CN110467538B - Synthesis method of 2-methyl-4-methoxydiphenylamine - Google Patents
Synthesis method of 2-methyl-4-methoxydiphenylamine Download PDFInfo
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- 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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- 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
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Abstract
The invention discloses a method for synthesizing 2-methyl-4-methoxydiphenylamine, which comprises the following steps: (1) sequentially adding o-chlorobenzoic acid, a copper catalyst, an acid-binding agent and a mixed solvent of toluene and DMF into a reaction vessel, heating to reflux, and stirring and mixing for 10-20 min; dropwise adding 2-methyl-4-methoxyaniline into a reaction container, and continuously carrying out reflux reaction for 6-10 h after the dropwise adding is finished; in the reflux reaction process, water generated in the reaction is separated out through an oil-water separator; neutralizing excessive alkali liquor after the reaction is finished, extracting with toluene, washing an extracted organic phase, evaporating the toluene, concentrating, and drying in vacuum to obtain an intermediate product; (2) and heating the obtained intermediate product in a methanol system for decarboxylation to obtain the target product 2-methyl-4-methoxydiphenylamine. The synthesis method of the invention improves the reaction conversion efficiency and selectivity, improves the raw material conversion rate, generates less process wastewater and has low production cost.
Description
Technical Field
The invention relates to the technical field of organic synthesis, in particular to a synthesis technology of 2-methyl-4-methoxydiphenylamine.
Background
The 2-methyl-4-methoxydiphenylamine is mainly used as an important intermediate of pressure-sensitive dyes, medicines, rubbers and pesticides.
The synthesis technology of 2-methyl-4-methoxydiphenylamine reported in the literature at present mainly comprises the following steps: 2-methyl-4-methoxyaniline and halogenated benzoic acid are added into an acid-binding agent to carry out condensation reaction in toluene to obtain a target product, and the system is subjected to negative pressure water removal in the reaction process. And then acid washing and water washing are carried out for three times to obtain a target product, and the product 2-methyl-4-methoxydiphenylamine is obtained after decarboxylation. The product yield of the preparation process is about 84 percent. The salt generated by the reaction with the acid-binding agent is insoluble in toluene, and a large amount of solid or even caking is generated in a system by adding all the acid-binding agent once, so that the smooth experiment is seriously influenced, the raw material conversion is incomplete, the product yield is low, the recovery of unreacted raw materials is time-consuming and labor-consuming, excessive alkali and salt in the product need to be washed for many times, the process wastewater is more, and the production cost is high; the reaction needs high vacuum distillation water diversion, so the process energy consumption is high; and because of the negative pressure, the boiling point of the material is reduced, and the reflux temperature of the system is lower, so that the reaction is slower. Therefore, the preparation process is difficult to industrially popularize at present.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: aiming at the defects in the prior art, the synthesis method of the 2-methyl-4-methoxydiphenylamine, which has the advantages of high raw material conversion rate, high reaction efficiency, high product yield and low production cost, is provided.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a method for synthesizing 2-methyl-4-methoxydiphenylamine comprises the following steps:
(1) sequentially adding o-chlorobenzoic acid, a copper catalyst, an acid-binding agent and a mixed solvent of toluene and DMF into a reaction vessel, heating to reflux, and stirring and mixing for 10-20 min; dropwise adding 2-methyl-4-methoxyaniline into a reaction container, and continuing reflux reaction for 6-10 hours after dropwise adding is finished for 1.5-2.5 hours; in the reflux reaction process, water generated in the reaction is separated out through an oil-water separator; sampling every 2h during the process, and testing. After the reaction is finished, neutralizing excessive alkali liquor by using dilute HCl, extracting by using methylbenzene, washing an extracted organic phase, evaporating the methylbenzene, concentrating, and drying in vacuum to obtain a white-like intermediate product 2-methyl-4-methoxy-2' -carboxyl diphenylamine;
(2) and heating the obtained intermediate product in a methanol system for decarboxylation to obtain the target product 2-methyl-4-methoxydiphenylamine.
Preferably, the copper catalyst is any one of copper, cupric chloride and cuprous chloride.
Preferably, the acid-binding agent is sodium carbonate or sodium hydroxide.
Preferably, the molar ratio of the o-chlorobenzoic acid to the 2-methyl-4-methoxy group is 1-1.1: 1.
As a preferable technical scheme, the using amount of the copper catalyst is 1-1.5% of the mass of the 2-methyl-4-methoxyaniline.
According to a preferable technical scheme, the mass ratio of the o-chlorobenzoic acid to the acid-binding agent is 1: 0.72-1.1.
As a preferable technical scheme, the using amount of the mixed solvent is 8-12 times of the mass of the 2-methyl-4-methoxyaniline.
According to a preferable technical scheme, the mass ratio of toluene to DMF in the mixed solvent is 6-10: 1.
As an improved technical scheme, water generated by the reaction is separated by an oil-water separator, and then is used for washing an organic phase obtained by extracting toluene for recycling.
Due to the adoption of the technical scheme, the invention has the beneficial effects that:
according to the synthesis method of the 2-methyl-4-methoxydiphenylamine, copper salt or cuprous salt is used as a reaction catalyst to directly catalyze the condensation reaction, so that the reaction conversion efficiency and selectivity are improved; DMF is added into the reaction system as a solvent, and is a solubilizer, so that the viscosity of the system is effectively reduced, the stirring is facilitated, the caking is prevented, and the mass transfer and heat transfer effects of the system are improved, therefore, the reaction efficiency is improved, the raw material conversion rate is improved, the raw material recovery is simple, impurities in the product do not need to be washed for many times, and therefore, the generated process wastewater is less, and the production cost is low. And 2-methyl-4-methoxyaniline is added in a dropwise manner, so that complete conversion of 2-methyl-4-methoxyaniline is ensured, the utilization rate of raw materials is further improved, and loss is reduced.
In the reaction process, an oil-water separator is used for separating water, the toluene carries water, and the toluene is returned to the system through the oil-water separator, so that the cost is reduced and the operation difficulty is simplified compared with the high-vacuum dewatering in the prior art. And the washing water in the technical process is recycled, so that the generation of waste water is greatly reduced.
The conversion rate of the 2-methyl-4-methoxyaniline is over 99.8 percent, and the conversion rate of the product 2-methyl-4-methoxydiphenylamine is over 90.5 percent.
Detailed Description
The invention is further illustrated below with reference to specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention can be made by those skilled in the art after reading the teaching of the present invention, and these equivalents also fall within the scope of the claims appended to the present application.
Example 1
Adding 15.6g (0.1mol) of o-chlorobenzoic acid, 0.2g of CuCl catalyst and 16.5g of sodium carbonate as an acid-binding agent, 143g of toluene and 17.2g of DMF (dimethyl formamide) into a 500ml reaction bottle in sequence, heating to reflux, stirring and mixing for 15min, adding 13.7g (0.1mol) of 2-methyl-4-methoxyaniline into a constant-pressure dropping funnel, dropwise adding into the reaction bottle, reacting for 8h in a reflux state after 2h dropwise adding is finished, separating water generated by the reaction through an oil-water separator in the reaction process, and sampling, assaying and detecting every 2h in the process. After the reaction is finished, dilute HCl is used for neutralizing excessive alkali liquor, toluene is used for extracting an intermediate product, an extracted organic phase is washed, toluene is evaporated, the mixture is concentrated and dried in vacuum, and the off-white 2-methyl-4-methoxy-2' -carboxyl diphenylamine 23.51g is obtained, the yield is 91.12 percent, and the conversion rate of 2-methyl-4-methoxyaniline is 99.88 percent. And heating the obtained intermediate product in a methanol system for decarboxylation to obtain 19.29g of the target product 2-methyl-4-methoxydiphenylamine, wherein the yield is 90.56%.
Example 2
15.6g (0.1mol) of o-chlorobenzoic acid, 0.16g of CuCl 2 The method comprises the following steps of sequentially adding 11.6(0.29mol) of sodium hydroxide serving as an acid binding agent, 120g of toluene and 10g of DMF (dimethyl formamide) into a 500ml reaction bottle, heating to reflux, stirring and mixing for 13min, dropwise adding 13.02g (0.095mol) of 2-methyl-4-methoxyaniline into a constant-pressure dropping funnel into the reaction bottle, reacting for 8.5h in a reflux state after dropwise adding for 1.8h, separating water generated by the reaction through an oil-water separator during the reaction process, and sampling, assaying and detecting every 2h during the process. After the reaction is finished, dilute HCl is used for neutralizing excessive alkali liquor, toluene is used for extracting an intermediate product, an extracted organic phase is washed, toluene is evaporated, 22.24g of off-white 2-methyl-4-methoxy-2' -carboxyl diphenylamine is obtained by concentration and vacuum drying, the yield is 90.74 percent, and the conversion rate of 2-methyl-4-methoxyaniline is 99.81 percent. The obtained intermediate product is heated in a methanol system for decarboxylation to obtain 18.31g of the target product 2-methyl-4-methoxydiphenylamine with the yield of 90.51%.
Example 3
15.6g (0.1mol) of o-chlorobenzoic acid, 0.15g of Cu catalyst, 16.5g (0.16mol) of sodium carbonate as an acid-binding agent, 120g of toluene and 17g of DMF are sequentially added into a 500ml reaction bottle, the temperature is raised to reflux, stirring and mixing are carried out for 15min, 13.7g (0.1mol) of 2-methyl-4-methoxyaniline is taken out from a constant pressure dropping funnel and is dripped into the reaction bottle, the dripping is finished within 1.6h, the reflux state reaction is carried out for 9h, water generated by the reaction is separated out through an oil-water separator in the reaction process, and sampling, testing and detecting are carried out every 2h in the process. After the reaction is finished, dilute HCl is used for neutralizing excessive alkali liquor, toluene is used for extracting an intermediate product, an extracted organic phase is washed, toluene is evaporated, and the white 2-methyl-4-methoxy-2' -carboxyl diphenylamine 23.6g, the yield is 91.47 percent and the conversion rate of the 2-methyl-4-methoxyaniline is 99.85 percent are obtained by concentration and vacuum drying. And heating the obtained intermediate product in a methanol system for decarboxylation to obtain 19.38g of the target product 2-methyl-4-methoxydiphenylamine, wherein the yield is 90.99%.
Comparative example 1
Comparative example 1 is different from example 1 in that a mixed solvent is not used, and only 160.2g of toluene is used as a solvent. The off-white intermediate obtained by vacuum drying was 22.56g of 2-methyl-4-methoxy-2' -carboxydiphenylamine, the yield was 87.44%, and the conversion of 2-methyl-4-methoxyaniline was 98.5%. The obtained intermediate product is heated in a methanol system for decarboxylation to obtain 18.23g of the target product 2-methyl-4-methoxydiphenylamine with the yield of 85.59%.
Comparative example 2
Comparative example 2 differs from example 1 in that no catalyst was added and the rest is the same. The white-like intermediate 2-methyl-4-methoxy-2' -carboxydiphenylamine obtained by vacuum drying was 2.91g, the yield was 11.28%, and the conversion of 2-methyl-4-methoxyaniline was 23.16%. And heating the obtained intermediate product in a methanol system for decarboxylation to obtain 2.32g of the target product 2-methyl-4-methoxydiphenylamine, wherein the yield is 10.89%.
Comparative example 3
Comparative example 3 is different from example 1 in that 153g of toluene and 7.2g of DMF are contained in the mixed solvent. The off-white intermediate obtained by vacuum drying was 23.12g of 2-methyl-4-methoxy-2' -carboxydiphenylamine, yield was 89.61%, and conversion of 2-methyl-4-methoxyaniline was 99.33%. The obtained intermediate product is heated in a methanol system for decarboxylation to obtain 18.97g of the target product 2-methyl-4-methoxydiphenylamine with the yield of 89.06%.
Comparative example 4
Comparative example 4 differs from example 1 in that 13.7g (0.1mol) of 2-methyl-4-methoxyaniline, 15.6g (0.1mol) of o-chlorobenzoic acid, 0.2g of CuCl catalyst, 16.5(0.16mmol) of sodium carbonate, 143g of toluene, 17.2g of DMF were sequentially added to a 500ml reaction flask without using a dropwise manner and reacted for 8 hours under direct reflux. The off-white intermediate obtained by vacuum drying was 22.94g of 2-methyl-4-methoxy-2' -carboxydiphenylamine, yield was 88.91%, and conversion of 2-methyl-4-methoxyaniline was 99.51%. And heating the obtained intermediate product in a methanol system for decarboxylation to obtain 18.35g of the target product 2-methyl-4-methoxydiphenylamine, wherein the yield is 86.15%.
Claims (7)
1. A method for synthesizing 2-methyl-4-methoxydiphenylamine is characterized by comprising the following steps:
(1) sequentially adding o-chlorobenzoic acid, a copper catalyst, an acid-binding agent and a mixed solvent of toluene and DMF into a reaction vessel, heating to reflux, and stirring and mixing for 10-20 min; dropwise adding 2-methyl-4-methoxyaniline into a reaction container, and continuing reflux reaction for 6-10 hours after dropwise adding is finished for 1.5-2.5 hours; the using amount of the mixed solvent is 8-12 times of the mass of the 2-methyl-4-methoxyaniline; the mass ratio of toluene to DMF in the mixed solvent is 6-10: 1; in the reflux reaction process, water generated in the reaction is separated out through an oil-water separator; after the reaction is finished, neutralizing excessive alkali liquor, extracting with toluene, washing an extracted organic phase, evaporating toluene, concentrating, and drying in vacuum to obtain an intermediate product 2-methyl-4-methoxy-2' -carboxyl diphenylamine;
(2) and heating the obtained intermediate product in a methanol system for decarboxylation to obtain the target product 2-methyl-4-methoxydiphenylamine.
2. The method of synthesizing 2-methyl-4-methoxydiphenylamine as claimed in claim 1, wherein: the copper catalyst is any one of copper, cupric chloride and cuprous chloride.
3. The method of synthesizing 2-methyl-4-methoxydiphenylamine as claimed in claim 1, wherein: the acid-binding agent is sodium carbonate or sodium hydroxide.
4. The method of synthesizing 2-methyl-4-methoxydiphenylamine as claimed in claim 1, wherein: the molar ratio of the o-chlorobenzoic acid to the 2-methyl-4-methoxyl is 1-1.1: 1.
5. The method of synthesizing 2-methyl-4-methoxydiphenylamine as claimed in claim 1, wherein: the dosage of the copper catalyst is 1-1.5% of the mass of the 2-methyl-4-methoxyaniline.
6. The method of synthesizing 2-methyl-4-methoxydiphenylamine according to claim 1, wherein: the mass ratio of the o-chlorobenzoic acid to the acid-binding agent is 1: 0.72-1.1.
7. The method of synthesizing 2-methyl-4-methoxydiphenylamine as claimed in claim 1, wherein: and water generated in the reaction is separated by an oil-water separator, and then is used for washing an organic phase obtained by toluene extraction for recycling.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4510139A (en) * | 1984-01-06 | 1985-04-09 | Sterling Drug Inc. | Substituted aminobenzamides and their use as agents which inhibit lipoxygenase activity |
| JPS62226950A (en) * | 1986-03-28 | 1987-10-05 | Sugai Kagaku Kogyo Kk | Production of p-alkoxydiphenylamine compound |
| CN105949075A (en) * | 2016-06-24 | 2016-09-21 | 江苏倍合德化工有限公司 | 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 |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4510139A (en) * | 1984-01-06 | 1985-04-09 | Sterling Drug Inc. | Substituted aminobenzamides and their use as agents which inhibit lipoxygenase activity |
| JPS62226950A (en) * | 1986-03-28 | 1987-10-05 | Sugai Kagaku Kogyo Kk | Production of p-alkoxydiphenylamine compound |
| CN105949075A (en) * | 2016-06-24 | 2016-09-21 | 江苏倍合德化工有限公司 | 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 |
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