CN109704916B - Synthesis process of substituted aromatic alcohol - Google Patents
Synthesis process of substituted aromatic alcohol Download PDFInfo
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- CN109704916B CN109704916B CN201711008251.4A CN201711008251A CN109704916B CN 109704916 B CN109704916 B CN 109704916B CN 201711008251 A CN201711008251 A CN 201711008251A CN 109704916 B CN109704916 B CN 109704916B
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Abstract
The invention discloses an economical synthesis process of substituted aromatic alcohol, which is characterized in that COOR is synthesized1‑C6F4‑COOR1(R1Represents C1‑C4Alkyl) into an organic solvent in NaBH4Reduction reaction under the action of the catalyst to obtain CH2OH‑C6F4‑CH2OH (II) and CH2OH‑C6F4-cooh (iii); dissolving the mixture in weak acid buffer solution, adjusting pH, and extracting to obtain water layer containing II and oil layer containing III; putting the oil layer into an aprotic solvent for decarboxylation to obtain CH2OH‑C6HF4. According to the invention, the reduction process stays in an intermediate state, the requirement of the process on the reduction completeness is reduced, and the use of a reducing agent is reduced; the mixture is separated by a chemical method, and products can be well utilized.
Description
Technical Field
The invention relates to an economical synthesis process of substituted aromatic alcohol, in particular to a preparation method for co-producing 2,3,5, 6-tetrafluoro-p-benzhydrol in the synthesis process of 2,3,5, 6-tetrafluoro-benzyl alcohol, and belongs to the field of organic synthesis.
Background
The pyrethroid insecticide is one of the support products in the world health insecticide market at present, and has the characteristics of high efficiency, spectrum, low toxicity, low residue and the like. The pyrethroid pesticide is a natural product mimic, is easy to decompose in nature, cannot generate adverse effects on the environment after being used, is easy to metabolize in a mammal body, has no accumulation effect, cannot be enriched through a biological chain, and is an environment-friendly green pesticide.
Transfluthrin belongs to a broad-spectrum pesticide, and can effectively prevent and control sanitary pests and storage pests; it can quickly knock down dipteran such as mosquito, and cockroach; the bedbugs have good residual effect. Transfluthrin has extremely low acute and chronic toxicity, and is widely applied to sanitary insecticidal products: mosquito-repellent incense, aerosol insecticide, and electric mosquito repellent incense.
2,3,5, 6-tetrafluorobenzyl alcohol and 2,3,5, 6-tetrafluoro-p-benzhydrol are important intermediates of novel fluorine-containing pyrethroid insecticides transfluthrin and chlorofluoroether pyrethrin. There are various synthetic methods for 2,3,5, 6-tetrafluorobenzyl alcohol, such as: EP0031199, WO9808795, WO2000068173, EP0060617, US4822912, WO2002034707, WO2002002504, WO20020026678, WO2002034706, etc. At present, the domestic manufacturers mainly adopt a tetrafluoro p-diphenylcyanic acid ester-decomposition reduction route, which is invented by Yangnong chemical industry Co., Ltd (CN 200310121743). The reaction conditions of the route are mild, fluorine-removing impurities possibly generated in the processes of other routes are avoided, and the purity of the product can reach more than 98%. The raw materials are all produced at home, the process is simple, the synthesis yield is high, the product purity is high, and the economic benefit is remarkable.
However, the process has certain disadvantages: 1. the reducing agent and the reducing auxiliary agent used in the reduction process are more than the required reaction equivalent by 1.5-2.0 times, and the excessive reducing agent cannot be recovered and needs to be completely destroyed in the treatment process, so that a large amount of high-salt-content wastewater is generated; 2. in the decarboxylation reaction process, because the intermediate has two carboxyl groups, the reaction time needs to be strictly controlled, so that the reaction stays in an intermediate state, and meanwhile, the selectivity and the conversion rate of the decarboxylation reaction are difficult to improve; 3. the generated solid waste cannot be treated or the treatment cost is higher.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides an economical synthesis process for replacing aromatic alcohol, and solves the technical problems of more reducing agent excessive wastewater, difficult control of decarboxylation process and more solid wastes in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
an economical synthesis process of substituted aromatic alcohol comprises the following steps:
(1) reduction reaction: under the stirring state, putting the compound I into an organic solvent for dissolving, and carrying out reduction reaction for 2-8 hours at the temperature of 0-60 ℃ under the action of a reducing agent NaBH4 to obtain a mixture of a compound II and a compound III;
(2) separation: dissolving the mixture obtained in the step (1) in a weak acid buffer solution system, adjusting the pH to 3.5-4.5, adding an extracting agent for extraction, wherein a water layer contains a compound II, and an oil layer contains a compound III;
(3) treating a compound III: putting the oil layer obtained in the step (2) into an aprotic solvent, and reacting at 60-140 ℃ to remove carboxyl to obtain a product IV; because only one carboxyl group is arranged, the reaction selectivity and the conversion rate can reach 99 percent;
the chemical reaction equation is as follows:
wherein R1 represents C1-C4Alkyl of (a) can be selected from-CH3、-CH2CH3、-CH2(CH3)2、-(CH2)2CH3、-(CH2)3CH3。
In the above technical solutions, the compound I is preferred, wherein: r1 is-CH3Namely, the compound I is 2,3,5, 6-tetrafluoro-p-dimethyl terephthalate.
In the above technical solution, in the step (1), the molar ratio of the compound I, NaBH4 to the organic solvent is compound I: NaBH 4: solvent 1: 0.75-1.60: 4-8; preferably, the molar ratio is, compound I: NaBH 4: solvent 1: 0.75-1.10: 4-8.
In the above technical scheme, in the step (1), the reaction temperature is preferably 0-30 ℃.
In the above technical solution, in the step (1), the organic solvent is any one of methyl tert-butyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran, cyclopentyl methyl ether and ethylene glycol dimethyl ether, or a mixture of two or more of them mixed in any proportion.
In the above technical scheme, in the step (2), the weak acidic buffer solution system is a weak acidic buffer solution, preferably an acetic acid/sodium acetate, formic acid/sodium formate or citric acid/sodium citrate buffer solution; the ratio of the used amount to the total mass of the product obtained in the step (1) is 1:1-1: 3.
In the technical scheme, in the step (2), the pH value of the water layer is adjusted by acid, then an extracting agent is added for extraction, an extract phase is washed by water to be neutral, and then the solid compound II is obtained after decompression and desolventization.
In the above technical scheme, in the step (2), the pH can be accurately adjusted to 3.5-4.5 by using the corresponding acid of the corresponding buffer solution.
In the above technical scheme, in the step (2), the extracting agent is any one of toluene, methyl isobutyl ketone, 2-methyltetrahydrofuran and cyclopentyl methyl ether, or a mixture of two or more of them.
In the above technical solution, in the step (3), the oil layer is preferably dissolved in an aprotic solvent after being subjected to a post-treatment, wherein the post-treatment means: washing the oil layer to be neutral, and then carrying out decompression and desolventization to obtain a solid of the compound III.
In the above technical scheme, in the step (3), the reaction temperature is preferably 80-120 ℃.
In the above technical solution, in the step (3), the aprotic solvent is any one of diethoxymethane, N-methylpyrrolidone, 1, 3-dimethylimidazolidin-2-one, N-dimethylformamide, N-diethylacetamide, and dimethylsulfoxide, or a mixture of two or more thereof; preferably, the solvent is a mixture of one, two or more of N, N-dimethylformamide, N-diethylacetamide and dimethylsulfoxide mixed at any ratio.
In the above technical scheme, in the step (3), the mass ratio of the compound III to the aprotic solvent in the oil layer is 1:1 to 1:5, preferably 1:1 to 1: 3.
The technical scheme of the invention has the advantages that: because the reduction process stays in the intermediate state, the requirement of the process on the reduction completeness is reduced, the use of a reduction auxiliary agent is eliminated, and the use of a reducing agent is reduced. The mixture product is separated by a chemical method, so that the synthesized product can be well utilized. The raw material for decarboxylation after separation only contains one carboxyl, so that the reaction selectivity and the conversion rate are improved to 99 percent, the problems of low single conversion rate and poor selectivity in the original synthesis process are solved, and the product IV obtained by reaction can be directly used for synthesizing pesticide products.
Detailed Description
The following detailed description of the embodiments of the present invention is provided, but the present invention is not limited to the following descriptions:
example 1:
an economical synthesis process of substituted aromatic alcohol comprises the following steps:
(1): 200g of ethylene glycol dimethyl ether (2.22mol) and 100g of 2,3,5, 6-tetrafluoroterephthalic acid methyl ester (0.376mol) were put into a 500ml four-necked flask, the temperature was raised to 30 ℃ and 13.0g of sodium borohydride (0.343mol) was intermittently added in a fully dissolved state, and after completion of the addition, the temperature was maintained at that temperature for 8 hours. After the reaction, the resultant was added to 200g of 10% aqueous hydrochloric acid, extracted with 200ml of toluene, washed with water to neutrality, and desolventized under reduced pressure to give 83.2g of an off-white solid product mixture.
(2) Putting the mixture obtained in the step 1 into a 1000ml four-mouth bottle, adding 0.2mol/L acetic acid/sodium acetate buffer solution with the value of 240gpH being 4.2, stirring until the mixture is completely dissolved, measuring the pH value of the system to be 4.0, adding 200g of toluene for extraction, washing an oil layer until the oil layer is neutral, and performing decompression and desolventization to obtain 72.1g of off-white solid 2,3,5, 6-tetrafluoro-p-hydroxybenzoic acid, wherein the content is 97.2 percent, and the yield is 82.6 percent. 30ml of 10% hydrochloric acid is added into the water layer to adjust the pH value to 1.0, 200g of toluene is added for extraction, the water layer is washed to be neutral, and then the pressure reduction and the desolventization are carried out to recover 9.5g of off-white solid 2,3,5, 6-tetrafluoro-p-benzhydryl alcohol, the content is 96.9 percent, and the yield is 11.57 percent.
(3) 72.1g of 2,3,5, 6-tetrafluoro-p-hydroxybenzoic acid obtained in the step 2 is put into a 500ml four-mouth bottle, 216g of dimethyl sulfoxide is added, the temperature is raised to 80-85 ℃, the reaction is carried out for 4 hours under the condition of heat preservation, the dimethyl sulfoxide is removed by desolventizing under reduced pressure, and the obtained product is rectified and purified to obtain 55.4g of 2,3,5, 6-tetrafluorobenzyl alcohol with the content of 98.4 percent and the yield of 96.77 percent.
Example 2:
(1): 144g (2mol) of tetrahydrofuran and 88.2g of 2,3,5, 6-tetrafluoroterephthalic acid ethyl ester (0.3mol) were put into a 500ml four-neck flask, the temperature was raised to 42 ℃, 17g (0.45mol) of sodium borohydride was intermittently added in a fully dissolved state, and after completion of the addition, the temperature was maintained at that temperature for 4 to 6 hours. After the reaction, the resultant was added to 150g of 10% aqueous hydrochloric acid, 150ml of toluene was added for extraction, the mixture was washed with water to neutrality, and the mixture was desolventized under reduced pressure to give 63g of an off-white solid product mixture.
(2): putting the mixture obtained in the step 1 into a 500ml four-mouth bottle, adding 100g of 10% sodium formate aqueous solution, stirring until the mixture is completely dissolved, adding 110g of 10% formic acid solution at room temperature to adjust the pH value to 3.5, adding 100g of methyl isobutyl ketone for extraction, washing an oil layer until the oil layer is neutral, and performing decompression and desolventization to obtain 50.1g of off-white solid 2,3,5, 6-tetrafluoro-p-hydroxybenzoic acid with the content of 97.6% and the yield of 74.9%. Adjusting the pH value of a water layer to 1, adding 150g of toluene for extraction, washing with water to be neutral, then carrying out decompression and desolventization, and collecting 12.9g of off-white solid which is 2,3,5, 6-tetrafluoro-p-benzhydryl alcohol, wherein the content is 95.7 percent, and the yield is 19.85 percent.
(3): 50.1g of 2,3,5, 6-tetrafluoro-p-hydroxymethylbenzoic acid is put into a 500ml four-mouth bottle, 195g of N, N-dimethylformamide is added, the temperature is raised to 95 ℃, the temperature is kept for 2 hours, the N, N-dimethylformamide is removed by desolventization under reduced pressure, and the obtained product is rectified and purified to obtain 39.7g of 2,3,5, 6-tetrafluorobenzyl alcohol with the content of 98.3 percent and the yield of 98.82 percent.
Example 3:
an economical synthesis process of substituted aromatic alcohol comprises the following steps:
(1): 120g of cyclopentyl methyl ether (1.2mol) and 80g of 2,3,5, 6-tetrafluoroterephthalic acid methyl ester (0.3mol) are put into a 500ml four-neck flask, stirred at room temperature of 25 ℃ and dissolved completely, 11.4g (0.3mol) of sodium borohydride is added intermittently, and after the addition, the temperature is maintained at the temperature for 4 hours. After the reaction, the resultant was added to 300g of 10% aqueous hydrochloric acid, extracted with 200ml of toluene, washed with water to neutrality, and desolventized under reduced pressure to obtain 65g of an off-white solid product mixture.
(2): putting the mixture obtained in the step 1 into a 500ml four-mouth bottle, adding a 0.1M citric acid/sodium citrate buffer solution with the 200gpH value of 3.8, stirring until the mixture is completely dissolved, adding 100g of cyclopentyl methyl ether for extraction, washing an oil layer until the oil layer is neutral, and performing decompression and desolventization to obtain 31.5g of off-white solid 2,3,5, 6-tetrafluoro-p-hydroxybenzoic acid with the content of 97.5 percent and the yield of 50.3 percent. Adjusting the pH of a water layer to 1, adding 150g of toluene for extraction, washing with water to be neutral, and then performing decompression and desolventization to recover 21.2g of off-white solid 2,3,5, 6-tetrafluoro-p-benzhydryl alcohol with the content of 95.1 percent and the yield of 38.8 percent.
(3): 31.5g of 2,3,5, 6-tetrafluoro-p-hydroxybenzoic acid obtained in the previous step was put into a 500ml four-necked flask, 100g of N, N-diethylacetamide was added, the temperature was raised to 120 ℃ and maintained for 1 hour, N-diethylacetamide was removed by desolventization under reduced pressure and purified by rectification to obtain 24.3g of 2,3,5, 6-tetrafluorobenzyl alcohol, the content was 98.6%, and the yield was 97.6%.
The above examples are only for illustrating the technical concept and features of the present invention, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (8)
1. A synthesis process of substituted aromatic alcohol is characterized by comprising the following steps:
(1) reduction reaction: dissolving the compound I in an organic solvent under stirring, and adding NaBH as a reducing agent4Under the action of (1), carrying out reduction reaction for 2-8 hours at the temperature of 0-60 ℃ to obtain a mixture of a compound II and a compound III;
(2) separation: dissolving the mixture obtained in the step (1) in a weak acid buffer solution system, adjusting the pH to 3.5-4.5, adding an extracting agent for extraction, wherein a water layer contains a compound II, and an oil layer contains a compound III;
(3) treating a compound III: putting the oil layer obtained in the step (2) into an aprotic solvent, and reacting at 60-140 ℃ to remove carboxyl to obtain a product IV;
the chemical reaction equation is as follows:
wherein R is1Is selected from-CH3、-CH2CH3、-(CH2)2CH3、-(CH2)3CH3；
In the step (1), the compound I, NaBH4The molar ratio of the organic solvent is that the compound I: NaBH4: solvent 1: 0.75-1.60: 4-8;
in the step (1), the organic solvent is any one of methyl tert-butyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, cyclopentyl methyl ether and ethylene glycol dimethyl ether, or a mixture of two or more of the methyl tert-butyl ether, the tetrahydrofuran, the 2-methyltetrahydrofuran, the cyclopentyl methyl ether and the ethylene glycol dimethyl ether which are mixed in any proportion.
2. The process of claim 1, wherein compound I is selected from the group consisting of: r1is-CH3Namely, the compound I is 2,3,5, 6-tetrafluoro-p-dimethyl terephthalate.
3. The process according to claim 1, wherein in the step (2), the weak acid buffer solution system is a weak acid buffer solution, and the weak acid buffer solution is acetic acid/sodium acetate, formic acid/sodium formate or citric acid/sodium citrate buffer solution; the ratio of the used amount to the total mass of the product obtained in the step (1) is 1:1-1: 3.
4. The process according to claim 1, wherein in step (2), the extractant is any one of toluene, methyl isobutyl ketone, 2-methyltetrahydrofuran, and cyclopentyl methyl ether, or a mixture of two or more thereof.
5. The process of claim 1, wherein in step (2), the aqueous layer is subjected to pH adjustment with an acid, then an extractant is added for extraction, the extract phase is washed with water to neutrality, and then the solid compound II is obtained after decompression and desolventization.
6. The synthetic process according to claim 1, wherein in step (3), the oil layer is dissolved in an aprotic solvent after post-treatment, wherein the post-treatment is: washing the oil layer to be neutral, and then carrying out decompression and desolventization to obtain a solid of the compound III.
7. The process according to claim 1, wherein in the step (3), the aprotic solvent is one or a mixture of two or more selected from diethoxymethane, N-methylpyrrolidone, 1, 3-dimethylimidazolidin-2-one, N-dimethylformamide, N-diethylacetamide, and dimethylsulfoxide.
8. The process according to claim 1, wherein in the step (3), the mass ratio of the compound III to the aprotic solvent in the oil layer is 1:1 to 1: 5.
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