Method for preparing 4, 4 '-diaminodiphenylmethane by utilizing dynamic tubular reactor

Abstract

The invention provides a method for preparing 4, 4 '-diaminodiphenylmethane by using a dynamic tubular reactor, and belongs to the field of organic material synthesis. According to the present invention, aniline and formaldehyde are adopted as raw materials, and under the action of the catalyst, 4, 4 '-diaminodiphenylmethane is catalytically synthesized in the dynamic tubular reactor, such that the operation is simple, the reaction condition control is accurate, the reaction time is short, the reaction selectivity is good, and the product purity is high.

Description

Technical Field

[0001] The present invention relates to the technical field of synthesis of organic monomers, and discloses a method for preparing 4,4'-diaminodiphenylmethane by using a dynamic tubular reactor. Background Art

[0002] 4,4'-Diaminodiphenylmethane is an important chemical intermediate, which can be mainly used for the production of diisocyanates such as MDI and HMDI, and can also be widely used for the preparation of high-grade insulating materials such as bismaleimide resin, polyimide (PI), polyesterimide (PEI), insulating materials, etc.; in addition, it can also be used as a chain extender for polyurethane elastomers and a curing agent for epoxy resins. The various products synthesized from MDA have excellent heat resistance, insulation properties, mechanical properties and wear resistance. It is a fine chemical product with wide uses and excellent properties, and its structure is as follows:

[0003]

[0004] Chinese Patent CN101007767A reported a catalytic synthesis process of MDA, which is prepared by an intermittent one-step condensation reaction of aniline and formaldehyde under the action of a solid acid catalyst.

[0005] Chinese Patent CN105294448A provides a method for continuously preparing 4,4'-diaminodiphenylmethane derivatives by solid acid catalysis. The condensation reaction is carried out by solid acid catalysis in a one-stage or two-stage fixed-bed reactor to obtain 4,4'-diaminodiphenylmethane derivatives.

[0006] Chinese Patent CN106986777B provides a method for preparing 4,4'-diaminodiphenylmethane derivatives by using a microreactor.

[0007] The methods reported above are either intermittent reactions carried out in traditional reactors, with longer reaction times; some have complex operation steps, which are not conducive to large-scale production; when solid materials participate in or produce solids in the microreactor, it will cause blockage of the pipeline and incomplete reaction. Summary of the Invention

[0008] Only some aspects of the present invention are briefly described below and are not limited thereto. When there are differences between the disclosure content of this specification and the cited literature, the disclosure content of this specification shall prevail.

[0009] The purpose of the present invention is to provide a method for preparing 4,4'-diaminodiphenylmethane by using a dynamic tubular reactor. By using a dynamic tubular reactor, the reaction pressure and temperature can be well controlled.

[0010] The technical solution adopted by the present invention is as follows:

[0011] A method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor, comprising the following steps:

[0012] Aniline, formaldehyde, and a catalyst are respectively pumped into the dynamic tubular reactor at a certain flow rate. The reaction solution is fully mixed in the reactor, heated under a certain pressure, and after staying for a certain time, it flows out of the reactor. The reaction solution is cooled, and an aqueous sodium hydroxide solution is added dropwise to adjust the pH. After filtration, ethanol is added for recrystallization to obtain 4,4'-diaminodiphenylmethane. The reaction formula is as follows:

[0013]

[0014] Furthermore, in the method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor, the formaldehyde is one or more of paraformaldehyde, trioxane, and a formaldehyde solution with a content of 35-40%, preferably a formaldehyde solution with a content of 37%.

[0015] Furthermore, in the method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor, the catalyst is selected from one or more of concentrated hydrochloric acid, concentrated sulfuric acid, p-toluenesulfonic acid, solid acid, and methanesulfonic acid, preferably one or more of concentrated hydrochloric acid or concentrated sulfuric acid.

[0016] Furthermore, in the method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor, the concentration of the hydrochloric acid or sulfuric acid is 20%-40%, preferably the concentration of concentrated hydrochloric acid is 35%.

[0017] Furthermore, in the method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor, the molar ratio of aniline to formaldehyde is 1:0.5-1.5, preferably 1:0.8.

[0018] Furthermore, in the method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor, the molar ratio of aniline to concentrated hydrochloric acid is 1:0.5-1.5, preferably 1:0.8.

[0019] Furthermore, in the method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor, the reaction temperature of the dynamic tubular reactor is 60-80°C, preferably 65°C.

[0020] Furthermore, in the method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor, the reaction residence time of the dynamic tubular reactor is 5-10 min, preferably 7 min.

[0021] Further, in the method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor, it is characterized in that the reaction solution is cooled to 15-20 °C, preferably 18 °C.

[0022] Further, in the method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor, it is characterized in that the pH is 7.5-8.5, preferably the pH is 8.

[0023] Advantageous technical effects of the present invention

[0024] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0025] 1. The continuous preparation process is realized, the reaction speed is fast, and the reaction time is shortened;

[0026] 2. The rapid heat transfer ability is easy to realize the isothermal reaction, improve the reaction yield, the reaction temperature is mild, and the potential safety hazard is reduced.

[0027] 3. Problems such as pipeline blockage and incomplete reaction caused by the generation of solid particles in the product are avoided, which is more conducive to industrial production. Specific embodiments

[0028] Unless otherwise specified or there is an obvious conflict in the context, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. If there is a contradiction, the definition provided in this application shall prevail. When a trade name appears in this article, it is intended to refer to its corresponding product or its active ingredient. All patents, published patent applications and publications cited herein are incorporated herein by reference.

[0029] Example 1:

[0030] (1) Aniline, formaldehyde (37%), and concentrated hydrochloric acid (35%) were respectively pumped into a dynamic tubular reactor at a certain flow rate, and the flow rate ratios of the three reaction solutions in the regulation step were controlled to make the molar ratio of aniline: formaldehyde: concentrated hydrochloric acid 1:0.8:0.8;

[0031] (2) The reaction temperature was set at 65 °C and the residence time was 7 min;

[0032] (3) The outlet was connected to the reaction solution, cooled to 18 °C, an aqueous sodium hydroxide solution was added dropwise until the pH was about 8, and after filtering the solid, recrystallization with ethanol was carried out to obtain 4,4'-diaminodiphenylmethane, with a yield of 97% and a purity of 99.4%.

[0033] Example 2:

[0034] (1) Pump aniline, formaldehyde (35%), and concentrated hydrochloric acid (20%) into a dynamic tubular reactor at a certain flow rate respectively, regulate the flow rate ratio of the three reaction liquids in the step, and control the molar ratio of aniline: formaldehyde: concentrated hydrochloric acid to be 1:0.5:0.5;

[0035] (2) Set the reaction temperature to 60 °C and the residence time to 5 min;

[0036] (3) Connect the outlet to the reaction liquid, cool it down to 15 °C, dropwise add an aqueous sodium hydroxide solution until the pH is about 7.5, filter the solid, and then add ethanol for recrystallization to obtain 4,4'-diaminodiphenylmethane with a yield of 93% and a purity of 99.2%.

[0037] Example 3:

[0038] (1) Pump aniline, formaldehyde (40%), and concentrated hydrochloric acid (40%) into a dynamic tubular reactor at a certain flow rate respectively, regulate the flow rate ratio of the three reaction liquids in the step, and control the molar ratio of aniline: formaldehyde: concentrated hydrochloric acid to be 1:1.5:1.5;

[0039] (2) Set the reaction temperature to 80 °C and the residence time to 10 min;

[0040] (3) Connect the outlet to the reaction liquid, cool it down to 20 °C, dropwise add an aqueous sodium hydroxide solution until the pH is about 8.5, filter the solid, and then add ethanol for recrystallization to obtain 4,4'-diaminodiphenylmethane with a yield of 92% and a purity of 99.1%.

[0041] Example 4:

[0042] (1) Pump aniline, formaldehyde (30%), and concentrated hydrochloric acid (15%) into a dynamic tubular reactor at a certain flow rate respectively, regulate the flow rate ratio of the three reaction liquids in the step, and control the molar ratio of aniline: formaldehyde: concentrated hydrochloric acid to be 1:0.3:0.3;

[0043] (2) Set the reaction temperature to 65 °C and the residence time to 6 min;

[0044] (3) Connect the outlet to the reaction liquid, cool it down to 16 °C, dropwise add an aqueous sodium hydroxide solution until the pH is about 7.8, filter the solid, and then add ethanol for recrystallization to obtain 4,4'-diaminodiphenylmethane with a yield of 83% and a purity of 98.7%.

[0045] Example 5:

[0046] (1) Pump aniline, formaldehyde (45%), and concentrated hydrochloric acid (45%) into a dynamic tubular reactor at a certain flow rate respectively, regulate the flow rate ratio of the three reaction liquids in the step, and control the molar ratio of aniline: formaldehyde: concentrated hydrochloric acid to be 1:2:2;

[0047] (2) Set the reaction temperature to 68 °C and the residence time to 8 min;

[0048] (3) Connect the outlet to the reaction solution, cool it down to 19 °C, add sodium hydroxide aqueous solution dropwise until the pH is about 8.2, filter the solid and then add ethanol for recrystallization to obtain 4,4'-diaminodiphenylmethane, with a yield of 84% and a purity of 98.5%.

[0049] Example 6:

[0050] (1) Pump aniline, formaldehyde (35%), and concentrated hydrochloric acid (20%) into a dynamic tubular reactor at a certain flow rate respectively, regulate the flow rate ratio of the three reaction solutions in the step, and control the molar ratio of aniline: formaldehyde: concentrated hydrochloric acid to be 1:0.5:0.7;

[0051] (2) Set the reaction temperature to 50 °C and the residence time to 3 min;

[0052] (3) Connect the outlet to the reaction solution, cool it down to 12 °C, add sodium hydroxide aqueous solution dropwise until the pH is about 7.2, filter the solid and then add ethanol for recrystallization to obtain 4,4'-diaminodiphenylmethane, with a yield of 88% and a purity of 97.6%.

[0053] Example 7:

[0054] (1) Pump aniline, formaldehyde (37%), and concentrated hydrochloric acid (32%) into a dynamic tubular reactor at a certain flow rate respectively, regulate the flow rate ratio of the three reaction solutions in the step, and control the molar ratio of aniline: formaldehyde: concentrated hydrochloric acid to be 1:1:1;

[0055] (2) Set the reaction temperature to 90 °C and the residence time to 15 min;

[0056] (3) Connect the outlet to the reaction solution, cool it down to 25 °C, add sodium hydroxide aqueous solution dropwise until the pH is about 9, filter the solid and then add ethanol for recrystallization to obtain 4,4'-diaminodiphenylmethane, with a yield of 85% and a purity of 98.7%.

[0057] Example 8:

[0058] (1) Pump aniline, formaldehyde (37%), and concentrated sulfuric acid (35%) into a dynamic tubular reactor at a certain flow rate respectively, regulate the flow rate ratio of the three reaction solutions in the step, and control the molar ratio of aniline: formaldehyde: concentrated sulfuric acid to be 1:0.8:0.8;

[0059] (2) Set the reaction temperature to 65 °C and the residence time to 7 min;

[0060] (3) The outlet is connected to the reaction solution, and the temperature is lowered to 18 °C. An aqueous sodium hydroxide solution is added dropwise until the pH is about 8. After filtering the solid, it is recrystallized with ethanol to obtain 4,4'-diaminodiphenylmethane with a yield of 95% and a purity of 99.3%.

[0061] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the limitations of the above embodiments, and the above embodiments and the descriptions in the specification are only for explaining the principles of the present invention.

[0062] Those skilled in the art can make various non-substantive changes and improvements to the present invention without departing from the concept of the present invention, and these all fall within the scope of protection required by the present invention.

Claims

1. A method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor, characterized in that: Aniline, formaldehyde and catalyst are pumped into the dynamic tubular reactor at a certain flow rate. The reaction liquid is fully mixed in the reactor, heated under a certain pressure, and flows out of the reactor after staying for a certain time. The reaction liquid is cooled, and sodium hydroxide aqueous solution is added dropwise to adjust the pH. After filtering, ethanol is added for recrystallization to obtain 4,4'-diaminodiphenylmethane. The reaction formula is as follows:

2. A method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor according to claim 1, characterized in that: The formaldehyde is one or more of paraformaldehyde, trioxymethylene, and a formaldehyde solution with a content of 35-40%, preferably with a content of 37%.

3. A method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor according to claim 1, characterized in that: The catalyst is selected from one or more of concentrated hydrochloric acid, concentrated sulfuric acid, p-toluenesulfonic acid, solid acid, and methanesulfonic acid, preferably one or more of concentrated hydrochloric acid or concentrated sulfuric acid.

4. A method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor according to claim 1, characterized in that: The concentration of the hydrochloric acid or sulfuric acid is 20%-40%, and the preferred concentration of concentrated hydrochloric acid is 35%.

5. A method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor according to claim 1, characterized in that: The molar ratio of aniline to formaldehyde is 1:0.5-1.5, preferably 1:0.

8.

6. A method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor according to claim 1, characterized in that: The molar ratio of aniline to concentrated hydrochloric acid is 1:0.5-1.5, preferably 1:0.

8.

7. A method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor according to claim 1, characterized in that: The reaction temperature of the dynamic tubular reactor is 60-80°C, preferably 65°C.

8. The method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor according to claim 1, characterized in that: The reaction residence time of the dynamic tubular reactor is 5 to 10 minutes, preferably 7 minutes.

9. The method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor according to claim 1, characterized in that: The reaction solution is cooled to 15-20°C, preferably 18°C.

10. The method for preparing 4,4'-diaminodiphenylmethane using a dynamic tubular reactor according to claim 1, characterized in that: The pH is 7.5 to 8.5, preferably pH 8.

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