阅读说明：本技术 一种3,3’-二氯-4,4’-二氨基二苯基甲烷的制备方法 (Preparation method of 3,3 '-dichloro-4, 4' -diaminodiphenylmethane ) 是由 王怡明 丁克鸿 徐林 胡丰献 刘相李 严绘 卞辰超 赵慧 张巍伟 魏震 于 2019-11-15 设计创作，主要内容包括：本发明提供一种3,3’-二氯-4,4’-二氨基二苯基甲烷的制备方法,以固体酸加液体酸组成混合酸的形式作为催化剂并采用共沸蒸馏循环利用反应液中的液体酸,既可以充分发挥固体酸和液体酸各自的优点,达到减少液体酸的用量,提高MOCA的收率的目的,又可以有效减少中和碱的用量,减少含盐废水的排放量,大大减少资源消耗,降低工业生产的成本,缓解对环境造成的负担。(The invention provides a preparation method of 3,3 '-dichloro-4, 4' -diaminodiphenylmethane, which takes the form of mixed acid formed by solid acid and liquid acid as a catalyst and adopts azeotropic distillation to recycle the liquid acid in reaction liquid, thereby not only fully playing respective advantages of the solid acid and the liquid acid and achieving the purposes of reducing the dosage of the liquid acid and improving the yield of MOCA, but also effectively reducing the dosage of neutralizing alkali, reducing the discharge amount of salt-containing wastewater, greatly reducing resource consumption, reducing the cost of industrial production and relieving the burden on the environment.)

1. A preparation method of 3,3 '-dichloro-4, 4' -diaminodiphenylmethane specifically comprises the following steps:

(1) salifying: adding mixed acid consisting of solid acid and hydrochloric acid into a reaction kettle according to a certain proportion, dropwise adding o-chloroaniline at a certain temperature under the protection of nitrogen, and stirring to react to form o-chloroaniline hydrochloride;

(2) condensation: mixing the o-chloroaniline hydrochloride obtained in the step (1) and formaldehyde according to a certain proportion, and mixing and stirring for a period of time under the protection of nitrogen at a certain temperature to react to obtain a condensation reaction solution;

(3) and (3) filtering: and (3) filtering the solid acid to remove the reaction system, and returning to the step (1) for recycling.

(4) Azeotropic distillation: carrying out azeotropic distillation on the condensation reaction liquid obtained in the step (2) to obtain hydrochloric acid distillate, and returning to the step (1) for recycling;

(5) neutralizing: adding the distilled reaction liquid obtained in the step (4) into a sodium hydroxide solution with a certain concentration for neutralization, heating to 100-110 ℃, and preserving heat for half an hour;

(6) separation: separating the neutralized liquid obtained in the step (5) to obtain an upper water layer, and washing and drying a lower oil layer to obtain the MOCA product.

2. The method for preparing 3,3 '-dichloro-4, 4' -diaminodiphenylmethane according to claim 1, wherein the molar mass ratio of hydrochloric acid to o-chloroaniline in step (1) is 0.5 to 1.5: 1.

3. the preparation method of 3,3 '-dichloro-4, 4' -diaminodiphenylmethane according to claim 1, characterized in that the solid acid in step (1) is selected from one or more of H β, HY, HZSM-5 molecular sieve and cationic acidic resin, and the amount of the solid acid is 4-20 wt%, preferably 7-12 wt% of the o-chloroaniline.

4. The preparation method of 3,3 '-dichloro-4, 4' -diaminodiphenylmethane according to claim 1, characterized in that the salt formation temperature in step (1) is 20-80 ℃, preferably 50-60 ℃.

5. A process for the preparation of 3,3 '-dichloro-4, 4' -diaminodiphenylmethane according to claim 1, characterised in that the hydrochloric acid concentration in step (1) is between 10% and 30%, preferably between 20% and 25%.

6. The method for preparing 3,3 '-dichloro-4, 4' -diaminodiphenylmethane according to claim 1, wherein the molar ratio of o-chloroaniline to formaldehyde in step (2) is 1.5-3: 1.

7. The process for preparing 3,3 '-dichloro-4, 4' -diaminodiphenylmethane according to claim 1, wherein the concentration of the aqueous formaldehyde solution in step (2) is in the range of 15% to 35%, preferably 20% to 30%.

8. The method for preparing 3,3 '-dichloro-4, 4' -diaminodiphenylmethane according to claim 1, wherein the condensation temperature in step (2) is 60-110 ℃ and the reaction time is 1-6 h.

9. The method for preparing 3,3 '-dichloro-4, 4' -diaminodiphenylmethane according to claim 8, wherein the condensation temperature in step (2) is 70-90 ℃ and the reaction time is 3-6 h.

10. The method for preparing 3,3 '-dichloro-4, 4' -diaminodiphenylmethane according to claim 1, wherein the pH of the neutralization control system in the step (5) is 7-11.

Technical Field

The invention belongs to the technical field of fine chemical engineering, and relates to a preparation method of 3,3 '-dichloro-4, 4' -diaminodiphenylmethane, in particular to a method for preparing 3,3 '-dichloro-4, 4' -diaminodiphenylmethane, which takes a mixed acid form of solid acid and liquid acid as a catalyst and adopts an azeotropic distillation process to recycle liquid acid in reaction mother liquor, so that the MOCA yield is ensured, the discharge amount of alkali liquor consumed by neutralization and salt-containing wastewater is reduced, and the purposes of reducing resource consumption and reducing wastewater discharge amount are achieved.

Background

3,3 '-dichloro-4, 4' -diaminodiphenylmethane (commonly known as MOCA, molecular formula: C)₁₃H₁₂Cl₂N₂Molecular weight: 267.15), CAS number 101-14-4, white or light yellow crystal at room temperature, good storage stability, and can be used as cross-linking agent and curing agent of polyurethane and epoxy resin, and vulcanizing agent of rubber, and can be used for preparing products with high electric resistance. The method is widely applied to the fields of automobile industry, machine manufacturing industry, mining industry, sports facilities and the like, so that the research on the synthesis process of the method has important significance.

In 1953, DuPont company in the United states firstly developed a synthesis process route of MOCA, which adopts o-chloroaniline, formaldehyde and hydrochloric acid as raw materials, salifies the o-chloroaniline and the hydrochloric acid, then dropwise adds the formaldehyde for condensation, and then obtains the MOCA through the steps of neutralization, steam distillation, washing, recrystallization and the like. The domestic Suzhou Xiangyuan chemical industry Co., Ltd also uses o-chloroaniline, formaldehyde and hydrochloric acid as raw materials, and the MOCA is synthesized through the steps of acidification, condensation, neutralization, washing, drying and the like. In both methods, liquid hydrochloric acid is used as a catalyst, a large amount of alkali liquor is used for neutralizing unreacted acid liquor after the reaction is finished, more than 5 tons of salt-containing wastewater can be generated when one ton of MOCA is produced, the treatment cost of the salt-containing wastewater is high, and the method of dilution discharge is adopted in industry, so that serious environmental pollution can be caused. The method has the disadvantages of low yield, long reaction period, complex operation, higher production cost and more byproducts.

In order to solve the problem, patent CN105294448A discloses a method for preparing 4,4 '-diaminodiphenylmethane derivatives by using solid acid as a catalyst, the method uses solid acid such as HY-type molecular sieve to catalyze formaldehyde and o-chloroaniline for condensation to prepare 4, 4' -diaminodiphenylmethane derivatives, but the method has the problems of low yield of 50% -70%, difficulty in realizing industrialization and the like.

Patent CN103936594A discloses a method for preparing 3,3 '-dichloro-4, 4' -diaminodiphenylmethane by using cation exchange resin, which uses cation exchange resin to replace liquid acid to catalyze the condensation reaction of o-chloroaniline and formaldehyde, and can reduce the discharge of salt-containing wastewater, but under the optimized conditions that n (o-chloroaniline):n (formaldehyde) ═ 2.0: 1 and the amount of catalyst is 4kg, the reaction is carried out at 95 ℃ for 7h, the yield of the method is only 32.5%, the regeneration process of cation exchange resin is complex, and the regeneration process also generates a large amount of inorganic and organic wastewater.

Patent CN107417544A discloses a method for synthesizing 3,3 '-dichloro-4, 4' -diaminodiphenylmethane by using heteropoly acid, which uses heteropoly acid as catalyst instead of common liquid acid, although the yield of MOCA can be ensured to be more than 80%, but heteropoly acid catalyst needs to be recovered by organic solvent recrystallization, the catalyst is difficult to recover, and industrialization is difficult to realize.

In the traditional process, liquid acid is used as a catalyst, so that equipment corrosion and pollution are serious, the equipment is difficult to recycle, resinous impurities are easy to generate in the reaction, and the yield of MOCA is reduced. The method needs neutralization, water washing and other processes, has the defects of multiple operation procedures, large three-waste discharge and the like, and does not accord with the green chemical development concept. Solid acid catalysis has many advantages over liquid acid catalysis, such as: the catalyst and the product are easy to separate, can be regenerated and used, omits the operation processes of neutralization, water washing and the like, and reduces the discharge amount of three wastes. However, according to the current research results, the problems of low yield of MOCA caused by insufficient conversion of intermediates or more byproducts and complicated operation of recycling and reusing the catalyst are generally existed.

Disclosure of Invention

The invention aims to provide a method for preparing 3,3 '-dichloro-4, 4' -diaminodiphenylmethane, which has high yield, less wastewater discharge and environmental protection. The method is improved on the basis of the traditional process for preparing 3,3 '-dichloro-4, 4' -diaminodiphenylmethane, namely, a mixed acid form formed by adding solid acid and liquid acid is used as a catalyst for synthesizing MOCA, o-chloroaniline raw material and liquid acid form o-chloroaniline hydrochloride, the o-chloroaniline hydrochloride and formaldehyde solution react under the catalytic action of the solid acid to produce MOCA acid salt, and an azeotropic distillation process is adopted to carry out azeotropic distillation on a reaction system so that azeotrope of hydrochloric acid and water is evaporated out for recycling, and then the azeotrope is neutralized by alkali solution. On one hand, the production process can greatly reduce the dosage of liquid acid by adding the solid acid, reduce the corrosion degree to equipment, reduce the generation of polymeric byproducts and further improve the yield of MOCA. On the other hand, the hydrochloric acid distilled off by azeotropy can be recycled, the consumption of the hydrochloric acid and sodium hydroxide consumed by subsequent neutralization is reduced, the discharge amount of salt-containing wastewater is further reduced, and the method has remarkable economic and environmental benefits.

The purpose of the invention is realized by the following method:

a preparation method of 3,3 '-dichloro-4, 4' -diaminodiphenylmethane specifically comprises the following steps:

(1) salifying: adding mixed acid consisting of solid acid and hydrochloric acid into a reaction kettle according to a certain proportion, dropwise adding o-chloroaniline at a certain temperature under the protection of nitrogen, and stirring to react to form o-chloroaniline hydrochloride;

(2) condensation: mixing the o-chloroaniline hydrochloride obtained in the step (1) and formaldehyde according to a certain proportion, and mixing and stirring for a period of time under the protection of nitrogen and at a certain temperature to react to obtain a condensation reaction solution;

(3) and (3) filtering: and (3) filtering the solid acid to remove the reaction system, and returning to the step (1) for recycling.

(4) Azeotropic distillation: carrying out azeotropic distillation on the condensation reaction liquid obtained in the step (2) to obtain hydrochloric acid distillate, and returning to the step (1) for recycling;

(5) neutralizing: adding the distilled reaction liquid obtained in the step (4) into a sodium hydroxide solution with a certain concentration for neutralization, heating to 100-110 ℃, and preserving heat for half an hour;

(6) separation: separating the neutralized liquid obtained in the step (5) to obtain an upper water layer, and washing and drying a lower oil layer to obtain the MOCA product.

The mass mol ratio range of the hydrochloric acid to the o-chloroaniline in the step (1) is 0.5-1.5: 1;

the solid acid in the step (1) is selected from one or a combination of H β, HY, HZSM-5 molecular sieve and cation acid resin, and the using amount of the solid acid is 4-20 wt% of the o-chloroaniline, preferably 7-12 wt%;

the salt forming temperature in the step (1) is 20-80 ℃, and preferably 50-60 ℃;

the concentration of the hydrochloric acid in the step (1) is 10 to 30 percent, preferably 20 to 25 percent;

the molar ratio of the o-chloroaniline to the formaldehyde in the step (2) is 1.5-3: 1;

the concentration range of the formaldehyde aqueous solution in the step (2) is 15-35%, preferably 20-30%;

the condensation temperature in the step (2) is 60-110 ℃, the time is 1-6 h, preferably 70-90 ℃, and the time is 3-6 h;

and (3) the pH value of the neutralization control system in the step (5) is 7-11.

Compared with the prior art, the invention has the following advantages:

(1) the product has stable quality and high yield: according to the invention, MOCA is catalytically synthesized in the form of mixed acid consisting of solid acid and liquid acid, the prepared MOCA product has stable quality, the yield is more than 85%, and meanwhile, the addition of the solid acid can reduce the using amount of the used liquid acid, reduce the corrosion degree on equipment, reduce the generation of polymeric byproducts and further improve the yield of MOCA;

(2) the mixed acid is recycled, so that the product cost is reduced: the solid acid is directly recycled and reused, and the liquid acid is recycled and reused for next salification through azeotropic distillation, so that the consumption of newly supplemented hydrochloric acid can be reduced, and the MOCA production cost can be reduced; hydrochloric acid is distilled out by azeotropy, so that the consumption of alkali in the neutralization process is reduced, and the discharge amount of salt-containing wastewater is reduced.

Drawings

FIG. 1 is a schematic flow chart of the present invention.

Detailed Description

The following examples further illustrate the process of the present invention. All percentages and ratios of ingredients are by mass unless otherwise indicated.