A process for preparing m-chloroperbenzoic acid using a molecular sieve catalyst

Abstract

The present invention discloses a process for preparing m-chloroperbenzoic acid by using a molecular sieve catalyst, belonging to the technical field of chemical catalytic preparation, and comprising the following steps: S1, dissolving m-chlorobenzoic acid in an organic solvent, adding the molecular sieve catalyst, uniformly stirring, and then dropwise adding an aqueous oxidant solution with a mass fraction of 15% to 30% for an oxidation reaction; S2, after the oxidation reaction is completed, separating the molecular sieve by using a filter for the next reaction; S3, after separation, extracting and separating the organic phase, distilling and recovering the organic solvent to obtain m-chloroperbenzoic acid crystals. The present invention overcomes the defects and deficiencies in the existing process methods, such as low effective yield and serious wastewater pollution. A solid molecular sieve is used as the catalyst. The catalyst has stable properties, simple separation, the solvent can be recycled and reused in the process, the product yield is high, environmental problems caused by other oxidation methods are avoided, and it is beneficial to large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical catalytic preparation, and in particular to a process for preparing m-chloroperbenzoic acid by using a molecular sieve catalyst. Background Art

[0002] m-Chloroperbenzoic acid is a commonly used oxidant in organic synthesis. It can oxidize olefins, carbonyl compounds, nitrogen, sulfur, phosphorus, selenium, iodine compounds, imines, alkanes, active methylene groups, enol silanes, etc., and is widely used in the fields of chemicals, pharmaceuticals, agrochemicals, etc. The existing technology mainly uses the hydrogen peroxide oxidation method to oxidize m-chlorobenzoyl chloride in an alkaline organic solvent, and then obtains m-chloroperbenzoic acid through acidification, extraction, drying, and solvent removal by vacuum distillation, or makes slight improvements on this basis. This process uses m-chlorobenzoyl chloride as the raw material and hydrogen peroxide as the oxidant, and reacts with an inorganic base in a mixed solvent of an organic solvent such as methanol, ethanol, acetone, dioxane, ethyl acetate, dimethylformamide and water, and then undergoes acidification, extraction, drying, and vacuum distillation. This process has the following problems: ① The raw material m-chlorobenzoyl chloride itself is unstable and is extremely easy to hydrolyze when encountering water; ② A large amount of heat is released during the reaction process, and the temperature is not easy to control; ③ Hydrogen peroxide is easy to decompose when heated under alkaline conditions; ④ Adding alkali first and then acid, the process is complex and increases the operation difficulty; ⑤ The reaction solvent has a relatively large polarity, which will affect the distribution of m-chloroperbenzoic acid during the extraction process, resulting in part of the product existing in the aqueous phase, requiring multiple extractions and being difficult to separate completely. Multiple factors lead to a low effective yield of m-chloroperbenzoic acid.

[0003] In the invention patent with the publication number CN1322713A and the name of "A Method for Preparing m-Chloroperbenzoic Acid", a method for obtaining the product m-chloroperbenzoic acid by carrying out an oxidation reaction in solvents such as methanol, ethanol, chloroform, and carbon tetrachloride using hydroxyethylidene diphosphonic acid as a catalyst is disclosed. This method is an improvement on the hydrogen peroxide oxidation method, and the product and the solvent are naturally separated by means such as centrifugal filtration and precipitation without vacuum distillation separation. However, the product has a certain solubility in solvents such as methanol, ethanol, chloroform, and carbon tetrachloride. Therefore, there is still part of the product in the solvent after centrifugation or filtration. The yield of m-chloroperbenzoic acid prepared by this method is low, and using hydroxyethylidene diphosphonic acid as a catalyst is expensive and not easily available, increasing the production cost and being unfavorable for industrial production.

[0004] In the invention patent with the publication number CN111039842A and the title "A Method for Preparing m-Chloroperbenzoic Acid by Phase Transfer Catalysis", it is disclosed that quaternary ammonium salts or phosphonium salt surfactants such as tetrabutylammonium bromide and methyltriphenylphosphonium chloride are used as phase transfer agents to prepare m-chloroperbenzoic acid. However, due to the type of phase transfer agent used in this process, a large amount of wastewater will be generated during the preparation process, resulting in serious pollution, high post-treatment costs, and not conforming to the development concept of green environmental protection.

[0005] Therefore, the present invention proposes a process method for preparing m-chloroperbenzoic acid using a molecular sieve catalyst to solve the above problems. Summary of the Invention

[0006] The object of the present invention is to provide a process method for preparing m-chloroperbenzoic acid using a molecular sieve catalyst, which overcomes the defects and deficiencies such as low effective yield and serious wastewater pollution in the existing process methods. A solid molecular sieve is used as the catalyst, which has stable properties and simple separation. The solvent in this process can be recovered and reused, the product yield is high, and the environmental problems brought by other oxidation methods are avoided, which is conducive to large-scale industrial production.

[0007] To achieve the above object, the present invention provides a process method for preparing m-chloroperbenzoic acid using a molecular sieve catalyst, including the following steps:

[0008] S1. Dissolve m-chlorobenzoic acid in an organic solvent, add a molecular sieve catalyst, stir evenly, and then dropwise add an aqueous oxidant solution with a mass fraction of 15% - 30% for an oxidation reaction.

[0009] S2. After the oxidation reaction is completed, use a filter to separate the molecular sieve for the next reaction.

[0010] S3. After separation, extract and separate the organic phase, distill and recover the organic solvent, and the distillation is carried out at normal pressure or reduced pressure to obtain m-chloroperbenzoic acid crystals.

[0011] Preferably, in S1, the molar ratio of m-chlorobenzoic acid to the oxidant is 1:(1.5 - 4), and the mass ratio of m-chlorobenzoic acid to the molecular sieve catalyst is 1:(0.05 - 0.1).

[0012] Preferably, in S1, the molar ratio of m-chlorobenzoic acid to the oxidant is 1:1.5, and the mass ratio of m-chlorobenzoic acid to the molecular sieve catalyst is 1:0.05.

[0013] Preferably, in S1, the pH of the aqueous oxidant solution is 1.5 - 4, and the mass fraction of the oxide aqueous solution is 30%.

[0014] Preferably, the pH of the aqueous oxide solution is 2.5 - 4, and the oxidizing property is stronger within this range; the oxide is one or more of hydrogen peroxide, potassium chlorate, benzoyl peroxide, potassium permanganate, sodium chlorate, potassium persulfate, sodium persulfate, and ammonium persulfate.

[0015] Preferably, the temperature of the oxidation reaction is 30°C; if the oxidation reaction temperature is too high, the volatilization of the organic solvent will be accelerated, which is not conducive to the continuous progress of the reaction, and the product m-chloroperbenzoic acid will decompose, resulting in a decrease in the yield; if the temperature is too low, the reaction rate is too slow, the time consumption is long, the reaction is incomplete, and the product yield will also decrease.

[0016] The time of the oxidation reaction is 12 - 15 h. If the oxidation reaction time is too short, the reaction is incomplete and the product yield is relatively low; as the reaction time extends, the product yield gradually increases; however, after the reaction time reaches a certain level, the yield tends to be stable. Further extending the reaction time will not cause much change in the yield, but will increase the energy consumption.

[0017] Preferably, the molecular sieve catalyst is one or more of titanium silicate molecular sieve TS-1 and aluminosilicate molecular sieve ZSM-5. The molecular sieve catalyst can efficiently catalyze the oxidation reaction of the oxidant and m-chlorobenzoic acid to produce m-chloroperbenzoic acid, and the molecular sieve can be reused.

[0018] Preferably, the molecular sieve catalyst is titanium silicate molecular sieve TS-1.

[0019] Preferably, the organic solvent is one or more of dichloromethane, dichloroethane, chloroform, and carbon tetrachloride.

[0020] Preferably, the volume ratio of the organic solvent to the mass of m-chlorobenzoic acid is (3 - 10):1 mL / g.

[0021] The reaction mechanism of the present invention is as follows: The active site of the TS-1 catalyst is precisely based on the Ti 4+ center in the framework structure, which is mononuclear and contains only one titanium atom. This ion will activate hydrogen peroxide, resulting in the formation of intermediate peroxy (O-O) or hydroperoxy (HO-O) substances, and then react with m-chlorobenzoic acid to form m-chloroperbenzoic acid.

[0022] Therefore, for the process method of preparing m-chloroperbenzoic acid using a molecular sieve catalyst in the present invention, a solid molecular sieve catalyst is used to catalyze the reaction of m-chlorobenzoic acid and an oxidant to obtain m-chloroperbenzoic acid. The catalyst has stable properties and simple separation, and the catalyst can be reused multiple times; the organic solvent can be recovered and reused. The reaction temperature is close to room temperature, the process is green and environmentally friendly, the product yield is high, and the molar yield of m-chloroperbenzoic acid can reach more than 80%, which is conducive to large-scale industrial production.

[0023] The technical solution of the present invention will be further described in detail through specific embodiments below. Specific Embodiments

[0024] The technical solution of the present invention will be further described through the following embodiments.

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0026] Example 1

[0027] This example provides a method for catalytically preparing m-chloroperbenzoic acid using TS-1 molecular sieve, specifically as follows:

[0028] S1. Dissolve 80 g of m-chlorobenzoic acid in 250 mL of dichloromethane, add 8 g of titanium silicate molecular sieve TS-1, stir evenly, and start dropping 90 g of hydrogen peroxide with a mass fraction of 30% at 15°C. The pH of the hydrogen peroxide is 4, and an oxidation reaction is carried out. The molar ratio of m-chlorobenzoic acid to hydrogen peroxide is 1:1.5, and the mass ratio to titanium silicate molecular sieve TS-1 is 1:0.1. Control the reaction temperature at 30°C and react for 12 h.

[0029] S2. After the oxidation reaction is completed, use a filter to separate the titanium silicate molecular sieve TS-1 for the next reaction.

[0030] S3. After separation, extract and separate the organic phase, and carry out reduced pressure distillation at 30°C to recover dichloromethane, obtaining white crystals of m-chloroperbenzoic acid with a yield of 86%.

[0031] Example 2

[0032] This example provides a method for catalytically preparing m-chloroperbenzoic acid using aluminosilicate molecular sieve ZSM-5, specifically as follows:

[0033] S1. Dissolve 80 g of m-chlorobenzoic acid in 400 mL of dichloromethane, add 4 g of titanium silicate molecular sieve ZSM-5, stir evenly, and start dropping 300 g of acidic potassium chlorate aqueous solution with a mass fraction of 30% at 15°C. The pH of the acidic potassium chlorate aqueous solution is 4, and an oxidation reaction is carried out. The molar ratio of m-chlorobenzoic acid to the acidic potassium chlorate aqueous solution is 1:1.5, and the mass ratio to titanium silicate molecular sieve ZSM-5 is 1:0.05. Control the reaction temperature at 30°C and react for 12 h.

[0034] S2. After the oxidation reaction is completed, use a filter to separate the titanium silicate molecular sieve ZSM-5 for the next reaction.

[0035] S3. After separation, the organic phase is extracted and separated, and then distilled under reduced pressure at 30 °C to recover dichloromethane, obtaining white crystals of m-chloroperbenzoic acid with a yield of 83.5%.

[0036] Example 3

[0037] This example provides a method for preparing m-chloroperbenzoic acid by using aluminosilicate zeolite ZSM-5 as a catalyst, specifically as follows:

[0038] S1. Dissolve 80 g of m-chlorobenzoic acid in 800 mL of dichloromethane, add 4 g of titanium silicate zeolite ZSM-5, and after stirring evenly, start dropping 600 g of an aqueous solution of sodium persulfate with a mass fraction of 30% at 15 °C. The pH of the aqueous solution of sodium persulfate is 4, and an oxidation reaction is carried out. The molar ratio of m-chlorobenzoic acid to the aqueous solution of sodium persulfate is 1:1.5, and the mass ratio to titanium silicate zeolite ZSM-5 is 1:0.05. Control the reaction temperature at 30 °C and react for 12 h.

[0039] S2. After the oxidation reaction is completed, use a filter to separate titanium silicate zeolite ZSM-5 for the next reaction.

[0040] S3. After separation, the organic phase is extracted and separated, and then distilled under reduced pressure at 30 °C to recover dichloromethane, obtaining white crystals of m-chloroperbenzoic acid with a yield of 80.5%.

[0041] Example 4

[0042] This example provides a method for preparing m-chloroperbenzoic acid by using aluminosilicate zeolite ZSM-5 as a catalyst, specifically as follows:

[0043] S1. Dissolve 80 g of m-chlorobenzoic acid in 300 mL of dichloromethane, add 4 g of titanium silicate zeolite ZSM-5, and after stirring evenly, start dropping 830 g of an aqueous solution of potassium persulfate with a mass fraction of 25% at 15 °C. The pH of the aqueous solution of potassium persulfate is 4, and an oxidation reaction is carried out. The molar ratio of m-chlorobenzoic acid to the aqueous solution of sodium persulfate is 1:1.5, and the mass ratio to titanium silicate zeolite ZSM-5 is 1:0.05. Control the reaction temperature at 30 °C and react for 12 h.

[0044] S2. After the oxidation reaction is completed, use a filter to separate titanium silicate zeolite ZSM-5 for the next reaction.

[0045] S3. After separation, the organic phase is extracted and separated, and then distilled under reduced pressure at 30 °C to recover dichloromethane, obtaining white crystals of m-chloroperbenzoic acid with a yield of 82.6%.

[0046] Therefore, a process for preparing m-chloroperbenzoic acid using a molecular sieve catalyst according to the present invention overcomes the defects and deficiencies such as low effective yield and serious wastewater pollution in the existing process methods. A solid molecular sieve is used as the catalyst, which has stable properties and simple separation. In this process, the solvent can be recovered and reused, the product yield is high, and the environmental problems brought by other oxidation methods are avoided, which is conducive to large-scale industrial production.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A process for preparing m-chloroperbenzoic acid using a molecular sieve catalyst, characterized in that: The following steps are involved: S1. Dissolve m-chlorobenzoic acid in an organic solvent, add a molecular sieve catalyst, stir evenly, and then dropwise add an oxidant aqueous solution with a mass fraction of 15% to 30% to carry out an oxidation reaction; the molar ratio of m-chlorobenzoic acid to the oxidant is 1:(1.5-4), and the mass ratio of m-chlorobenzoic acid to the molecular sieve catalyst is 1:(0.05-0.1); the pH of the oxidant aqueous solution is 2.5-4, and the oxidant is one or more of potassium chlorate, potassium persulfate, and sodium persulfate; the ratio of the volume of the organic solvent to the mass of m-chlorobenzoic acid is (3-10): 1 mL / g; S2. After the oxidation reaction is completed, the molecular sieve is separated by a filter. The molecular sieve catalyst is one or more of titanium silicon molecular sieve TS-1 and aluminum silicon molecular sieve ZSM-5; S3. After separation, extract and separate the organic phase, and distill and recover the organic solvent to obtain meta-chloroperbenzoic acid crystals.

2. A process for preparing meta-chloroperbenzoic acid using a molecular sieve catalyst according to claim 1, characterized in that: In S1, the molar ratio of m-chlorobenzoic acid to the oxidant is 1:1.5, and the mass ratio of m-chlorobenzoic acid to the molecular sieve catalyst is 1:0.

05.

3. The process for preparing m-chloroperbenzoic acid using a molecular sieve catalyst according to claim 1, characterized in that: The organic solvent is one or more of dichloromethane, dichloroethane, chloroform and carbon tetrachloride.