Method for preparing polyesteramide monomer and method for removing DMAP

Abstract

The invention discloses a method for preparing a polyesteramide monomer and a method for removing DMAP in the process of preparing the polyesteramide monomer, which comprises the following steps: adding anhydride, alcohol and DMAP into a reaction solvent, and carrying out esterification reaction on the anhydride and the alcohol; and after the esterification reaction is finished, adding water and an organic solvent, adjusting the pH value to be less than or equal to 3.5, carrying out liquid separation, and collecting an organic phase. DMAP in the reaction product can be removed through extraction and pH adjustment, and the obtained powder or mixed liquid product can be directly used for further synthesis of polyesteramide and is not influenced by DMAP, so that more types of polyesteramide and polyimide can be synthesized.

Description

Technical Field

[0001] The invention relates to a method for preparing a polyamide ester monomer, in particular to a method for preparing a polyamide ester monomer and a method for removing DMAP during the preparation of the polyamide ester monomer. Background Art

[0002] Polyimide is a polymer material with high temperature resistance, low temperature resistance, radiation resistance, excellent chemical stability, excellent electrical properties and good mechanical strength. It is widely used in high-tech fields such as aviation, aerospace and microelectronics. Because polyimide cannot or is not easy to melt and dissolve, polyamic acid or polyamide ester is usually obtained first, and then heated and dehydrated into a ring (imidization) to obtain polyimide.

[0003] Therefore, polyamide ester or polyamic acid are both common polyimide prepolymers or precursors, but polyamic acid is not stable, sensitive to water vapor, easy to degrade during storage, and the molecular weight often changes during the heating imidization process. In contrast, polyamide ester, as another prepolymer or precursor, is relatively stable, insensitive to water vapor, can be stored in solid or solution form for a longer time, and the main chain does not degrade during the heating imidization process. The solubility performance is also better than polyamic acid. Therefore, polyamide ester has received more and more attention in recent years.

[0004] Polyamide esters also have an important advantage that they can be given different properties by changing the ester group structure. Therefore, different polyamide ester monomers are used to synthesize different polyamide esters, and the properties of the polyimide resins corresponding to different polyamide esters are also different.

[0005] In the current main polyamide ester synthesis process, after the polyamide ester monomer is synthesized using carboxylic acid and alcohol, the mixed solution obtained by the reaction is used to continue to synthesize polyamide ester. However, in the process of synthesizing polyamide ester monomer, 4-dimethylaminopyridine (DMAP) is a relatively effective catalyst, but due to the strong alkalinity of DMAP, if it exists in the reaction solution, it will affect the next condensation reaction, so that the types of synthesized polyamide esters have certain limitations.

[0006] Therefore, removing DMAP during the synthesis of polyamide ester monomers can increase the types of synthesized polyamide esters and obtain more types of polyimide resins with different properties. Summary of the invention

[0007] The invention provides a method for preparing a polyamide ester monomer and a method for removing DMAP during the preparation of the polyamide ester monomer.

[0008] The first aspect of the present application is to provide a method for preparing a polyamide ester monomer, comprising:

[0009] Acid anhydride, alcohol and DMAP are added to the reaction solvent, and the acid anhydride and alcohol undergo esterification reaction;

[0010] After the esterification reaction is completed, water and an organic solvent are added to adjust the pH value to ≤3.5, and the liquids are separated to collect the organic phase.

[0011] In a preferred embodiment, the method for preparing polyamide ester monomer further comprises removing the reaction solvent, organic solvent, and possibly mixed water from the collected organic phase, and drying the collected organic phase.

[0012] The second aspect of the present application is to provide a method for removing DMAP in the process of preparing polyamide ester monomers, wherein the preparation of the polyamide ester monomer is an esterification reaction of anhydride and alcohol in the presence of DMAP and a reaction solvent, and the method for removing DMAP comprises:

[0013] After the esterification reaction for preparing the polyamide ester monomer is completed, water and an organic solvent are added for liquid separation, the pH value is adjusted to ≤3.5, and the organic phase is collected.

[0014] In a preferred embodiment, the acid anhydride is an anhydride of an organic tetracarboxylic acid that can be used as a monomer for synthesizing polyimide, for example, it can be selected from:

[0015]

[0016]

[0017] In a preferred embodiment, the alcohol structure is R-OH, and R is a carbon chain, a cyclic structure or a combination thereof.

[0018] In a preferred embodiment, the carbon chain or cyclic structure may be branched or unbranched.

[0019] In a preferred embodiment, the carbon chain or cyclic structure may contain heteroatoms or may not contain heteroatoms, wherein the heteroatoms may be one or more of O, N, S, and Si.

[0020] In a preferred embodiment, the carbon chain is preferably a C1-C20 carbon chain, more preferably a C1-C18 carbon chain, more preferably a C1-C15 carbon chain, more preferably a C1-C12 carbon chain, more preferably a C1-C8 carbon chain, more preferably a C1-C6 carbon chain, especially an alkyl group.

[0021] In a preferred embodiment, the cyclic structure may be an aliphatic ring or an aromatic ring, and may be one or more of a monocyclic ring, a linked ring, a condensed ring, a spiro ring, and a bridged ring. It is preferably a C5-C30 ring, more preferably a C6-C25 ring, more preferably a C6-C20 ring, more preferably a C6-C15 ring, and more preferably a C6-C10 ring.

[0022] In a preferred embodiment, the alcohol can be selected from methanol, ethanol, n-propanol, isopropanol, 1-butanol, isobutanol, 1-pentanol, neopentyl alcohol, 1-hexanol, 1-octanol, 1-decanol, 2-methyl-1-propanol, 2-methyl-2-propanol, benzyl alcohol, allyl alcohol, propargyl alcohol, 2-chloroethanol, 2-methylbenzyl alcohol, 3-methylbenzyl alcohol, 3-fluorobenzyl alcohol, 4-fluorobenzyl alcohol, 4-chlorobenzyl alcohol, 4-bromobenzyl alcohol, 4-methylbenzyl alcohol, 1,1-diphenyl-1-ol, 1-phenylethanol, 2-methyl-4-hydroxymethylpyridine, (5-methylfuran-3-yl)methanol, and (5-methylthiophen-3-yl)methanol.

[0023] In a preferred embodiment, the reaction solvent is a non-alcohol solvent, a non-carboxylic acid solvent, and preferably contains a solvent capable of dissolving any one of anhydride, alcohol or DMAP, for example, it can be one or more of alkanes, aromatic hydrocarbons, aldehydes, ethers, esters, halogenated hydrocarbons, amides, sulfur-containing compounds, and heterocyclic compounds, for example, it can be selected from benzene, toluene, xylene, butyltoluene, pentane, hexane, octane, cyclohexane, ethyl acetate, methyl acetate, propyl acetate, acetic acid Butyl acetate, isobutyl acetate, acetone, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, cyclohexanone, acetonitrile, pyridine, phenol, benzyl chloride, chloroform, dichloromethane, tetrachloromethane, trichloropropane, dichloroethane, dichlorobenzene, chlorobenzene, chlorocyclohexane, petroleum ether, ethyl ether, phenyl ether, carbon disulfide, dimethyl carbonate, diethyl carbonate, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, 1,3-dimethyl-2-imidazolidinone.

[0024] More preferably, the reaction solvent is an aprotic solvent.

[0025] In a preferred embodiment, the esterification reaction temperature is preferably 20-100°C, more preferably 25-80°C, more preferably 35-70°C, more preferably 50-60°C.

[0026] In a preferred embodiment, the organic solvent may be a solvent that is insoluble, poorly soluble or slightly soluble in water, for example, it may be one or more of esters, ethers, and halogenated hydrocarbons, for example, ethyl acetate, methyl acetate, ether, petroleum ether, dichloromethane, chloroform, etc. The organic solvent is preferably an ester.

[0027] In a preferred embodiment, after the esterification reaction is completed, the reaction mixture is first concentrated, and then the water and the organic solvent are added.

[0028] In a preferred embodiment, the concentration is to concentrate the mass of the reaction mixture to ≤50%, such as preferably ≤45%, more preferably 35-40%.

[0029] In a preferred embodiment, the amount of water and organic solvent added is preferably at least 1 times the volume of the reaction mixture (preferably, if concentrated, the volume of the concentrated reaction mixture), more preferably at least 2 times, more preferably 3-20 times, more preferably 5-15 times, more preferably 8-13 times, more preferably 10-12 times.

[0030] In a preferred embodiment, the pH value is adjusted to 1-3.5, more preferably 2-3.

[0031] In a preferred embodiment, after the separation, the aqueous phase is extracted with the organic solvent, and the organic phases are combined.

[0032] In a preferred embodiment, the organic phase is freed of the reaction solvent and the organic solvent by rotary evaporation.

[0033] In a preferred embodiment, the pH value can be adjusted by using an organic acid or an inorganic acid, wherein the organic acid or the inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, formic acid, and benzoic acid.

[0034] In the process of synthesizing polyamide ester monomers, the present invention can remove 4-dimethylaminopyridine used in the process of synthesizing polyamide ester monomers through simple extraction and adjustment of pH value. The operation is simple and the 4-dimethylaminopyridine removal efficiency is high. A reaction product free of 4-dimethylaminopyridine is obtained. The polyamide ester monomer is used to synthesize polyamide ester in the next step, so that the types of synthesized polyamide esters can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The result of HPLC detection of DMAP after synthesizing the polyamide ester monomer of the present invention;

[0036] Figure 2 The figure is the HPLC test result after DMAP is removed by the method of the present invention. DETAILED DESCRIPTION

[0037] The present invention provides a method for preparing a polyamide ester monomer and a method for removing DMAP in the process of preparing a polyamide ester monomer. In order to make the purpose, technical scheme and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0038] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0039] Embodiment 1:

[0040] Build a four-necked bottle stirring device, set the oil bath temperature to 60°C, set the stirring speed to 200 rpm, and place the four-necked bottle in the oil bath.

[0041] Into a four-necked flask, N,N-dimethylformamide (DMF), pyromellitic dianhydride (PMDA), 4-dimethylaminopyridine (DMAP) and benzyl alcohol were added in sequence, and then reacted at 60° C. for 3 h.

[0042]

[0043] After the reaction is completed, the reaction liquid is sampled and tested by HPLC to confirm that the raw materials have reacted completely, and then the temperature is lowered to room temperature to stop the reaction. Figure 1 shown.

[0044] The reaction solution was concentrated by rotary evaporation to 40% of the total mass, and then 10 times the mass of water and 10 times the mass of ethyl acetate (EA) were added, and concentrated hydrochloric acid was added to adjust the pH value to 2. After stirring for 30 minutes, the liquids were separated and the organic phase was collected.

[0045] Test the organic phase by HPLC, refer to Figure 2 , HPLC showed that the DMAP peak disappeared in the organic phase ( Figure 1 The peak at 2.332 in Figure 2 disappears in the organic phase), that is, DMAP is removed from the organic phase.

[0046] The aqueous phase was then extracted with 5 times the amount of ethyl acetate until HPLC confirmed that the polyamide ester monomer in the aqueous phase was less than 3%. The organic phases were combined, concentrated, and dried by rotary evaporation to obtain polyamide ester monomer powder.

[0047] Embodiment 2:

[0048] Build a four-necked bottle stirring device, set the oil bath temperature to 60°C, set the stirring speed to 200 rpm, and place the four-necked bottle in the oil bath.

[0049] Into a four-necked flask, N,N-dimethylformamide (DMF), pyromellitic dianhydride (PMDA), 4-dimethylaminopyridine (DMAP) and 4-methyl-benzyl alcohol were added in sequence, and then reacted at 60° C. for 3 h.

[0050] After the reaction was completed, the reaction liquid was sampled and tested by HPLC to confirm that the raw materials had reacted completely, and then the temperature was lowered to room temperature to stop the reaction.

[0051] The reaction solution was concentrated by rotary evaporation to 35% of the total mass, and then 10 times the mass of water and 10 times the mass of ethyl acetate (EA) were added, and concentrated hydrochloric acid was added to adjust the pH value to 2.5. After stirring for 30 minutes, the liquids were separated and the organic phase was collected.

[0052] The aqueous phase was then extracted with 5 times the amount of ethyl acetate until HPLC confirmed that the polyamide ester monomer in the aqueous phase was less than 3%. The organic phases were combined, concentrated, and dried by rotary evaporation to obtain polyamide ester monomer powder.

[0053] Embodiment 3:

[0054] Build a four-necked bottle stirring device, set the oil bath temperature to 60°C, set the stirring speed to 200 rpm, and place the four-necked bottle in the oil bath.

[0055] Into a four-necked flask, N,N-dimethylformamide (DMF), pyromellitic dianhydride (PMDA), 4-dimethylaminopyridine (DMAP) and 4-fluoro-benzyl alcohol were added in sequence, and then reacted at 60° C. for 3 h.

[0056] After the reaction was completed, the reaction liquid was sampled and tested by HPLC to confirm that the raw materials had reacted completely, and then the temperature was lowered to room temperature to stop the reaction.

[0057] The reaction solution was concentrated by rotary evaporation to 30% of the total mass, and then 10 times the mass of water and 10 times the mass of ethyl acetate (EA) of the remaining reaction solution were added, and concentrated hydrochloric acid was added to adjust the pH value to 3. After stirring for 30 minutes, the liquids were separated and the organic phase was collected.

[0058] The aqueous phase was then extracted with 5 times the amount of ethyl acetate until HPLC confirmed that the polyamide ester monomer in the aqueous phase was less than 3%, and the organic phases were combined to obtain a polyamide ester monomer mixed solution.

[0059] Embodiment 4:

[0060] Build a four-necked bottle stirring device, set the oil bath temperature to 60°C, set the stirring speed to 200 rpm, and place the four-necked bottle in the oil bath.

[0061] Into a four-necked flask, N,N-dimethylformamide (DMF), pyromellitic dianhydride (PMDA), 4-dimethylaminopyridine (DMAP) and benzyl alcohol were added in sequence, and then reacted at 60° C. for 3 h.

[0062] After the reaction was completed, the reaction liquid was sampled and tested by HPLC to confirm that the raw materials had reacted completely, and then the temperature was lowered to room temperature to stop the reaction.

[0063] The reaction solution was concentrated by rotary evaporation to 30% of the total mass, and then 10 times the mass of water and 10 times the mass of ethyl acetate (EA) were added, and concentrated hydrochloric acid was added to adjust the pH value to 2. After stirring for 30 minutes, the liquids were separated and the organic phase was collected.

[0064] The aqueous phase was then extracted with 5 times the amount of ethyl acetate until HPLC confirmed that the polyamide ester monomer in the aqueous phase was less than 3%, and the organic phases were combined to obtain a polyamide ester monomer mixed solution.

[0065] The final product obtained in the above embodiment is Figure 1 and Figure 2 , HPLC results show that the DMAP peak in the product almost disappears, indicating that there is no DMAP in the final product. Therefore, in the embodiment of the present invention, both the obtained polyamide ester monomer powder and the polyamide ester monomer mixed solution can be used for the next step of polyamide ester synthesis.

[0066] The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a polyamide ester monomer, characterized in that: include: Acid anhydride, alcohol and DMAP are added to the reaction solvent, and the acid anhydride and alcohol undergo esterification reaction; After the esterification reaction is completed, water and an organic solvent are added to adjust the pH value to ≤3.5, preferably 1-3.5, more preferably 2-3, and the liquids are separated to collect the organic phase.

2. The method according to claim 1, characterized in that Also includes: The collected organic phase is freed from the reaction solvent, organic solvent, and possibly mixed water, and then dried.

3. The method according to claim 1, characterized in that The acid anhydride is an anhydride of an organic tetracarboxylic acid that can be used as a monomer for synthesizing polyimide, for example, it can be selected from:

4. The method according to claim 1, characterized in that: The alcohol structure is R-OH, R is a carbon chain, a cyclic structure or a combination thereof, the carbon chain or cyclic structure is branched or unbranched, and the carbon chain or cyclic structure contains or does not contain heteroatoms, wherein the heteroatoms are one or more of O, N, S, and Si.

5. The method according to claim 1, characterized in that: The reaction solvent is a non-alcohol solvent, a non-carboxylic acid solvent, and preferably contains a solvent capable of dissolving any one of anhydride, alcohol or DMAP, more preferably a non-protonic solvent, for example, it can be one or more of alkanes, aromatic hydrocarbons, aldehydes, ethers, esters, halogenated hydrocarbons, amides, sulfur-containing compounds, and heterocyclic compounds, for example, it can be selected from benzene, toluene, xylene, butyltoluene, pentane, hexane, octane, cyclohexane, ethyl acetate, methyl acetate, propyl acetate, acetic acid Butyl acetate, isobutyl acetate, acetone, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, cyclohexanone, acetonitrile, pyridine, phenol, benzyl chloride, chloroform, dichloromethane, tetrachloromethane, trichloropropane, dichloroethane, dichlorobenzene, chlorobenzene, chlorocyclohexane, petroleum ether, ethyl ether, phenyl ether, carbon disulfide, dimethyl carbonate, diethyl carbonate, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, 1,3-dimethyl-2-imidazolidinone.

6. The method according to claim 1, characterized in that The esterification reaction temperature is preferably 20-100°C, more preferably 25-80°C, more preferably 35-70°C, more preferably 50-60°C.

7. The method according to claim 1, characterized in that The organic solvent may be a solvent that is insoluble, poorly soluble or slightly soluble in water, for example, it may be one or more of esters, ethers, and halogenated hydrocarbons, for example, ethyl acetate, methyl acetate, ether, petroleum ether, dichloromethane, chloroform, and the like.

8. A method for removing DMAP in the process of preparing polyamide ester monomers, characterized in that: The polyamide ester monomer is prepared by subjecting the acid anhydride of claim 1 and the alcohol of claim 1 to an esterification reaction in the presence of DMAP and the reaction solvent of claim 1, and the method for removing DMAP comprises: After the esterification reaction for preparing the polyamide ester monomer is completed, water and the organic solvent according to claim 1 are added for liquid separation, the pH value is adjusted to ≤3.5, preferably 1-3.5, more preferably 2-3, and the organic phase is collected.

9. The method according to claim 8, characterized in that After the esterification reaction is completed, the reaction mixture is first concentrated, and then the water and organic solvent are added. Preferably, the concentration is to concentrate the reaction mixture to a mass of ≤50%, such as preferably ≤45%, more preferably 35-40%.

10. The method according to claim 8, characterized in that After the separation, the aqueous phase is extracted with the organic solvent, and the organic phases are combined.

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