Water-soluble manganese metal complex catalyst as well as preparation method and application thereof

Abstract

The invention relates to a water-soluble manganese metal complex catalyst as well as a preparation method and application thereof. The catalyst disclosed by the invention is used for preparing epoxy chloropropane by a solvent-free hydrogen peroxide method, and epoxy chloropropane can be efficiently synthesized under the conditions that the reaction temperature is 10-40 DEG C, the total reaction time is 1.5-4 hours, no solvent is added and the dosage of the catalyst is extremely small. According to the invention, the technical defects in the production of the epoxy chloropropane by the hydrogen peroxide method are overcome, and the reaction process is simple, stable and reliable, so that the catalyst for producing the epoxy chloropropane has a very good industrial application prospect.

Description

[Technical Field]

[0001] This invention belongs to the field of catalyst technology. More specifically, this invention relates to a water-soluble manganese metal complex catalyst, a method for preparing the water-soluble manganese metal complex catalyst, and the use of the water-soluble manganese metal complex catalyst. [Background Technology]

[0002] Epichlorohydrin (ECH), a core raw material for the synthesis of epoxy resins, chlorohydrin rubbers, and pharmaceutical intermediates, is projected to have a global demand of 2.5 million tons by 2025. Currently, industrial production of ECH primarily relies on the glycerol saponification method and the propylene high-temperature chlorination method. However, these traditional processes suffer from the following technical drawbacks: the chlorohydrin method has a chlorine atom utilization rate of less than 50%, generates large amounts of high-salt wastewater during production, and causes severe equipment corrosion; the glycerol method has led to a "high cost, low profit" dilemma for enterprises due to soaring raw material costs. With the government's strong promotion of green synthesis technologies, the direct hydrogen peroxide epoxidation method has become the focus of the industry due to its high atom economy, but its industrialization process is still constrained by multiple technical bottlenecks.

[0003] Epichlorohydrin (ECH) via hydrogen peroxide decomposition typically employs a titanium-silicon molecular sieve catalyst to directly epoxidize allyl chloride with hydrogen peroxide. Current technologies generally rely on excess solvent to promote two-phase mixing, leading to hydrolysis of ECH with the solvent during subsequent distillation, reducing product purity from 99.8% to below 97.5%. Reducing solvent usage to lower costs results in excessively high local hydrogen peroxide concentrations, causing ineffective decomposition, prolonged reaction time, and decreased equipment utilization. Furthermore, in fixed-bed reactors, the catalyst is prone to pore blockage due to carbon deposits and colloidal polymers, and micron-sized TS-1 particles exhibit high wear rates in slurry beds, leading to high energy consumption costs for the circulation system. Regarding safety risks, oxygen generated from hydrogen peroxide decomposition accumulates within the reactor, forming an explosive mixture with combustibles. Existing oxygen content monitoring technologies suffer from lag, making real-time control of reaction kinetics difficult.

[0004] The liquid-solid circulating fluidized bed process (CN 115894400B) developed by the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, optimizes mass transfer efficiency through reverse feeding. However, its industrial-scale testing shows a continuous operating cycle of only 45 days, far below the design value of 90 days. Meanwhile, the hydrogen peroxide method requires high-concentration hydrogen peroxide preparation facilities, but hazardous chemical approval barriers and transportation restrictions increase production costs. In terms of environmental remediation, epoxidation wastewater contains colloidal polymers and chloropropanediol monomethyl ether; direct reuse leads to prolonged phase separation time in the extraction tower, while alkaline catalytic degradation, although capable of treating organic matter, generates highly alkaline wastewater, increasing neutralization costs. Therefore, developing an integrated process that combines high catalytic efficiency, low solvent dependence, safety and controllability, and wastewater reusability has become a key direction for overcoming the industrialization bottleneck of the hydrogen peroxide method.

[0005] In response to the technical deficiencies of existing technologies, the inventors, based on a summary of existing technologies and through extensive experimental research and analysis, finally completed this invention. [Summary of the Invention]

[0006] [Technical problem to be solved]

[0007] The purpose of this invention is to provide a water-soluble manganese metal complex catalyst.

[0008] Another object of the present invention is to provide a method for preparing the water-soluble manganese metal complex catalyst.

[0009] Another object of the present invention is to provide the use of the water-soluble manganese metal complex catalyst.

[0010] [Technical Solution]

[0011] The present invention is achieved through the following technical solution.

[0012] This invention relates to a water-soluble manganese metal complex catalyst. The catalyst has the following chemical structural formula:

[0013]

[0014] In the formula:

[0015] R1 and R5 represent H, methyl, or tert-butyl;

[0016] R2, R3, R4, R6, R7, and R8 represent one or more selections from H, C1 to C1. 12 Saturated alkyl or C1-C 12 Unsaturated alkyl groups; or they form one or more cyclic imidazole structures with N;

[0017] X represents one or more selected from C. 1-6 Alkyl or cycloalkanes;

[0018] TOf is a trifluoromethanesulfonic acid group; Cl is a chloride ion.

[0019] The present invention also relates to a method for preparing the catalyst.

[0020] The preparation steps of this method are as follows:

[0021] A. Synthesis of chloromethyl salicylaldehyde compounds

[0022] Under nitrogen protection, salicylaldehyde compounds, paraformaldehyde, and hydrochloric acid were subjected to a chloromethylation reaction in a reactor at a temperature of 40–70°C for 10–30 h at a molar ratio of 1:1.5–3.0:3.0–10.0. The reactants were then washed with water 2–4 times at a volume ratio of 1:3.0–8.0 to water to obtain the chloromethyl salicylaldehyde compounds.

[0023] B. Synthesis of salicylaldehydes containing quaternary ammonium salts

[0024] The chloromethyl salicylaldehyde compound obtained in step A is dissolved in an aldehyde solvent. Then, a secondary amine or imidazole compound solution is slowly added dropwise to the resulting solution. The chloromethyl salicylaldehyde compound reacts with the secondary amine or imidazole compound under nitrogen protection at a molar ratio of 1:1.0-2.0 and a temperature of 20-30°C for 3-8 hours. Then, the reactant is washed 2-4 times with the washing solvent at a volume ratio of 1:2.5-4.0 to its total amount, thus obtaining a salicylaldehyde compound containing quaternary ammonium salt.

[0025] C. Synthesis of water-soluble salten ligands

[0026] Under nitrogen protection, the salicylaldehyde compound containing quaternary ammonium salt obtained in step B was dissolved in a salicylaldehyde compound solvent. Then, X-diamine solution was slowly added dropwise to the resulting solution. The salicylaldehyde compound containing quaternary ammonium salt and X-diamine reacted at a molar ratio of 1:2.0-3.0 and a temperature of 40-80℃ for 4-10 hours. Then, the mixture was separated and purified by ion exchange column chromatography to obtain a water-soluble salen ligand containing quaternary ammonium salt.

[0027] D. Synthesis of manganese metal complex catalysts

[0028] The water-soluble salen ligand containing quaternary ammonium salt obtained in step C was dissolved in salen ligand solvent, and manganese salt was added. The reaction was carried out under the conditions of a water-soluble salen ligand to manganese salt molar ratio of 1:1.0 to 1.2 and a temperature of 40 to 60°C. Then, anhydrous lithium chloride was added according to a water-soluble salen ligand to anhydrous lithium chloride molar ratio of 1:0 or 1:3 to continue the reaction. The total reaction time was 8 to 20 hours. After the reaction was completed, the manganese metal complex catalyst was obtained by separation and purification.

[0029] According to a preferred embodiment of the present invention, in step A, the salicylaldehyde compound is salicylaldehyde, 3-methylsalicylaldehyde, or 3-tert-butylsalicylaldehyde.

[0030] According to another preferred embodiment of the present invention, in step B, the secondary amine is one or more secondary amine compounds selected from diethylamine, dipropylamine, or diisopropylamine; the imidazole compound is one or more imidazole compounds selected from N-methylimidazole, 2-ethyl-4-methylimidazole, 4-methylimidazole, or 2-phenylimidazole; the aldehyde compound solvent is one or more solvents selected from benzene, toluene, xylene, or anisole; and the washing solvent is one or more solvents selected from benzene, toluene, xylene, or anisole.

[0031] According to another preferred embodiment of the present invention, in step C, the X diamine is one or more diamine compounds selected from ethylenediamine, cyclohexanediamine, butanediamine or o-phenylenediamine; and the salicylaldehyde solvent is one or more solvents selected from ethanol, acetonitrile or acetone.

[0032] According to another preferred embodiment of the present invention, in step D, the manganese salt is manganese acetate tetrahydrate, manganese chloride, or bis(trifluoromethanesulfonic acid) manganese; the salon ligand solvent is one or more solvents selected from ethanol, acetonitrile, or acetone.

[0033] According to another preferred embodiment of the present invention, in step D, the separation and purification involves separating the reactants of the water-soluble quaternary ammonium salt-containing salon ligand with manganese salt and anhydrous lithium chloride by ion exchange column chromatography until the content of substances other than the water-soluble salon ligand compound is less than 1.0% by weight.

[0034] This invention also relates to water-soluble manganese metal complex catalysts prepared by the aforementioned preparation method.

[0035] The present invention also relates to the use of the water-soluble manganese metal complex catalyst in the preparation of epichlorohydrin from chloropropylene.

[0036] According to a preferred embodiment of the present invention, the preparation steps for epichlorohydrin from allyl chloride are as follows:

[0037] I. Catalyst Dissolution

[0038] According to the molar ratio of hydrogen peroxide, allyl chloride, water-soluble manganese metal complex catalyst and sodium dihydrogen phosphate being 1:1.1~2.0:0.001~0.005:0.001~0.005, and the volume ratio of water to hydrogen peroxide being 1:10~20, the water-soluble manganese metal complex catalyst and sodium dihydrogen phosphate are dissolved in water, and then allyl chloride is added and stirred to dissolve, to obtain a reaction mixture;

[0039] II. Epoxidation reaction

[0040] The reaction mixture obtained in step I is heated to a temperature of 10-40°C, and hydrogen peroxide with a concentration of 20%-70% by volume is added dropwise over 0.5-1.0 hours. The reaction is kept at this temperature for 1-3 hours. The resulting reaction solution is then separated into an oil phase and an aqueous phase. The separated oil phase is a product containing epichlorohydrin.

[0041] The invention will now be described in more detail.

[0042] This invention relates to a water-soluble manganese metal complex catalyst. The catalyst has the following chemical structural formula:

[0043]

[0044] In the formula:

[0045] R1 and R5 represent H, methyl, or tert-butyl;

[0046] R2, R3, R4, R6, R7, and R8 represent one or more selections from H, C1 to C1. 12 Saturated alkyl or C1-C 12 Unsaturated alkyl groups; or they form one or more cyclic imidazole structures with N;

[0047] X represents one or more selected from C. 1-6 Alkyl or cycloalkanes;

[0048] TOf is a trifluoromethanesulfonic acid group; Cl is a chloride ion.

[0049] The present invention also relates to a method for preparing the catalyst.

[0050] The preparation steps of this method are as follows:

[0051] A. Synthesis of chloromethylsalicylaldehyde compounds

[0052] Under nitrogen protection, salicylaldehyde compounds, paraformaldehyde, and hydrochloric acid were subjected to a chloromethylation reaction in a reactor at a temperature of 40–70°C for 10–30 h at a molar ratio of 1:1.5–3.0:3.0–10.0. The reactants were then washed with water 2–4 times at a volume ratio of 1:3.0–8.0 to water to obtain the chloromethyl salicylaldehyde compounds.

[0053] In the method for preparing water-soluble manganese metal complex catalyst of the present invention, the main function of step A is to introduce chloromethyl groups into salicylaldehyde compounds through a chloromethylation reaction to obtain chloromethyl salicylaldehyde compounds, so as to facilitate subsequent quaternary ammonium salt functionalization treatment.

[0054] Salicylic aldehydes and paraformaldehyde undergo the following chloromethylation reaction with hydrochloric acid:

[0055] Paraformaldehyde generates chloromethyl cation (CH2Cl+) or oxonium salt intermediates under acidic conditions. The aromatic ring of salicylaldehyde, as an electron-rich system, undergoes an electrophilic substitution reaction with the chloromethyl cation to generate the intermediate hydroxymethyl salicylaldehyde. This intermediate is further dehydrated to obtain the target product, methyl salicylaldehyde compounds.

[0056] In this step, the chloromethylation reaction of salicylaldehydes, paraformaldehyde, and hydrochloric acid needs to be carried out under nitrogen protection. The main function of nitrogen is to protect the aldehydes from oxidation; the pressure of the protective nitrogen is usually 0 to 0.1 MPa.

[0057] In this step, salicylaldehyde compounds, paraformaldehyde, and hydrochloric acid undergo a chloromethylation reaction at a molar ratio of 1:1.5–3.0:3.0–10.0. When the molar ratio of salicylaldehyde compounds to hydrochloric acid is within the specified range, if the molar ratio is greater than 1:1.5, a large amount of salicylaldehyde compounds will remain unreacted in the reaction solution after the chloromethylation reaction, increasing the difficulty of subsequent separation. If the molar ratio is less than 1:3.0, a significant amount of paraformaldehyde will remain unreacted in the reaction solution after the chloromethylation reaction, resulting in waste of raw materials. Therefore, a molar ratio of 1:1.5–3.0 for salicylaldehyde compounds to paraformaldehyde is reasonable, preferably 1:1.8–2.8, and more preferably 1:2.0–2.5.

[0058] In this step, when the molar ratio of salicylaldehyde to paraformaldehyde is within the specified range, if the molar ratio of salicylaldehyde to hydrochloric acid is greater than 1:3.0, a large amount of salicylaldehyde will remain unreacted in the reaction solution after the chloromethylation reaction, thus increasing the difficulty of subsequent separation. If the molar ratio of salicylaldehyde to hydrochloric acid is less than 1:10.0, a large amount of hydrochloric acid will remain unreacted in the reaction solution after the chloromethylation reaction, thus significantly increasing the difficulty of subsequent processing. Therefore, a molar ratio of salicylaldehyde to hydrochloric acid of 1:3.0 to 10.0 is appropriate, preferably 1:4.2 to 8.0, and more preferably 1:5.0 to 7.2.

[0059] In this step, salicylaldehyde compounds, paraformaldehyde, and hydrochloric acid undergo a chloromethylation reaction at a temperature of 40–70°C for 10–30 hours. If the reaction temperature is below 40°C within this range, the chloromethylation reaction may be incomplete; if the reaction temperature is above 70°C, a series of side reactions will occur, resulting in low purity and significantly reduced yield of the product obtained in this step. Therefore, a reaction temperature of 40–70°C is suitable, preferably 46–65°C, and more preferably 50–60°C. If the reaction time is less than 10 hours within this range, the chloromethylation reaction will be incomplete, affecting the purity of the product of this invention; if the reaction time is longer than 30 hours, the chloromethylation reaction time is too long, leading to a significant increase in time costs. Therefore, a reaction time of 10–30 hours is appropriate, preferably 14–26 hours, and more preferably 16–24 hours.

[0060] The salicylaldehyde compounds used in this invention are salicylaldehyde, 3-methylsalicylaldehyde, or 3-tert-butylsalicylaldehyde, all of which are currently marketed products, such as those sold by Shanghai Maclean Biochemical Technology Co., Ltd. under the trade names salicylaldehyde and 3-methylsalicylaldehyde, and those sold by Shanghai Aladdin Biochemical Technology Co., Ltd. under the trade name 3-tert-butylsalicylaldehyde.

[0061] After the chloromethylation reaction is complete, the reactant needs to be washed with water to remove water-soluble impurities.

[0062] The reactants are washed with water 2 to 4 times at a volume ratio of 1:3.0 to 8.0 (total reactants to water). If the volume ratio of reactants to water is greater than 1:3.0 within this range, most impurities cannot be removed, affecting product purity. If the volume ratio is less than 1:8.0, excessive water usage will reduce the product yield in this step. Therefore, a volume ratio of 1:3.0 to 8.0 is suitable, preferably 1:3.6 to 7.4, and more preferably 1:4.2 to 6.8. If the number of washes is less than 2 within this range, it is too few and not conducive to impurity removal. If the number of washes is more than 4, it is too many and not conducive to the separation step. Therefore, 2 to 4 washes are feasible.

[0063] Using existing 1 H nuclear magnetic resonance spectrum ( 1 Detection using 1H NMR technology confirmed that the chloromethylation reaction product is a chloromethyl salicylic aldehyde compound, as detailed in the specific embodiments section of this application.

[0064] B. Synthesis of salicylaldehydes containing quaternary ammonium salts

[0065] The chloromethyl salicylaldehyde compound obtained in step A is dissolved in an aldehyde solvent. Then, a secondary amine or imidazole compound solution is slowly added dropwise to the resulting solution. The chloromethyl salicylaldehyde compound reacts with the secondary amine or imidazole compound under nitrogen protection at a molar ratio of 1:1.0-2.0 and a temperature of 20-30°C for 3-8 hours. Then, the reactant is washed 2-4 times with the washing solvent at a volume ratio of 1:2.5-4.0 to its total amount, thus obtaining a salicylaldehyde compound containing quaternary ammonium salt.

[0066] In the method for preparing water-soluble manganese metal complex catalyst of the present invention, the main function of step B is to react chloromethyl salicylaldehyde compounds with secondary amines or imidazole compounds to obtain salicylaldehyde compounds containing quaternary ammonium salts.

[0067] Chloromethyl salicylaldehydes react with secondary amines or imidazoles as follows:

[0068] In chloromethyl salicylaldehyde, the chloromethyl group (-CH2Cl) acts as a good leaving group, and the nitrogen atom on the amino group (-NH2) or imidazole ring of the secondary amine acts as a nucleophile to attack the α-carbon, forming a CN bond, thus yielding salicylaldehyde compounds containing quaternary ammonium salts.

[0069] In this step, chloromethyl salicylaldehydes react with secondary amines or imidazoles under nitrogen protection. The main function of nitrogen is to protect the aldehyde and phenolic hydroxyl groups from oxidation. The pressure of the nitrogen is usually 0–0.1 MPa.

[0070] First, the chloromethyl salicylaldehyde compound obtained in step A is dissolved in an aldehyde compound solvent. The aldehyde compound solvent used in this invention is one or more solvents selected from benzene, toluene, xylene, or anisole. These are all products currently sold on the market, such as products sold by Sinopharm Chemical Reagent Co., Ltd. under the trade name benzene, products sold by Sinopharm Chemical Reagent Co., Ltd. under the trade name toluene, products sold by Anhui Zesheng Technology Co., Ltd. under the trade name xylene, and products sold by Anhui Zesheng Technology Co., Ltd. under the trade name anisole.

[0071] Then, slowly add a solution of a secondary amine or imidazole compound to the resulting solution. The secondary amine compounds used in this invention are one or more secondary amine compounds selected from diethylamine, dipropylamine, or diisopropylamine, all of which are currently commercially available products. Examples include diethylamine sold by Shanghai Maclean Biochemical Technology Co., Ltd. under the trade name diethylamine, dipropylamine sold by Shanghai Maclean Biochemical Technology Co., Ltd. under the trade name di-n-propylamine, and diisopropylamine sold by Shanghai Maclean Biochemical Technology Co., Ltd. under the trade name diisopropylamine. The imidazole compounds used in this invention are one or more imidazole compounds selected from N-methylimidazole, 2-ethyl-4-methylimidazole, 4-methylimidazole, or 2-phenylimidazole, all of which are currently commercially available products. Examples include N-methylimidazole sold by Anhui Zesheng Technology Co., Ltd. under the trade name N-methylimidazole, 2-ethyl-4-methylimidazole sold by Anhui Zesheng Technology Co., Ltd. under the trade name 2-ethyl-4-methylimidazole, 4-methylimidazole sold by Anhui Zesheng Technology Co., Ltd. under the trade name 4-methylimidazole, and 2-phenylimidazole sold by Anhui Zesheng Technology Co., Ltd. under the trade name 2-phenylimidazole.

[0072] Next, under nitrogen protection, chloromethyl salicylic aldehyde compounds are reacted with secondary amines or imidazole compounds at a molar ratio of 1:1.0–2.0 and a temperature of 20–30°C for 3–8 hours. When the reaction temperature and time are within the aforementioned range, if the molar ratio of chloromethyl salicylic aldehyde compounds to secondary amines or imidazole compounds is higher than 1:1.0, the amount of chloromethyl salicylic aldehyde compound used will be insufficient, resulting in incomplete reaction with the secondary amine or imidazole compounds and failure to obtain the target product. If the molar ratio of chloromethyl salicylic aldehyde compounds to secondary amines or imidazole compounds is lower than 1:2.0, it will lead to excessive use of chloromethyl salicylic aldehyde compounds, resulting in waste of raw materials. Therefore, a molar ratio of chloromethyl salicylic aldehyde compounds to secondary amines or imidazole compounds of 1:1.0–2.0 is reasonable, preferably 1:1.2–1.8, and more preferably 1:1.3–1.6.

[0073] When the molar ratio of chloromethyl salicylaldehyde compounds to secondary amines or imidazole compounds and the reaction time are within the aforementioned range, if the reaction temperature is below 20°C, the reaction will be incomplete; if the temperature is above 30°C, a series of side reactions will occur, resulting in low purity of the product obtained in this step and a significantly reduced yield. Therefore, a reaction temperature of 20–30°C is appropriate, preferably 22–28°C.

[0074] When the molar ratio of chloromethyl salicylaldehyde compounds to secondary amines or imidazole compounds and the reaction temperature are within the range described, if the reaction time is less than 3 hours, the reaction will be incomplete, affecting the purity of the product of the present invention; if the reaction time is longer than 8 hours, the reaction will be too time-consuming, increasing the preparation cost of the product of the present invention. Therefore, a reaction time of 3 to 8 hours is feasible, preferably 3.8 to 7.2 hours, and more preferably 4.2 to 6.8 hours.

[0075] After the reaction is complete, the reactants are washed 2 to 4 times with the washing solvent at a volume ratio of 1:2.5 to 4.0. The main purpose of washing the reactants with the washing solvent is to remove some of the unreacted raw materials.

[0076] When the number of washes using the washing solvent is within the aforementioned range, if the volume ratio of the total reactant to the washing solvent is higher than 1:2.5, the amount of washing solvent used is too small, resulting in poor washing effect; if the volume ratio of the total reactant to the washing solvent is lower than 1:4.0, the amount of washing solvent used is too large, which will cause product loss. Therefore, a volume ratio of the total reactant to the washing solvent of 1:2.5 to 4.0 is suitable, preferably 1:2.8 to 3.8; more preferably 1:3.0 to 3.6.

[0077] The washing solvent used in this invention is one or more solvents selected from benzene, toluene, xylene or anisole, all of which are currently commercially available products.

[0078] Using existing 1 H nuclear magnetic resonance spectrum ( 1 H NMR analysis confirmed that the product obtained in this step is a salicylaldehyde compound containing quaternary ammonium salt, as detailed in the specific embodiments section of this application.

[0079] C. Synthesis of water-soluble salten ligands

[0080] Under nitrogen protection, the salicylaldehyde compound containing quaternary ammonium salt obtained in step B was dissolved in a salicylaldehyde compound solvent. Then, X-diamine solution was slowly added dropwise to the resulting solution. The salicylaldehyde compound containing quaternary ammonium salt and X-diamine reacted at a molar ratio of 1:2.0-3.0 and a temperature of 40-80℃ for 4-10 hours. Then, the mixture was separated and purified by ion exchange column chromatography to obtain a water-soluble salen ligand containing quaternary ammonium salt.

[0081] In the method for preparing water-soluble manganese metal complex catalyst of the present invention, the main function of step C is to react salicylaldehyde compounds containing quaternary ammonium salts with X-diamine to obtain water-soluble salen ligands containing quaternary ammonium salts.

[0082] Salicylic aldehydes containing quaternary ammonium salts react with diamine X as follows:

[0083] The aldehyde group (-CHO) of salicylaldehyde undergoes a nucleophilic addition-dehydration reaction with the amino group (-NH2) of an X-diamine (such as cyclohexanediamine or ethylenediamine) to form a Schiff base structure (C=N bond). Two salicylaldehyde molecules are connected by a methylene bridge (-CH2-), forming a planar quadrilateral Salen skeleton together with the X-diamine, retaining two phenolic hydroxyl groups and two chiral centers.

[0084] In this step, the salicylaldehyde compound containing quaternary ammonium salt reacts with X-diamine under nitrogen protection. The main function of nitrogen is to protect the aldehyde group and phenolic hydroxyl group from oxidation. The pressure of the protective nitrogen is usually 0 to 0.1 MPa.

[0085] Under nitrogen protection, the salicylaldehyde compound containing quaternary ammonium salt obtained in step B is dissolved in a salicylaldehyde solvent at a ratio of 1:10 to 30 (grams) to obtain a salicylaldehyde compound solution containing quaternary ammonium salt. This ratio can be higher or lower, as long as the concentration of the solution obtained by dissolving in the salicylaldehyde solvent does not negatively affect subsequent processing. The salicylaldehyde solvent used in this invention is one or more solvents selected from ethanol, acetonitrile, or acetone, all of which are commonly used in the chemical technology field and are currently commercially available products.

[0086] The X-diamine used in this invention is C 1-6 The diamine is an alkane or cycloalkane, specifically one or more diamine compounds selected from ethylenediamine, cyclohexanediamine, butanediamine, or o-phenylenediamine. These are commercially available products, such as ethylenediamine sold by Shanghai Aladdin Biochemical Technology Co., Ltd. under the trade name ethylenediamine, cyclohexanediamine sold by Shanghai Aladdin Biochemical Technology Co., Ltd. under the trade name hexanediamine, butanediamine sold by Shanghai Aladdin Biochemical Technology Co., Ltd. under the trade name butanediamine, and o-phenylenediamine sold by Shanghai Aladdin Biochemical Technology Co., Ltd. under the trade name o-phenylenediamine. The X-diamine solution used in this step is a solution of X-diamine in ethanol, acetonitrile, acetone, or a mixture thereof, and the concentration of this solution is typically 3-10% by weight. Of course, this concentration can be higher or lower, as long as the concentration of the X-diamine solution does not have a negative impact on its subsequent processing.

[0087] The salicylaldehyde compound solution containing quaternary ammonium salt was slowly added dropwise to the X diamine solution, and the salicylaldehyde compound containing quaternary ammonium salt and X diamine were allowed to react for 4 to 10 hours at a molar ratio of 1:2.0 to 3.0 and a temperature of 40 to 80°C.

[0088] In this step, when the reaction temperature and reaction time are within the aforementioned range, if the molar ratio of the quaternary ammonium salt-containing salicylaldehyde compound to X-diamine is higher than 1:2.0, a large amount of the quaternary ammonium salt-containing salicylaldehyde compound will be difficult to recover, increasing the catalyst synthesis cost; if the molar ratio of the quaternary ammonium salt-containing salicylaldehyde compound to X-diamine is lower than 1:3.0, the reaction cannot generate the target product, the reaction product contains too many impurities, and the yield of its water-soluble salen ligand is significantly reduced; therefore, a molar ratio of quaternary ammonium salt-containing salicylaldehyde compound to X-diamine of 1:2.0 to 3.0 is appropriate, preferably 1:2.2 to 2.8, and more preferably 1:2.4 to 2.6;

[0089] When the molar ratio of salicylaldehyde compounds containing quaternary ammonium salts to X-diamine and the reaction time are within the aforementioned range, if the reaction temperature is below 40°C, the reaction may be incomplete, affecting the purity of the water-soluble salon ligand and increasing raw material consumption. If the reaction temperature is above 80°C, a series of side reactions will occur, resulting in low purity of the water-soluble salon ligand product and a significantly reduced yield. Therefore, a reaction temperature of 40–80°C is reasonable, preferably 46–72°C, and more preferably 50–68°C.

[0090] When the molar ratio of salicylaldehyde compounds containing quaternary ammonium salts to X-diamine and the reaction temperature are within the aforementioned range, if the reaction time is less than 4 hours, the reaction may be incomplete, affecting the purity of the water-soluble salon ligand product and increasing raw material consumption. If the reaction time is longer than 10 hours, the reaction result is not significantly affected, but increasing the synthesis time will significantly increase the cost of the method. Therefore, a reaction time of 4–10 hours is feasible, preferably 5–9 hours, and more preferably 6–8 hours.

[0091] After the reaction was completed, the reaction solution was separated and purified by ion exchange column chromatography to obtain a water-soluble salon ligand containing quaternary ammonium salt.

[0092] The ion-exchange column chromatography method used in this invention is a commonly employed method in the field of organic synthesis technology. For details, please refer to the "Organic Syntheses" series of books.

[0093] Using existing 1 H nuclear magnetic resonance spectrum ( 1 Detection using H NMR technology confirmed that the product obtained in this step is a water-soluble salon ligand containing a quaternary ammonium salt. For details, please refer to the specific implementation section of this application specification.

[0094] D. Synthesis of manganese metal complex catalysts

[0095] The water-soluble salen ligand containing quaternary ammonium salt obtained in step C was dissolved in salen ligand solvent, and manganese salt was added. The reaction was carried out under the conditions of a water-soluble salen ligand to manganese salt molar ratio of 1:1.0 to 1.2 and a temperature of 40 to 60°C. Then, anhydrous lithium chloride was added according to a water-soluble salen ligand to anhydrous lithium chloride molar ratio of 1:0 or 1:3 to continue the reaction. The total reaction time was 8 to 20 hours. After the reaction was completed, the manganese metal complex catalyst was obtained by separation and purification.

[0096] In the method for preparing water-soluble manganese metal complex catalyst of the present invention, the main function of step D is to obtain a water-soluble manganese metal complex catalyst with catalytic activity by reacting water-soluble salten ligand with manganese salt and anhydrous lithium chloride in succession.

[0097] The water-soluble salon ligand reacts with manganese salt and anhydrous lithium chloride as follows:

[0098] Salen ligands react with Mn(OAc)₂ in the presence of anhydrous LiCl to oxidize manganese to +3 valence via air or oxygen. LiCl acts as a co-catalyst in this process, lowering the activation energy of the oxidation reaction and promoting the valence transition of manganese. The N and O atoms of the Salen ligand react with Mn... 3+ It forms a six-coordinated octahedral structure. Li + By embedding the product into the complex lattice through ion exchange, the solubility of the product in aqueous phase or polar solvents is enhanced, ultimately forming a coordination compound of general formula 2. Alternatively, the salen ligand reacts with Mn(TOf)₂ under oxygen or air oxidation to generate +3 valent manganese (Mn₂). 3+ ). Trifluoromethanesulfonate (TOf) - As a strong coordinating group, it participates in the coordination of manganese, forming a stable six-coordinated octahedral structure and a coordination compound of general formula 1.

[0099] First, the water-soluble quaternary ammonium salt-containing salon ligand obtained in step C is dissolved in a salon ligand solvent to obtain a water-soluble quaternary ammonium salt-containing salon ligand solution. The salon ligand solvent is one or more solvents selected from ethanol, acetonitrile, or acetone, all of which are commonly used in the chemical technology field and are currently commercially available products.

[0100] In this step, the ratio of water-soluble salon ligand (in grams) to salon ligand solvent (in milliliters) is 1:10–40. Of course, this ratio can be higher or lower, as long as the concentration of the solution obtained by dissolving the ligand in the salon ligand solvent does not negatively impact subsequent processing.

[0101] Next, manganese salt selected from manganese acetate tetrahydrate, manganese chloride, or bis(trifluoromethanesulfonic acid) manganese is added to the water-soluble leaven ligand solution containing quaternary ammonium salt at a molar ratio of 1:1.0 to 1.2. After the manganese salt is completely dissolved, the reaction is carried out at a temperature of 40 to 60°C. Then, anhydrous lithium chloride is added at a molar ratio of 1:0 or 1:3 to the water-soluble leaven ligand to continue the reaction for a total of 8 to 20 hours.

[0102] In this step, the molar ratio of the water-soluble salon ligand to the manganese salt is 1:1.0–1.2. If the molar ratio is higher than 1:1.0–1.2, the reaction solution will contain some unreacted water-soluble salon ligands containing quaternary ammonium salts, which will increase the difficulty of subsequent separation. If the molar ratio is lower than 1:1.2, some manganese salt will not participate in the reaction, resulting in waste and increasing the catalyst preparation cost. Therefore, a molar ratio of 1:1.0–1.2 for the water-soluble salon ligand to the manganese salt is reasonable.

[0103] In this step, if the manganese salt used is manganese chloride or manganese acetate tetrahydrate, the molar ratio of the water-soluble salen ligand to the manganese salt is 1:3.0. If the manganese salt used is manganese chloride or bis(trifluoromethanesulfonic acid) manganese, the trifluoromethanesulfonate ion (TOf-) in bis(trifluoromethanesulfonic acid) manganese is a strong σ-donor / π-acceptor ligand and can directly interact with Mn. 3+ The ligand coordinates to form a stable six-coordinated octahedral structure. Therefore, the molar ratio of the water-soluble salon ligand to anhydrous lithium chloride is 1:0.

[0104] In this step, the water-soluble quaternary ammonium salt-containing salon ligand is reacted sequentially with manganese salt and anhydrous lithium chloride at a temperature of 40–60°C for 8–20 hours. Within this reaction time range, if the reaction temperature is below 40°C, the reaction between the water-soluble quaternary ammonium salt-containing salon ligand and the manganese salt is incomplete, resulting in a significantly reduced product yield. If the reaction temperature is above 60°C, some side reactions will occur, thus affecting the product purity. Therefore, a reaction temperature of 40–60°C is appropriate, preferably 44–56°C, and more preferably 48–52°C. Within this reaction temperature range, if the reaction time is less than 8 hours, a large amount of raw material will not react, resulting in a reduced product yield. If the reaction time is longer than 20 hours, extending the reaction time has no beneficial effect on the reaction but greatly increases the catalyst synthesis time. Therefore, a reaction time of 8–20 hours is desirable, preferably 10–18 hours, and more preferably 12–16 hours.

[0105] The manganese salts used in this invention are all products currently sold on the market, such as those sold by Shanghai Aladdin Biochemical Technology Co., Ltd. under the trade name manganese acetate tetrahydrate, those sold by Shanghai Aladdin Biochemical Technology Co., Ltd. under the trade name manganese chloride, and those sold by Anhui Zesheng Technology Co., Ltd. under the trade name bis(trifluoromethanesulfonic acid) manganese.

[0106] In this step, the water-soluble salon ligand containing the quaternary ammonium salt is successively reacted with manganese salt and anhydrous lithium chloride, followed by separation and purification using ion-exchange column chromatography until the content of substances other than the manganese metal complex compound is less than 1.0% by weight. The ion-exchange column chromatography method used in this invention is a commonly employed method in the field of organic synthesis; for details, please refer to the "Organic Syntheses" series of books.

[0107] Using existing 1 H nuclear magnetic resonance spectrum ( 1 H NMR analysis confirmed that the product obtained in this step is a manganese metal complex catalyst, as detailed in the specific implementation section of this application.

[0108] This invention also relates to water-soluble manganese metal complex catalysts prepared by the aforementioned preparation method.

[0109] The present invention also relates to the use of the water-soluble manganese metal complex catalyst in the preparation of epichlorohydrin from chloropropylene.

[0110] Specifically, the preparation steps of epichlorohydrin from allyl chloride in this invention are as follows:

[0111] I. Catalyst Dissolution

[0112] According to the molar ratio of hydrogen peroxide, allyl chloride, water-soluble manganese metal complex catalyst and sodium dihydrogen phosphate being 1:1.1~2.0:0.001~0.005:0.001~0.005, and the volume ratio of water to hydrogen peroxide being 1:10~20, the water-soluble manganese metal complex catalyst and sodium dihydrogen phosphate are dissolved in water, and then allyl chloride is added and stirred to dissolve, to obtain a reaction mixture;

[0113] In this step, the water-soluble manganese metal complex catalyst is dissolved in water to allow the catalyst to be better dispersed in the system, while sodium dihydrogen phosphate acts as a buffer in the system, and hydrogen peroxide acts as a reactant to provide an oxygen source.

[0114] When the amounts of water-soluble manganese metal complex catalyst and sodium dihydrogen phosphate are within the aforementioned range, if the molar ratio of hydrogen peroxide to allyl chloride is greater than 1:1.1, the ineffective decomposition of hydrogen peroxide during the reaction will significantly increase, thus reducing the effective utilization rate of hydrogen peroxide. If the molar ratio of hydrogen peroxide to allyl chloride is less than 1:2.0, the excess allyl chloride remaining after the reaction will increase the difficulty of subsequent separation. Therefore, a molar ratio of hydrogen peroxide to allyl chloride of 1:1.1 to 2.0 is feasible, and preferably 1:1.3 to 1.6.

[0115] When the amounts of allyl chloride and sodium dihydrogen phosphate are within the aforementioned range, if the molar ratio of hydrogen peroxide to the water-soluble manganese metal complex catalyst is greater than 1:0.001, the amount of catalyst used is too low, resulting in poor catalytic effect. If the molar ratio of hydrogen peroxide to the water-soluble manganese metal complex catalyst is less than 1:0.005, the amount of catalyst used is too high, leading to excessively high catalytic activity and causing a large amount of hydrogen peroxide to decompose ineffectively, thereby reducing product yield. Therefore, a molar ratio of hydrogen peroxide to the water-soluble manganese metal complex catalyst of 1:0.001 to 0.005 is reasonable, and preferably 1:0.002 to 0.004.

[0116] When the amount of allyl chloride and water-soluble manganese metal complex catalyst is within the aforementioned range, if the molar ratio of hydrogen peroxide to sodium dihydrogen phosphate is greater than 1:0.001, the buffering effect of sodium dihydrogen phosphate is poor, and the ineffective decomposition of hydrogen peroxide will significantly increase. If the molar ratio of hydrogen peroxide to sodium dihydrogen phosphate is less than 1:0.005, excessive inorganic salts will be introduced, increasing the difficulty of subsequent wastewater treatment. Furthermore, increasing the amount of sodium dihydrogen phosphate used will also increase production costs. Therefore, a molar ratio of hydrogen peroxide to sodium dihydrogen phosphate of 1:0.001 to 0.005 is preferable, and more preferably 1:0.002 to 0.004.

[0117] Preferably, the molar ratio of hydrogen peroxide, allyl chloride, water-soluble manganese metal complex catalyst, and sodium dihydrogen phosphate is 1:1.3-1.6:0.002-0.004:0.002-0.004.

[0118] The hydrogen peroxide, allyl chloride, and sodium dihydrogen phosphate used in this invention are all products currently available on the market.

[0119] II. Epoxidation reaction

[0120] The reaction mixture obtained in step I is heated to a temperature of 10-40°C, and hydrogen peroxide with a concentration of 20%-70% by volume is added dropwise over 0.5-1.0 hours. The reaction is kept at this temperature for 1-3 hours. The resulting reaction solution is then separated into an oil phase and an aqueous phase. The separated oil phase is a product containing epichlorohydrin.

[0121] The main purpose of this step is to carry out an epoxidation reaction between hydrogen peroxide and chloropropylene under the action of the water-soluble manganese metal complex catalyst of the present invention to obtain the epichlorohydrin.

[0122] In this step, if the temperature of the reaction mixture is below 10°C, the catalytic activity of the catalyst of the present invention decreases, resulting in excessive hydrogen peroxide residue after the reaction, thus reducing the product yield and increasing the difficulty of subsequent processing. If the temperature of the reaction mixture is above 40°C, the excessively high reaction temperature will cause a large amount of hydrogen peroxide to decompose ineffectively, resulting in a decrease in hydrogen peroxide utilization. Therefore, a reaction temperature of 10–40°C is appropriate, preferably 16–35°C.

[0123] In this step, hydrogen peroxide is added dropwise to allow it to react and be added simultaneously, thereby controlling the concentration of hydrogen peroxide in the system and preventing the ineffective decomposition of large amounts of hydrogen peroxide.

[0124] The concentration of hydrogen peroxide used is 20% to 70% by volume. If the concentration is below 20%, the amount of wastewater after the reaction will increase significantly; if the concentration is above 70%, the risks during the reaction will increase, and excessively high concentrations will increase the ineffective decomposition of hydrogen peroxide, reducing its effective utilization rate. Therefore, a concentration of 20% to 70% by volume is appropriate, preferably 28% to 60%.

[0125] The dripping time for hydrogen peroxide is 0.5–1.0 hours. If the dripping time is less than 0.5 hours, the dripping speed is too fast, which will cause a large amount of hydrogen peroxide to decompose ineffectively, reducing the effective utilization rate of hydrogen peroxide; if the dripping time is longer than 1 hour, it will prolong the epoxidation reaction time. Therefore, a dripping time of 0.5–1.0 hours for hydrogen peroxide is acceptable, and 0.6–0.8 hours is preferred.

[0126] In this step, the reaction is kept at a constant temperature for 1 to 3 hours after the hydrogen peroxide is added. If the reaction time is less than 1 hour, a large amount of hydrogen peroxide will remain in the reactants after the reaction, affecting the product yield; if the reaction time is longer than 3 hours, extending the reaction time will not improve the product yield. Therefore, keeping the reaction at a constant temperature for 1 to 3 hours after the hydrogen peroxide is added is appropriate, preferably 1.6 to 2.4 hours.

[0127] According to conventional gas chromatography with internal standard analysis, the oil phase product obtained by the epichlorohydrin preparation method of the present invention contains 10% to 40% epichlorohydrin, 20% to 70% allyl chloride and 0.1% to 1.0% water by weight; the aqueous phase product contains 0.5% to 2.0% epichlorohydrin, 0.2% to 1.0% allyl chloride and 97% to 99% water by weight.

[0128] The hydrogen peroxide conversion rate and utilization rate of the epichlorohydrin preparation method of this invention are calculated according to the following formula:

[0129] Hydrogen peroxide conversion rate = {(molar amount of hydrogen peroxide added - molar amount of hydrogen peroxide remaining) / molar amount of hydrogen peroxide added} x 100%;

[0130] Effective utilization rate of hydrogen peroxide = (molar amount of epichlorohydrin generated / molar amount of hydrogen peroxide consumed) x 100%.

[0131] [Beneficial Effects]

[0132] The beneficial effects of this invention are: the catalyst of this invention, used in the solvent-free hydrogen peroxide method for the preparation of epichlorohydrin, can efficiently synthesize epichlorohydrin under conditions of reaction temperature of 10–40°C, total reaction time of 1.5–4 hours, no solvent addition, and extremely low catalyst dosage. This invention solves the defects of existing hydrogen peroxide method epichlorohydrin production technology, and the reaction process is simple, stable, and reliable. Therefore, the use of the catalyst of this invention for epichlorohydrin production has very good prospects for industrial application.

Detailed Implementation Methods

[0133] The invention will be better understood through the following examples.

[0134] Example 1: Synthesis of the water-soluble manganese metal complex catalyst of the present invention

[0135] The implementation steps of this embodiment are as follows:

[0136] A. Synthesis of chloromethylsalicylaldehyde compounds

[0137] Under nitrogen protection, salicylaldehyde, paraformaldehyde and hydrochloric acid were subjected to chloromethylation reaction in a reactor at 50°C for 16 h at a molar ratio of 1:2.0:5. The reactants were then washed three times with water at a volume ratio of 1:5.0 to water to obtain the chloromethyl salicylaldehyde compound, which is a light yellow crystal.

[0138] Based on the product weight, the yield is 94%.

[0139] Using existing 1 H nuclear magnetic resonance spectrum ( 1 Detection using H NMR technology, 1¹H NMR (400 MHz, DMSO-d6) characterization results (chemical shift δ): 10.73 (¹H, s), 10.24 (¹H, s), 7.82 (¹H, d, J = 2.4), 7.63 (¹H, dd, J = 8.5, 2.4), 7.22 (¹H, d, J = 8.5), 4.67 (²H, s).

[0140] According to the analytical method of ASTM D5291-21, the elemental analysis results (wt%) are as follows:

[0141] Measured values: 56.24% C, 4.26% H;

[0142] Calculated values: 56.33% C, 4.14% H;

[0143] B. Synthesis of salicylaldehydes containing quaternary ammonium salts

[0144] The chloromethyl salicylaldehyde compound obtained in step A was dissolved in toluene. Then, a solution of N-methylimidazole in toluene was slowly added dropwise to the resulting solution. The chloromethyl salicylaldehyde compound and N-methylimidazole were reacted under nitrogen protection at a molar ratio of 1:1.3 and a temperature of 26°C for 6 hours. The reactant was then washed twice with toluene at a volume ratio of 1:4.0 to the total amount of the reactant, thus yielding 2-hydroxy-5-(N-methylimidazole)-benzaldehyde hydrochloride, which was a white crystal.

[0145] The yield of the product was determined to be 78% based on the methods described above.

[0146] 1 ¹H NMR (400 MHz, DMSO-d6) characterization results (chemical shift δ): 11.27 (¹H, s), 10.32 (¹H, s), 9.28 (¹H, s), 7.79 (¹H, t, J = 1.7), 7.76 (²H, m), 7.68 (¹H, m), 7.33 (¹H, d, J = 8.5), 5.42 (²H, s), 3.79 (³H, s).

[0147] Its elemental analysis results (wt%):

[0148] Measured values: 55.49% C, 4.40% H, 11.78% N;

[0149] Calculated values: 55.59% C, 4.24% H, 11.79% N.

[0150] C. Salen ligand synthesis

[0151] Under nitrogen protection, the 2-hydroxy-5-(N-methylimidazolium)-benzaldehyde hydrochloride obtained in step B was dissolved in acetone. Then, a solution of 1,2-cyclohexanediamine in acetone was slowly added dropwise to the resulting solution. The 2-hydroxy-5-(N-methylimidazolium)-benzaldehyde hydrochloride and 1,2-cyclohexanediamine were reacted at a molar ratio of 1:2.4 and a temperature of 50°C for 8 hours. The mixture was then separated and purified by ion exchange column chromatography to obtain a water-soluble salen ligand containing quaternary ammonium salt. The product was a bright yellow solid.

[0152] The yield of the product was determined to be 76% based on the methods described above.

[0153] 1 ¹H NMR (400MHz, DMSO-d6) characterization results (chemical shift δ): 13.49 (2H, s), 9.38 (2H, m), 8.53 (2H, s), 7.79 (2H, dt, J = 5.2, 1.6), 7.68 (2H, dt, J = 4.4, 1.9), 7.49 (2H, dd, J = 5.6, 2.3), 7.52 (2H, ddd, J = 8.5, 4.0, 2.2), 6.76 (2H, d, J = 8.5), 5.38 (4H, d, J = 3.9), 3.79 (6H, d, J = 1.3), 3.53 (2H, d, J = 9.8), 1.83–1.40 (8H, m).

[0154] Its elemental analysis results (wt%):

[0155] Measured values: 61.78% C, 6.30% H, 14.35% N;

[0156] Calculated values: 61.75% C, 6.22% H, 14.40% N.

[0157] D. Synthesis of manganese metal complex catalysts

[0158] The water-soluble salen ligand containing quaternary ammonium salt obtained in step C was dissolved in acetonitrile solvent, and manganese acetate was added. The reaction was carried out at a molar ratio of water-soluble salen ligand to manganese salt of 1:1.0 and a temperature of 40°C. Then, anhydrous lithium chloride was added at a molar ratio of water-soluble salen ligand to anhydrous lithium chloride of 1:3 to continue the reaction. The reaction was carried out for a total of 8 hours. After the reaction was completed, ion exchange column chromatography was used to separate the substances until the content of substances other than manganese metal complex compounds was less than 1.0% by weight, thus obtaining the manganese metal complex catalyst.

[0159] The yield of the product was determined to be 98% based on the methods described above.

[0160] FT-IR (KBr) characterization results (wavenumber, cm⁻¹)-1 ): 3133(m), 2859(m), 1622(vs), 1553(s), 1444(s), 1379(s), 1332(m), 1281(s), 1176(s), 832(m), 763(m), 679(m), 578(m), 474(w).

[0161] Its elemental analysis results (wt%):

[0162] Measured values: 53.60% C, 5.09% H, 12.59% N;

[0163] Calculated values: 53.63% C, 5.10% H, 12.51% N.

[0164] Example 2: Synthesis of the water-soluble manganese metal complex catalyst of the present invention

[0165] The implementation steps of this embodiment are as follows:

[0166] A. Synthesis of chloromethyl salicylaldehyde compounds

[0167] Under nitrogen protection, 3-methylsalicylaldehyde, paraformaldehyde, and hydrochloric acid were reacted in a reactor at a molar ratio of 1:1.5:3.0 at 40°C for 10 h for chloromethylation. The reactants were then washed twice with water at a volume ratio of 1:3.0 to water to obtain 2-hydroxy-3-tert-butyl-5-chloromethylbenzaldehyde, which is a light yellow crystal.

[0168] The yield of the product was determined to be 90% based on the methods described above.

[0169] 1 ¹H NMR (250 MHz, CDCl₃) characterization results (chemical shift δ): 11.89 (¹H, s), 9.98 (¹H, s), 7.62 (¹H, d, J = 2.2 Hz), 7.52 (¹H, d, J = 2.3 Hz), 4.63 (²H, s), 1.53 (⁹H, s).

[0170] Its elemental analysis results (wt%):

[0171] Measured values: 61.12% C, 4.58% H;

[0172] Calculated values: 61.08% C, 4.61% H.

[0173] B. Synthesis of salicylaldehydes containing quaternary ammonium salts

[0174] The 2-hydroxy-3-tert-butyl-5-chloromethylbenzaldehyde compound obtained in step A was dissolved in toluene. Then, a solution of diisopropylamine in toluene was slowly added dropwise to the resulting solution. The 2-hydroxy-3-tert-butyl-5-chloromethylbenzaldehyde compound and diisopropylamine were reacted under nitrogen protection at a molar ratio of 1:1.0 and a temperature of 20°C for 3 hours. Then, the reactant was washed three times with toluene at a volume ratio of 1:2.5 (total amount to toluene washing solvent) to obtain 2-hydroxy-3-methyl-5-(methyldiisopropylamine)benzaldehyde hydrochloride, which is a white crystal.

[0175] The yield of the product was determined to be 78% based on the methods described above.

[0176] 1 ¹H NMR (400 MHz, CDCl₃) characterization results (chemical shift δ): 11.36 (¹H, s), 10.12 (¹H, s), 7.58 (¹H, d, J = 1.7 Hz), 7.01 (¹H, d, J = 1.7 Hz), 4.37–4.47 (²H, 4.42(s), 4.42(s)), 3.53–3.63 (²H, m), 1.28–1.41 (²¹H, m).

[0177] Its elemental analysis results (wt%):

[0178] Measured values: 65.22% C, 9.22% H, 6.89% N;

[0179] Calculated values: 65.17% C, 9.19% H, 6.86% N.

[0180] C. Salen ligand synthesis

[0181] The 2-hydroxy-3-methyl-5-(methyldiisopropylamine)benzaldehyde hydrochloride obtained in step B was dissolved in ethanol. Then, a solution of 1,2-cyclohexanediamine in ethanol was slowly added dropwise to the resulting solution. The 2-hydroxy-3-methyl-5-(methyldiisopropylamine)benzaldehyde hydrochloride and 1,2-cyclohexanediamine were reacted at a molar ratio of 1:2.0 and a temperature of 40°C for 10 h. The product was then separated and purified by ion exchange column chromatography to obtain a water-soluble salen ligand containing a quaternary ammonium salt. The product was a bright yellow solid.

[0182] The yield of the product was determined to be 85% based on the methods described above.

[0183] 1¹H NMR (400 MHz, DMSO-d6) characterization results (chemical shift δ): 13.48 (2H, brs), 8.22 (2H, s), 7.69 (2H, brs), 7.12 (2H, brs), 3.74 (2H, d, J = 17.0 Hz), 3.71 (2H, d, J = 17.0 Hz), 3.32 (2H, m), 3.07–3.02 (4H, m), 1.92–1.84 (4H, m), 1.52 (2H, m), 1.31 (2H, m), 1.24 (18H, s), 1.03 (24H, d, J = 6.3 Hz).

[0184] Its elemental analysis results (wt%):

[0185] Measured values: 65.50% C, 9.10% H, 9.02% N;

[0186] Calculated values: 65.47% C, 9.05% H, 8.98% N.

[0187] D. Synthesis of manganese metal complex catalysts

[0188] The water-soluble salen ligand containing quaternary ammonium salt obtained in step C was dissolved in ethanol solvent, and anhydrous manganese chloride was added. The reaction was carried out for 12 hours at a molar ratio of water-soluble salen ligand to manganese salt of 1:1.2 and a temperature of 54°C. After the reaction was completed, the contents of substances other than manganese metal complex compounds were separated by ion exchange column chromatography until the contents were less than 1.0% by weight, thus obtaining the manganese metal complex catalyst.

[0189] The yield of the product was determined to be 94% based on the methods described above.

[0190] FT-IR (KBr) characterization results (wavenumber, cm⁻¹) -1 ): 3215(w,br), 2887(w), 1636(vs), 1597(s), 1524(m), 1458(s), 1382(m), 13 05(s), 1240(s), 1150(m), 1025(m), 845(s), 774(m), 688(m), 554(m), 481(w).

[0191] Its elemental analysis results (wt%):

[0192] Measured values: 61.45% C, 8.30% H, 6.77% N;

[0193] Calculated values: 61.35% C, 8.34% H, 6.81% N.

[0194] Example 3: Synthesis of the water-soluble manganese metal complex catalyst of the present invention

[0195] The implementation steps of this embodiment are as follows:

[0196] A. Synthesis of chloromethyl salicylaldehyde compounds

[0197] Under nitrogen protection, 3-methylsalicylaldehyde, paraformaldehyde, and hydrochloric acid were reacted in a reactor at a molar ratio of 1:3.0:10.0 at 60°C for 30 h. The reactants were then washed four times with water at a volume ratio of 1:8.0 to water to obtain 3-methyl-5-chloromethyl-2-hydroxybenzaldehyde, which is a light yellow crystal.

[0198] The yield of the product was determined to be 96% based on the methods described above.

[0199] 1 1H NMR (200MHz, CDCl3) characterization results (chemical shift δ): 11.32 (1H, s), 9.87 (1H, s), 7.44 (2H, brs), 4.57 (2H, s), 2.29 (3H, s).

[0200] Its elemental analysis results (wt%):

[0201] Measured values: 58.47% C, 4.96% H;

[0202] Calculated values: 58.55% C, 4.91% H.

[0203] B. Synthesis of salicylaldehydes containing quaternary ammonium salts

[0204] The 3-methyl-5-chloromethyl-2-hydroxybenzaldehyde compound obtained in step A was dissolved in benzene solvent. Then, a solution of diethylamine in benzene solvent was slowly added dropwise to the resulting solution. The 3-methyl-5-chloromethyl-2-hydroxybenzaldehyde compound and diethylamine reacted under nitrogen protection at a molar ratio of 1:2.0 and a temperature of 30°C for 8 hours. Then, the reactant was washed four times with xylene solvent at a volume ratio of 1:3.5 to its total amount, thus obtaining 2-hydroxy-3-methyl-5-(methyldiethylamine)benzaldehyde hydrochloride, which is a white crystal.

[0205] The yield of the product was determined to be 79% based on the methods described above.

[0206] 1¹H NMR (400 MHz, DMSO-d6) characterization results (chemical shift δ): 11.33 (¹H, s), 10.01 (¹H, s), 7.57 (¹H, d, J = 1.7 Hz), 7.04 (¹H, d, J = 1.7 Hz), 4.28–4.38 (²H, s), 3.14–3.26 (⁴H, q), 2.29–2.39 (³H, s), 1.28–1.40 (⁶H, t).

[0207] Its elemental analysis results (wt%):

[0208] Measured values: 60.42% C, 7.94% H, 5.48% N;

[0209] Calculated values: 60.58% C, 7.82% H, 5.43% N.

[0210] C. Salen ligand synthesis

[0211] Under nitrogen protection, the 2-hydroxy-3-methyl-5-(methyldiethylamine)benzaldehyde hydrochloride obtained in step B was dissolved in ethanol. Then, a solution of ethylenediamine in ethanol was slowly added dropwise to the resulting solution. The 2-hydroxy-3-methyl-5-(methyldiethylamine)benzaldehyde hydrochloride and ethylenediamine reacted at a molar ratio of 1:2.8 and a temperature of 80°C for 4 hours. The product was then separated and purified by ion exchange column chromatography to obtain a water-soluble salen ligand containing quaternary ammonium salt. The product was a bright yellow solid.

[0212] The yield of the product was determined to be 72% based on the methods described above.

[0213] 1 ¹H NMR (400 MHz, DMSO-d6) characterization results (chemical shift δ): 6.85–7.02 (4H, d), 4.29 (2H, s), 3.58–3.68 (3H, s), 3.14–3.27 (8H, q), 2.83–2.94 (7H, q), 2.68 (1H, dt, J = 10.3, 2.8 Hz), 2.54 (6H, s), 2.33 (1H, s), 2.18 (2H, s), 1.65–1.86 (4H, m), 1.41–1.62 (4H, m), 1.28–1.40 (12H, t).

[0214] Its elemental analysis results (wt%):

[0215] Experimental values: 65.33% C, 9.41% H, 8.90% N

[0216] Calculated values: 65.26% C, 9.34% H, 8.95% N.

[0217] D. Synthesis of manganese metal complex catalysts

[0218] The water-soluble salen ligand containing quaternary ammonium salt obtained in step C was dissolved in ethanol solvent, and bis(trifluoromethanesulfonic acid) manganese was added to carry out the reaction. The reaction was carried out for 16 h at a molar ratio of water-soluble salen ligand to bis(trifluoromethanesulfonic acid) manganese of 1:1.1 and a temperature of 60 °C. After the reaction was completed, the contents of substances other than manganese metal complex compounds were separated by ion exchange column chromatography until the contents were less than 1.0% by weight, thus obtaining the manganese metal complex catalyst.

[0219] The yield of the product was determined to be 91% based on the methods described above.

[0220] FT-IR (KBr) characterization results (wavenumber, cm⁻¹) -1 ): 3118(m), 2935(w), 1635(vs), 1592(s), 1544(s), 1487(m), 1368(vs,br),1223(s), 1209(vs), 1137 (m), 1086(s), 1023(m), 954(s), 877(m), 833(vs), 784(s), 752(m), 686(s), 614(m), 553(s), 482(m).

[0221] Its elemental analysis results (wt%):

[0222] Experimental values: 47.68% C, 6.12% H, 6.13% N;

[0223] Calculated values: 47.84% C, 6.02% H, 6.20% N.

[0224] Example 4: Synthesis of the water-soluble manganese metal complex catalyst of the present invention

[0225] The implementation steps of this embodiment are as follows:

[0226] A. Synthesis of chloromethyl salicylaldehyde compounds

[0227] Under nitrogen protection, salicylaldehyde, paraformaldehyde and hydrochloric acid were subjected to chloromethylation reaction in a reactor at 70°C for 24 h at a molar ratio of 1:2.5:8. The reactants were then washed three times with water at a volume ratio of 1:6.0 to water to obtain the chloromethyl salicylaldehyde compound, which is a light yellow crystal.

[0228] The yield of the product was determined to be 96% based on the methods described above.

[0229] 1¹H NMR (400 MHz, DMSO-d6) characterization results (chemical shift δ): 10.94 (¹H, s), 10.28 (¹H, s), 7.76 (¹H, d, J = 2.4), 7.59 (¹H, dd, J = 8.5, 2.4), 7.03 (¹H, d, J = 8.5), 4.78 (²H, s).

[0230] Its elemental analysis results (wt%):

[0231] Measured values: 56.44% C, 4.24% H;

[0232] Calculated values: 56.33% C, 4.14% H.

[0233] B. Synthesis of salicylaldehydes containing quaternary ammonium salts

[0234] The chloromethyl salicylic aldehyde compound obtained in step A was dissolved in xylene solvent. Then, a solution of N-methylimidazole in xylene solvent was slowly added dropwise to the resulting solution. The chloromethyl salicylic aldehyde compound and N-methylimidazole were reacted under nitrogen protection at a molar ratio of 1:1.7 and a temperature of 24°C for 5 hours. Then, the reactant was washed three times with xylene solvent at a volume ratio of 1:3.0 to its total amount, thus obtaining 2-hydroxy-5-(N-methylimidazole)-benzaldehyde hydrochloride, which is a white crystal.

[0235] The yield of the product was determined to be 77% based on the methods described above.

[0236] 1 ¹H NMR (400 MHz, DMSO-d6) characterization results (chemical shift δ): 11.31 (¹H, s), 10.25 (¹H, s), 9.33 (¹H, s), 7.86 (¹H, t, J = 1.7), 7.77–7.71 (²H, m), 7.66–7.61 (¹H, m), 7.26 (¹H, d, J = 8.5), 5.39 (²H, s), 3.86 (³H, s).

[0237] Its elemental analysis results (wt%):

[0238] Measured values: 55.52% C, 4.43% H, 11.69% N;

[0239] Calculated values: 55.59% C, 4.24% H, 11.79% N.

[0240] C. Salen ligand synthesis

[0241] Under nitrogen protection, the 2-hydroxy-5-(N-methylimidazolium)-benzaldehyde hydrochloride obtained in step B was dissolved in acetonitrile. Then, a solution of ethylenediamine in acetonitrile was slowly added dropwise to the resulting solution. The 2-hydroxy-5-(N-methylimidazolium)-benzaldehyde hydrochloride and ethylenediamine reacted at a molar ratio of 1:3.0 and a temperature of 60°C for 6 hours. The mixture was then separated and purified by ion exchange column chromatography to obtain a water-soluble salen ligand containing a quaternary ammonium salt. The product was a bright yellow solid.

[0242] The yield of the product was determined to be 85% based on the methods described above.

[0243] 1 1H NMR (400MHz, DMSO-d6) characterization results (chemical shift δ): 9.44 (2H, s), 8.5 (2H, s), 7.75-7.82 (4H, s), 7.47-7.53 (4H, s), 6.88-6.90 (2H, s), 5.34 (4H, s), 3.87 (6H, s), 3.85-3.86 (4H, m).

[0244] Its elemental analysis results (wt%):

[0245] Measured values: 59.02% C, 5.62% H, 15.69% N;

[0246] Calculated values: 58.98% C, 5.71% H, 15.87% N.

[0247] D. Synthesis of manganese metal complex catalysts

[0248] The water-soluble salen ligand containing quaternary ammonium salt obtained in step C was dissolved in acetonitrile solvent, and bis(trifluoromethanesulfonic acid) manganese was added. The reaction was carried out for 20 hours at a molar ratio of water-soluble salen ligand to bis(trifluoromethanesulfonic acid) manganese of 1:1.1 and a temperature of 46°C. After the reaction was completed, the mixture was separated by ion exchange column chromatography until the content of substances other than manganese metal complex compounds was less than 1.0% by weight, thus obtaining the manganese metal complex catalyst.

[0249] The yield of the product was determined to be 92% based on the methods described above.

[0250] FT-IR (KBr) characterization results (wavenumber, cm⁻¹) -1 ): 3417(m,br), 3095(m), 1642(vs), 1552(s), 1489(m), 1397(vs), 1310(s), 1225(s), 1164(vs), 1054(m), 853(w), 758(m), 671(m), 620(m).

[0251] Its elemental analysis results (wt%):

[0252] Measured values: 38.25% C, 3.34% H, 9.48% N;

[0253] Calculated values: 38.19% C, 3.21% H, 9.54% N.

[0254] Example 5: Method for preparing epichlorohydrin according to the present invention

[0255] The implementation steps of this embodiment are as follows:

[0256] I. Catalyst Dissolution

[0257] The catalyst prepared in Example 1 and sodium dihydrogen phosphate were dissolved in water according to the following conditions: the molar ratio of hydrogen peroxide, allyl chloride, and sodium dihydrogen phosphate was 1:1.4:0.003:0.002, and the volume ratio of water to hydrogen peroxide was 1:16. Allyl chloride was then added and stirred to dissolve the mixture to obtain a reaction mixture.

[0258] II. Epoxidation reaction

[0259] The reaction mixture obtained in step I was heated to 20°C, and hydrogen peroxide with a concentration of 20% by volume was added dropwise over 0.8 hours. The reaction was kept at this temperature for 1.0 hour. The resulting reaction solution was then subjected to oil phase and water phase separation. The separated oil phase was a product containing epichlorohydrin.

[0260] The results of this embodiment, obtained by testing according to the method described in this application specification, are listed in Table 1.

[0261] Example 6: Method for preparing epichlorohydrin according to the present invention

[0262] The implementation steps of this embodiment are as follows:

[0263] I. Catalyst Dissolution

[0264] The catalyst prepared in Example 2 and sodium dihydrogen phosphate were dissolved in water according to the following formula: hydrogen peroxide, allyl chloride, and sodium dihydrogen phosphate were in a molar ratio of 1:1.1:0.001:0.003. The volume ratio of water to hydrogen peroxide was 1:10. Allyl chloride was then added and stirred to dissolve the mixture to obtain a reaction mixture.

[0265] II. Epoxidation reaction

[0266] The reaction mixture obtained in step I was heated to 10°C, and hydrogen peroxide with a concentration of 70% by volume was added dropwise over 0.5 hours. The reaction was kept at this temperature for 3.0 hours. The resulting reaction solution was then subjected to oil and water phase separation. The separated oil phase was a product containing epichlorohydrin.

[0267] The results of this embodiment, obtained by testing according to the method described in this application specification, are listed in Table 1.

[0268] Example 7: Method for preparing epichlorohydrin according to the present invention

[0269] The implementation steps of this embodiment are as follows:

[0270] I. Catalyst Dissolution

[0271] The catalyst prepared in Example 3 and sodium dihydrogen phosphate were dissolved in water according to the following conditions: the molar ratio of hydrogen peroxide, allyl chloride, and sodium dihydrogen phosphate was 1:2.0:0.004:0.001, and the volume ratio of water to hydrogen peroxide was 1:20. Allyl chloride was then added and stirred to dissolve the mixture to obtain a reaction mixture.

[0272] II. Epoxidation reaction

[0273] The reaction mixture obtained in step I was heated to 40°C, and hydrogen peroxide with a concentration of 50% by volume was added dropwise over 1.0 hour. The reaction was kept at this temperature for 2.5 hours. The resulting reaction solution was then separated into an oil phase and an aqueous phase. The separated oil phase was a product containing epichlorohydrin.

[0274] The results of this embodiment, obtained by testing according to the method described in this application specification, are listed in Table 1.

[0275] Example 8: Method for preparing epichlorohydrin according to the present invention

[0276] The implementation steps of this embodiment are as follows:

[0277] I. Catalyst Dissolution

[0278] The catalyst prepared in Example 4 was dissolved in water with hydrogen peroxide, allyl chloride, and sodium dihydrogen phosphate in a molar ratio of 1:1.6:0.005:0.005, and the volume ratio of water to hydrogen peroxide was 1:14. Allyl chloride was then added and stirred to dissolve the catalyst and sodium dihydrogen phosphate to obtain a reaction mixture.

[0279] II. Epoxidation reaction

[0280] The reaction mixture obtained in step I was heated to 30°C, and hydrogen peroxide with a concentration of 40% by volume was added dropwise over 0.6 hours. The reaction was kept at this temperature for 1.5 hours. The resulting reaction solution was then separated into an oil phase and an aqueous phase. The separated oil phase was a product containing epichlorohydrin.

[0281] The results of this embodiment, obtained by testing according to the method described in this application specification, are listed in Table 1.

[0282] Table 1: Implementation Results of Examples 5-8

[0283]

[0284] The results in Table 1 clearly demonstrate that the water-soluble manganese metal complex catalyst of this invention exhibits excellent comprehensive performance in the one-step synthesis of epichlorohydrin under solvent-free conditions. The catalytic activity is significantly enhanced, completely eliminating organic solvents to achieve a green process, greatly simplifying the post-processing steps and reducing production costs, providing a highly atom-economical innovative solution for the industrial synthesis of epichlorohydrin.

Claims

1. A water-soluble manganese metal complex catalyst, characterized in that... The catalyst has the following chemical structural formula: In the formula: R1 and R5 represent H, methyl, or tert-butyl; R2, R3, R4, R6, R7, and R8 represent one or more selections from H, C1 to C1. 12 Saturated alkyl or C1-C 12 Unsaturated alkyl groups; or they form one or more cyclic imidazole structures with N; X represents one or more selected from C. 1-6 Alkyl or cycloalkanes; TOf is a trifluoromethanesulfonic acid group; Cl is a chloride ion.

2. The method for preparing the catalyst according to claim 1, characterized in that... The preparation steps of this method are as follows: A. Synthesis of chloromethylsalicylaldehyde compounds Under nitrogen protection, salicylaldehyde compounds, paraformaldehyde, and hydrochloric acid were subjected to a chloromethylation reaction in a reactor at a temperature of 40–70°C for 10–30 h at a molar ratio of 1:1.5–3.0:3.0–10.

0. The reactants were then washed with water 2–4 times at a volume ratio of 1:3.0–8.0 to water to obtain the chloromethyl salicylaldehyde compounds. B. Synthesis of salicylaldehydes containing quaternary ammonium salts The chloromethyl salicylaldehyde compound obtained in step A is dissolved in an aldehyde solvent. Then, a secondary amine or imidazole compound solution is slowly added dropwise to the resulting solution. The chloromethyl salicylaldehyde compound reacts with the secondary amine or imidazole compound under nitrogen protection at a molar ratio of 1:1.0-2.0 and a temperature of 20-30°C for 3-8 hours. Then, the reactant is washed 2-4 times with the washing solvent at a volume ratio of 1:2.5-4.0 to its total amount, thus obtaining a salicylaldehyde compound containing quaternary ammonium salt. C. Synthesis of water-soluble salten ligands Under nitrogen protection, the salicylaldehyde compound containing quaternary ammonium salt obtained in step B was dissolved in a salicylaldehyde compound solvent. Then, X-diamine solution was slowly added dropwise to the resulting solution. The salicylaldehyde compound containing quaternary ammonium salt and X-diamine reacted at a molar ratio of 1:2.0-3.0 and a temperature of 40-80℃ for 4-10 hours. Then, the mixture was separated and purified by ion exchange column chromatography to obtain a water-soluble salen ligand containing quaternary ammonium salt. D. Synthesis of manganese metal complex catalysts The water-soluble salen ligand containing quaternary ammonium salt obtained in step C was dissolved in salen ligand solvent, and manganese salt was added. The reaction was carried out under the conditions of a water-soluble salen ligand to manganese salt molar ratio of 1:1.0 to 1.2 and a temperature of 40 to 60°C. Then, anhydrous lithium chloride was added according to a water-soluble salen ligand to anhydrous lithium chloride molar ratio of 1:0 or 1:3 to continue the reaction. The total reaction time was 8 to 20 hours. After the reaction was completed, the manganese metal complex catalyst was obtained by separation and purification.

3. The preparation method according to claim 2, characterized in that... In step A, the salicylaldehyde compound is salicylaldehyde, 3-methylsalicylaldehyde, or 3-tert-butylsalicylaldehyde.

4. The preparation method according to claim 2, characterized in that... In step B, the secondary amine is one or more secondary amine compounds selected from diethylamine, dipropylamine, or diisopropylamine; the imidazole compound is one or more imidazole compounds selected from N-methylimidazole, 2-ethyl-4-methylimidazole, 4-methylimidazole, or 2-phenylimidazole; the aldehyde compound solvent is one or more solvents selected from benzene, toluene, xylene, or anisole; and the washing solvent is one or more solvents selected from benzene, toluene, xylene, or anisole.

5. The preparation method according to claim 2, characterized in that... In step C, the X-diamine is one or more diamine compounds selected from ethylenediamine, cyclohexanediamine, butanediamine, or o-phenylenediamine; the salicylaldehyde solvent is one or more solvents selected from ethanol, acetonitrile, or acetone.

6. The preparation method according to claim 2, characterized in that... In step D, the manganese salt is manganese acetate tetrahydrate, manganese chloride, or bis(trifluoromethanesulfonic acid) manganese; the salon ligand solvent is one or more solvents selected from ethanol, acetonitrile, or acetone.

7. The preparation method according to claim 2, characterized in that... In step D, the separation and purification involves using ion exchange column chromatography to separate the reaction product containing quaternary ammonium salt salicylaldehyde compounds and X-diamine until the content of substances other than quaternary ammonium salt salicylaldehyde compounds is less than 1.0% by weight.

8. The water-soluble manganese metal complex catalyst prepared by the preparation method according to any one of claims 1-7.

9. Use of the water-soluble manganese metal complex catalyst according to claim 8 in the preparation of epichlorohydrin from chloropropylene.

10. The use according to claim 9, characterized in that... The preparation steps for epichlorohydrin from allyl chloride are as follows: I. Catalyst Dissolution According to the molar ratio of hydrogen peroxide, allyl chloride, water-soluble manganese metal complex catalyst and sodium dihydrogen phosphate being 1:1.1~2.0:0.001~0.005:0.001~0.005, and the volume ratio of water to hydrogen peroxide being 1:10~20, the water-soluble manganese metal complex catalyst and sodium dihydrogen phosphate are dissolved in water, and then allyl chloride is added and stirred to dissolve, to obtain a reaction mixture; II. Epoxidation reaction The reaction mixture obtained in step I is heated to a temperature of 10-40°C, and hydrogen peroxide with a concentration of 20%-70% by volume is added dropwise over 0.5-1.0 hours. The reaction is kept at this temperature for 1-3 hours. The resulting reaction solution is then separated into an oil phase and an aqueous phase. The separated oil phase is a product containing epichlorohydrin.

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