Method for preparing diacyl compound by taking activated carbon as additive for preventing diacyl product from being excessively oxidized
By using activated carbon to prevent excessive oxidation, the problems of metal oxidants prone to moisture absorption and environmental pollution in the prior art are solved, and efficient, green and environmentally friendly synthesis of even-acyl compounds is achieved.
Patent Information
- Application Number
- CN202510491920.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-18
- Publication Date
- 2025-06-13
AI Technical Summary
In the prior art, metal oxidants used to synthesize oxyl compounds are prone to moisture absorption, difficult to preserve, and have problems of environmental pollution and high costs.
Activated carbon is used as an additive to prevent excessive oxidation of the oxyaceous products, and the oxyaceous compounds are rapidly synthesized by reacting with oxyaceous compounds, inorganic bases and aqueous ethanol in air or in oxygen.
A green and environmentally friendly synthesis method is realized, the reaction operation is simple, the product does not require additional separation and purification, the reaction speed is fast, the yield is significantly improved, and environmental pollution and reaction costs are reduced.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of organic synthesis, and relates to the synthesis of key organic intermediate benzilide compounds. Specifically, it relates to a method for preparing benzilide compounds by using activated carbon as an additive to prevent over-oxidation of benzilide products. Background Art
[0002] Benzilide compounds are a class of important organic synthesis intermediates. Especially among them, aromatic ring benzilide compounds have always been a research hotspot due to their good reactivity and important application value.
[0003] Taking benzil as an example:
[0004]
[0005] Taking benzil as the starting material, drugs or intermediates such as phenytoin, fosphenytoin, and benzilic acid can be synthesized. The currently commonly used synthesis method is: synthesizing benzil by an oxidation reaction using benzoin as the raw material. During the reaction process, a metal oxidant usually needs to be added.
[0006] The metal oxidants reported in the literature mainly involve Zn(NO 3 ) 2 / SiO 2 、MnO 2 、Cu 2+ 、Fe 3+ salts, etc. Among them, the most deeply studied and widely used is Fe 3+ salt. However, due to the characteristics of Fe 3+ salt such as being easy to absorb moisture, difficult to store, and easy to form a colloid with water, the application prospects of this type of oxidant are greatly limited.
[0007] With the proposal of the concept of green chemistry, researchers are committed to exploring simple, efficient, and green oxidation technologies, and looking for new and efficient oxidation systems without metal or metal salt additives, which is in line with the development direction of green chemistry and provides a green and effective way for the oxidation of benzoin compounds to prepare benzilide compounds. Summary of the Invention
[0008] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a method for preparing acylbenzene compounds with activated carbon as an additive to prevent over-oxidation of acylbenzene products. The present invention uses benzoin compounds as raw materials and activated carbon as an additive to prevent over-oxidation of acylbenzene products, and quickly synthesizes acylbenzene compounds. The synthesis method of the present invention is green and environmentally friendly, the reaction operation is simple, the product does not require additional separation and purification steps, the reaction speed is fast, the reaction yield is significantly improved, air is used as the oxidant, alcohol is used as the solvent, metal additives are not used, the environmental pollution is low, the reaction cost can be effectively reduced, and it is easy to promote and use.
[0009] The present invention is achieved through the following technical solutions:
[0010] A method for preparing acylbenzene compounds with activated carbon as an additive to prevent over-oxidation of acylbenzene products, comprising the following steps:
[0011] In a reactor, a benzoin compound, activated carbon, an inorganic base, and an ethanol aqueous solution are added in sequence, and stirred and reacted in air or oxygen for 20 to 240 minutes. After the reaction is complete, it is filtered, extracted, and separated to obtain an organic phase. After the organic phase is dried and concentrated, the finished acylbenzene compound can be obtained.
[0012] A further improvement of the present invention is:
[0013] The benzoin compound is benzoin, substituted benzoin, or heterocyclic benzoin.
[0014] Preferably, the benzoin compound is selected from benzoin, anisoin, or 2-hydroxy-1,2-bis(2-thienyl)ethan-1-one.
[0015] Further, the inorganic base is sodium hydroxide or potassium hydroxide or a mixture of the two.
[0016] Further, the mass ratio of the benzoin compound to the activated carbon is 1:1 to 2, and the molar ratio of the benzoin compound to the inorganic base is 1:1 to 3.
[0017] Further, when charging, 1 to 3 mL of ethanol needs to be added for every 1 mmol of the benzoin compound
[0018] Further, in the ethanol aqueous solution, the volume ratio of ethanol to water is 2 to 5:1;
[0019] And / or, dimethyl sulfoxide can also be added to the ethanol aqueous solution, and the volume ratio of ethanol, water, and dimethyl sulfoxide is 2 to 5:1:1.
[0020] Further, the temperature of the stirring reaction is -20 - 50 °C.
[0021] Preferably, the temperature of the stirring reaction is 0 - 30 °C.
[0022] Furthermore, during extraction, saturated brine and ethyl acetate are used for extraction.
[0023] The beneficial effects of the present invention are as follows:
[0024] In the present invention, activated carbon is used as an additive to prevent over-oxidation. The reaction proceeds through a free radical mechanism during the reaction process, generating hydrogen radicals and superoxide radical anions. The two will quickly combine to produce a hydroperoxide anion (HOO — ), and HOO — will further react with o-acyl compounds and produce benzoic anhydride through rearrangement. Benzoic anhydride will hydrolyze into sodium benzoate in an alkaline aqueous solution, resulting in a low yield of o-acyl compounds. After adding activated carbon, the free radicals and active functional groups in the activated carbon can not only react with hydrogen radicals and / or superoxide radical anions, but also stabilize superoxide radical anions, thereby reducing the generation of hydroperoxide anions, preventing the over-oxidation of o-acyl compounds, and increasing the yield of o-acyl compounds.
[0025] The synthesis method of the present invention is green and environmentally friendly. The reaction operation is simple, carried out at low temperature or room temperature, the product does not require additional separation and purification steps, the reaction rate is fast, the reaction yield is significantly increased, air is used as the oxidant, alcohol is used as the solvent, no metal additives are used, the amount of solvent is less, it is more green and environmentally friendly, the environmental pollution is low, the reaction cost can be effectively reduced, and it is easy to promote and use. Specific Embodiments
[0026] The present invention will be introduced in detail below in combination with specific embodiments.
[0027] The activated carbon used in the specific embodiments of the present invention is ordinary commercially available activated carbon.
[0028] Example 1: Preparation of Benzil
[0029]
[0030] 424 mg of benzoin, 509 mg of activated carbon, 160 mg of sodium hydroxide, 3.75 mL of ethanol, and 1.25 mL of water were successively added to a reaction flask, and the mixture was stirred and reacted at room temperature with an open mouth for 30 min. After the reaction was completed, 20 mL of saturated brine and 50 mL of ethyl acetate were added. After mixing evenly, the mixture was poured into a separatory funnel, the organic phase was collected, dried over anhydrous sodium sulfate, and concentrated to obtain 395 mg of benzil, with a yield of 94%. 91–93 °C.
[0031] 1 H NMR (400 MHz DMSO-d 6): δ 7.93 (d, J = 8.00 Hz, 4H), 7.80 (t, J = 8.00, 2H), 7.63 (t, J = 8.00 Hz, 4H) ppm.
[0032] 13 C NMR (100 MHz DMSO-d 6 ): δ 195.3, 136.0, 132.7, 130.1, 130.0 ppm.
[0033] Example 2: Preparation of Anisil
[0034]
[0035] Add 544 mg of anisoin, 653 mg of activated carbon, 160 mg of sodium hydroxide, 3.75 mL of ethanol, and 1.25 mL of water into the reaction flask in sequence. React at room temperature with stirring and an open mouth for 30 min. After the reaction is completed, add 20 mL of saturated brine and 50 mL of ethyl acetate. After mixing evenly, pour it into a separating funnel, collect the organic phase, dry it with anhydrous sodium sulfate, and concentrate to obtain 486 mg of anisil, with a yield of 90%. 132–134 °C.
[0036] 1 H NMR (400 MHz DMSO-d 6 ): δ 7.86 (d, J = 8.00 Hz, 4H), 7.12 (d, J = 8.00, 4H), 3.87 (s, 6H) ppm.
[0037] 13 C NMR (100 MHz DMSO-d 6 ): δ 194.0, 165.3, 132.5, 125.9, 115.3, 56.3 ppm.
[0038] Example 3: Preparation of 1,2-Bis(furan-2-yl)ethanedione
[0039]
[0040] Add 384 mg of furoin, 461 mg of activated carbon, 160 mg of sodium hydroxide, 3.75 mL of ethanol, and 1.25 mL of water into the reaction flask in sequence. React at 0 °C with stirring and an open mouth for 30 min. After the reaction is completed, add 20 mL of saturated brine and 50 mL of ethyl acetate. After mixing evenly, pour it into a separating funnel, collect the organic phase, dry it with anhydrous sodium sulfate, and concentrate to obtain the product: 209 mg of 1,2-bis(furan-2-yl)ethanedione, with a yield of 55%.
[0041] 1 H NMR (400 MHz DMSO-d 6): δ 8.23 (d, J = 1.6 Hz), 7.65 (d, J = 3.6 Hz, 2H), 6.84 (dd, J = 1.6 Hz, J’ = 3.6 Hz, 2H).
[0042] 13 C NMR (100 MHz DMSO-d 6 ): δ 178.3, 151.4, 149.1, 125.2, 114.3.
[0043] Example 4: Preparation of 1,2-bis(furan-2-yl)ethanedione
[0044] In this example, the reaction temperature was controlled at -20 °C, and other operations were substantially the same as those in Example 3, which will not be elaborated here. After concentration, 289 mg of 1,2-bis(furan-2-yl)ethanedione was obtained, with a yield of 76%.
[0045] Example 5: Preparation of benzil
[0046] In this example, 225 mg of potassium hydroxide was added, and other operations were substantially the same as those in Example 1, which will not be elaborated here. After concentration, 361 mg of benzil was obtained, with a yield of 86%.
[0047] Example 6: Preparation of benzil
[0048] In this example, the solvent was 3.75 mL of ethanol, 1.25 mL of water, and 1 mL of dimethyl sulfoxide. Other operations were substantially the same as those in Example 1, which will not be elaborated here. After concentration, 390 mg of benzil was obtained, with a yield of 93%.
[0049] Comparative Example 1
[0050] In this comparative example, 87 mg of activated carbon was added, and other operations were substantially the same as those in Example 1, which will not be elaborated here. After concentration, 239 mg of benzil was obtained, with a yield of 57%.
[0051] Comparative Example 2
[0052] In this comparative example, CharcoalActivated [Catalyst for Oxidation using Molecular Oxygen] activated carbon was used. Other operations were substantially the same as those in Example 1, which will not be elaborated here. After concentration, 284 mg of benzil was obtained, with a yield of 68%.
[0053] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and shall not be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit and essence of the present invention shall be covered within the protection scope of the present invention.
Claims
1. A method for preparing an acyl compound using activated carbon as an additive to prevent the acyl product from being over-oxidized, characterized in that: The method comprises the following steps: sequentially adding an acyloin compound, activated carbon, an inorganic base, and an ethanol aqueous solution (or a DMSO ethanol aqueous solution) into a reactor, stirring and reacting for 20 to 240 minutes in air or oxygen, filtering, extracting, and separating to obtain an organic phase after the reaction is complete, and drying and concentrating the organic phase to obtain a finished acyloyl compound.
2. The method for preparing aziridine compounds using activated carbon as an additive to prevent aziridine products from being over-oxidized according to claim 1, characterized in that: The acyloin compound is benzoin, substituted benzoin or heterocyclic acyloin.
3. The method for preparing aziridine compounds using activated carbon as an additive to prevent aziridine products from being over-oxidized according to claim 2, characterized in that: The acyloin compound is selected from benzoin, anise acyloin or 2-hydroxy-1,2-di(2-thienyl)ethane-1-one.
4. The method for preparing aziridine compounds using activated carbon as an additive to prevent aziridine products from being over-oxidized according to claim 1, characterized in that: The inorganic base is sodium hydroxide or potassium hydroxide or a mixture of the two.
5. The method for preparing aziridine compounds using activated carbon as an additive to prevent aziridine products from being over-oxidized according to claim 1, characterized in that: The mass ratio of the acyloin compound to the activated carbon is 1:1-2, and the molar ratio of the acyloin compound to the inorganic base is 1:1-3.
6. The method for preparing aziridine compounds using activated carbon as an additive to prevent aziridine products from being over-oxidized according to claim 1, characterized in that: When adding the feed, 1-3 mL of ethanol should be added for every 1 mmol of acyloin compound.
7. The method for preparing aziridine compounds using activated carbon as an additive to prevent aziridine products from being over-oxidized according to claim 1, characterized in that: In the ethanol aqueous solution, the volume ratio of ethanol to water is 2 to 5:
1. And / or, dimethyl sulfoxide may be added to the ethanol aqueous solution, and the volume ratio of the ethanol, water and dimethyl sulfoxide is 2-5:1:
1.
8. The method for preparing aziridine compounds using activated carbon as an additive to prevent aziridine products from being over-oxidized according to claim 1, characterized in that: The temperature of the stirring reaction is -20-50°C.
9. The method for preparing aziridine compounds using activated carbon as an additive to prevent aziridine products from being over-oxidized according to claim 8, characterized in that: The temperature of the stirring reaction is 0-30°C.
10. The method for preparing aziridine compounds using activated carbon as an additive to prevent aziridine products from being over-oxidized according to claim 1, characterized in that: The extraction is performed using saturated saline and ethyl acetate.