CN109651120B - Preparation method of 4- (4-formylphenoxy) benzaldehyde - Google Patents
Preparation method of 4- (4-formylphenoxy) benzaldehyde Download PDFInfo
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Abstract
The invention relates to the technical field of chemical synthesis, and particularly discloses a preparation method of 4- (4-formylphenoxy) benzaldehyde. The preparation method comprises the steps of firstly, reacting 4-hydroxybenzaldehyde with potassium carbonate in the presence of a polymerization inhibitor and an antioxidant to generate potassium salt, removing water generated in the reaction through azeotropic reflux, and then reacting the potassium salt with which water is removed with 4-fluorobenzaldehyde to obtain the 4- (4-formylphenoxy) benzaldehyde product. The purity of the 4- (4-formylphenoxy) benzaldehyde product prepared by the invention can reach more than 99 percent, the molar yield can reach more than 97 percent, the industrial production of the 4- (4-formylphenoxy) benzaldehyde is realized, and the method has wide application prospect.
Description
Technical Field
The invention relates to the technical field of chemical synthesis, in particular to a preparation method of 4- (4-formylphenoxy) benzaldehyde.
Background
4- (4-formylphenoxy) benzaldehyde having the structural formula:
the phenolic resin prepared by taking the phenolic resin as the raw material has excellent insulativity, heat resistance and processability, and is widely applied to various fields of electronics, solar energy, photovoltaic power generation, aviation, aerospace and the like.
At present, the method for synthesizing 4- (4-formylphenoxy) benzaldehyde mainly comprises the following steps: (1) the 4- (4-formylphenoxy) benzaldehyde is prepared by taking p-hydroxybenzaldehyde and p-bromobenzoic acid as raw materials and adopting a mode of etherification and reduction, but lithium aluminum hydride and tetrahydrofuran are used in the synthetic method, so the method has high danger and great operation difficulty and is difficult to realize industrial production; (2) 4- (4-formylphenoxy) benzaldehyde is obtained by taking 4-hydroxybenzaldehyde as a raw material and carrying out self-condensation reaction under the action of a catalyst, but the yield of the 4- (4-formylphenoxy) benzaldehyde obtained by the method is only 79%; (3) 4- (4-formylphenoxy) benzaldehyde is obtained by reduction reaction by using 4, 4' -oxydibenzoyl chloride as a raw material, tetrahydrofuran as a catalyst and lithium aluminum tributylhydride as a reducing agent, and the method has the advantages of high corrosivity of the raw material and poor safety, and the yield of the 4- (4-formylphenoxy) benzaldehyde is only 84%. Therefore, in order to improve the yield of 4- (4-formylphenoxy) benzaldehyde and reduce potential safety hazards, a safer and industrialized production process needs to be found.
Disclosure of Invention
Aiming at the problems of low yield, high risk and difficult realization of industrialization in the process for preparing 4- (4-formylphenoxy) benzaldehyde in the prior art, the invention provides a preparation method of 4- (4-formylphenoxy) benzaldehyde.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a preparation method of 4- (4-formylphenoxy) benzaldehyde comprises the following steps:
adding 4-hydroxybenzaldehyde, potassium carbonate, a polymerization inhibitor, an antioxidant and a water-carrying agent into a solvent, heating to reflux, and stirring for reaction to obtain an intermediate solution;
step two, adding 4-fluorobenzaldehyde into the intermediate solution for etherification reaction to obtain a 4- (4-formylphenoxy) benzaldehyde solution;
and step three, removing the water carrying agent in the 4- (4-formylphenoxy) benzaldehyde solution, filtering, cooling and crystallizing to obtain a 4- (4-formylphenoxy) benzaldehyde product.
The reaction equation of the preparation process is as follows:
compared with the prior art, the preparation method of 4- (4-formylphenoxy) benzaldehyde provided by the invention uses 4-hydroxybenzaldehyde and 4-fluorobenzaldehyde as raw materials, the 4-hydroxybenzaldehyde and potassium carbonate react to generate potassium salt before the reaction of the 4-hydroxybenzaldehyde and the 4-fluorobenzaldehyde, water generated by the reaction is removed through azeotropic reflux, and then the removed water potassium salt reacts with the 4-fluorobenzaldehyde, so that the side reaction of the 4-fluorobenzaldehyde and the water is avoided, the conversion rate of the 4-fluorobenzaldehyde is improved, and the conversion rate of the 4-fluorobenzaldehyde can reach 99.5%; the added polymerization inhibitor can reduce the generation of polymerization byproducts such as aldol condensation and the like; the added antioxidant protects the aldehyde group of the prepared 4- (4-formylphenoxy) benzaldehyde product, and improves the appearance of the product while reducing the side oxidation reaction. The product 4- (4-formylphenoxy) benzaldehyde is white to off-white crystal, the HPLC content is more than 99 percent, the molar yield is more than 97 percent, the raw materials are easy to obtain, the operation is simple, the safety is high, and the industrial production of the 4- (4-formylphenoxy) benzaldehyde is realized.
Preferably, in the first step, the stirring reaction time is 2-4 h.
The preferable stirring reaction time can ensure that the 4-hydroxybenzaldehyde and the potassium carbonate fully react, and the water generated in the reaction is completely removed, so that the side reaction of the 4-fluorobenzaldehyde and the water is avoided, and the product yield and the purity are reduced.
Preferably, in the second step, the temperature of the etherification reaction is 110-130 ℃, and the reaction time is 14-17 h.
The preferable reaction temperature and reaction time can ensure that the potassium salt prepared in the step one can fully react with the 4-fluorobenzaldehyde, and can also reduce the occurrence of side reactions and improve the conversion rate of the 4-fluorobenzaldehyde.
Preferably, in the second step, the 4-fluorobenzaldehyde is added into the intermediate solution in a dropwise manner, and the dropwise adding time is 20-40 min.
The preferable addition mode of the 4-fluorobenzaldehyde can fully carry out the reaction and reduce the occurrence of side reaction.
Preferably, in the first step, the polymerization inhibitor is phenothiazine.
The preferable polymerization inhibitor can reduce the generation of polymerization byproducts such as aldol condensation and the like, and improve the conversion rate of raw materials and the purity of products.
Preferably, the antioxidant is 2, 6-di-tert-butyl-p-cresol (BHT).
The optimized antioxidant can effectively protect aldehyde groups of the product, and improve the appearance of the product while reducing oxidation side reactions, so that the 4- (4-formylphenoxy) benzaldehyde product prepared by the invention has better quality.
Preferably, the water-carrying agent is one or two of toluene or xylene.
The solvent is at least one of N, N-dimethylformamide, N-dimethylacetamide or dimethyl sulfoxide.
The preferred solvent can fully dissolve the 4-hydroxybenzaldehyde, the polymerization inhibitor and the antioxidant, and the preferred water-carrying agent can quickly remove water generated by the reaction of the 4-hydroxybenzaldehyde and the potassium carbonate.
Preferably, the mass ratio of the polymerization inhibitor to 4-hydroxybenzaldehyde is 0.0001 to 0.0005: 1.
Preferably, the mass ratio of the antioxidant to the 4-hydroxybenzaldehyde is 0.0002-0.0005: 1.
The preferable addition amount of the polymerization inhibitor and the antioxidant can effectively reduce the side reaction possibly generated at high temperature on the premise of ensuring that impurities are introduced as little as possible, thereby improving the purity of the 4- (4-formylphenoxy) benzaldehyde product.
Preferably, the molar ratio of potassium carbonate to 4-hydroxybenzaldehyde is 0.6-0.8: 1.
Preferably, the molar ratio of the 4-fluorobenzaldehyde to the 4-hydroxybenzaldehyde is 1:1.01 to 1.05.
The optimized ratio of each reactant can improve the utilization rate of raw materials, thereby improving the yield of the 4- (4-formylphenoxy) benzaldehyde product.
Preferably, the mass ratio of the solvent to the water-carrying agent is 1: 0.1-0.3.
Preferably, the solvent is N, N-dimethylformamide, and the water-carrying agent is toluene.
Preferably, the mass ratio of the solvent to the 4-hydroxybenzaldehyde is 3-5: 1.
The preferable adding amount of the water-carrying agent and the solvent can fully dissolve the 4-hydroxybenzaldehyde, the polymerization inhibitor and the antioxidant, and the problems that the raw materials are not reacted completely and the polymerization inhibitor and the antioxidant cannot play a full role due to non-uniform mixing are avoided. Meanwhile, when the reflux temperature is reached, the 4-hydroxybenzaldehyde and potassium carbonate are fully reacted to generate sylvite, the water generated in the reaction is rapidly removed, the reaction time is shortened, and the conversion rate of the 4-hydroxybenzaldehyde is improved.
Preferably, in the third step, the step of cooling crystallization is: adding water into the filtrate obtained by filtering, cooling to 10-20 ℃, and carrying out heat preservation and crystallization for 2-4 h.
The preferable crystallization temperature and crystallization time can ensure that the 4- (4-formylphenoxy) benzaldehyde is fully precipitated, the yield of the product is improved, the precipitation of metal ions can be avoided, and the purity of the product is improved.
Preferably, in the third step, the mass ratio of the water in the filtrate to the solvent is 0.9-1.2: 1.
Preferably, the water added to the filtrate is hot water at 80-90 deg.C.
The N, N-dimethylformamide has good solubility for the 4- (4-formylphenoxy) benzaldehyde crude product, the 4- (4-formylphenoxy) benzaldehyde crude product can be fully dissolved, the solution formed after water is added has good dissolving capacity for inorganic impurities such as metal ions and the like remained in the 4- (4-formylphenoxy) benzaldehyde crude product, the impurities in the 4- (4-formylphenoxy) benzaldehyde crude product can be fully removed, and the yield and the purity of the product are improved.
Optionally, in the third step, the conditions for removing the water-carrying agent are as follows: distilling under normal pressure until the vapor phase temperature is 145 ℃.
The purpose of this step is to remove toluene or xylene from the solution, but to retain the N, N-dimethylformamide in the solution as one of the solvents for the subsequent crystallization.
Optionally, in the third step, the reaction solution without the water-carrying agent is cooled to 80-90 ℃ by a hot filtration mode, and is filtered while hot.
Filtering at 80-90 deg.c to ensure high 4- (4-formyl phenoxy) benzaldehyde solubility, avoid the separation of metal ion in salt form and raise the product purity.
According to the preparation method of the 4- (4-formylphenoxy) benzaldehyde, the used raw materials are common reagents, the price is low, the production cost is low, the operation is simple, the safety is high, the prepared 4- (4-formylphenoxy) benzaldehyde is white to off-white crystals, the HPLC content is more than 99%, the molar yield is more than 97%, and the industrial production of the 4- (4-formylphenoxy) benzaldehyde is realized.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
A preparation method of 4- (4-formylphenoxy) benzaldehyde comprises the following steps:
step one, putting 303kg of 4-hydroxybenzaldehyde, 240kg of potassium carbonate, 90.9g of phenothiazine, 121.2g of BHT, 1212kg of N, N-dimethylformamide and 242.4kg of methylbenzene into an enamel reaction kettle with a reflux device, stirring, heating to 120 ℃, preserving heat, and performing reflux dehydration for 3 hours to obtain an intermediate solution;
step two, dripping 299g of 4-fluorobenzaldehyde into the intermediate solution for 0.5h, continuously keeping the temperature of 120 ℃ for reacting for 16h, sampling HPLC (high performance liquid chromatography) to detect that the content of 4-fluorobenzaldehyde is less than 0.2%, and ending the reaction to obtain a 4- (4-formylphenoxy) benzaldehyde solution;
distilling toluene under normal pressure, and stopping distilling until the gas phase temperature is 145 ℃; cooling to 85 ℃, keeping the temperature and performing filter pressing while the mixture is hot, washing a filter cake by 200kgN, N-dimethylformamide, combining filtrate and washing liquid, stirring, adding 1212kg of hot water at 85 ℃, cooling to 15 ℃, keeping the temperature and crystallizing for 3 hours, centrifuging, and washing to obtain a white 4- (4-formylphenoxy) benzaldehyde crystal with the HPLC content of 99.7 percent and the molar yield of 98.6 percent.
Example 2
A preparation method of 4- (4-formylphenoxy) benzaldehyde comprises the following steps:
step one, putting 303kg of 4-hydroxybenzaldehyde, 205.8kg of potassium carbonate, 151.5g of phenothiazine, 60.6g of BHT, 909kg of N, N-dimethylacetamide and 272.2kg of methylbenzene into an enamel reaction kettle with a reflux device, stirring, heating to 130 ℃, preserving heat, and performing reflux dehydration for 2 hours to obtain an intermediate solution;
step two, 304.9kg of 4-fluorobenzaldehyde is dropwise added into the intermediate solution for 0.5h, the temperature of 130 ℃ is kept continuously for reaction for 14h, the content of the 4-fluorobenzaldehyde is detected to be less than 0.2% by sampling HPLC, and the reaction is finished to obtain a 4- (4-formylphenoxy) benzaldehyde solution;
distilling toluene under normal pressure, and stopping distilling until the gas phase temperature is 145 ℃; cooling to 90 ℃, keeping the temperature and performing filter pressing while the mixture is hot, washing a filter cake by 200kgN, N-dimethylformamide, combining filtrate and washing liquid, stirring, adding 1091kg of hot water at 90 ℃, cooling to 20 ℃, keeping the temperature and crystallizing for 2 hours, centrifuging and washing to obtain a white 4- (4-formylphenoxy) benzaldehyde crystal with the HPLC content of 99.3 percent and the molar yield of 97.6 percent.
Example 3
Step one, putting 303kg of 4-hydroxybenzaldehyde, 274.3kg of potassium carbonate, 33g of phenothiazine, 151.5g of BHT, 1515kg of a mixture of N, N-dimethylformamide and dimethyl sulfoxide (the mass ratio is 1:1) and 151.5kg of a mixture of toluene and xylene (the mass ratio is 1:1) into an enamel reaction kettle with a reflux device, stirring, heating to 110 ℃, preserving heat, and performing reflux dehydration for 4 hours to obtain an intermediate solution;
step two, dripping 293.3kg of 4-fluorobenzaldehyde into the intermediate solution for 0.5h, continuously keeping the temperature of 110 ℃ for reacting for 17h, sampling HPLC (high performance liquid chromatography) to detect that the content of the 4-fluorobenzaldehyde is less than 0.2%, and finishing the reaction to obtain a 4- (4-formylphenoxy) benzaldehyde solution;
distilling toluene under normal pressure, and stopping distilling until the gas phase temperature is 145 ℃; cooling to 80 ℃, keeping the temperature and performing filter pressing while the mixture is hot, washing a filter cake by 200kgN, N-dimethylformamide, combining filtrate and washing liquid, stirring, adding 1364kg of hot water at 80 ℃, cooling to 10 ℃, keeping the temperature and crystallizing for 4h, centrifuging, and washing to obtain a white 4- (4-formylphenoxy) benzaldehyde crystal with the HPLC content of 99.5 percent and the molar yield of 98.6 percent.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (6)
1. A preparation method of 4- (4-formylphenoxy) benzaldehyde is characterized by comprising the following steps:
adding 4-hydroxybenzaldehyde, potassium carbonate, a polymerization inhibitor, an antioxidant and a water-carrying agent into a solvent, heating to reflux, and stirring for reaction to obtain an intermediate solution; the molar ratio of the potassium carbonate to the 4-hydroxybenzaldehyde is 0.6-0.8: 1; the polymerization inhibitor is phenothiazine, the antioxidant is 2, 6-di-tert-butyl-p-cresol, and the water-carrying agent is one or two of toluene or xylene; the mass ratio of the polymerization inhibitor to the 4-hydroxybenzaldehyde is 0.0001-0.0005:1, the mass ratio of the antioxidant to the 4-hydroxybenzaldehyde is 0.0002-0.0005:1, and the mass ratio of the solvent to the water-carrying agent is 1: 0.1-0.3;
step two, adding 4-fluorobenzaldehyde into the intermediate solution for etherification reaction to obtain a 4- (4-formylphenoxy) benzaldehyde solution; the molar ratio of the 4-fluorobenzaldehyde to the 4-hydroxybenzaldehyde is 1: 1.01-1.05;
and step three, removing the water carrying agent in the 4- (4-formylphenoxy) benzaldehyde solution, filtering, adding water into the filtrate obtained by filtering, cooling to 10-20 ℃, and carrying out heat preservation and crystallization for 2-4h to obtain the 4- (4-formylphenoxy) benzaldehyde product.
2. The process for producing 4- (4-formylphenoxy) benzaldehyde according to claim 1, wherein in the first step, the reaction time is 2 to 4 hours under stirring; and/or
In the second step, the temperature of the etherification reaction is 110-130 ℃, and the reaction time is 14-17 h.
3. The process for producing 4- (4-formylphenoxy) benzaldehyde according to claim 1, wherein the solvent is at least one of N, N-dimethylformamide, N-dimethylacetamide and dimethylsulfoxide.
4. The method of preparing 4- (4-formylphenoxy) benzaldehyde according to claim 1, wherein the solvent is N, N-dimethylformamide and the water-carrying agent is toluene.
5. The method for producing 4- (4-formylphenoxy) benzaldehyde according to claim 1, wherein the mass ratio of the solvent to 4-hydroxybenzaldehyde is 3 to 5: 1.
6. The process for producing 4- (4-formylphenoxy) benzaldehyde according to claim 1, wherein the mass ratio of water to the solvent in the filtrate is 0.9 to 1.2: 1.
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