CN115043714A - Environment-friendly method for synthesizing benzil - Google Patents
Environment-friendly method for synthesizing benzil Download PDFInfo
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- CN115043714A CN115043714A CN202210852585.4A CN202210852585A CN115043714A CN 115043714 A CN115043714 A CN 115043714A CN 202210852585 A CN202210852585 A CN 202210852585A CN 115043714 A CN115043714 A CN 115043714A
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- benzoin
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
- C07C45/29—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation of hydroxy groups
Abstract
A green and environment-friendly method for synthesizing benzil adopts potassium hydrogen persulfate composite salt as an oxidant and bromide salt as a catalyst, and synthesizes the benzil with high yield and high purity in a mixed solvent of water and an organic solvent at room temperature. Compared with the prior industrial method for producing the benzil by nitric acid oxidation, the method has the advantages of mild reaction conditions, simple operation, environmental protection, safety, high conversion rate and purity and the like, and has better application prospect and higher practical value.
Description
Technical Field
The invention relates to the technical field of chemical production, in particular to a green and environment-friendly method for synthesizing benzil.
Background
Diphenylethanedione is also named as benzil and benzil, is yellow rhombic crystal powder, shows special reaction activity due to the fact that the diphenylethanedione has a non-conjugated aromatic alpha-dicarbonyl structure, has wide application in production of biological medicines, pesticides and daily chemicals, is an important organic synthesis intermediate and organic chemical raw material, and is widely used for synthesizing pesticides, photosensitizers, photocuring agents of photocuring coatings, medical intermediates and the like. The synthetic method is that benzoin is used as raw material and is obtained by oxidation. The oxidation of benzoin can be divided into catalytic oxidation and non-catalytic oxidation, the catalytic oxidation is carried out by oxidant in the presence of catalyst such as metal oxide, metal organic complex, organic catalyst, nano-particle, etc.; the non-catalytic oxidation method is to directly oxidize benzoin to synthesize benzil without any catalyst. Can be used for oxidation of benzoinThere are many types of agents, which can be classified into inorganic oxidizing agents, organic oxidizing agents, carrier oxidizing agents, and the like. Inorganic oxidants such as HNO 3 、KMnO 4 、MnO 2 、CuCl 2 、NH 4 NO 3 /CH 3 COOH、Cu( OAc) 2 /NH 4 NO 3 /CH 3 COOH、FeCl 3 ·6H 2 O/CH 3 COOH、(NO 3 ) 3 CeBrO 3 ，BaFeO 4 The oxidation of inorganic oxidant is the most mature method with the advantages of simple operation in the synthesis process and suitability for large-scale production. The disadvantages are obvious, firstly, many inorganic oxidants have strong corrosivity and high toxicity, generate great corrosivity on chemical production equipment and bring great danger to related operators; secondly, the wastewater generated by the inorganic oxidant contains a large amount of metal ions, has high pollution, causes great pollution to the environment, brings harm to human survival, and does not conform to the concept of green chemistry; thirdly, many inorganic oxidants have the disadvantages of easy decomposition and difficult storage, and the oxidation performance is uncertain, the reaction conditions are complex, and the reaction is difficult to control in the oxidation process of benzoin, so that a stable, low-corrosivity and safe oxidant is urgently needed to replace the inorganic oxidants.
Organic oxidizers have the advantages of good solubility, high oxidation, mild reaction, and the like, and are often used to replace inorganic oxidizers. Dimethyl sulfoxide (DMSO) is a commonly used organic oxidizer, and DMSO/(COCl) is used as reported by Mancuso et al 2 As an oxidant, it can achieve 95% oxidation yield for benzoin (manuso a, Brownfain D,J. Org. Chem,1979, 44: 4148-4150). As an effective oxidizing agent, benzil tribromide (PTT) and N-bromosuccinimide (NBS) have also been reported in Hymine (Onmunol), and when PTT is used as the oxidizing agent, the reaction proceeds with stirring at room temperature (Hymenen (Onmunol), a study of benzoin oxidation, chemical and adhesive bonding, 1994, 48: 78-80). Ph for Ho 3 PBr 2 The oxidation of benzoin by/MeCN as an oxidant (Tse-Lok Ho,Synthesis，1972,697；Isao Furukawa , Mitsuhiro Sasaki , Takeshi Inoue & Tetsuo Ohta，Phosphorus, Sulfur and Silicon, 1998, 143, 85-99), Suman et al utilize NBS/NH 4 Cl system in CH 3 CN/H 2 Benzil was synthesized in 94% yield in a mixed solvent of O (Suman L. Jain and Bir Sain, Synth. Comm., 2006, 36: 1459-. Although the organic oxidants show the superior performance of the organic oxidants in the synthesis reaction of the benzil and have great success, many organic oxidants have serious environmental pollution, and many metal organic oxidants have higher manufacturing cost than common inorganic oxidants, are difficult to post-treat and cannot be recycled, and the defects limit the application of the organic oxidants in the industrial synthesis field.
H 2 O 2 The best benzoin oxidizing agent is/HBr, Vishal B. Sharma reports H without metal catalyst 2 O 2 Benzoin is oxidized by a/HBr oxidation system to obtain benzoin, and the yield reaches 96% in 30 minutes (Vishal B. Sharma,Synlett, 2005, 173-175). However, the reaction can only be carried out in a small amount, which has a good effect, cannot be scaled up and industrialized, and the bond cleavage often occurs to generate the benzoic acid by-product.
The synthesis of benzil by oxygen oxidation of benzoin is a green synthesis method, but can be carried out under the Catalysis of a catalyst or under other conditions meeting the requirement of an oxidant (Duzhongtian et al, a method for preparing benzil by catalytic oxidation of benzoin, CN 107903155, Yongke Hu, Lei Chen, binding Li, Catalysis Communications, 83 (2016) 82-87), the most commonly used catalyst is a Salen cobalt catalyst, but the Salen cobalt catalyst cannot be recycled, which increases the cost.
The synthesis of benzil, which is industrially mature at present, generally adopts a technology of oxidizing benzoin by nitric acid (Wang Xingshan et al, a synthesis process of benzoin dimethyl ether, CN 106563509A), adopts concentrated nitric acid as an oxidizing agent, and adopts a stirring kettle as a reactor. The process has the problems of long reaction time (8-12 h), low production efficiency, complex operation, poor safety and the like. And the products in the reaction contain a large amount of nitrogenOxides such as NO, NO 2 The environment is polluted greatly, and the physical and mental harms to operators are caused greatly. Therefore, the development of a novel method for preparing the benzil by oxidizing the benzoin, which is green, safe, stable and easy to operate, has important significance.
Disclosure of Invention
In view of the problems in the prior benzil production, the invention aims to provide a green benzil synthesis method which is simple to operate, safe in production, high in yield and purity and basically free of pollution to the environment. The organic solvent used in the production can be recycled, and the wastewater after the reaction contains partial inorganic salts which can be directly discharged after dilution. The specific invention content is as follows:
the invention provides a method for synthesizing benzil, which comprises the following steps:
(1) dissolving benzoin in an organic solvent, stirring until the benzoin is completely dissolved, then adding water and stirring to obtain a two-phase solution;
(2) adding bromide salt and oxone complex salt into the two-phase solution, and stirring the mixture to react until the raw material benzoin disappears;
(3) separating the reacted mixture to obtain water phase and organic phase, extracting the water phase with organic solvent, mixing the extract phase and organic phase, and adding saturated Na 2 SO 3 Washing with solution, water, anhydrous Na 2 SO 4 Drying;
(4) after filtering out the drying agent, the organic solvent was concentrated to give a pale yellow benzil product.
According to the method, the benzoin is oxidized by adopting the potassium hydrogen persulfate composite salt to prepare the benzil, a heavy metal catalyst is not needed, an oxidant which causes great pollution to the environment is not used, and a byproduct which causes environmental pollution is not generated after the reaction is finished. The method has the advantages of low production cost, mild reaction conditions, simple and convenient operation, greenness, cleanness and easy separation of product solvent, and is suitable for industrial production.
Preferably, in step (1), the organic solvent is selected from one of ethyl acetate, dichloromethane, dichloroethane, dimethyl carbonate or toluene, preferably ethyl acetate.
Preferably, the volume ratio of the organic solvent to the water in step (1) is 3:1 to 1:1, exemplary include 2.5:1, 2:1 or 1.5:1, etc., preferably 2:1 to 1: 1.
Preferably, the ratio of the volume of the organic solvent to the mass of benzoin in step (1) is 1:1 to 20:1mL/g, e.g., 2:1mL/g, 3:1mL/g, 4mL/g, 5mL/g, 6mL/g, 7mL/g, 8mL/g, 9mL/g, 10mL/g, 11mL/g, 12mL/g, 13mL/g, 14mL/g, 15mL/g, 16mL/g, 17mL/g, 18mL/g, or 19mL/g, etc.
Preferably, the bromide salt in step (2) is NaBr, KBr or NH 4 At least one of Br.
Preferably, the amount of bromide salt added in step (2) is 1wt% to 10wt% of the mass of benzoin, such as 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, or 9wt%, etc., preferably 4wt% to 6 wt%.
Preferably, the adding amount of the potassium hydrogen persulfate composite salt in the step (2) is 150wt% -300wt% of the mass of the benzoin, and preferably 200wt% -250 wt%.
Preferably, the operations in step (1) and step (2) are carried out at room temperature.
Compared with the prior art, the invention has the following beneficial effects:
the method for synthesizing the benzil adopts the oxone complex salt as the oxidant and the bromide salt as the catalyst, synthesizes the benzil in a mixed solvent of water and an organic solvent at high yield, and has the advantages of mild reaction conditions, simple operation, environmental protection, safety, high conversion rate and the like compared with the prior industrial method for producing the benzil by nitric acid oxidation, thereby having better application prospect and higher practical value.
The specific implementation mode is as follows:
the technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
1001.06g of benzoin was added to a mL round-bottomed flask, 20mL of ethyl acetate was added, the mixture was dissolved with stirring at room temperature, 10mL of water was added, 3.07g of oxonium complex salt was added to the reaction mixture, 0.05g of NaBr was added, and the temperature was controlled at 30 o C below, after reacting for 4 hours, the brownish red basically disappears, a reaction liquid aqueous phase and an organic phase are separated, the aqueous phase is extracted once by 10mL ethyl acetate, the extraction phase and the organic phase are combined, saturated Na is used for 2 SO 3 Washing the solution once, and anhydrous Na 2 SO 4 Drying, filtering the drying agent, concentrating and recovering the organic solvent to obtain light yellow crystals with the yield of 100 percent.
Example 2
1.06g of benzoin was added to a 100mL round-bottomed flask, 20mL of ethyl acetate was added, the mixture was dissolved with stirring at room temperature, 10mL of water was added, 2.1g of oxonium complex salt was added to the reaction mixture, 0.05g of NaBr was added, and the temperature was controlled at 30 deg.C o C below, after reacting for 4 hours, the brownish red basically disappears, a reaction liquid aqueous phase and an organic phase are separated, the aqueous phase is extracted once by 10mL ethyl acetate, the extraction phase and the organic phase are combined, saturated Na is used for 2 SO 3 Washing the solution once, and anhydrous Na 2 SO 4 Drying, filtering the drying agent, concentrating and recovering the organic solvent to obtain light yellow crystals with the yield of 95 percent.
Example 3
24.38g of benzoin was added to a 1L reaction flask, 250mL of ethyl acetate was added thereto, and after dissolving the resulting mixture with stirring at room temperature, 200mL of water was added thereto, 49.2g of oxone complex salt and 1.1g of NaBr were added to the reaction mixture, and after completion of the addition, the reaction was carried out at room temperature for 4 hours. The brown red basically disappears, the water phase and the organic phase of the reaction solution are separated, the water phase is extracted once by 100mL ethyl acetate, the extraction phase and the organic phase are combined, saturated Na is used for 2 SO 3 Washing the solution once, and anhydrous Na 2 SO 4 Drying, filtering the drying agent, concentrating and recovering the organic solvent to obtain light yellow crystals with the weight of 24g and the yield of 99.6 percent.
Example 4
In a 1L reaction flask, 21.2g of benzoin was added, 200mL of ethyl acetate was added, and after dissolving with stirring at room temperature, 150 g of benzoin was addedmL of water, 1.1g of NaBr was added to the reaction mixture, 49.2g of oxone complex salt was added to the reaction mixture, and the temperature was raised to 40% o C, stirring and reacting for 4 hours. Filtering the reaction solution, washing the solid with 100mL ethyl acetate, separating the aqueous phase, extracting the aqueous phase with 100mL ethyl acetate once more, combining the extract phase and the organic phase, and adding saturated Na 2 SO 3 Washing the solution once, and anhydrous Na 2 SO 4 Drying, filtering the drying agent, concentrating and recovering the organic solvent to obtain light yellow crystals, weighing 21.0g and having the yield of 100 percent.
Example 5
In a 1L reaction flask, 21.2g of benzoin was added, 150mL of ethyl acetate was added, and after dissolving with stirring at room temperature, 100mL of water was added, 1.1g of NaBr was added to the reaction mixture, 49.2g of oxone complex salt was added to the reaction mixture, and the reaction was stirred at room temperature for 4 hours. Filtering the reaction solution, washing the solid with 50mL ethyl acetate, separating the aqueous phase, extracting the aqueous phase with 50mL ethyl acetate once more, combining the extract phase and the organic phase, and adding saturated Na 2 SO 3 Washing the solution once, and anhydrous Na 2 SO 4 Drying, filtering the drying agent, concentrating and recovering the organic solvent to obtain light yellow crystals with the weight of 20.8g and the yield of 99 percent.
Example 6
1.06g of benzoin and 20mL of dichloroethane were added to a 100mL round-bottomed flask, and after dissolving the mixture with stirring at room temperature, 10mL of water was added, 2.46g of oxone complex salt and 0.05g of NaBr were added to the reaction mixture, and the temperature was controlled at 30 deg.C o C below, after reacting for 4 hours, the brownish red basically disappears, the water phase and the organic phase of the reaction liquid are separated, extracted once by 10mL ethyl acetate, the extraction phase and the organic phase are combined, and saturated Na is used for 2 SO 3 Washing the solution once, and anhydrous Na 2 SO 4 Drying, filtering the drying agent, concentrating and recovering the organic solvent to obtain light yellow crystals with the yield of 100 percent.
Example 7
In a 100mL round bottom flask, 1.06g of benzoin was added, 20mL of dimethyl carbonate was added, and after dissolving with stirring at room temperature, 10mL of water was added to the reaction mixtureAdding 2.46g of potassium hydrogen persulfate composite salt, then adding 0.05g of NaBr, and controlling the temperature at 30 DEG o C below, after reacting for 4 hours, the brownish red basically disappears, a reaction liquid aqueous phase and an organic phase are separated, the aqueous phase is extracted once by 10mL ethyl acetate, the extraction phase and the organic phase are combined, saturated Na is used for 2 SO 3 Washing the solution once, and anhydrous Na 2 SO 4 Drying, filtering the drying agent, concentrating and recovering the solvent to obtain light yellow crystals with the yield of 100 percent.
Example 8
1.06g of benzoin was added to a 100mL round-bottomed flask, 20mL of toluene was added, the resulting mixture was dissolved with stirring at room temperature, 10mL of water was added, 2.46g of oxonium complex salt was added to the reaction mixture, and 0.05g of NaBr was added thereto at a controlled temperature of 30 deg.C o C below, after reacting for 4 hours, the brownish red basically disappears, the water phase of the reaction solution is separated, the water phase is extracted once by 10mL ethyl acetate, the extraction phase and the organic phase are combined, saturated Na is used for 2 SO 3 Washing the solution once, and anhydrous Na 2 SO 4 Drying, filtering the drying agent, concentrating and recovering the solvent to obtain light yellow crystals with the yield of 93 percent.
The above description is only for the preferred embodiment of the present invention, but not limited to the description and the embodiments, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.
Claims (10)
1. The method for synthesizing the benzil is characterized by comprising the following steps
(1) Dissolving benzoin in an organic solvent, stirring until the benzoin is completely dissolved, then adding water and stirring to obtain a two-phase solution;
(2) adding bromide salt and oxone complex salt into the two-phase solution, and stirring the mixture to react until the raw material benzoin disappears;
(3) separating the reacted mixture to obtain water phase and organic phase, extracting the water phase with organic solvent, mixing the extract phase and organic phase, and adding saturated Na 2 SO 3 Washing with solution, water, anhydrous Na 2 SO 4 Drying;
(4) after filtering out the drying agent, the organic solvent was concentrated to give a pale yellow benzil product.
2. The method according to claim 1, wherein in step (1), the organic solvent is selected from one of ethyl acetate, dichloromethane, dichloroethane, dimethyl carbonate or toluene.
3. The method of claim 2, wherein the organic solvent is ethyl acetate.
4. The method according to claim 2 or 3, wherein in step (1), the volume ratio of the organic solvent to water is 3:1 to 1: 1.
5. The method according to claim 4, wherein in step (1), the volume ratio of the organic solvent to the water is 2:1 to 1: 1.
6. The method as claimed in claim 2, wherein in the step (1), the ratio of the volume of the organic solvent to the mass of the benzoin is 1:1-20:1 mL/g.
7. The method of claim 1, wherein the bromide salt in step (2) is NaBr, KBr or NH 4 At least one of Br.
8. A process according to claim 7, wherein in step (2) the bromide salt is added in an amount of from 1wt% to 10wt% based on the mass of benzoin.
9. The method as claimed in claim 1, wherein the oxone complex salt is added in the step (2) in an amount of 150wt% to 300wt% based on the mass of benzoin.
10. The method of claim 1, wherein the steps (1) and (2) are performed at room temperature.
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| CN115745762A (en) * | 2022-12-06 | 2023-03-07 | 内蒙古久日新材料有限公司 | Oxidation method for preparing benzil from benzoin |
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| CN115745762A (en) * | 2022-12-06 | 2023-03-07 | 内蒙古久日新材料有限公司 | Oxidation method for preparing benzil from benzoin |
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