Preparation method of low-viscosity aminophenol polyglycidyl derivative

Abstract

The invention discloses a preparation method of a low-viscosity aminophenol polyglycidyl derivative, which comprises the following steps: (1) under the condition that the reaction temperature is not higher than 25 DEG C and in the presence of a catalyst, enabling aminophenol and epoxy chloropropane to be subjected to full ring-opening reaction by utilizing a water-soluble polar cosolvent; (2) adding water accounting for 0.5-10% of the mass of the epichlorohydrin at the temperature not higher than 60 DEG C, adding alkali metal hydroxide in batches, and carrying out dehydrochlorination reaction; (3) dissolving the crude product obtained in the step (2) in a water-insoluble solvent, and washing with a low-concentration alkali metal hydroxide aqueous solution at 30-100 DEG C; and (4) washing with a low-concentration sodium dihydrogen phosphate solution, and carrying out reduced pressure distillation on a solvent layer to remove the solvent, thereby obtaining the aminophenol polyglycidyl derivative. Through the mode, the aminophenol polyglycidyl derivative with close to three functionality degrees can be synthesized.

Description

Technical Field

[0001] The present invention relates to the field of preparation of aminophenol polyglycidyl derivatives, in particular to a method for preparing low-viscosity aminophenol polyglycidyl derivatives. Background Art

[0002] The preparation method of polyphenol-type glycidyl derivatives or glycidyl ethers without amino groups has been reported in a large number of literatures. They are prepared by adding an alkali metal hydroxide solid or solution to a polyphenol in excess epichlorohydrin, such as those described in US2467171, US2631138, US2739160, US2801227, US2840541, and US2879259.

[0003] The preparation methods of glycidyl derivatives of aromatic amines without phenolic hydroxyl groups have also been reported in a large number of literatures, such as US2915822, US4487948, US4450769, etc. Aromatic amines include aniline, p-methylaniline, m-chloroaniline, 2,6-dimethylaniline, p-phenylenediamine, m-phenylenediamine and 4,4'-methylenedianiline.

[0004] Some high-temperature resistant applications require high heat-deformation composite materials. The resin must possess the fundamental characteristics of low viscosity and three or more epoxy functional groups per molecule. This allows for easy mixing with fillers such as glass or carbon fibers before curing, and allows for a suitable formulation viscosity. A higher number of epoxy groups increases the heat-deformation temperature after curing. Neither phenolic nor aromatic amine glycidyl derivatives meet these essential requirements for high heat-deformation resins.

[0005] The present invention aims to provide a method for preparing low-viscosity aminophenol polyglycidyl derivatives, in particular a method for preparing low-viscosity N,N-diglycidyl-4-glycidyloxyaniline. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing low-viscosity aminophenol polyglycidyl derivatives.

[0007] In order to solve the above technical problems, the present invention adopts a technical solution: providing a method for preparing a low-viscosity aminophenol polyglycidyl derivative, comprising the following steps:

[0008] (1) using a water-soluble polar cosolvent to allow aminophenol and epichlorohydrin to undergo a ring-opening reaction at a reaction temperature not higher than 25° C. and in the presence of a catalyst;

[0009] (2) adding water accounting for 0.5-10% by mass of epichlorohydrin at a temperature not higher than 60° C., and then adding alkali metal hydroxide in batches to carry out dehydrochlorination reaction;

[0010] (3) dissolving the crude product obtained in step (2) in a non-water-soluble solvent and washing with a low-concentration alkali metal hydroxide aqueous solution at 30-100° C.;

[0011] (4) After washing with a low concentration sodium dihydrogen phosphate solution, the solvent layer is distilled under reduced pressure to remove the solvent, thereby obtaining aminophenol polyglycidyl derivatives.

[0012] The aminophenol polyglycidyl derivative refers to a product in which all hydrogen atoms of the primary amino group and phenolic hydroxyl group are replaced by glycidyl groups. Taking the preparation method of N,N-diglycidyl-4-glycidyloxyaniline as an example, the chemical reaction equation is:

[0013]

[0014] In a preferred embodiment of the present invention, in step (1), epichlorohydrin serves as both a reactant and a solvent, and the molar ratio of the hydroxyl groups of epichlorohydrin to aminophenol is in the range of 3:1-20:1, with the optimal range being between 5:1 and 15:1.

[0015] In a preferred embodiment of the present invention, in step (1), the catalyst is an organic acid, including fatty acids and aromatic acids, such as formic acid, acetic acid, propionic acid, butyric acid and benzoic acid, preferably a fatty acid with a carbon number not exceeding 4, and the amount of the catalyst is 0.1-10% of the mass of aminophenol.

[0016] Furthermore, the preferred range of the amount of the catalyst is 1.0-3.0% of the mass of aminophenol.

[0017] In a preferred embodiment of the present invention, in step (1), the water-soluble polar cosolvent includes one or more of an alcohol solvent such as methanol, ethanol, isopropanol, etc., a ketone solvent including acetone, butanone, etc., tetrahydrofuran and DMF.

[0018] In a preferred embodiment of the present invention, in step (1), the reaction time of aminophenol and epichlorohydrin is not less than 7 days, and the optimal range is 7-10 days.

[0019] In a preferred embodiment of the present invention, in step (2), the alkali metal hydroxide is solid sodium hydroxide or a sodium hydroxide solution. The amount of solid sodium hydroxide should not exceed the theoretical amount, and the optimal range is 2.85-3.0 times the molar amount of aminophenol. The reaction temperature does not exceed 60°C, and the optimal temperature range is 40-60°C. The water content in the sodium hydroxide solution is 0.5-5% by mass of epichlorohydrin, and the optimal range is 1-3%.

[0020] In a preferred embodiment of the present invention, in step (3), the non-water-soluble solvent includes one of aromatic hydrocarbons and ketones.

[0021] In a preferred embodiment of the present invention, in step (3), the mass of the aqueous alkali metal hydroxide solution is 1-3 times the mass of the crude product obtained in step (2), and the concentration is 2-5%.

[0022] In a preferred embodiment of the present invention, in step (4), the mass of the sodium dihydrogen phosphate solution is 1-3 times the mass of the crude product obtained in step (2), and the concentration is 2-5%.

[0023] The first step of the present invention is the ring-opening reaction of amino groups with epichlorohydrin. Epichlorohydrin serves as both a reactant and a solvent. The amino groups must react completely, otherwise the residual amino groups will react with the generated epoxy groups, resulting in the production of oligomer byproducts and increased product viscosity. The reaction temperature should not exceed 25°C. If the temperature is too high, the phenolic hydroxyl groups will react with epichlorohydrin under the catalysis of the amino groups to form phenolic glycidyl ethers, and the epoxy groups will react with the amino groups again, resulting in increased viscosity. At a temperature not exceeding 25°C, in order to allow the amino groups to fully react with epichlorohydrin, a catalyst must be added and the reaction time must be extended. In the first step, although epichlorohydrin is greatly in excess, the aminophenol cannot be completely dissolved. In order to further increase the solubility of aminophenol in the reaction system and thus increase the reaction rate, a water-soluble polar solvent is usually added. Due to the solubility of aminophenol and the reaction temperature, even with the addition of a catalyst, the reaction rate of the amino group and the epoxy group is very low, and a longer reaction time is required to allow the amino group and the epoxy group to react completely. The reaction time at 25°C is at least 7 days.

[0024] The second step is a dehydrochlorination reaction, which requires the addition of an alkali metal hydroxide solid or solution, and sodium hydroxide is commonly used in industry;

[0025] The crude N,N-diglycidyl-4-glycidyloxyaniline obtained by the above reaction must be further separated and purified. First, solid salts are filtered off, and then excess epichlorohydrin is recovered by distillation. Then, 1-3 times the amount of toluene and 1-3 times the amount of 2% sodium hydroxide solution are added to wash at 30-100° C. for 2 hours. After separation and removal of the aqueous solution, the upper layer is washed once with 1-3 times the amount of 2% sodium dihydrogen phosphate aqueous solution. After separation and removal of the aqueous solution, the toluene is distilled off to obtain the target product with a functionality close to 3 and a viscosity in the range of 1000-2000 mPa.s at 25° C.

[0026] The beneficial effects of the present invention are as follows: the present invention can prepare aminophenol polyglycidyl derivatives with low viscosity and a functionality close to 3. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention are described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0028] Example 1:

[0029] To a 500 mL four-necked flask equipped with a stirring paddle and a condenser, 25.10 g (0.23 mol) of p-aminophenol, 323.83 g (3.5 mol) of epichlorohydrin, 0.25 g of acetic acid, and 80 g of ethanol were added, and the mixture was stirred and reacted at 25° C. for 7 days. 3.64 g of water was added, and the temperature was raised to 55-60° C. Solid sodium hydroxide was added in three equal portions, one portion being added every 1 hour. After the addition was complete, the reaction was continued at 55-60° C. for 2 hours. The mixture was filtered, and the filtrate was distilled under reduced pressure to remove excess epichlorohydrin to obtain the target crude product. The crude product was added to 100 g of toluene, washed with 100 g of 2% sodium hydroxide solution at 60° C. for 2 hours, cooled and allowed to stand, and the lower aqueous layer was removed. The mixture was then washed once with 100 g of 2% sodium dihydrogen phosphate aqueous solution, allowed to stand, and the lower aqueous layer was removed. The toluene in the upper layer was distilled under reduced pressure to obtain N,N-diglycidyl-4-glycidyloxyaniline.

[0030] Example 2:

[0031] The amount of acetic acid used in Example 1 was increased by 2 times. Other details were the same as in Example 1 and will not be described in detail here.

[0032] Example 3:

[0033] Lactic acid was used to replace the acetic acid in Example 1. Other details were the same as in Example 1 and will not be described in detail here.

[0034] Comparative Example 1:

[0035] No acetic acid was added during the reaction. Other steps were the same as in Example 1 and will not be described in detail here.

[0036] Comparative Example 2:

[0037] No ethanol was added during the reaction. Other steps were the same as in Example 1 and will not be described in detail here.

[0038] Comparative Example 3:

[0039] The reaction temperature of the first step was increased by 25° C. to 45° C., and the rest was the same as in Example 1 and will not be described in detail here.

[0040] The different reaction conditions of the above examples and the properties of the obtained N,N-diglycidyl-4-glycidyloxyaniline are summarized in the following Table 1:

[0041] Table 1

[0042]

[0043] In the table, catalyst dosage is calculated as a percentage based on p-aminophenol; epoxy equivalent is determined according to the method of GB / T4612-2008; functionality is the molecular weight of N,N-diglycidyl-4-glycidyloxyaniline (277.20) divided by the measured epoxy equivalent.

[0044] It can be seen from Table 1 that at 25°C, adding a catalyst and a cosolvent is beneficial for obtaining a target product with lower viscosity.

[0045] This embodiment is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above content as a guide to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiment that do not depart from the technical essence of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for preparing a low-viscosity aminophenol polyglycidyl derivative, characterized in that: The following steps are involved: (1) using a water-soluble polar cosolvent to allow aminophenol and epichlorohydrin to undergo a ring-opening reaction at a reaction temperature not higher than 25° C. and in the presence of a catalyst; (2) adding water accounting for 0.5-10% by mass of epichlorohydrin at a temperature not higher than 60° C., and then adding alkali metal hydroxide in batches to carry out dehydrochlorination reaction; (3) dissolving the crude product obtained in step (2) in a non-water-soluble solvent and washing with a low-concentration alkali metal hydroxide aqueous solution at 30-100° C.; (4) After washing with a low concentration sodium dihydrogen phosphate solution, the solvent layer is distilled under reduced pressure to remove the solvent, thereby obtaining aminophenol polyglycidyl derivatives.

2. The method for preparing the low-viscosity aminophenol polyglycidyl derivative according to claim 1, wherein: In step (1), the molar ratio of the hydroxyl groups of epichlorohydrin and aminophenol is in the range of 3:1-20:

1.

3. The method for preparing the low-viscosity aminophenol polyglycidyl derivative according to claim 1, characterized in that: In step (1), the catalyst is an organic acid, including fatty acid and aromatic acid, and the amount of the catalyst is 0.1-10% of the mass of aminophenol.

4. The method for preparing the low-viscosity aminophenol polyglycidyl derivative according to claim 3, characterized in that: The preferred range of the amount of the catalyst is 1.0-3.0% of the mass of aminophenol.

5. The method for preparing the low-viscosity aminophenol polyglycidyl derivative according to claim 1, characterized in that: In step (1), the water-soluble polar co-solvent includes one or more of an alcohol solvent, a ketone solvent, tetrahydrofuran and DMF.

6. The method for preparing the low-viscosity aminophenol polyglycidyl derivative according to claim 1, characterized in that: In step (1), the reaction time of aminophenol and epichlorohydrin is not less than 7 days.

7. The method for preparing a low-viscosity aminophenol polyglycidyl derivative according to claim 1, wherein: In step (2), the alkali metal hydroxide is sodium hydroxide solid or sodium hydroxide solution, the amount of sodium hydroxide solid is 2.85-3.0 times the molar amount of aminophenol, and the water content in the sodium hydroxide solution accounts for 0.5-5% of the mass percentage of epichlorohydrin.

8. The method for preparing a low-viscosity aminophenol polyglycidyl derivative according to claim 1, wherein: In step (3), the non-water-soluble solvent includes one of aromatic hydrocarbons and ketones.

9. The method for preparing a low-viscosity aminophenol polyglycidyl derivative according to claim 1, wherein: In step (3), the mass of the alkali metal hydroxide aqueous solution is 1-3 times the mass of the crude product obtained in step (2), and the concentration is 2-5%.

10. The method for preparing a low-viscosity aminophenol polyglycidyl derivative according to claim 1, characterized in that: In step (4), the mass of the sodium dihydrogen phosphate solution is 1-3 times the mass of the crude product obtained in step (2), and the concentration is 2-5%.

Images