CN115974663B - Preparation method and application of trifluoromethyl ketone compound - Google Patents

Abstract

The application discloses a preparation method and application of trifluoromethyl ketone compounds, which adopts the general formula as followsThe compound and trifluoroacetic anhydride are used as reaction raw materials, pyridine compounds are used as catalysts, and under the catalysis of the catalysts, the reaction raw materials react to generate trifluoromethyl ketone compounds, and the molar ratio of the compound with the structure shown in the general formula to the pyridine compounds is limited to be 1: (1-8) controlling the dosage of the pyridine compound, effectively avoiding salt reaction between the pyridine compound and the product, reducing the types of reaction byproducts, reducing the difficulty of separating and purifying the product, further improving the yield of the trifluoromethyl ketone compound, wherein the yield of the trifluoromethyl ketone compound can reach more than 75 percent, and the purity can reach more than 98 percent.

Description

Preparation method and application of trifluoromethyl ketone compounds

Technical Field

The present application relates to the technical field of compound synthesis, and in particular to a preparation method and application of a trifluoromethyl ketone compound.

Background technique

Trifluoromethyl ketone compounds are a class of organic compounds containing trifluoromethyl and carbonyl groups. Trifluoromethyl ketone compounds can be used as enzyme inhibitors, as monomers for new polymer materials, and as important intermediates for organic compounds such as fluorinated functional polymers and fluorinated drugs. Trifluoromethyl ketone compounds are widely used in the fields of membrane materials and medicines.

At present, trifluoromethyl ketone compounds are mainly prepared by chemical synthesis, which has the disadvantages of more by-products and difficult separation and purification, resulting in a low yield of the target product. Therefore, optimizing the preparation and purification methods of trifluoromethyl ketone compounds and reducing the generation of by-products are of great significance to the application and development of trifluoromethyl ketone compounds.

Summary of the invention

The present application provides a preparation method of a trifluoromethyl ketone compound and application thereof, so as to reduce the generation of by-products in the preparation process of the trifluoromethyl ketone compound.

The technical solution of this application is as follows:

In a first aspect, the present application provides a method for preparing a trifluoromethyl ketone compound, wherein the trifluoromethyl ketone compound has a structure represented by general formula (I), and the preparation method comprises the steps of: using a pyridine compound as a catalyst, reacting a compound represented by general formula (II) with trifluoroacetic anhydride to obtain a product, wherein the product comprises a compound represented by general formula (I);

Wherein, the molar ratio of the compound represented by the general formula (II) to the pyridine compound is 1:(1-8);

The general formula (I) is as follows:

The general formula (II) is as follows:

In the general formula (I) and the general formula (II), R ₁ is selected from -(CH ₂ ) _n -, n is 3 to 20; R ₂ is selected from unsubstituted or substituted alkyl, or halogen group;

The pyridine compound is selected from unsubstituted or substituted pyridine.

Optionally, n is 3 to 10;

and/or, said R ₂ is selected from -Cl, -Br, -I, -CH(CH ₃ ) ₂ or -C(CH ₃ ) ₃ ;

And/or, the substituted pyridine is a compound obtained by replacing the hydrogen atom located at the position opposite to the nitrogen atom in the pyridine ring with a substituent, wherein the substituent is selected from an electron donating group.

Optionally, n is 3 to 5;

And/or, the electron donating group is selected from dimethylamino or pyrrolidinyl.

Optionally, the pyridine compound is selected from one or more of anhydrous pyridine, 4-pyrrolidinopyridine and 4-dimethylaminopyridine.

Optionally, the compound represented by the general formula (I) is selected from:

The compound represented by the general formula (II) is selected from:

Optionally, the reaction of the compound of the structure represented by the general formula (II) and trifluoroacetic anhydride using a pyridine compound as a catalyst comprises the steps of: providing a solution containing the compound of the structure represented by the general formula (II) and trifluoroacetic anhydride, adding the pyridine compound to the solution, and mixing;

And/or, the reaction is carried out at an ambient temperature of 0°C to 30°C, and the reaction time is 1h to 4h;

And/or, the preparation method further comprises the steps of: mixing the product with an acid solution for washing and extraction, collecting the organic phase, then removing the solvent of the organic phase, and distilling to obtain the purified compound of the structure represented by the general formula (I).

Optionally, the solvent of the solution is selected from one or more of dichloromethane, chloroform and carbon tetrachloride;

and/or, in the solution, the concentration of the compound of the structure represented by the general formula (II) is 0.5 mol/L to 5 mol/L;

And/or, the acid in the acid solution is selected from one or more of acetic acid, hydrochloric acid, nitric acid and sulfuric acid;

And/or, the acid concentration in the acid solution is 0.01 mol/L to 2 mol/L.

In some embodiments of the present application, the molar ratio of the compound of the structure represented by the general formula (II) to the trifluoroacetic anhydride is 1:(4-6);

And/or, the molar ratio of the pyridine compound to the trifluoroacetic anhydride is 1:(1-3).

In a second aspect, the present application provides a trifluoromethyl ketone compound prepared by any preparation method described in the first aspect.

In a third aspect, the present application provides use of a trifluoromethyl ketone compound prepared by any preparation method described in the first aspect, or a trifluoromethyl ketone compound described in the second aspect in the preparation of an ion exchange membrane.

The present application provides a preparation method of a trifluoromethyl ketone compound and its application, which has the following technical effects:

In the preparation method of the trifluoromethyl ketone compound of the present application, a compound of the structure shown in the general formula (II) and trifluoroacetic anhydride are used as reaction raw materials, and a pyridine compound is used as a catalyst. Under the catalytic action of the catalyst, the reaction raw materials react to generate trifluoromethyl ketone compounds. By limiting the molar ratio of the compound of the structure shown in the general formula (II) to the pyridine compound to 1: (1-8) to control the amount of the pyridine compound, the salt-forming reaction between the pyridine compound and the product is effectively avoided, thereby reducing the types of reaction by-products and effectively improving the yield of the product. In addition, the present application The preparation method of trifluoromethyl ketone compounds reduces the difficulty of separating and purifying the product. The separation and purification, for example, includes the steps of: mixing the product with an acid solution, washing and extracting, collecting the organic phase, then removing the solvent of the organic phase, and distilling to obtain a purified compound of the structure represented by the general formula (I). After removing the solvent of the organic phase, only distillation is required to obtain a product with a purity of more than 98%, and there is no need to use column chromatography for separation and purification. Compared with column chromatography, distillation has a smaller negative impact on the product yield, which is conducive to further improving the product yield, so that the product yield can reach more than 75%.

The trifluoromethyl ketone compound prepared by the preparation method of the trifluoromethyl ketone compound can be used to prepare ion exchange membranes. The trifluoromethyl ketone compound is used as one of the polymerization monomers, and is condensed or copolymerized with a biphenyl aromatic compound to form a polyfluoroketone biphenyl polymer resin, and then the ion exchange membrane is prepared by polymer processing techniques such as tape casting.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

Figure 1 is a thin layer chromatogram of the crude product mixed solution containing the target product (7-bromo-1,1,1-trifluoro-2-heptanone) in Example 1, Example 5, Example 6 and the comparative example, wherein A0 represents the standard sample of 7-bromo-1,1,1-trifluoro-2-heptanone, A1 represents the crude product mixed solution containing the target product (7-bromo-1,1,1-trifluoro-2-heptanone) in the comparative example, A2 represents the crude product mixed solution containing the target product (7-bromo-1,1,1-trifluoro-2-heptanone) in Example 1, A3 represents the crude product mixed solution containing the target product (7-bromo-1,1,1-trifluoro-2-heptanone) in Example 5, and A4 represents the crude product mixed solution containing the target product (7-bromo-1,1,1-trifluoro-2-heptanone) in Example 6.

Detailed ways

The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art, and the materials or reagents used in the examples and comparative examples of the present application are commercially available. In addition, any methods and materials similar or equivalent to those described herein can be applied to the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only and cannot limit the content of the present application.

It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. The various embodiments of the present application may be in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered ranges, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited numbers (fractions or integers) within the indicated range.

In the description of the present application, the term “including” means “including but not limited to”.

The term "at least one" means one or more, and "plurality" means two or more. The term "at least one", "at least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b or c" or "at least one of a, b and c" can be expressed as: a, b, c, a-b (i.e. a and b), a-c, b-c or a-b-c, where a, b and c can be single or plural, respectively.

The selection scope of the term "and/or" includes any one of two or more related listed items, and also includes any and all combinations of the related listed items, and the said any and all combinations include any combination of two related listed items, any more related listed items, or all related listed items. For example, "A and/or B" includes three parallel solutions of A, B and A+B. For another example, the technical solution of "A, and/or, B, and/or, C, and/or, D" includes any one of A, B, C, and D (that is, the technical solution connected by "logical or"), and also includes any and all combinations of A, B, C, and D, that is, the combination of any two or any three of A, B, C, and D, and also includes the combination of four items of A, B, C, and D (that is, the technical solution connected by "logical and").

The present application provides a method for preparing a trifluoromethyl ketone compound, wherein the trifluoromethyl ketone compound has a structure shown in the general formula (I):

In the general formula (I), _R1 is selected from -( _CH2 ) _n- , and n is 3-20, for example, 3-5, 3-8, 3-10, 3-15, 3-18, 4-6, 4-8, 4-10, 4-15, 4-20, 5-8, 5-10, 5-15, 5-20, 10-15, 10-20, or 15-20.

In the general formula (I), R ₂ is selected from unsubstituted or substituted alkyl groups, or halogen groups, and R ₂ is, for example, selected from -Cl, -Br, -I, -CH(CH ₃ ) ₂ or -C(CH ₃ ) ₃ .

The preparation method of trifluoromethyl ketone compounds provided in the embodiment of the present application comprises the steps of: using a pyridine compound as a catalyst, reacting a compound of the structure represented by the general formula (II) with trifluoroacetic anhydride to obtain a product, wherein the product comprises a compound of the structure represented by the general formula (I), wherein the molar ratio of the compound of the structure represented by the general formula (II) to the pyridine compound is 1:(1 to 8).

In the above preparation method, a compound with a structure represented by general formula (II) and trifluoroacetic anhydride are used as reaction raw materials, and a pyridine compound is used as a catalyst. Under the catalytic action of the catalyst, the reaction raw materials react to generate a product containing a compound with a structure represented by general formula (I). By limiting the molar ratio of the compound with a structure represented by general formula (II) to the pyridine compound to 1: (1 to 8) to control the amount of the pyridine compound, the salt-forming reaction between the pyridine compound and the product is effectively avoided, thereby reducing the types of reaction by-products, reducing the difficulty of separating and purifying the product, and thereby improving the yield of the trifluoromethyl ketone compound.

Specifically, the compound represented by the general formula (II) is as follows:

In the general formula (II), _R1 and _R2 are the same as those described in the general formula (I).

In some embodiments of the present application, the compound represented by the general formula (I) is selected from:

Correspondingly, the compound represented by the general formula (II) is selected from:

In the above preparation method, the pyridine compound is selected from unsubstituted or substituted pyridine. In some embodiments of the present application, the substituted pyridine is a compound obtained by replacing the hydrogen atom located at the position opposite to the nitrogen atom in the pyridine ring with a substituent, and the substituent is selected from an electron donating group, and the electron donating group is selected from dimethylamino or pyrrolidinyl. Examples of pyridine compounds are selected from one or more of anhydrous pyridine, 4-pyrrolidinylpyridine and 4-dimethylaminopyridine.

In some embodiments of the present application, the molar ratio of the compound of the structure represented by the general formula (II) to the pyridine compound is 1: (1-2), 1: (1-3), 1: (1-4), 1: (2-3), 1: (2-4), 1: (2-5), 1: (3-4), 1: (3-5), or 1: (4-5), examples being 1: 1, 1: 2, 1: 3, 1: 4, or 1: 5.

In some embodiments of the present application, the pyridine compound is used as a catalyst, and the compound of the structure shown in the general formula (II) reacts with trifluoroacetic anhydride, including the steps of: providing a solution containing the compound of the structure shown in the general formula (II) and trifluoroacetic anhydride, adding the pyridine compound to the solution, and mixing. The addition method of the pyridine compound includes but is not limited to dropwise addition, uniform flow addition, etc. In order to prevent the reaction phenomenon from being violent and to ensure the safety of the experiment and production process, the pyridine compound needs to be added slowly to the solution.

The solvent of the solution is selected from solvents in which the compound of the structure represented by the general formula (II) and trifluoroacetic anhydride have good dissolution performance, including but not limited to one or more of dichloromethane, chloroform and carbon tetrachloride.

In some embodiments of the present application, in the solution, the concentration of the compound of the structure represented by general formula (II) is 0.5 mol/L to 5 mol/L, for example, it can be 0.5 mol/L to 1 mol/L, 1 mol/L to 2 mol/L, 2 mol/L to 3 mol/L, 3 mol/L to 4 mol/L, or 4 mol/L to 5 mol/L.

In some embodiments of the present application, the reaction is carried out at an ambient temperature of 10°C to 25°C, and the ambient temperature can be, for example, 10°C to 15°C, 10°C to 20°C, 10°C to 25°C, 15°C to 20°C, 15°C to 25°C, or 20°C to 25°C, exemplified by 10°C, 15°C, 20°C, or 25°C. The reaction time is 1h to 4h, for example, 1h to 2h, 1h to 3h, 2h to 3h, 2h to 4h, or 3h to 4h, exemplified by 1h, 2h, 3h, or 4h.

In at least one embodiment of the present application, the reaction of the compound of the structure shown in the general formula (II) and trifluoroacetic anhydride using a pyridine compound as a catalyst comprises the steps of: dissolving the compound of the structure shown in the general formula (II) and trifluoroacetic anhydride in a solvent, stirring for 5 min to 60 min at an ambient temperature of 10°C to 25°C to mix to obtain a solution containing the compound of the structure shown in the general formula (II) and trifluoroacetic anhydride, maintaining the ambient temperature of 10°C to 25°C unchanged, slowly adding the pyridine compound to the solution, mixing, and reacting for 2h to 4h.

In order to control the cost of raw materials and improve the yield of the product, in some embodiments of the present application, the molar ratio of the compound of the structure represented by the general formula (II) to trifluoroacetic anhydride is 1: (4-6), for example, 1: (4-4.5), 1: (4-5), 1: (4-5.5), 1: (5-5.5), or 1: (5-6), exemplified by 1: 4, 1: 5 or 1: 6.

In order to control the amount of catalyst used and improve the catalytic effect of the reaction, in some embodiments of the present application, the molar ratio of the pyridine compound to trifluoroacetic anhydride is 1:(1-3), for example, 1:(1-1.5), 1:(1-2), 1:(1-2.5), 1:(2-2.5), or 1:(2-3), exemplified by 1:1, 1:2, or 1:3.

In order to improve the purity of the product, in some embodiments of the present application, the method for preparing trifluoromethyl ketone compounds also includes the steps of: mixing the product with an acid solution for washing and extraction, collecting the organic phase, and then removing the solvent of the organic phase, and distilling to obtain a purified compound of the structure shown in general formula (I).

In some embodiments of the present application, before the step of mixing the product with the acid solution, the method for preparing trifluoromethyl ketone compounds further comprises the step of adding a quencher to the product to perform a quenching reaction. The quencher may be, for example, deionized water, and the quenching reaction may be performed at a temperature of, for example, 0°C.

Specifically, the acid solution is used as a washing agent and an extractant to transfer impurities in the product to the aqueous phase, while the target product is retained in the organic phase, and the acid in the acid solution includes but is not limited to one or more of acetic acid, hydrochloric acid, nitric acid, and sulfuric acid. In order to further improve the purity of the target product, in some embodiments of the present application, the concentration of the acid in the acid solution is 0.01 mol/L to 2 mol/L, and 1 mol/L is exemplified.

Specifically, the method of "removing the solvent of the organic phase" is mainly evaporation concentration, and the method of evaporation concentration includes but is not limited to one or more of rotary evaporation, vortex evaporation or falling film evaporation. The method of "distillation" includes but is not limited to one or more of vacuum distillation, short-path distillation, molecular distillation and membrane distillation. It should be noted that in the preparation method of the embodiment of the present application, since the amount of pyridine compounds used is small, the salt-forming reaction between the pyridine compounds and the product is effectively avoided, thereby reducing the types of reaction by-products and reducing the difficulty of product separation and purification. After removing the solvent of the organic phase, only distillation is required to obtain a purified product with a purity of more than 98%, thereby eliminating the need for column chromatography for separation and purification, effectively simplifying the separation and purification process. In addition, compared with column chromatography, evaporation has less negative impact on the yield, thereby improving the yield of the product.

The present application also provides a trifluoromethyl ketone compound, which is prepared by any preparation method described in the present application. The trifluoromethyl ketone compound has a structure shown in general formula (I).

The present application also provides an application of a trifluoromethyl ketone compound prepared by a preparation method as described in any one of the embodiments of the present application in the preparation of an ion exchange membrane. The trifluoromethyl ketone compound is used as one of the polymerization monomers, and is polycondensed or copolymerized with a biphenyl aromatic compound to form a polyfluoroketone biphenyl polymer resin, and then the ion exchange membrane is prepared by a polymer processing process such as tape casting.

The technical scheme and technical effects of the present application are described in detail below through specific embodiments, comparative examples and experimental examples. The following embodiments are only some embodiments of the present application and do not specifically limit the present application. It should be noted that in the embodiments and comparative examples of the present application, the yield calculation formula of the product is: yield (%) = actual yield/theoretical yield × 100%.

Example 1

This embodiment provides a method for preparing a trifluoromethyl ketone compound and the trifluoromethyl ketone compound (7-bromo-1,1,1-trifluoro-2-heptanone) obtained therefrom. The trifluoromethyl ketone compound in this embodiment has a structure shown in the following formula (1.1):

The preparation method of trifluoromethyl ketone compounds in this embodiment comprises the following steps:

S1.1, 0.1 mol of the compound of formula (1.2) was dissolved in 450 mL of anhydrous dichloromethane, and then 0.43 mol of trifluoroacetic anhydride was slowly added thereto, and stirred at an ambient temperature of 25°C for 0.5 h to obtain a mixed solution;

S1.2. At an ambient temperature of 25°C, slowly add 0.4 mol of anhydrous pyridine to the mixed solution of step S1.1, mix, and react for 2 h, then cool the entire reaction system to 0°C, add 100 mL of deionized water to quench the reaction, and obtain a crude product mixed solution containing the target product (7-bromo-1,1,1-trifluoro-2-heptanone);

S1.3, adding 300 mL of hydrochloric acid solution (the solvent is water, and the hydrochloric acid concentration is 1 mol/L) to the crude product mixture obtained in step S1.2, after washing and extraction, collecting the organic phase, and rotary evaporating the organic phase to obtain a crude product;

S1.4. The crude product of step S1.3 is subjected to reduced pressure distillation to obtain 7-bromo-1,1,1-trifluoro-2-heptanone.

Among them, the compound with the structure shown in formula (1.2) is as follows:

In the preparation method of this embodiment, the yield of 7-bromo-1,1,1-trifluoro-2-heptanone was 71% and the purity was 98%. ¹ H-NMR (400 MHz, CDCl ₃ ) δ3.41 (t, 2H), 2.74 (t, 2H), 1.89 (m, 2H), 1.71 (m, 2H), 1.50 (m, 2H).

Example 2

This embodiment provides a method for preparing a trifluoromethyl ketone compound and the trifluoromethyl ketone compound (6-bromo-1,1,1-trifluoro-2-hexanone) prepared therefrom. The trifluoromethyl ketone compound in this embodiment has a structure shown in the following formula (2.1):

The preparation method of trifluoromethyl ketone compounds in this embodiment comprises the following steps:

S2.1. Take 0.9 mol of the compound represented by the structure of formula (2.2) and dissolve it in 4 L of anhydrous dichloromethane, then slowly add 3.9 mol of trifluoroacetic anhydride thereto, stir at an ambient temperature of 25°C for 0.5 h, and obtain a mixed solution;

S2.2, at an ambient temperature of 25°C, slowly add 2 mol of 4-dimethylaminopyridine to the mixed solution of step S2.1, mix, and react for 3 hours, then cool the entire reaction system to 0°C, add 0.5 L of deionized water to quench the reaction, and obtain a crude product mixed solution containing the target product (6-bromo-1,1,1-trifluoro-2-hexanone);

S2.3, add 3L of acetic acid solution (the solvent is water, and the concentration of hydrochloric acid is 1 mol/L) to the crude product mixture obtained in step S2.2, wash and extract, collect the organic phase, and rotary evaporate the organic phase to obtain a crude product;

S2.4. The crude product of step S2.3 is subjected to molecular distillation to obtain 6-bromo-1,1,1-trifluoro-2-hexanone.

Among them, the compound with the structure shown in formula (2.2) is as follows:

The yield of 6-bromo-1,1,1-trifluoro-2-hexanone prepared by the preparation method of this embodiment is 76% and the purity is 98%. The nuclear magnetic resonance detection data of the prepared 6-bromo-1,1,1-trifluoro-2-hexanone are: ¹ H-NMR (500MHz, CDCl ₃ )δ3.47(t,2H),2.40(t,2H),1.83(m,2H),1.53(m,2H).

Example 3

This embodiment provides a method for preparing a trifluoromethyl ketone compound and the trifluoromethyl ketone compound (5-bromo-1,1,1-trifluoro-2-pentanone) prepared therefrom. The trifluoromethyl ketone compound in this embodiment has a structure shown in the following formula (3.1):

The preparation method of trifluoromethyl ketone compounds in this embodiment comprises the following steps:

S3.1. Dissolve 1 mol of the compound of formula (3.2) in 5 L of anhydrous dichloromethane, then slowly add 4 mol of trifluoroacetic anhydride, and stir at an ambient temperature of 25°C for 0.5 h to obtain a mixed solution;

S3.2, at an ambient temperature of 25°C, slowly add 1.5 mol of 4-pyrrolidinylpyridine to the mixed solution of step S6.1, mix, and react for 3 hours, then cool the entire reaction system to 0°C, add 0.5 L of deionized water to quench the reaction, and obtain a crude product mixed solution containing the target product (5-bromo-1,1,1-trifluoro-2-pentanone);

S3.3, adding 3 L of sulfuric acid solution (the solvent is water, and the hydrochloric acid concentration is 1 mol/L) to the crude product mixture obtained in step S3.2, washing and extracting, collecting the organic phase, and rotary evaporating the organic phase to obtain a crude product;

S3.4. The crude product of step 3.3 is subjected to short-path distillation to obtain 5-bromo-1,1,1-trifluoro-2-pentanone.

Among them, the compound with the structure shown in formula (3.2) is as follows:

The yield of 5-bromo-1,1,1-trifluoro-2-pentanone prepared by the preparation method of this embodiment is 77% and the purity is 98%. The NMR detection data of the prepared 5-bromo-1,1,1-trifluoro-2-pentanone are: ¹ H-NMR (500MHz, CDCl ₃ )δ3.46(t,2H),2.40(t,2H),2.21(s,2H).

Example 4

This embodiment provides a method for preparing a trifluoromethyl ketone compound and the trifluoromethyl ketone compound (1,1,1-trifluorooctane-2-one) prepared therefrom. The trifluoromethyl ketone compound in this embodiment has a structure shown in the following formula (4.1):

The preparation method of trifluoromethyl ketone compounds in this embodiment comprises the following steps:

S4.1. Dissolve 1 mol of the compound of formula (4.2) in 4 L of anhydrous dichloromethane, then slowly add 3.5 mol of trifluoroacetic anhydride, and stir at an ambient temperature of 20°C for 0.5 h to obtain a mixed solution;

S4.2. At an ambient temperature of 20°C, slowly add 2.5 mol of anhydrous pyridine to the mixed solution of step S4.1, mix, and react for 3.5 hours, then cool the entire reaction system to 0°C, add 1 L of deionized water to quench the reaction, and obtain a crude product mixed solution containing the target product (1,1,1-trifluorooctane-2-one);

S4.3, add 3 L of hydrochloric acid solution (the solvent is water, and the hydrochloric acid concentration is 1 mol/L) to the crude product mixture obtained in step S4.2, wash and extract, collect the organic phase, and rotary evaporate the organic phase to obtain a crude product;

S4.4. The crude product of step 4.3 is subjected to short-path distillation to obtain 1,1,1-trifluorooctane-2-one.

Among them, the compound with the structure shown in formula (7.2) is as follows:

The yield of 1,1,1-trifluorooctane-2-one prepared by the preparation method of this embodiment is 74% and the purity is 98%. The NMR detection data of the prepared 1,1,1-trifluorooctane-2-one are: ¹ H-NMR (500MHz, CDCl ₃ )δ2.40(t,2H),1.53(m,2H),1.32(m,J＝10.0Hz,6H),0.89(t,3H).

Example 5

The present embodiment provides a method for preparing a trifluoromethyl ketone compound and the trifluoromethyl ketone compound (7-bromo-1,1,1-trifluoro-2-heptanone) prepared therefrom. Compared with the method for preparing a trifluoromethyl ketone compound in Example 1, the difference of the method for preparing a trifluoromethyl ketone compound in the present embodiment is that step S1.2 is replaced by "slowly adding 0.4 mol of 4-dimethylaminopyridine to the mixed solution of step S1.1 at an ambient temperature of 25°C, mixing, reacting for 2h, then cooling the entire reaction system to 0°C, adding 100 mL of deionized water to quench the reaction, and obtaining a crude product mixed solution containing 7-bromo-1,1,1-trifluoro-2-heptanone".

The yield of 7-bromo-1,1,1-trifluoro-2-heptanone prepared by the preparation method of this example is 75% and the purity is 98%.

Example 6

The present embodiment provides a method for preparing a trifluoromethyl ketone compound and the trifluoromethyl ketone compound (7-bromo-1,1,1-trifluoro-2-heptanone) prepared therefrom. Compared with the method for preparing a trifluoromethyl ketone compound in Example 1, the difference of the method for preparing a trifluoromethyl ketone compound in the present embodiment is that step S1.2 is replaced by "at an ambient temperature of 25°C, slowly add 0.3 mol of 4-pyrrolidinopyridine to the mixed solution of step S1.1, mix, react for 2 hours, then cool the entire reaction system to 0°C, add 100 mL of deionized water to quench the reaction, and obtain a crude product mixed solution containing the target product (7-bromo-1,1,1-trifluoro-2-heptanone)".

The yield of 7-bromo-1,1,1-trifluoro-2-heptanone prepared by the preparation method of this example is 81% and the purity is 98%.

Comparative Example

This comparative example provides a method for preparing a trifluoromethyl ketone compound and a trifluoromethyl ketone compound (7-bromo-1,1,1-trifluoro-2-heptanone) prepared therefrom. The method for preparing the trifluoromethyl ketone compound in this comparative example comprises the following steps:

S10.1. Take 6.53 mmol of the compound represented by the structure of formula (1.2) and dissolve it in 50 mL of anhydrous dichloromethane, then slowly add 44.8 mmol of trifluoroacetic anhydride thereto, and stir at an ambient temperature of 25°C for 0.5 h to obtain a mixed solution;

S10.2, at an ambient temperature of 25°C, add 59.8 mmol of anhydrous pyridine dropwise to the mixed solution of step S10.1, mix, react for 2 h, then cool the entire reaction system to 0°C, add 20 mL of deionized water to quench the reaction, and obtain a crude product mixed solution containing the target product (7-bromo-1,1,1-trifluoro-2-heptanone);

S10.3. Add 50 mL of hydrochloric acid solution (the solvent is water and the hydrochloric acid concentration is 1 mol/L) to the crude product mixture obtained in step S10.2. After washing and extraction, collect the organic phase, rotary evaporate the organic phase, and separate and purify it by column chromatography and vacuum distillation respectively. The first product is separated and purified by column chromatography, and the second product is separated and purified by vacuum distillation.

In step S10.3, the purity of 7-bromo-1,1,1-trifluoro-2-heptanone in the first product is 95%, and the yield of 7-bromo-1,1,1-trifluoro-2-heptanone is 30%. The purity of 7-bromo-1,1,1-trifluoro-2-heptanone in the second product is 95%, and the yield of 7-bromo-1,1,1-trifluoro-2-heptanone is 41%. It can be seen that when the molar ratio of the compound of the structure shown in formula (1.2) to anhydrous pyridine is 1:9.2, due to the large amount of anhydrous pyridine used, the excess anhydrous pyridine will react with the product to form a salt, increasing the types of reaction by-products, so that whether the separation and purification method of column chromatography or the separation and purification method of reduced pressure distillation is adopted, the yield of the product is relatively low.

analysis test

Thin layer chromatography (TLC) was used to detect and analyze the crude product mixture containing the target product (7-bromo-1,1,1-trifluoro-2-heptanone) in Example 1, Example 5, Example 6 and the comparative example. The mobile phase of TLC was a mixture of n-hexane and ethyl acetate (the volume ratio of n-hexane: ethyl acetate was 5:1), and iodine fumigation was used for color development. The detection results are shown in Figure 1.

As can be seen from Figure 1, compared with the content of 7-bromo-1,1,1-trifluoro-2-heptanone in the crude product mixed solution of the comparative example, the content of 7-bromo-1,1,1-trifluoro-2-heptanone in the crude product mixed solution of Example 1, Example 5 and Example 6 is significantly higher, and compared with the content of impurities in the crude product mixed solution of the comparative example, the content of impurities in the crude product mixed solution of Example 1, Example 5 and Example 6 is lower, which shows that: when a pyridine compound is used as a catalyst, the compound with the structure shown in formula (1.2) is reacted with trifluoroacetic anhydride to generate 7-bromo-1,1,1-trifluoro-2- When preparing heptanone, the molar ratio of the compound of the structure shown in formula (1.2) to the pyridine compound is limited to the range of 1:(1-8), which can effectively improve the yield of 7-bromo-1,1,1-trifluoro-2-heptanone and simplify the process of product separation and purification. After removing the solvent of the organic phase, 7-bromo-1,1,1-trifluoro-2-heptanone with a purity of more than 98% can be obtained by distillation only, without the need for column chromatography for separation and purification. Compared with column chromatography, distillation has less negative impact on product yield, which is conducive to further improving the product yield, and the yield can reach more than 75%.

In addition, compared with using pyridine as a catalyst, using substituted pyridine (a compound obtained by replacing the hydrogen atom located opposite to the nitrogen atom in the pyridine ring with a substituent, the substituent being an electron-donating group) as a catalyst can further enhance the catalytic effect, further reduce the amount of catalyst used, and help to further reduce the difficulty of product separation and purification, thereby further improving the yield of the product.

The above is a detailed introduction to the preparation method and application of a trifluoromethyl ketone compound provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present application; ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein by equivalents; and these modifications or replacements do not make the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims (9)

1. A method for preparing a trifluoromethyl ketone compound, characterized in that the trifluoromethyl ketone compound has a structure represented by general formula (I), and the preparation method comprises the steps of: using a pyridine compound as a catalyst, reacting a compound represented by general formula (II) with trifluoroacetic anhydride to obtain a product, wherein the product contains the compound represented by general formula (I); and mixing the product with an acid solution for washing and extraction, collecting an organic phase, then removing the solvent of the organic phase, and distilling to obtain a purified compound represented by general formula (I); Wherein, the molar ratio of the compound represented by the general formula (II) to the pyridine compound is 1:(1-5); The general formula (I) is as follows: (Ⅰ) The general formula (II) is as follows: (Ⅱ) In the general formula (I) and the general formula (II), R ₁ is selected from -(CH ₂ ) _n -, n is 3 to 20; R ₂ is selected from unsubstituted or substituted alkyl, or halogen group; The pyridine compound is selected from one or more of 4-pyrrolidinopyridine and 4-dimethylaminopyridine. 2. The preparation method according to claim 1, characterized in that n is 3 to 10; And/or, said R ₂ is selected from -Cl, -Br, -I, -CH(CH ₃ ) ₂ or -C(CH ₃ ) ₃ . 3. The preparation method according to claim 2, characterized in that n is 3 to 5. 4. The preparation method according to claim 1, characterized in that the compound represented by the general formula (I) is selected from: 、/> 、/> or/> ; The compound represented by the general formula (II) is selected from: 、/> 、/> or/> . 5. The preparation method according to claim 1, characterized in that the reaction of the compound of the general formula (II) and trifluoroacetic anhydride using a pyridine compound as a catalyst comprises the steps of: providing a solution containing the compound of the general formula (II) and trifluoroacetic anhydride, adding the pyridine compound to the solution, and mixing; And/or, the reaction is carried out at an ambient temperature of 0°C to 30°C, and the reaction time is 1 h to 4 h. 6. The preparation method according to claim 5, characterized in that the solvent of the solution is selected from one or more of dichloromethane, chloroform and carbon tetrachloride; And/or, in the solution, the concentration of the compound having the structure represented by the general formula (II) is 0.5 mol/L to 5 mol/L. 7. The preparation method according to claim 1, characterized in that the acid in the acid solution is selected from one or more of acetic acid, hydrochloric acid, nitric acid and sulfuric acid; And/or, the acid concentration in the acid solution is 0.01 mol/L to 2 mol/L. 8. The preparation method according to any one of claims 1 to 7, characterized in that the molar ratio of the compound represented by the general formula (II) to the trifluoroacetic anhydride is 1:(2-4); And/or, the molar ratio of the pyridine compound to the trifluoroacetic anhydride is 1:(1-3). 9. Use of the method for preparing trifluoromethyl ketone compounds according to any one of claims 1 to 8 in preparing ion exchange membranes.