Preparation method of organic acid hydrazide

Abstract

The invention relates to the technical field of preparation of organic acid hydrazide, and particularly discloses a preparation method of organic acid hydrazide, which comprises the following steps: dissolving catechol and ethylene nitrile in an organic solvent dimethyl sulfoxide, adding sodium hydroxide as a catalyst, and reacting in a three-necked flask to obtain a mixed solution; reacting the mixed solution with water, adding concentrated sulfuric acid as a catalyst, and purifying after the reaction to obtain a viscous liquid; putting the viscous liquid and benzotriazole into a mortar at room temperature, uniformly grinding the viscous liquid and benzotriazole, adding SOCl2, continuously grinding the viscous liquid and benzotriazole uniformly, and treating the viscous liquid and benzotriazole to obtain a white solid; and dissolving the white solid in absolute ethyl alcohol at room temperature, adding hydrazine hydrate, and treating by using an acetonitrile-chloroform mixed solvent after the reaction is finished to obtain a target product. The amide synthesized by the method can well solve the defects of high reaction temperature, long reaction time and low yield, and has certain practical value, and the prepared epoxy structural adhesive has high bonding strength.

Description

Technical Field

[0001] The invention relates to the technical field of organic acid hydrazide preparation, in particular to a method for preparing organic acid hydrazide. Background Art

[0002] Epoxy adhesives have been widely used in aviation, aerospace, automobile, machinery, electronics and other fields due to their advantages such as high bonding strength, small curing shrinkage and good corrosion resistance. Traditional epoxy adhesives are mostly composed of two components, epoxy resin and curing agent, which are prone to material loss and environmental pollution during the batching process. After the latent curing agent is combined with the epoxy resin, the composition is relatively stable when left at room temperature for a long time, but once it is exposed to heat, light, moisture or pressure, it can trigger a curing reaction and cross-link the epoxy resin into a cured product. Utilizing this characteristic of the curing agent, the epoxy resin composition can be formulated into a single component, which can avoid the defects caused by the batching of the epoxy resin and curing agent components.

[0003] Organic acid hydrazide, a latent curing agent, is solid at room temperature and insoluble in epoxy resin. Once heated to near the melting point, it begins to dissolve and react rapidly, and belongs to a heat-curing latent curing agent. Currently, the most common method for synthesizing hydrazide derivatives is through hydrazinolysis of esters, but the disadvantages of this method are high reaction temperature, long reaction time and low yield. Therefore, a preparation method of organic acid hydrazide is provided. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing an organic acid hydrazide in view of the defects of the prior art, so as to solve the problems raised by the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing organic acid hydrazide, the specific steps are as follows:

[0006] Step 1: dissolving catechol and acrylonitrile in an organic solvent, dimethyl sulfoxide, adding sodium hydroxide as a catalyst, reacting in a three-necked flask to obtain a mixed solution; the catechol is 20-40 parts, the acrylonitrile is 10-40 parts, the organic solvent is 20-30 parts, and the sodium hydroxide is 1-5 parts;

[0007] Step 2: react the mixed solution with water, add concentrated sulfuric acid as a catalyst, and purify after the reaction to obtain a viscous liquid;

[0008] Step 3: Take the viscous liquid and benzotriazole in a mortar at room temperature, grind them evenly and add SOCl 2 , continue to grind evenly, and then get a white solid after treatment; the viscous liquid is 10-15 parts, benzotriazole is 10-20 parts, SOCl 2 For 10-20 portions;

[0009] Step 4: dissolve the white solid obtained in step 3 in anhydrous ethanol at room temperature, add hydrazine hydrate, and after the reaction is completed, treat with acetonitrile-chloroform mixed solvent to obtain the target product; the white solid is 10-15 parts, and the hydrazine hydrate is 30-40 parts.

[0010] As a preferred technical solution of the present invention, the reaction temperature in the three-necked flask in step 1 is 50-60° C., and the reaction time is 5-8 h.

[0011] As a preferred technical solution of the present invention, the reaction temperature of step 2 is 80-100° C. and the reaction time is 5-8 h.

[0012] As a preferred technical solution of the present invention, the grinding time in step 3 is 30-40 minutes.

[0013] As a preferred technical solution of the present invention, the reaction temperature of step 4 is 20-30° C., and the reaction time is 30-40 minutes.

[0014] An organic acid hydrazide is prepared by the above-mentioned preparation method.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The invention uses catechol as a raw material, introduces a cyano group by reacting with acrylonitrile, synthesizes a carboxyl group from the reaction result of the cyano group and water, activates the carboxyl group of the aromatic acid by using benzotriazole, and then obtains an organic acid hydrazide by hydrazine hydrate hydrazine hydrolysis; synthesizing amide by this method can well solve the disadvantages of high reaction temperature, long reaction time and low yield, has certain practical value, and the prepared epoxy structural adhesive has high bonding strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The synthetic route of the invention. DETAILED DESCRIPTION

[0018] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings 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 definite definition of the protection scope of the present invention.

[0019] Example 1: Figure 1 As shown, a method for preparing an organic acid hydrazide, the specific steps are as follows:

[0020] Step 1: dissolving 20 parts of catechol and 30 parts of acrylonitrile in an organic solvent, adding sodium hydroxide, reacting in a three-necked flask to obtain a mixed solution, reacting the mixed solution with water, adding concentrated sulfuric acid, and purifying after the reaction to obtain a viscous liquid;

[0021] Step 2: Take 10 parts of the viscous liquid obtained in step 1 and 12 parts of benzotriazole in a mortar at room temperature, grind evenly and add 15 parts of SOCl 2 , and then continue to grind evenly, and then obtain a white solid after treatment;

[0022] Step 3: Dissolve 10 parts of the white solid in a solvent at room temperature, add 15 parts of hydrazine hydrate, and after the reaction is completed, treat with the mixed solution to obtain the target product;

[0023] Step 4: Using E51 bisphenol A epoxy resin as the base material, the curing agent dosage is 3-5 / 10, and the shear bonding strength of the adhesive to the steel sheet after curing at 150°C for 4 hours is 15.2MPa.

[0024] Example 2: Figure 1 As shown, a method for preparing an organic acid hydrazide, the specific steps are as follows:

[0025] Step 1: Take 20 parts of catechol and 30 parts of acrylonitrile and dissolve them in an organic solvent, add sodium hydroxide, react in a three-necked flask to obtain a mixed solution, react the mixed solution with water, add concentrated sulfuric acid, and purify after the reaction to obtain a viscous liquid;

[0026] Step 2: Take 10 parts of viscous liquid and 12 parts of benzotriazole in a mortar at room temperature, grind evenly and add 15 parts of SOCl 2 , and then continue to grind evenly, and then obtain a white solid after treatment;

[0027] Step 3: Dissolve 10 parts of the white solid in a solvent at room temperature, add 20 parts of hydrazine hydrate, and after the reaction is completed, treat with the mixed solution to obtain the target product;

[0028] Step 4: Using E51 bisphenol A epoxy resin as the base material, the curing agent dosage is 3-5 / 10, and the shear bonding strength of the adhesive to the steel sheet after curing at 150°C for 4 hours is 17.5MPa.

[0029] Example 3: Figure 1 As shown, a method for preparing an organic acid hydrazide, the specific steps are as follows:

[0030] Step 1: Take 20 parts of catechol and 30 parts of acrylonitrile and dissolve them in an organic solvent, add sodium hydroxide, react in a three-necked flask to obtain a mixed solution, react the mixed solution with water, add concentrated sulfuric acid, and purify after the reaction to obtain a viscous liquid;

[0031] Step 2: Take 10 parts of viscous liquid and 12 parts of benzotriazole in a mortar at room temperature, grind evenly and add 15 parts of SOCl 2 , and then continue to grind evenly, and then obtain a white solid after treatment;

[0032] Step 3: Take 10 parts of the white solid and dissolve it in a solvent at room temperature, add 25 parts of hydrazine hydrate, and after the reaction is completed, treat it with the mixed solution to obtain the target product;

[0033] Step 4: Using E51 bisphenol A epoxy resin as the base material, the curing agent dosage is 3-5 / 10, and the shear bonding strength of the adhesive to the steel sheet after curing at 150°C for 4 hours is 18.9 MPa.

[0034] Example 4: Figure 1 As shown, a method for preparing an organic acid hydrazide, the specific steps are as follows:

[0035] Step 1: Take 20 parts of catechol and 30 parts of acrylonitrile and dissolve them in an organic solvent, add sodium hydroxide, react in a three-necked flask to obtain a mixed solution, react the mixed solution with water, add concentrated sulfuric acid, and purify after the reaction to obtain a viscous liquid;

[0036] Step 2: Take 10 parts of viscous liquid and 12 parts of benzotriazole in a mortar at room temperature, grind evenly and add 15 parts of SOCl 2 , and then continue to grind evenly, and then obtain a white solid after treatment;

[0037] Step 3: Dissolve 10 parts of the white solid in a solvent at room temperature, add 30 parts of hydrazine hydrate, and after the reaction is completed, treat with the mixed solution to obtain the target product;

[0038] Step 4: Using E51 bisphenol A epoxy resin as the base material, the curing agent dosage is 3-5 / 10, and the shear bonding strength of the adhesive to the steel sheet after curing at 150°C for 4 hours is 16.2MPa.

[0039] Comparative example: Organic acid hydrazides currently sold on the market include sebacic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, etc., one or more of which are selected.

[0040] Test example: The products in each embodiment were selected to test the shear bonding strength of the adhesive; the adhesive was evenly applied to the bonding area (size 25mm×15mm) at both ends of the steel sheet; then the steel sheets were overlapped in a single lap manner; the bonding structure was fixed with a clamp, and the shear strength test of the sample was performed according to the standard GB / T7124-2008 during the test, with a test speed of 2mm / min; the specific results are shown in Table 1;

[0041] Table 1: Shear bond strength of adhesives of Examples 1-4 and Comparative Examples

[0042] Group Adhesive shear bond strength (MPa) Example 1 15.2 Example 2 17.5 Example 3 18.9 Example 4 16.2 Comparative Example 10.3

[0043] In summary, it can be seen that the curing agent is simple to prepare, the reaction conditions are mild, and it can be produced on a large scale. The curing agent can realize the curing of general epoxy resins (bisphenol A, bisphenol F, hydrogenated bisphenol A, etc.), and has a high shear bonding strength after curing with the epoxy resin, which solves the problems of on-site batching, material loss and environmental pollution of traditional curing agents, and is conducive to use in automated assembly lines.

[0044] The above embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims

1. A method for preparing an organic acid hydrazide, characterized in that: The specific steps are as follows: Step 1: dissolving catechol and acrylonitrile in an organic solvent, dimethyl sulfoxide, adding sodium hydroxide as a catalyst, reacting in a three-necked flask to obtain a mixed solution; the catechol is 20-40 parts, the acrylonitrile is 10-40 parts, the organic solvent is 20-30 parts, and the sodium hydroxide is 1-5 parts; Step 2: react the mixed solution with water, add concentrated sulfuric acid as a catalyst, and purify after the reaction to obtain a viscous liquid; Step 3: Put the viscous liquid and benzotriazole into a mortar at room temperature, grind them evenly, add SOCl2, continue to grind evenly, and obtain a white solid after treatment; the viscous liquid is 10-15 parts, the benzotriazole is 10-20 parts, and the SOCl2 is 10-20 parts; Step 4: dissolve the white solid obtained in step 3 in anhydrous ethanol at room temperature, add hydrazine hydrate, and after the reaction is completed, treat with acetonitrile-chloroform mixed solvent to obtain the target product; the white solid is 10-15 parts, and the hydrazine hydrate is 30-40 parts.

2. The preparation method of organic acid hydrazide according to claim 1, wherein: In step 1, the reaction temperature in the three-necked flask is 50-60° C., and the reaction time is 5-8 h.

3. The preparation method of organic acid hydrazide according to claim 1, characterized in that: The reaction temperature of step 2 is 80-100°C and the reaction time is 5-8h.

4. The method for preparing an organic acid hydrazide according to claim 1, wherein: The grinding time in step 3 is 30-40 minutes.

5. The method for preparing organic acid hydrazide according to claim 1, wherein: The reaction temperature of step 4 is 20-30°C, and the reaction time is 30-40 minutes.

6. An organic acid hydrazide, characterized in that The invention is prepared by the preparation method according to any one of claims 1 to 5.

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