trifluoromethylaniline and 494.8mg (1.9mmol) of ferrocenyl alkynyl cuprous oxide (prepared in example 1) were added into a 25mL closed-loop reactor, and the reaction was stirred at 99 ℃ for 25 h; after the reaction is finished, cooling to room temperature, adding 20mL of dichloromethane for extraction, and removing dichloromethane by adopting a rotary evaporator through reduced pressure evaporation to obtain a crude product; the crude product was subjected to silica gel column chromatography (300 mesh silica gel) using dichloromethane and petroleum ether as eluents (dichloromethane: petroleum ether volume ratio: 2: 6) by gradient elution to obtain 4321.5mg of 3, 3' -bistrifluoromethylazobenzene as a red-yellow solid with a purity of 99% (melting point was determined to be 81-82 ℃), and the separation yield was 68.3%.

The nuclear magnetic resonance hydrogen spectrum and carbon spectrum data of the product are as follows:

nuclear magnetic resonance data:¹H NMR(500MHz,CDCl₃):δ7.69(t,2H),7.77(d,2H),8.10(d,2H),8.22(s,2H).

¹³C NMR(125MHz,CDCl₃):δ119.9,126.6,128.0,129.8,152.4.

infrared spectrum data IR (KBr) v 694,811,1124,1189,1331,1440,1604,2924,3083cm^-1.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.