CN111170846B - Method for preparing 3,3-dimethyl-2-oxo-butyric acid - Google Patents
Method for preparing 3,3-dimethyl-2-oxo-butyric acid Download PDFInfo
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- CN111170846B CN111170846B CN201910243467.1A CN201910243467A CN111170846B CN 111170846 B CN111170846 B CN 111170846B CN 201910243467 A CN201910243467 A CN 201910243467A CN 111170846 B CN111170846 B CN 111170846B
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- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/06—Preparation of carboxylic acids or their salts, halides or anhydrides from carboxylic acid amides
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- C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
- C07D233/54—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members
- C07D233/66—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
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- C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
- C07D233/96—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
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Abstract
The invention relates to the technical field of chemical industry, and discloses a method for preparing 3,3-dimethyl-2-oxo-butyric acid, which comprises the following steps: (1) Reacting oxalyl chloride with N, N' -diphenylurea in a contact manner to obtain 1,3-diphenyl-2,4,5-imidazoline trione; (2) Reacting 1,3-diphenyl-2,4,5-imidazolinetrione with a grignard reagent containing a tert-butyl group to obtain 5-tert-butyl-5-hydroxy-1,3-diphenyl-2,4-imidazolinedione; (3) And (2) carrying out hydrolysis reaction on the 5-tert-butyl-5-hydroxy-1,3-diphenyl-2,4-imidazolidinedione, and acidifying a product obtained after the hydrolysis reaction to obtain 3,3-dimethyl-2-oxo-butyric acid. The method has the advantages of environmental protection and high efficiency.
Description
Technical Field
The invention relates to the technical field of chemical industry, in particular to a method for preparing 3,3-dimethyl-2-oxo-butyric acid.
Background
Triazinone is a raw material for synthesizing herbicide metribuzin, and 3,3-dimethyl-2-oxo-butyric acid is an important intermediate without replacement in the synthesis of triazinone.
The synthesis of 3,3-dimethyl-2-oxo-butanoic acid is now generally a synthetic route using dichloropinacolone as an intermediate, as follows:
the route takes pinacolone as a raw material, and 3,3-dimethyl-2-oxo-butyric acid is obtained by the steps of chlorination, alkaline hydrolysis, sodium hypochlorite oxidation, acidification and the like.
Wherein, chlorination and sodium hypochlorite preparation both need to use a large amount of chlorine, and in the process of obtaining dichloro-pinacolone by pinacolone chlorination, byproducts (monochloro, trichloro and tert-butyl chlorination) are generated, the generation of the byproducts can reduce the yield of target products, and the byproducts are close to the boiling point of the products, and have certain difficulty in separation.
In the process of preparing 3,3-dimethyl-2-oxo-butyric acid from dichloropinacolone, a large amount of high-salt and high-pollution wastewater difficult to treat can be obtained through the steps of alkaline hydrolysis, sodium hypochlorite oxidation, acidification and the like, and the treatment cost is high.
Therefore, even if the common route has the advantage of cheap raw materials, the separation of some byproducts and the treatment of wastewater can greatly increase the production cost, and the common route does not meet the requirements of environmental protection.
Therefore, the development of a new environment-friendly and efficient production process of 3,3-dimethyl-2-oxo-butyric acid is of great significance.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a novel method for preparing 3,3-dimethyl-2-oxo-butyric acid.
Specifically, the novel method for preparing 3,3-dimethyl-2-oxo-butyric acid provided by the invention has the advantages of environmental friendliness, simple process, low cost and suitability for industrial production.
To achieve the above object, the present invention provides a method for preparing 3,3-dimethyl-2-oxo-butyric acid, comprising:
(1) Carrying out contact reaction on oxalyl chloride and N, N' -diphenylurea to obtain 1,3-diphenyl-2,4,5-imidazolinetrione shown in a formula (1);
(2) Reacting 1,3-diphenyl-2,4,5-imidazolinetrione with a grignard reagent containing a tert-butyl group to obtain 5-tert-butyl-5-hydroxy-1,3-diphenyl-2,4-imidazolinedione represented by formula (2);
(3) Hydrolyzing the 5-tert-butyl-5-hydroxy-1,3-diphenyl-2,4-imidazolidinedione, and acidifying a product obtained after the hydrolysis reaction to obtain 3,3-dimethyl-2-oxo-butyric acid shown in a formula (3);
preferably, in step (1), the contact reaction is carried out in the presence of at least one inert solvent selected from the group consisting of dichloromethane, chloroform, benzene, toluene, xylene. Particularly preferably, toluene is used as a solvent, most of products can be separated out from the toluene, and toluene mother liquor after product filtration can be recycled.
In the present invention, in step (1), the contact reaction may be carried out at 65 ℃ or lower; preferably, in step (1), the contact reaction conditions include: the temperature is 25-65 ℃.
According to a preferred embodiment, in order to increase the yield of the target product, the process of the invention further comprises: after the contact reaction in the step (1) is carried out, the obtained reaction liquid is heated to 70-100 ℃ and kept for 0.5-5h, and then cooled to obtain a solid product of 1,3-diphenyl-2,4,5-imidazolinetrione shown in the formula (1). The cooling operation may be carried out, for example, by naturally cooling the reaction solution to room temperature.
Preferably, in the step (2), the grignard reagent is selected from at least one of tert-butyl magnesium chloride, tert-butyl magnesium bromide and tert-butyl magnesium iodide. In order to increase the yield and purity of the target product, the grignard reagent is particularly preferably tert-butyl magnesium chloride.
In the step (2) of the invention, 1,3-diphenyl-2,4,5-imidazoline trione reacts with the grignard reagent containing the tert-butyl group, and the grignard reagent can be added dropwise into 1,3-diphenyl-2,4,5-imidazoline trione solution or 1,3-diphenyl-2,4,5-imidazoline trione solution, namely the feeding sequence is not different.
Preferably, in step (2), the reaction is carried out in the presence of an anhydrous solvent; preferably, the anhydrous solvent is at least one selected from the group consisting of anhydrous diethyl ether, anhydrous tetrahydrofuran and anhydrous 2-methyltetrahydrofuran.
Preferably, in step (2), the reaction conditions include: the reaction temperature is below 0 ℃.
Preferably, in the step (2), the 1,3-diphenyl-2,4,5-imidazoline trione and the Grignard reagent are used in a molar ratio of 1: (1.5-2).
Preferably, in step (3), the hydrolysis reaction is carried out under alkaline conditions.
Preferably, the alkaline condition is provided by at least one substance selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide.
Preferably, in step (3), the hydrolysis reaction is carried out in the presence of an alcoholic solvent.
Preferably, the alcohol solvent is selected from at least one of methanol, ethanol, propanol, isopropanol.
Preferably, in step (3), the acidifying conditions include: the pH value is below 3.
According to a particularly preferred embodiment, the method of the invention further comprises: in step (3), before acidifying the product obtained after the hydrolysis reaction, the solid in the product obtained after the hydrolysis reaction is separated to recover the recovered N, N' -diphenylurea. The method can realize the recovery rate of the N, N' -diphenyl urea of more than 95 percent. The recovered N, N' -diphenyl urea can be recycled after being dried.
3,3-dimethyl-2-oxo-butyric acid has certain water solubility, and can be extracted by organic solvent such as ethyl acetate and dichloromethane, and 3,3-dimethyl-2-oxo-butyric acid can be obtained by removing the solvent by evaporation.
Various post-treatment means conventional in the art, such as washing, liquid separation, drying, column chromatography, quenching reaction, and the like, may also be included in the preparation method of the present invention. The present invention is not described in detail herein, and those skilled in the art should not be construed as limited to the method of the present invention.
The method of the present invention may be carried out in the presence of a protective gas such as argon, helium, nitrogen, or the like.
Compared with the synthetic method of 3,3-dimethyl-2-oxo-butyric acid provided by the prior art, the novel method provided by the invention has the following specific advantages:
1. the main raw materials of the route are oxalyl chloride, N '-diphenylurea and tert-butyl Grignard reagent, wherein the oxalyl chloride and the tert-butyl Grignard reagent are C, H, O sources of 3,3-dimethyl-2-oxo-butyric acid and are consumables, and the N, N' -diphenylurea can be completely recycled and reused. The cost of the route is oxalyl chloride and tert-butyl Grignard reagent, wherein the oxalyl chloride is a large commodity, and tert-butyl magnesium chloride can also be produced in large quantities and has lower cost. The produced by-product is magnesium salt (such as magnesium chloride), and can be comprehensively utilized.
2. In the existing dichloro pinacolone route, pinacolone is used as a raw material, and steps of chlorination, alkaline hydrolysis, sodium hypochlorite oxidation, acidification and the like are carried out to obtain 3,3-dimethyl-2-oxo-butyric acid. In the chlorination reaction, toxic chlorine gas is needed, and the main problems to be considered in workshops are equipment corrosion, possible gas leakage and absorption of unreacted chlorine gas; secondly, although dichloropinacolone is the major product, the isolation and disposal of the by-products (monochloro, trichloro, tert-butyl chloride) are both of concern. In the sodium hypochlorite oxidation reaction, sodium hypochlorite is prepared by introducing chlorine gas into a NaOH solution, and a large amount of salt-containing wastewater is generated. In general, the dichloropinacolone route must be attached to a plant for the electrolytic production of NaOH, which supplies chlorine and NaOH; the use of chlorine leads to the increase of the investment of equipment and frequent overhaul; the amount of waste water to be treated is large.
3. The advantage of synthesizing 3,3-dimethyl-2-oxo-butyric acid by the grignard reaction mainly lies in mild reaction condition, simpler operation, low equipment investment, less waste water amount and avoidance of the use of chlorine. In consideration of the requirement of environmental protection, the new route provided by the invention also has the advantage of environmental protection and can be applied to large-scale production.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The present invention will be described in detail below by way of examples. In the following examples, the starting materials used were all commercially available analytical pure materials unless otherwise specified.
The room temperatures described herein all represent 25 ± 3 ℃.
Example 1
(1) Preparation of 1,3-diphenyl-2,4,5-imidazolinetrione
N, N' -diphenylurea (0.24 mol) was dissolved in 800mL of anhydrous toluene, stirred, warmed to 60 ℃ and oxalyl chloride (0.288 mol) was added dropwise. After the addition, the temperature is raised to 80 ℃ and kept for 2.5h. Cooling to room temperature, precipitating a large amount of colorless needle crystals, filtering, washing with a small amount of toluene, and vacuum drying to obtain 1,3-diphenyl-2,4,5-imidazoline trione with the yield of 90%.
(2) Preparation of 5-tert-butyl-5-hydroxy-1,3-diphenyl-2,4-imidazolidinedione
1,3-diphenyl-2,4,5-imidazolinetrione (0.16 mol) was dissolved in 250mL of anhydrous THF, stirred and cooled to-5 ℃. N is a radical of 2 A THF solution of tert-butylmagnesium chloride (1.0 mol/L,240 mL) was added dropwise with protection, keeping the temperature below 0 deg.C. After the addition is finished, the reaction is continued to be stirred for 1 hour at the temperature of minus 5 ℃. The Grignard reaction was quenched with dilute hydrochloric acid (1 mol/L), separated, and the organic phase was collected. The aqueous phase was extracted with ethyl acetate (200 mL. Times.3), the organic phases were combined, spun dry to give a white solid, which was directly charged to the next reaction.
(3) Preparation of 3,3-dimethyl-2-oxo-butanoic acid
Dissolving the 5-tert-butyl-5-hydroxy-1,3-diphenyl-2,4-imidazolidinedione obtained in the previous step into 500mL of methanol, adding a NaOH solution (4 mol/L,160 mL) at room temperature, stirring, heating to 50 ℃, and reacting for 2h. After the reaction was completed, most of the white solid of methanol and N, N '-diphenylurea was distilled off, filtered, washed with water, and N, N' -diphenylurea was recovered (recovery rate 98%). The filtrate and the water wash were combined, acidified to pH 3 with hydrochloric acid and extracted with ethyl acetate (200 mL. Times.3). The ethyl acetate phases were combined, dried and the solvent was spin-dried, and distilled under reduced pressure to give 3,3-dimethyl-2-oxo-butanoic acid as a colorless liquid, in 84% yield and 98% purity by HPLC.
Example 2
(1) Preparation of 1,3-diphenyl-2,4,5-imidazolinetrione
N, N' -diphenylurea (0.24 mol) was dissolved in 800mL of anhydrous toluene, stirred, warmed to 50 ℃ and oxalyl chloride (0.3 mol) was added dropwise. After the addition, the temperature is raised to 85 ℃ and kept for 2h. Cooling to room temperature, precipitating a large amount of colorless needle crystals, filtering, washing with a small amount of toluene, and vacuum drying to obtain 1,3-diphenyl-2,4,5-imidazoline trione with the yield of 91%.
(2) Preparation of 5-tert-butyl-5-hydroxy-1,3-diphenyl-2,4-imidazolidinedione
1,3-diphenyl-2,4,5-imidazolinetrione (0.16 mol) was dissolved in 250mL of anhydrous THF, stirred and cooled to 0 ℃. N is a radical of hydrogen 2 A THF solution of tert-butylmagnesium chloride (1.0 mol/L,250 mL) was added dropwise with protection, and the temperature of the reaction solution was kept at 0 ℃ or lower during the addition. After the addition was complete, the reaction was continued for 1h with stirring at below 0 ℃. The Grignard reaction was quenched with dilute hydrochloric acid (1 mol/L), separated, and the organic phase was collected. The aqueous phase was extracted with ethyl acetate (200 mL. Times.3), the organic phases were combined, spun dry to give a white solid, which was directly charged to the next reaction.
(3) Preparation of 3,3-dimethyl-2-oxo-butanoic acid
Dissolving the 5-tert-butyl-5-hydroxy-1,3-diphenyl-2,4-imidazolidinedione obtained in the previous step into 500mL of methanol, adding a NaOH solution (4 mol/L and 180 mL) at room temperature, stirring, heating to 55 ℃, and reacting for 2h. After the reaction was completed, most of the white solid of methanol and N, N '-diphenylurea was distilled off, filtered, washed with water, and N, N' -diphenylurea was recovered (recovery rate: 97%). The filtrate and the water wash were combined, acidified to pH 2 with hydrochloric acid and extracted with ethyl acetate (200 mL. Times.3). The ethyl acetate phases were combined, dried and the solvent was spin-dried, and distilled under reduced pressure to give 3,3-dimethyl-2-oxo-butanoic acid as a colorless liquid, in 85% yield and 98% purity by HPLC.
Example 3
This example was carried out in a similar manner to example 1, except that, in step (1) of this example, after completion of the dropwise addition of oxalyl chloride, the temperature was raised to 100 ℃ and maintained for 15min. Cooling to room temperature, precipitating a large amount of colorless needle crystals, filtering, washing with a small amount of toluene, and vacuum drying to obtain 1,3-diphenyl-2,4,5-imidazoline trione with the yield of 88%.
The rest is the same as in example 1.
As a result, 3,3-dimethyl-2-oxo-butanoic acid obtained in this example was in 82% yield and 98% HPLC purity.
Example 4
This example was carried out in a similar manner to example 2, except that in step (2) of this example, the Grignard reagent used was tert-butyl magnesium bromide, that is, the tert-butyl magnesium chloride in example 2 was replaced with the same molar amount of tert-butyl magnesium bromide.
The rest is the same as in example 2.
As a result, 3,3-dimethyl-2-oxo-butanoic acid obtained in this example was in a yield of 82%, and HPLC purity was 97%.
The results of the invention show that the method for preparing 3,3-dimethyl-2-oxo-butyric acid provided by the invention has the advantages of environmental protection, simple process, low cost and suitability for industrial production.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (1)
1. A method of making 3,3-dimethyl-2-oxo-butyric acid comprising:
(1) Preparation of 1,3-diphenyl-2,4,5-imidazolinetrione
Dissolving 0.24mol of N, N' -diphenylurea in 800mL of anhydrous toluene, stirring, heating to 60 ℃, and dropwise adding 0.288mol of oxalyl chloride; after the addition, the temperature is raised to 80 ℃ and kept for 2.5h; cooling to room temperature, precipitating a large amount of colorless needle crystals, filtering, washing with a small amount of toluene, and vacuum drying to obtain 1,3-diphenyl-2,4,5-imidazoline trione with the yield of 90%;
(2) Preparation of 5-tert-butyl-5-hydroxy-1,3-diphenyl-2,4-imidazolidinedione
Dissolving 0.116mol of 1, 3-diphenyl-2,4,5-imidazoline trione in 250mL of anhydrous THF, stirring and cooling to minus 5 ℃, dropwise adding 240mL of 1.0mol/L THF solution of tert-butyl magnesium chloride under the protection of N2, keeping the temperature of the reaction solution below 0 ℃ during dropwise adding, continuing stirring and reacting at minus 5 ℃ for 1h after finishing adding, quenching the Grignard reaction by using 1mol/L dilute hydrochloric acid, separating liquid, collecting an organic phase, extracting the aqueous phase by using 200mL of multiplied by 3 ethyl acetate, combining the organic phases, performing spin drying to obtain a white solid, and directly feeding the white solid into the next step for reaction;
(3) Preparation of 3,3-dimethyl-2-oxo-butanoic acid
Dissolving the 5-tert-butyl-5-hydroxy-1,3-diphenyl-2,4-imidazolidinedione obtained in the previous step in 500mL of methanol, adding 160mL of 4mol/L NaOH solution at room temperature, stirring, heating to 50 ℃, reacting for 2h, evaporating most of methanol after the reaction is finished, separating out white solid of N, N '-diphenylurea, filtering, washing with water, recovering N, N' -diphenylurea with the recovery rate of 98%, combining the filtrate and the water washing solution, acidifying with hydrochloric acid until the pH value is 3, extracting with 200mL of multiplied by 3 ethyl acetate, combining ethyl acetate phases, drying, spin-drying the solvent, and distilling under reduced pressure to obtain colorless liquid 3,3-dimethyl-2-oxo-butyric acid with the yield of 84% and the HPLC purity of 98%.
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| CN114409602B (en) * | 2022-01-06 | 2024-01-30 | 武汉大学 | Method for synthesizing alpha-keto acid by using oxalyl chloride and Grignard reagent as raw materials |
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| US20040030186A1 (en) * | 2002-08-12 | 2004-02-12 | Helmut Fiege | Process for preparing 3,3-dimethyl-2-oxobutyric acid |
| CN108503531A (en) * | 2018-04-28 | 2018-09-07 | 江苏八巨药业有限公司 | A kind of preparation method of 3,3- dimethyl-2-oxo-butyric acids |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040030186A1 (en) * | 2002-08-12 | 2004-02-12 | Helmut Fiege | Process for preparing 3,3-dimethyl-2-oxobutyric acid |
| CN108503531A (en) * | 2018-04-28 | 2018-09-07 | 江苏八巨药业有限公司 | A kind of preparation method of 3,3- dimethyl-2-oxo-butyric acids |
Non-Patent Citations (1)
| Title |
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| Diphenylparabanic Acid as a Synthon for the Synthesis of α-Diketones and α-Ketocarboxylic Acids;Nobuko Watanabe, et al.,;《J.O.C.》;20111202;第77卷;第632-639页 * |
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