CN117142954A - Preparation method of ethyl 4, 4-trifluoroacetoacetate - Google Patents

Preparation method of ethyl 4, 4-trifluoroacetoacetate Download PDF

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CN117142954A
CN117142954A CN202311272674.2A CN202311272674A CN117142954A CN 117142954 A CN117142954 A CN 117142954A CN 202311272674 A CN202311272674 A CN 202311272674A CN 117142954 A CN117142954 A CN 117142954A
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trifluoroacetoacetate
ethyl
reaction
organic solvent
trifluoro
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夏凯
田鹏辉
窦志群
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Zibo Feiyuan Chemical Co ltd
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Zibo Feiyuan Chemical Co ltd
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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00Preparation of carboxylic acid esters
    • C07C67/30Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group
    • C07C67/333Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group by isomerisation; by change of size of the carbon skeleton
    • C07C67/343Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group by isomerisation; by change of size of the carbon skeleton by increase in the number of carbon atoms

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The invention belongs to the technical field of organic synthesis, and particularly relates to a preparation method of 4, 4-trifluoro acetoacetic acid ethyl ester. The preparation method of the 4, 4-trifluoro acetoacetic acid ethyl ester comprises the following steps: dissolving alkali in an organic solvent, adding trifluoroacetyl chloride to react for 0.5-3h at the temperature not higher than 0 ℃, adding ethyl acetate, heating to 20-30 ℃ to react for 2-6h, washing the reactant with water, drying the organic phase with anhydrous sodium sulfate, and finally steaming the organic solvent to obtain the 4, 4-trifluoroacetoacetate. The preparation method of the 4, 4-trifluoro acetoacetic acid ethyl ester has the advantages of mild condition, simple operation, high reaction speed and easy separation of products, and is suitable for industrial production.

Description

Preparation method of ethyl 4, 4-trifluoroacetoacetate
Technical Field
The invention belongs to the technical field of organic synthesis, and particularly relates to a preparation method of 4, 4-trifluoro acetoacetic acid ethyl ester.
Background
The ethyl 4, 4-trifluoroacetoacetate, namely ethyl trifluoroacetoacetate, has two configurations of enol type and ketone type, and can be freely converted under normal conditions, and the specific structure is as follows:
ethyl trifluoroacetoacetate is an important fine intermediate and can be used for synthesizing some pesticides, medicines and organic intermediates. The synthesis method mainly comprises the steps of reacting alkali with trifluoroacetyl chloride to generate a trifluoroacetyl alkali intermediate, and then condensing with ethyl acetate to generate trifluoroacetoacetate. At present, the main methods for synthesizing the ethyl trifluoroacetoacetate at home and abroad are as follows:
claisen condensation is prepared from ethyl trifluoroacetate, ethyl acetate and sodium ethoxide solution as raw materials. The method is the most classical method for preparing the ethyl trifluoroacetoacetate, but the method has the defects of more side reactions, low yield, difficult separation of products and the like, for example: the reaction has the process of removing ethanol, and the reaction system contains ethanol, so that the ethanol removal reaction is inhibited; under the reaction condition of ethyl acetate, self-condensation reaction is easy to generate ethyl acetoacetate, and meanwhile, the existence of sodium ethoxide needs to control the anhydrous reaction system. The method is adopted to synthesize the ethyl trifluoroacetoacetate in the patents CN106565475A, WO2015085464 and CN106188013A, CN106699506A, CN 115260174A.
Furthermore, patent CN113072449a reports that the reaction is carried out in a pipeline reactor under the catalysis of hydrogen chloride gas using trifluoroacetone and methyl chloroformate as raw materials. However, the method has the defects of harsh reaction conditions, difficult byproduct treatment, unsafe reaction and the like, for example, the method needs higher reaction temperature and pressure, and the energy consumption and equipment requirements in the production process can be increased; in addition, the reaction also produces a large amount of byproducts such as hydrogen chloride, formic acid and the like, and the byproducts need to be properly treated and disposed of, thus increasing the production cost and the operation difficulty; trifluoroacetone and hydrogen chloride are flammable, explosive and toxic chemicals that may increase the risk of accidents.
Disclosure of Invention
The purpose of the invention is that: the preparation method of the 4, 4-trifluoro acetoacetic acid ethyl ester is mild in condition, simple in operation, high in reaction speed, easy to separate products and suitable for industrial production.
According to the preparation method of the 4, 4-trifluoro-acetoacetic acid ethyl ester, firstly trifluoro-acetyl chloride and alkali are added into an organic solvent to react, and then ethyl acetate is added to react, so that the 4, 4-trifluoro-acetoacetic acid ethyl ester is obtained.
In the invention, the organic solvent is at least one of dichloromethane, chloroform, tetrahydrofuran, toluene and cyclohexane; preferably chloroform.
In the invention, the mass of the organic solvent is 3-5 times of that of the alkali.
In the invention, the alkali is at least one of diethylamine, pyridine, potassium carbonate, sodium hydroxide and dimethylaminopyridine; pyridine is preferred.
In the invention, the molar ratio of the trifluoroacetyl chloride to the alkali is 1 (1-3).
In the invention, the molar ratio of the trifluoroacetyl chloride to the ethyl acetate is 1 (1-2).
In the invention, firstly, alkali is dissolved in an organic solvent, and trifluoroacetyl chloride is added to react for 0.5-3h under the condition that the temperature is not higher than 0 ℃.
In the invention, after ethyl acetate is added, the temperature is raised to 20-30 ℃ for reaction for 2-6h.
In the invention, after the reaction is finished, the reactant is washed by water, the organic phase is dried by anhydrous sodium sulfate, and finally the organic solvent is distilled off, thus obtaining the 4, 4-trifluoro acetoacetic acid ethyl ester.
Taking pyridine as an example, the reaction mechanism in the preparation process of the ethyl 4, 4-trifluoroacetoacetate is as follows:
compared with the prior art, the invention has the following beneficial effects:
according to the invention, the 4, 4-trifluoro-ethyl acetoacetate is prepared by condensation reaction of trifluoro-ethyl acetoacetate, alkali and ethyl acetate in an organic solvent, and the preparation method has the advantages of mild condition, simple operation, high reaction speed and easy separation of products, and is suitable for industrial production.
Detailed Description
The present invention will be further illustrated by the following examples, wherein the raw materials used in the examples are commercially available conventional raw materials unless otherwise specified; the process used in the examples, unless otherwise specified, is conventional in the art.
Example 1
The ethyl 4, 4-trifluoroacetoacetate was prepared as follows:
1.5mol of pyridine is dissolved in 360g of chloroform, 1mol of trifluoroacetyl chloride is added at the temperature of not higher than 0 ℃, stirring is carried out for 0.5h, 1.5mol of ethyl acetate is added, stirring is carried out for 3h at the temperature of 25 ℃, then the reaction product is washed by water, the organic phase is dried by anhydrous sodium sulfate, finally chloroform is distilled off, thus obtaining 4, 4-trifluoroacetoacetate, the ethyl ester is weighed to 173.5g, the yield is 94.3% (calculated by the ethyl trifluoroacetate), and the GC purity is 98.2%.
Example 2
The ethyl 4, 4-trifluoroacetoacetate was prepared as follows:
1.5mol of pyridine is dissolved in 590g of dichloromethane, 1mol of trifluoroacetyl chloride is added at the temperature of not higher than 0 ℃, stirring is carried out for 1h, 2mol of ethyl acetate is added, stirring is carried out at the temperature of 25 ℃ for 4h, then the reaction product is washed by water, the organic phase is dried by anhydrous sodium sulfate, finally chloroform is distilled off, thus obtaining 4, 4-trifluoroacetoacetate, 175.7g of 4, 4-trifluoroacetoacetate is weighed, the yield is 95.5% (calculated by the ethyl trifluoroacetate), and the GC purity is 98.0%.
Example 3
The ethyl 4, 4-trifluoroacetoacetate was prepared as follows:
3mol of pyridine is dissolved in 800g of tetrahydrofuran, 1mol of trifluoroacetyl chloride is added at the temperature of not higher than 0 ℃, stirring is carried out for 2 hours, 1.2mol of ethyl acetate is added, stirring is carried out at the temperature of 20 ℃ for 2 hours, then the reactant is washed by water, the organic phase is dried by anhydrous sodium sulfate, finally chloroform is distilled off, 4-trifluoroacetoacetate is obtained, 175.2g of ethyl 4, 4-trifluoroacetoacetate is weighed, the yield is 95.2% (calculated by ethyl trifluoroacetate), and the GC purity is 97.9%.
Example 4
The ethyl 4, 4-trifluoroacetoacetate was prepared as follows:
1mol of pyridine is dissolved in 300g of cyclohexane, 1mol of trifluoroacetyl chloride is added at the temperature of not higher than 0 ℃, stirring is carried out for 3 hours, 1mol of ethyl acetate is added, stirring is carried out for 6 hours at the temperature of 30 ℃, then the reactant is washed by water, the organic phase is dried by anhydrous sodium sulfate, finally chloroform is distilled off, thus obtaining 4, 4-trifluoroacetoacetate, the weight is 172.2g, the yield is 93.6% (calculated by the ethyl trifluoroacetate), and the GC purity is 97.4%.
Comparative example 1
In contrast to the synthesis of ethyl 4, 4-trifluoroacetoacetate disclosed in patent CN113072449a, example 1 is specifically as follows:
(1) 114.3g (1.0 mol) of trifluoroacetone and 228.6g of toluene are weighed and stirred uniformly in a mixing bottle to obtain solution A; 110.2g (1.0 mol) of ethyl chloroformate (content 98.5%) as liquid B;
(2) Setting the temperature of the pipeline reactor to be 50 ℃ and the pressure to be 0.5MPa, setting the flow rate of the pump A to be 8ml/min, setting the flow rate of the pump B to be 2ml/min, and opening a tail gas evacuation valve and a hydrogen chloride gas inlet valve after the set temperature is reached, and introducing hydrogen chloride gas; starting a pump A to feed mixed solution of trifluoroacetone and toluene, and starting a pump B to feed ethyl chloroformate;
(3) Sampling and detecting 0.49% of ethyl chloroformate residue in the reaction liquid at the outlet of the reactor after 20min, and reacting to obtain qualified products;
(4) After the reaction is finished, the reaction liquid is subjected to primary normal pressure rectification to recover toluene and a small amount of residual raw materials, and the rectification end point temperature is 115 ℃; and then, performing secondary reduced pressure rectification to obtain 174g of 4, 4-trifluoro acetoacetic acid ethyl ester, wherein the GC purity is 97.2%, and the folding purity yield is 92.0%.
Comparative example 2
In contrast to the process for the preparation of ethyl 4, 4-trifluoroacetoacetate disclosed in patent CN103694119a, example 1 is specifically as follows:
200mL of absolute ethanol was added to the reactor at 25℃followed by 510g (1.5 mol) of 20% sodium ethoxide in ethanol and then 105.6g (1.2 mol) of ethyl acetate. The reaction mixture was cooled to 5-10℃and then 142g (1.0 mol) of ethyl trifluoroacetate was started to be added dropwise, and the temperature was controlled at 10-20 ℃. After the addition, the temperature was raised to 60℃for 2 hours, and then the reaction mixture was cooled to 10-15 ℃. 166.6g (1.7 mol) of concentrated sulfuric acid is added dropwise into the reaction solution, the temperature is controlled to be 20-30 ℃, and the reaction is carried out for 2.5 hours at the temperature of 30 ℃ after the completion of the dripping, so as to obtain turbid liquid containing sodium sulfate precipitate. The sodium sulfate precipitate was removed by filtration, the filter cake was washed with ethyl acetate, and the obtained filtrate was subjected to rectification under reduced pressure to obtain 157.0g of ethyl trifluoroacetoacetate in a yield of 85.3% (based on ethyl trifluoroacetate) and a purity of 95.2%.

Claims (9)

1. A preparation method of 4, 4-trifluoro acetoacetic acid ethyl ester is characterized in that: in an organic solvent, firstly adding trifluoroacetyl chloride and alkali for reaction, and then adding ethyl acetate for reaction to obtain 4, 4-trifluoroacetoacetate.
2. The process for producing ethyl 4, 4-trifluoroacetoacetate according to claim 1, wherein: the organic solvent is at least one of dichloromethane, chloroform, tetrahydrofuran, toluene and cyclohexane.
3. The process for producing ethyl 4, 4-trifluoroacetoacetate according to claim 2, wherein: the mass of the organic solvent is 3-5 times of that of the alkali.
4. The process for producing ethyl 4, 4-trifluoroacetoacetate according to claim 1, wherein: the base is at least one of diethylamine, pyridine, potassium carbonate, sodium hydroxide and dimethylaminopyridine.
5. The process for producing ethyl 4, 4-trifluoroacetoacetate according to claim 4, wherein: the molar ratio of the trifluoroacetyl chloride to the alkali is 1 (1-3).
6. The process for producing ethyl 4, 4-trifluoroacetoacetate according to claim 1, wherein: the molar ratio of the trifluoroacetyl chloride to the ethyl acetate is 1 (1-2).
7. The process for producing ethyl 4, 4-trifluoroacetoacetate according to claim 1, wherein: firstly, dissolving alkali in an organic solvent, and adding trifluoroacetyl chloride to react for 0.5-3h at the temperature of not higher than 0 ℃.
8. The process for producing ethyl 4, 4-trifluoroacetoacetate according to claim 1, wherein: after adding ethyl acetate, the temperature is raised to 20-30 ℃ for reaction for 2-6h.
9. The process for producing ethyl 4, 4-trifluoroacetoacetate according to claim 1, wherein: after the reaction is finished, the reactant is washed by water, the organic phase is dried by anhydrous sodium sulfate, and finally the organic solvent is distilled off, thus obtaining the 4, 4-trifluoro acetoacetic acid ethyl ester.
CN202311272674.2A 2023-09-28 2023-09-28 Preparation method of ethyl 4, 4-trifluoroacetoacetate Pending CN117142954A (en)

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