Method for preparing 3, 3 '-dichloro-4, 4'-diaminodiphenylmethane by utilizing dynamic tubular reactor

Abstract

The invention provides a method for preparing 3, 3 '-dichloro-4, 4'-diaminodiphenylmethane by using a dynamic tubular reactor, and belongs to the field of organic material synthesis. According to the present invention, o-chloroaniline and formaldehyde are adopted as raw materials, and under the action of the catalyst, the 3, 3 '-dichloro-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 invention relates to the technical field of synthesis of organic monomers and discloses a method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane by utilizing a dynamic tubular reactor. Background Art

[0002] 3,3'-Dichloro-4,4'-diaminodiphenylmethane (commonly known as MOCA, molecular formula: C 13 H 12 N2C l2 , molecular weight: 267.16, white or light yellow crystals at room temperature, relative density of 1.44 at 25°C, melting point of 110°C, decomposition temperature of 296°C). 3,3'-dichloro-4,4'-diaminodiphenylmethane is insoluble in water, but soluble in organic solvents such as isopropanol, acetone, toluene, chlorobenzene, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), and tetrahydrofuran (THF). When heated at high temperatures or for a long time, 3,3'-dichloro-4,4'-diaminodiphenylmethane will oxidize and the color will become darker. 3,3'-Dichloro-4,4'-diaminodiphenylmethane is mainly used as a chain extender and curing agent for toluene diisocyanate (TDI)-based prepolymers. It is widely used in the machinery industry, automobile and aircraft manufacturing industries, mining industries, sports facilities and various light manufacturing industries. It can also be used as a crosslinker for polyurethane (PU) coatings and adhesives, a curing agent for epoxy resins, and high electrical resistance products. Its structure is as follows:

[0003]

[0004] Chinese patent CN103936594A provides a method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane by adding o-chloroaniline, cation exchange resin and distilled water into a reaction container, stirring evenly and then adding formaldehyde aqueous solution.

[0005] Chinese patent CN105294448A provides a method for continuously preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane derivatives with solid acid catalysis, wherein a condensation reaction is carried out with solid acid catalysis in a one-stage or two-stage fixed bed reactor to obtain 3,3'-dichloro-4,4'-diaminodiphenylmethane derivatives.

[0006] Chinese patent CN106986777B provides a method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane derivatives using a microreactor.

[0007] Some of the methods used in the above reports are intermittent reactions carried out in traditional reactors, which have a long reaction time; some have complex operating steps and are not conducive to large-scale production; when solid materials are involved in the microreactor or solids are produced, it will cause pipeline blockage and incomplete reaction. Summary of the invention

[0008] The following is a summary of some aspects of the present invention, but is not intended to limit the present invention. When there is a discrepancy between the disclosure of this specification and the referenced document, the disclosure of this specification shall prevail.

[0009] The object of the present invention is to provide a method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane by using a dynamic tubular reactor. The dynamic tubular reactor can be used to control the reaction pressure and temperature well.

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

[0011] A method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor comprises the following steps:

[0012] o-Chloroaniline, 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, isopropanol is added and recrystallized to obtain 3,3'-dichloro-4,4'-diaminodiphenylmethane. The reaction formula is as follows:

[0013]

[0014] Furthermore, the method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor is 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%.

[0015] Furthermore, the method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor is 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 concentrated hydrochloric acid.

[0016] Furthermore, the method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor is characterized in that the concentration of the hydrochloric acid is 20%-40%, preferably 37%.

[0017] Furthermore, the method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor is characterized in that the molar ratio of o-chloroaniline to formaldehyde is 1:0.5-1.5, preferably 1:0.8.

[0018] Furthermore, the method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor is characterized in that the molar ratio of o-chloroaniline to concentrated hydrochloric acid is 1:0.5-1.5, preferably 1:0.8.

[0019] Furthermore, the method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor is characterized in that the reaction temperature of the dynamic tubular reactor is 60-80°C, preferably 65°C.

[0020] Furthermore, the method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor is characterized in that the reaction residence time of the dynamic tubular reactor is 5 to 10 minutes, preferably 7 minutes.

[0021] Furthermore, the method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor is characterized in that the reaction solution is cooled to 15-20°C, preferably 18°C.

[0022] Furthermore, the method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor is characterized in that the pH is 7.5 to 8.5, preferably pH 8.

[0023] Beneficial 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. A continuous preparation process is realized, the reaction speed is fast, and the reaction time is shortened;

[0026] 2. Rapid heat transfer capability makes it easy to achieve constant temperature reaction, improve reaction yield, mild reaction temperature, and reduce safety hazards.

[0027] 3. Avoid problems such as pipeline blockage and incomplete reaction caused by the generation of solid particles in the product, which is more conducive to industrial production. DETAILED DESCRIPTION

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

[0029] Embodiment 1:

[0030] (1) pumping o-chloroaniline, formaldehyde (37%), and concentrated hydrochloric acid (37%) into a dynamic tubular reactor at a certain flow rate, respectively, and adjusting the flow ratio of the three reaction liquids in the step to control the molar ratio of o-chloroaniline: formaldehyde: concentrated hydrochloric acid to be 1:0.8:0.8;

[0031] (2) Set the reaction temperature to 65 °C and the residence time to 7 min;

[0032] (3) The outlet is connected to the reaction liquid, cooled to 18° C., and sodium hydroxide aqueous solution is added dropwise until the pH value is about 8. The solid is filtered and then is recrystallized by adding isopropanol to obtain 3,3'-dichloro-4,4'-diaminodiphenylmethane with a yield of 93% and a purity of 99.2%.

[0033] Embodiment 2:

[0034] (1) o-chloroaniline, formaldehyde (35%), and concentrated hydrochloric acid (20%) are pumped into a dynamic tubular reactor at a certain flow rate, and the flow rate ratio of the three reaction liquids in the step is adjusted to control the molar ratio of o-chloroaniline: formaldehyde: concentrated hydrochloric acid to be 1:05:0.5;

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

[0036] (3) The outlet is connected to the reaction liquid, cooled to 15° C., and sodium hydroxide aqueous solution is added dropwise until the pH value is about 7.5. The solid is filtered and then is recrystallized by adding isopropanol to obtain 3,3'-dichloro-4,4'-diaminodiphenylmethane with a yield of 87% and a purity of 99.1%.

[0037] Embodiment 3:

[0038] (1) o-chloroaniline, formaldehyde (40%), and concentrated hydrochloric acid (40%) are pumped into a dynamic tubular reactor at a certain flow rate, and the flow rate ratio of the three reaction liquids in the step is adjusted to control the molar ratio of o-chloroaniline: 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) The outlet is connected to the reaction liquid, the temperature is lowered to 20° C., and a sodium hydroxide aqueous solution is added dropwise until the pH value is about 8.5. After the solid is filtered, isopropanol is added for recrystallization to obtain 3,3'-dichloro-4,4'-diaminodiphenylmethane with a yield of 88% and a purity of 99.2%.

[0041] Embodiment 4:

[0042] (1) o-chloroaniline, formaldehyde (30%), and concentrated hydrochloric acid (15%) are pumped into a dynamic tubular reactor at a certain flow rate, and the flow rate ratio of the three reaction liquids in the step is adjusted to control the molar ratio of o-chloroaniline: formaldehyde: concentrated hydrochloric acid to be 2:1:0.3;

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

[0044] (3) The outlet is connected to the reaction liquid, cooled to 17° C., and sodium hydroxide aqueous solution is added dropwise until the pH value is about 7.8. The solid is filtered and then is recrystallized by adding isopropanol to obtain 3,3'-dichloro-4,4'-diaminodiphenylmethane with a yield of 71% and a purity of 98.2%.

[0045] Embodiment 5:

[0046] (1) pumping o-chloroaniline, formaldehyde (45%), and concentrated hydrochloric acid (45%) into a dynamic tubular reactor at a certain flow rate, respectively, and adjusting the flow ratio of the three reaction liquids in the step to control the molar ratio of o-chloroaniline: 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) The outlet is connected to the reaction liquid, cooled to 19° C., and sodium hydroxide aqueous solution is added dropwise until the pH value is about 8.2. The solid is filtered and then is recrystallized by adding isopropanol to obtain 3,3'-dichloro-4,4'-diaminodiphenylmethane with a yield of 73% and a purity of 98.5%.

[0049] Embodiment 6:

[0050] (1) o-chloroaniline, formaldehyde (35%), and concentrated hydrochloric acid (20%) are pumped into a dynamic tubular reactor at a certain flow rate, and the flow rate ratio of the three reaction liquids in the step is adjusted to control the molar ratio of o-chloroaniline: formaldehyde: concentrated hydrochloric acid to be 1:1:0.7;

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

[0052] (3) The outlet is connected to the reaction liquid, the temperature is lowered to 12° C., and a sodium hydroxide aqueous solution is added dropwise until the pH value is about 7.2. The solid is filtered and then is recrystallized by adding isopropanol to obtain 3,3'-dichloro-4,4'-diaminodiphenylmethane with a yield of 79% and a purity of 97.8%.

[0053] Embodiment 7:

[0054] (1) o-chloroaniline, formaldehyde (37%), and concentrated hydrochloric acid (32%) are pumped into a dynamic tubular reactor at a certain flow rate, and the flow rate ratio of the three reaction liquids in the step is adjusted to control the molar ratio of o-chloroaniline: 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) The outlet is connected to the reaction liquid, cooled to 25° C., and sodium hydroxide aqueous solution is added dropwise until the pH value is about 9. The solid is filtered and then is recrystallized by adding isopropanol to obtain 3,3'-dichloro-4,4'-diaminodiphenylmethane with a yield of 75% and a purity of 98.3%.

[0057] The above is a description of a specific embodiment of the present invention. It should be understood that the present invention is not limited to the above embodiment, and the above embodiment and description are only for illustrating the principle of the present invention.

[0058] Those skilled in the art may make various non-substantial changes and improvements to the present invention without departing from the concept of the present invention, all of which fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor, characterized in that: o-Chloroaniline, 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, isopropanol is added and recrystallized to obtain 3,3'-dichloro-4,4'-diaminodiphenylmethane. The reaction formula is as follows:

2. A method for preparing 3,3'-dichloro-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 3,3'-dichloro-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 concentrated hydrochloric acid.

4. A method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor according to claim 1, characterized in that: The concentration of the hydrochloric acid is 20%-40%, preferably 37%.

5. A method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor according to claim 1, characterized in that: The molar ratio of o-chloroaniline to formaldehyde is 1:0.5-1.5, preferably 1:0.

8.

6. A method for preparing 3,3'-dichloro-4,4'-diaminodiphenylmethane using a dynamic tubular reactor according to claim 1, characterized in that: The molar ratio of o-chloroaniline to concentrated hydrochloric acid is 1:0.5-1.5, preferably 1:0.

8.

7. A method for preparing 3,3'-dichloro-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. A method for preparing 3,3'-dichloro-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. A method for preparing 3,3'-dichloro-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 3,3'-dichloro-4,4'-diaminodiphenylmethane by using a dynamic tubular reactor according to claim 1, characterized in that: The pH is 7.5 to 8.5, preferably pH 8.

Images