CN113004158A - Preparation method and application of 2-methyl-4-methoxydiphenylamine - Google Patents
Preparation method and application of 2-methyl-4-methoxydiphenylamine Download PDFInfo
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- CN113004158A CN113004158A CN202110241931.0A CN202110241931A CN113004158A CN 113004158 A CN113004158 A CN 113004158A CN 202110241931 A CN202110241931 A CN 202110241931A CN 113004158 A CN113004158 A CN 113004158A
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C213/00—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton
- C07C213/08—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton by reactions not involving the formation of amino groups, hydroxy groups or etherified or esterified hydroxy groups
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C227/00—Preparation of compounds containing amino and carboxyl groups bound to the same carbon skeleton
- C07C227/04—Formation of amino groups in compounds containing carboxyl groups
- C07C227/06—Formation of amino groups in compounds containing carboxyl groups by addition or substitution reactions, without increasing the number of carbon atoms in the carbon skeleton of the acid
- C07C227/08—Formation of amino groups in compounds containing carboxyl groups by addition or substitution reactions, without increasing the number of carbon atoms in the carbon skeleton of the acid by reaction of ammonia or amines with acids containing functional groups
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Abstract
The invention relates to the field of preparation of diphenylamine, in particular to a preparation method and application of 2-methyl-4-methoxydiphenylamine, and the preparation method of 2-methyl-4-methoxydiphenylamine comprises the following steps: (1) in a solvent, 2-methyl-4-methoxyaniline and halogenated benzoic acid react in the presence of a catalyst and an acid-binding agent to obtain a condensation product; the acid-binding agent is selected from one or more of carbonate, phosphate and hydroxide of alkali metal; (2) acidifying, filtering, washing and drying the condensation product to obtain a product 1; (3) and decarboxylating and purifying the product 1 to obtain the product. The preparation method of the 2-methyl-4-methoxydiphenylamine is convenient to operate and short in time, greatly improves the production efficiency, and is suitable for large-scale production.
Description
Technical Field
The invention relates to the field of preparation of diphenylamine, in particular to a preparation method and application of 2-methyl-4-methoxydiphenylamine.
Background
2-methyl-4-methoxydiphenylamine (DPA) is an important intermediate for synthesizing pressure-sensitive dyes, medicines, rubbers, pesticides and adhesive auxiliary materials. With the development of society, the demand for the intermediate is increasing day by day, and the market potential is huge. Currently, there are two main types of synthetic methods: the first is condensation method of 2-methyl-4-methoxy bromobenzene as material and acetanilide, formanilide or aniline, and the method has complex synthesis of 2-methyl-4-methoxy bromobenzene as material, high toxicity and complicated operation; the second method is condensation of 2-methyl-4-methoxyaniline (MMA) as raw material and halogeno-benzene (or phenol), and the halogeno-benzene method is generally prepared by acetylating or formylating amino of MMA, reacting with halogeno-benzene under the action of strong alkali, and then performing alkaline hydrolysis. The phenol method adopts MMA and phenol to react at high temperature, although the reaction is completed in one step, noble metal palladium is used as a catalyst and is difficult to recover and reuse, so that the cost is too high and industrialization is difficult to realize.
Disclosure of Invention
In view of the problems in the prior art, the first aspect of the present invention provides a method for preparing 2-methyl-4-methoxydiphenylamine, which comprises the following steps:
(1) in a solvent, 2-methyl-4-methoxyaniline and halogenated benzoic acid react in the presence of a catalyst and an acid-binding agent to obtain a condensation product; the acid-binding agent is selected from one or more of carbonate, phosphate and hydroxide of alkali metal;
(2) acidifying, filtering, washing and drying the condensation product to obtain a product 1;
(3) and decarboxylation and purification of the product 1.
In a preferred embodiment of the present invention, the acid-binding agent is carbonate or phosphate.
In a preferred embodiment of the present invention, the phosphate is phosphoric acid and/or tripotassium phosphate trihydrate.
As a preferable technical scheme of the invention, the weight ratio of the carbonate to the phosphate is (2.2-5.6): 1.
in a preferred embodiment of the present invention, the carbonate is selected from one or more of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.
As a preferred embodiment of the present invention, the step (3) includes: the product 1 is obtained after decarboxylation by a decarboxylation reagent and purification; the decarboxylation reagent is a nitrogen-containing organic solvent.
In a preferred embodiment of the present invention, the nitrogen-containing organic solvent has a viscosity of 0.8 to 1.8 mPas at 25 ℃.
In a preferred embodiment of the present invention, the catalyst is selected from one or more of copper, cupric chloride and cuprous chloride.
In a preferred embodiment of the present invention, the solvent is toluene and/or N, N-dimethylformamide.
As a preferred embodiment of the present invention, the step (1) includes: in a solvent, 2-methyl-4 methoxyaniline and halogenated benzoic acid react at the temperature of 110-120 ℃ in the presence of a catalyst and an acid-binding agent to obtain a condensation product; the acid-binding agent is selected from one or more of carbonate, phosphate and alkali metal hydroxide.
The second aspect of the invention provides an application of the preparation method of the 2-methyl-4-methoxydiphenylamine in preparation of pressure-sensitive dyes, medicines, rubbers, pesticides and adhesives.
Compared with the prior art, the invention has the following beneficial effects:
(1) the acid-binding agent in the application is sodium carbonate and tripotassium phosphate trihydrate, and the weight ratio is (2.2-5.6): 1, the generation of tar-like by-products caused by the existence of tripotassium phosphate trihydrate is avoided.
(2) In the preparation process of the 2-methyl-4-methoxydiphenylamine, when the molar ratio of the 2-methyl-4-methoxyaniline to the halogenated benzoic acid to the acid-binding agent is 1: (1-1.1): (0.7-1.3), the condensation reaction is faster, the production efficiency is improved, and the purity of the obtained 2-methyl-4-methoxydiphenylamine is further improved.
(3) In the preparation method of the 2-methyl-4-methoxydiphenylamine, when the decarboxylation reagent is N-methylformamide, the decarboxylation can be completed after the reaction is carried out for 8-10h, so that the production efficiency is improved, and the large-scale production is facilitated.
(4) The preparation method of the 2-methyl-4-methoxydiphenylamine is convenient to operate and short in time, greatly improves the production efficiency, and is suitable for large-scale production.
Detailed Description
The present invention is illustrated by the following specific embodiments, but is not limited to the specific examples given below.
The invention provides a preparation method of 2-methyl-4-methoxydiphenylamine, which comprises the following steps:
(1) in a solvent, 2-methyl-4-methoxyaniline and halogenated benzoic acid react in the presence of a catalyst and an acid-binding agent to obtain a condensation product; the acid-binding agent is selected from one or more of carbonate, phosphate and hydroxide of alkali metal;
(2) acidifying, filtering, washing and drying the condensation product to obtain a product 1;
(3) and decarboxylation and purification of the product 1.
Step (1)
In one embodiment, the acid scavenger is a carbonate and a phosphate.
Preferably, the phosphate is phosphoric acid and/or tripotassium phosphate trihydrate; more preferably, the phosphate is tripotassium phosphate trihydrate.
Preferably, the carbonate is selected from one or more of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate; more preferably, the carbonate is sodium carbonate.
In one embodiment, the weight ratio of carbonate to phosphate is (2.2-5.6): 1.
preferably, the weight ratio of carbonate to phosphate is 4.3: 1.
in experiments, in the preparation process of the 2-methyl-4-methoxydiphenylamine, the yield of the obtained 2-methyl-4-methoxydiphenylamine is low and is about 50 wt% when the acid-binding agent is carbonate, and tar-like byproducts are generated when the acid-binding agent is phosphate, particularly tripotassium phosphate trihydrate, so that the reaction is influenced, and the yield is reduced. The applicant has found that, when the acid-binding agent is sodium carbonate and tripotassium phosphate trihydrate, the weight ratio is (2.2-5.6): at 1, no tarry by-products were produced. The application considers that the possible reason is that under the condition that tripotassium phosphate trihydrate and sodium carbonate exist simultaneously, acid generated by reaction can be timely disposed, and meanwhile, under the condition, the reduction of the electron cloud density of nitrogen atoms in a reaction product and the existence of steric hindrance avoid the generation of tar-like byproducts caused by the tripotassium phosphate trihydrate.
In one embodiment, the solvent is toluene and/or N, N-dimethylformamide.
Preferably, the solvent is toluene.
In one embodiment, the weight ratio of the solvent to the 2-methyl-4-methoxyaniline is (8-12): 1.
preferably, the weight ratio of the solvent to the 2-methyl-4-methoxyaniline is 10: 1.
the halogenated benzoic acid of the present invention is not particularly limited and may be conventionally selected by those skilled in the art.
In one embodiment, the halobenzoic acid is o-chlorobenzoic acid.
In one embodiment, the molar ratio of the 2-methyl-4-methoxyaniline, the halobenzoic acid and the acid scavenger is 1: (1-1.1): (0.7-1.3).
Preferably, the molar ratio of the 2-methyl-4-methoxyaniline to the halogenated benzoic acid to the acid-binding agent is 1: 1.05: 1.2.
in the preparation process of the 2-methyl-4-methoxydiphenylamine, when the molar ratio of the 2-methyl-4-methoxyaniline to the halogenated benzoic acid to the acid-binding agent is 1: (1-1.1): (0.7-1.3), the condensation reaction is faster, the production efficiency is improved, and the purity of the obtained 2-methyl-4-methoxydiphenylamine is further improved.
In one embodiment, the catalyst comprises 1 to 1.5 wt% of the 2-methyl-4-methoxyaniline.
Preferably, the catalyst comprises 1.2 wt% of the 2-methyl-4-methoxyaniline.
In one embodiment, the catalyst is selected from one or more of copper, cupric chloride, cuprous chloride.
Preferably, the catalyst is cuprous chloride.
In one embodiment, the step (1) comprises: in a solvent, 2-methyl-4-methoxyaniline and halogenated benzoic acid react at the temperature of 110-120 ℃ in the presence of a catalyst and an acid-binding agent to obtain a condensation product.
In a preferred embodiment, the step (1) comprises: adding a solvent and a catalyst into a reaction kettle, adding 2-methyl-4-methoxyaniline and halogenated benzoic acid under stirring, adding an acid binding agent after uniformly stirring, and heating to 110-120 ℃ for reflux reaction for 5-8h to obtain a condensation product.
In a more preferred embodiment, the step (1) comprises: adding a solvent and a catalyst into a reaction kettle, adding 2-methyl-4-methoxyaniline and halogenated benzoic acid under stirring, adding an acid-binding agent after uniformly stirring, and heating to 115 ℃ for reflux reaction for 5.6 hours to obtain a condensation product.
Step (2)
In one embodiment, the step (2) comprises: distilling the condensation product at the temperature of 130-145 ℃ to recover the solvent, adding water and the condensation product into a reaction kettle, adding an acidifying reagent to enable the pH value to reach 2-3 under stirring, filtering, washing with water to be neutral, and drying to obtain a product 1.
In a preferred embodiment, the step (2) comprises: distilling the condensation product at 140 ℃ to recover the solvent, adding water and the condensation product into a reaction kettle, adding an acidifying reagent to enable the pH value to reach 2.5 under stirring, filtering, washing with water to be neutral, and drying to obtain a product 1.
The amount of water added in step (2) of the present application is not particularly limited and may be selected conventionally by those skilled in the art.
The acidifying agent is not particularly limited in this application and can be routinely selected by those skilled in the art.
In one embodiment, the acidifying agent is hydrochloric acid.
Step (3)
In one embodiment, the step (3) comprises: the product 1 is decarboxylated by a decarboxylation reagent and purified to obtain the product; the decarboxylation reagent is a nitrogen-containing organic solvent.
In a preferred embodiment, the step (3) comprises: adding a decarboxylation reagent and the product 1 into a reaction kettle, heating to 50-60 ℃ to completely dissolve solid substances, heating to 180 ℃, reacting for 8-10h, and purifying to obtain the product.
The purification procedure described herein is not particularly limited and can be routinely selected by those skilled in the art.
In a more preferred embodiment, the step (3) comprises: adding a decarboxylation reagent and the product 1 into a reaction kettle, heating to 55 ℃ to completely dissolve solid substances, heating to 180 ℃, reacting for 9h, and purifying to obtain the product.
In one embodiment, the decarboxylating reagent is a nitrogen-containing organic solvent.
Preferably, the nitrogen-containing organic solvent has a viscosity of 0.8 to 1.8 mPas at 25 ℃.
Preferably, the nitrogen-containing organic solvent is N-methylformamide.
The applicant unexpectedly discovers that in the preparation method of the 2-methyl-4-methoxydiphenylamine, when the decarboxylation reagent is N-methylformamide, the decarboxylation can be completed after the reaction is carried out for 8-10 hours, so that the production efficiency is improved, and the large-scale production is facilitated.
In one embodiment, the weight ratio of decarboxylating reagent to product 1 is (6.2-7.4): 1.
preferably, the weight ratio of the decarboxylating reagent to the product 1 is 6.6: 1.
the second aspect of the invention provides an application of the preparation method of the 2-methyl-4-methoxydiphenylamine in preparation of pressure-sensitive dyes, medicines, rubbers, pesticides and adhesives.
Examples
Hereinafter, the present invention will be described in more detail by way of examples, but it should be understood that these examples are merely illustrative and not restrictive. The starting materials used in the examples which follow are all commercially available unless otherwise stated.
Example 1
Embodiment 1 of the present invention provides a preparation method of 2-methyl-4-methoxydiphenylamine, which comprises:
(1) adding toluene and cuprous chloride into a reaction kettle, adding 2-methyl-4-methoxyaniline and o-chlorobenzoic acid under stirring, adding an acid-binding agent after uniformly stirring, and heating to 110 ℃ for reflux reaction for 5 hours to obtain a condensation product;
(2) distilling the condensation product at 130 deg.C to recover all toluene, adding 3m into the reaction kettle3Adding industrial hydrochloric acid into water and condensation product under stirring to make pH 2, filtering, and using 5m3Washing with water to neutrality, and drying to obtain a product 1;
(3) adding N-methylformamide and the product 1 into a reaction kettle, heating to 50 ℃ to completely dissolve solid substances, heating to 180 ℃, reacting for 8 hours, and purifying to obtain the N-methylformamide-N-methylformamide solid solution.
The acid-binding agent is sodium carbonate and tripotassium phosphate trihydrate, and the weight ratio is 2.2: 1; the weight ratio of the toluene to the 2-methyl-4-methoxyaniline is 8: 1; the molar ratio of the 2-methyl-4-methoxyaniline to the o-chlorobenzoic acid to the acid-binding agent is 1: 1: 0.7; the cuprous chloride accounts for 1 wt% of the 2-methyl-4-methoxyaniline.
The weight ratio of the N-methylformamide to the product 1 is 6.2: 1.
example 2
Embodiment 2 of the present invention provides a preparation method of 2-methyl-4-methoxydiphenylamine, which comprises:
(1) adding toluene and cuprous chloride into a reaction kettle, adding 2-methyl-4-methoxyaniline and o-chlorobenzoic acid under stirring, adding an acid-binding agent after uniformly stirring, and heating to 120 ℃ for reflux reaction for 5 hours to obtain a condensation product;
(2) distilling the condensation product at 145 deg.C to recover all toluene, adding 3m3Adding industrial hydrochloric acid into water and condensation product under stirring to make pH 3, filtering, and using 5m3Washing with water to neutrality, and drying to obtain a product 1;
(3) adding N-methylformamide and the product 1 into a reaction kettle, heating to 60 ℃ to completely dissolve solid substances, heating to 180 ℃, reacting for 10 hours, and purifying to obtain the N-methylformamide-N-methylformamide solid solution.
The acid-binding agent is sodium carbonate and tripotassium phosphate trihydrate, and the weight ratio is 5.6: 1; the weight ratio of the toluene to the 2-methyl-4-methoxyaniline is 12: 1; the molar ratio of the 2-methyl-4-methoxyaniline to the o-chlorobenzoic acid to the acid-binding agent is 1: 1.1: 1.3; the cuprous chloride accounts for 1.5 wt% of the 2-methyl-4-methoxyaniline.
The weight ratio of the N-methylformamide to the product 1 is 7.4: 1.
example 3
Embodiment 3 of the present invention provides a preparation method of 2-methyl-4-methoxydiphenylamine, which comprises:
(1) adding toluene and cuprous chloride into a reaction kettle, adding 2-methyl-4-methoxyaniline and o-chlorobenzoic acid under stirring, adding an acid-binding agent after uniformly stirring, and heating to 115 ℃ for reflux reaction for 5 hours to obtain a condensation product;
(2) distilling the condensation product at 140 deg.C to recover all toluene, adding 3m3Adding industrial hydrochloric acid into water and condensation product under stirring to make pH 2.5, filtering, and using 5m3Washing with water to neutrality, and drying to obtain a product 1;
(3) adding N-methylformamide and the product 1 into a reaction kettle, heating to 50 ℃ to completely dissolve solid substances, heating to 180 ℃, reacting for 9 hours, and purifying to obtain the N-methylformamide-N-methylformamide.
The acid-binding agent is sodium carbonate and tripotassium phosphate trihydrate, and the weight ratio is 4.3: 1; the weight ratio of the toluene to the 2-methyl-4-methoxyaniline is 10: 1; the molar ratio of the 2-methyl-4-methoxyaniline to the o-chlorobenzoic acid to the acid-binding agent is 1: 1.05: 1.2; the cuprous chloride accounts for 1.2 wt% of the 2-methyl-4-methoxyaniline.
The weight ratio of the N-methylformamide to the product 1 is 6.6: 1.
example 4
The embodiment 4 of the invention provides a preparation method of 2-methyl-4-methoxydiphenylamine, which is the same as the embodiment 3 in specific implementation mode, and is characterized in that the acid-binding agent is tripotassium phosphate trihydrate.
Example 5
The embodiment 5 of the invention provides a preparation method of 2-methyl-4-methoxydiphenylamine, which is the same as the embodiment 3 in specific implementation mode, and is characterized in that the acid-binding agent is sodium bicarbonate and tripotassium phosphate trihydrate, and the weight ratio of the acid-binding agent to the tripotassium phosphate trihydrate is 4.3: 1.
example 6
The embodiment 6 of the invention provides a preparation method of 2-methyl-4-methoxydiphenylamine, which is the same as the embodiment 3 in specific implementation mode, and is characterized in that the acid-binding agent is sodium hydroxide and tripotassium phosphate trihydrate, and the weight ratio of the acid-binding agent to the tripotassium phosphate trihydrate is 4.3: 1.
example 7
Embodiment 7 of the present invention provides a preparation method of 2-methyl-4-methoxydiphenylamine, which is the same as embodiment 3 in specific embodiment, except that in step (3), methanol and the product 1 are added into a reaction kettle, heated to 60 ℃ so that solid substances are completely dissolved, heated to 180 ℃, reacted for 13 hours, and then purified to obtain the 2-methyl-4-methoxydiphenylamine.
Performance evaluation
1. Appearance: the occurrence of tarry substances after the completion of the reaction in step (1) of examples 1 to 7 was recorded, respectively.
2. Decarboxylation time: the time for heating to 180 ℃ in step (3) to react until the weight of 2-methyl-4-methoxydiphenylamine is constant is recorded respectively.
TABLE 1
The foregoing examples are merely illustrative and serve to explain some of the features of the method of the present invention. The appended claims are intended to claim as broad a scope as is contemplated, and the examples presented herein are merely illustrative of selected implementations in accordance with all possible combinations of examples. Accordingly, it is applicants' intention that the appended claims are not to be limited by the choice of examples illustrating features of the invention. Also, where numerical ranges are used in the claims, subranges therein are included, and variations in these ranges are also to be construed as possible being covered by the appended claims.
Claims (10)
1. A preparation method of 2-methyl-4-methoxydiphenylamine is characterized by comprising the following steps:
(1) in a solvent, 2-methyl-4-methoxyaniline and halogenated benzoic acid react in the presence of a catalyst and an acid-binding agent to obtain a condensation product; the acid-binding agent is selected from one or more of carbonate, phosphate and hydroxide of alkali metal;
(2) acidifying, filtering, washing and drying the condensation product to obtain a product 1;
(3) and decarboxylation and purification of the product 1.
2. The method for preparing 2-methyl-4-methoxydiphenylamine according to claim 1, wherein the acid-binding agent is carbonate and phosphate, and the weight ratio of the carbonate to the phosphate is (2.2-5.6): 1.
3. the method for producing 2-methyl-4-methoxydiphenylamine according to claim 2, wherein the phosphate is phosphoric acid and/or tripotassium phosphate trihydrate.
4. The method for preparing 2-methyl-4-methoxydiphenylamine according to claim 3, wherein the carbonate is selected from one or more of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate.
5. The process for producing 2-methyl-4-methoxydiphenylamine according to any one of claims 1 to 4, wherein the step (3) comprises: the product 1 is obtained after decarboxylation by a decarboxylation reagent and purification; the decarboxylation reagent is a nitrogen-containing organic solvent.
6. The process for producing 2-methyl-4-methoxydiphenylamine according to claim 5, wherein the nitrogen-containing organic solvent has a viscosity of 0.8 to 1.8 mPas at 25 ℃.
7. The method for preparing 2-methyl-4-methoxydiphenylamine according to claim 6, wherein the catalyst is selected from one or more of copper, cupric chloride and cuprous chloride.
8. The method for producing 2-methyl-4-methoxydiphenylamine according to claim 7, wherein the solvent is toluene and/or N, N-dimethylformamide.
9. The process for producing 2-methyl-4-methoxydiphenylamine according to any one of claims 6 to 8, wherein the step (1) comprises: in a solvent, 2-methyl-4 methoxyaniline and halogenated benzoic acid react at the temperature of 110-120 ℃ in the presence of a catalyst and an acid-binding agent to obtain a condensation product; the acid-binding agent is selected from one or more of carbonate, phosphate and alkali metal hydroxide.
10. Use of a process for the preparation of 2-methyl-4-methoxydiphenylamine according to any one of claims 1 to 9 for the preparation of pressure-sensitive dyes, pharmaceuticals, rubbers, pesticides, adhesives.
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| US4339601A (en) * | 1979-01-26 | 1982-07-13 | Union Carbide Corporation | Terephthalic acid derivatives and process for preparing them |
| US5003103A (en) * | 1989-11-20 | 1991-03-26 | Occidental Chemical Corporation | Preparation of 2-choloro-4,5-difluorobenzoic acid from 4,5-difluorophthalic anhydride of 4,5-difluorophthalic acid |
| CN1201779A (en) * | 1998-07-09 | 1998-12-16 | 华东理工大学 | Preparation of 2,3,4,5-tetrafluorobenzoic acid |
| CN101704761A (en) * | 2009-10-23 | 2010-05-12 | 宁波斯迈克制药有限公司 | Synthesis method of mefenamic acid |
| CN106946720A (en) * | 2017-03-23 | 2017-07-14 | 康爱特维迅（蓬莱）化学有限公司 | A kind of preparation method of diphenylamines |
| CN110467538A (en) * | 2019-09-20 | 2019-11-19 | 山东道可化学有限公司 | A kind of synthetic method of 2- methyl -4- methoxy diphenylamine |
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2021
- 2021-03-04 CN CN202110241931.0A patent/CN113004158A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4339601A (en) * | 1979-01-26 | 1982-07-13 | Union Carbide Corporation | Terephthalic acid derivatives and process for preparing them |
| US5003103A (en) * | 1989-11-20 | 1991-03-26 | Occidental Chemical Corporation | Preparation of 2-choloro-4,5-difluorobenzoic acid from 4,5-difluorophthalic anhydride of 4,5-difluorophthalic acid |
| CN1201779A (en) * | 1998-07-09 | 1998-12-16 | 华东理工大学 | Preparation of 2,3,4,5-tetrafluorobenzoic acid |
| CN101704761A (en) * | 2009-10-23 | 2010-05-12 | 宁波斯迈克制药有限公司 | Synthesis method of mefenamic acid |
| CN106946720A (en) * | 2017-03-23 | 2017-07-14 | 康爱特维迅（蓬莱）化学有限公司 | A kind of preparation method of diphenylamines |
| CN110467538A (en) * | 2019-09-20 | 2019-11-19 | 山东道可化学有限公司 | A kind of synthetic method of 2- methyl -4- methoxy diphenylamine |
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