阅读说明：本技术 邻苯二甲醚及其制备方法 (Phthalic ether and preparation method thereof ) 是由 霍世勇 王晓刚 涂俊清 路风奇 付裕 张艳芳 于 2019-11-28 设计创作，主要内容包括：本发明涉及有机化合物的醚化领域,公开了一种邻苯二甲醚及其制备方法,该方法包括以下步骤,1)在催化剂的存在下,以邻苯二酚为原料,以碳酸二甲酯为甲基化试剂,进行甲基化反应,得到邻苯二甲醚,其中,所述催化剂为1,8-二氮杂双环[5.4.0]十一碳-7-烯；2)将步骤1)得到的反应产物蒸馏回收碳酸二甲酯,然后再减压蒸馏得到邻苯二甲醚。本发明的方法采用绿色环保的甲基化试剂碳酸二甲酯,无废水废固产生,收率高,非常适合工业化生产,符合绿色环保工艺要求。(The invention relates to the field of etherification of organic compounds and discloses a dimethyl phthalate and a preparation method thereof, wherein the method comprises the following steps of 1) carrying out methylation reaction by using catechol as a raw material and dimethyl carbonate as a methylation reagent in the presence of a catalyst to obtain the dimethyl phthalate, wherein the catalyst is 1, 8-diazabicyclo [5.4.0] undec-7-ene; 2) distilling the reaction product obtained in the step 1) to recover dimethyl carbonate, and then carrying out reduced pressure distillation to obtain the o-dimethyl ether. The method adopts the green and environment-friendly methylating reagent dimethyl carbonate, has no waste water and solid, has high yield, is very suitable for industrial production, and meets the requirements of green and environment-friendly processes.)

1. A method for preparing o-dimethyl ether is characterized by comprising the following steps,

1) in the presence of a catalyst, performing methylation reaction by using catechol as a raw material and dimethyl carbonate as a methylation reagent to obtain the dimethyl phthalate, wherein the catalyst is 1, 8-diazabicyclo [5.4.0] undec-7-ene;

2) distilling the reaction product obtained in the step 1) to recover dimethyl carbonate, and then carrying out reduced pressure distillation to obtain the o-dimethyl ether.

2. The process of claim 1, wherein the molar ratio of catechol to dimethyl carbonate is from 1: 2-10.

3. The process of claim 2, wherein the molar ratio of catechol to dimethyl carbonate is from 1: 3-8.

4. The process according to claim 1, wherein the molar ratio of catechol to catalyst is 1: 0.0001-10.

5. The process of any one of claims 1-4, wherein the methylation reaction conditions comprise: the reaction temperature is 100-250 ℃, the reaction time is 2-20 hours, and the reaction pressure is 1-10 MPa.

6. The process according to any one of claims 1 to 4, wherein the process for recovering dimethyl carbonate by distillation of the reaction product obtained in step 1) comprises: obtaining a mixture containing dimethyl carbonate and methanol through atmospheric distillation, and then removing the methanol through rectification to obtain the dimethyl carbonate;

preferably, the process further comprises using dimethyl carbonate recovered by distillation as a methylating agent.

7. The process according to any one of claims 1 to 6, further comprising using the residue after the distillation under reduced pressure as a catalyst.

8. The process of claim 1, wherein the atmospheric distillation temperature is 65-200 ℃.

9. The process of claim 1, wherein the conditions of the reduced pressure distillation comprise: the temperature of the reduced pressure distillation is 50-200 ℃, and the pressure of the reduced pressure distillation is-0.01 to-0.1 MPa.

10. A phthalic ether produced by the method according to any one of claims 1 to 9.

Technical Field

The invention relates to the field of etherification of organic compounds, in particular to o-dimethyl ether and a preparation method thereof.

Background

The o-dimethyl ether is also called veratrole, which is an intermediate of bactericide dimethomorph and flumorph. Also used as an organic synthesis intermediate for synthesizing tetrahydropalmatine, verapamil and the like in the medical industry. In addition, the o-dimethyl ether is also a common reagent for detecting lactic acid and glycerol in blood.

At present, the main synthesis methods of the dimethyl phthalate comprise a catechol method, a guaiacol method, an o-halogen anisole method and the like.

CN102863320A discloses a method for preparing o-dimethyl ether, which takes catechol as raw material and dimethyl sulfate as methylating agent to prepare the o-dimethyl ether. The method mainly aims to generate a large amount of salt-containing wastewater, and the intermediate needs extraction, water washing, distillation and the like, so that the method has multiple operation steps and higher cost.

CN101811942B discloses a method for preparing o-dimethyl ether, which takes catechol as raw material to react with chloromethane under alkaline condition to prepare the o-dimethyl ether. The method also produces a large amount of waste water and waste solids, and the excessive chloromethane is not easy to recover, thereby greatly increasing the environmental protection cost.

Therefore, the problems of large waste water amount, more waste solids and long operation period in the prior synthesis of the o-dimethyl ether are urgently needed to be changed, and meanwhile, the environmental protection pressure is reduced, and the operation cost is reduced.

Disclosure of Invention

The invention aims to solve the problems of large waste water amount, more waste solids, long operation period and the like in the prior art in the prior synthesis of the o-dimethyl ether, and provides a novel preparation method of the o-dimethyl ether.

In order to achieve the above objects, the present invention provides a novel method for preparing o-dimethylether, comprising the steps of,

1) in the presence of a catalyst, performing methylation reaction by using catechol as a raw material and dimethyl carbonate as a methylation reagent to obtain the dimethyl phthalate, wherein the catalyst is 1, 8-diazabicyclo [5.4.0] undec-7-ene;

2) distilling the reaction product obtained in the step 1) to recover dimethyl carbonate, and then carrying out reduced pressure distillation to obtain the o-dimethyl ether.

Preferably, the molar ratio of the catechol to the dimethyl carbonate is 1: 2-10.

Preferably, the molar ratio of the catechol to the dimethyl carbonate is 1: 3-8.

Preferably, the molar ratio of catechol to the catalyst is 1: 0.0001-10.

Preferably, the methylation reaction conditions include: the reaction temperature is 120-220 ℃, the reaction time is 4-18 hours, and the reaction pressure is 1.5-8 MPa.

Preferably, the method for recovering dimethyl carbonate by distilling the reaction product obtained in the step 1) comprises the following steps: a mixture containing dimethyl carbonate and methanol is obtained by atmospheric distillation, and then the methanol is removed by rectification to obtain the dimethyl carbonate.

Preferably, the method further comprises using dimethyl carbonate obtained by distillation as a methylating agent.

Preferably, the process further comprises using the residue after distillation as a catalyst.

Preferably, the atmospheric distillation temperature is 70-180 ℃.

Preferably, the conditions of the reduced pressure distillation include: the temperature of the reduced pressure distillation is 60-180 ℃, and the pressure of the reduced pressure distillation is-0.01 to-0.1 MPa.

The invention also provides the o-dimethyl ether prepared by the method.

Through the technical scheme, the invention can provide a novel preparation method of the o-dimethyl ether, which adopts the green and environment-friendly methylating reagent dimethyl carbonate, has no waste water and solid, high yield, is very suitable for industrial production, and meets the requirements of green and environment-friendly processes.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides a novel method for preparing o-dimethyl ether, which comprises the following steps,

1) in the presence of a catalyst, performing methylation reaction by using catechol as a raw material and dimethyl carbonate as a methylation reagent to obtain the dimethyl phthalate, wherein the catalyst is 1, 8-diazabicyclo [5.4.0] undec-7-ene;

2) distilling the reaction product obtained in the step 1) to recover dimethyl carbonate, and then carrying out reduced pressure distillation to obtain the o-dimethyl ether.

According to the invention, a methylation reagent dimethyl carbonate which is green and environment-friendly is used, a specific raw material and a catalyst are used for methylation reaction, the dimethyl carbonate is used as a methylation reagent and a solvent in the reaction, after the reaction is finished, the dimethyl carbonate can be recovered by distillation, the dimethyl carbonate recovered by distillation can be used as the methylation reagent for continuous use, and after the dimethyl carbonate is recovered by distillation, a target product dimethyl phthalate can be obtained quantitatively and in high purity by reduced pressure distillation, and the distillation residue can be used as the catalyst for continuous use.

According to the invention, the molar ratio of the catechol to the dimethyl carbonate may be 1: 2-10; however, from the viewpoint of further improving the solvent recovery performance, it is preferable that catechol and dimethyl carbonate are used in a molar ratio of 1: 3-8.

According to the invention, the molar ratio of the catechol to the catalyst may be 1: 0.0001-10; preferably, the molar ratio of catechol to the catalyst is 1: 0.1-5.

According to the present invention, preferably, the methylation reaction conditions include: the reaction temperature is 120-220 ℃, the reaction time is 4-18 hours, and the reaction pressure is 1.5-8 Mpa; more preferably, the methylation reaction conditions comprise: the reaction temperature is 140-200 ℃, the reaction time is 5-16 hours, and the reaction pressure is 2-6 MPa; further preferably, the methylation reaction conditions include: the reaction temperature is 140-200 ℃, the reaction time is 5-16 hours, and the reaction pressure is 2-6 MPa.

According to the invention, the method for recovering dimethyl carbonate by distilling the reaction product obtained in the step 1) comprises the following steps: a mixture containing dimethyl carbonate and methanol is obtained by atmospheric distillation, and then the methanol is removed by rectification to obtain the dimethyl carbonate.

According to the present invention, the conditions of the atmospheric distillation are not particularly limited as long as dimethyl carbonate can be obtained with high purity. Preferably, the temperature of the atmospheric distillation is 70-180 ℃; more preferably, the atmospheric distillation temperature is 80-160 ℃.

According to the present invention, the conditions of the atmospheric distillation are not particularly limited as long as dimethyl carbonate can be obtained with high purity. Preferably, the temperature of the rectification is 50-150 ℃; more preferably, the temperature of the rectification is 80 to 140 ℃.

The present inventors have also surprisingly found that the recovered dimethyl carbonate can be reused many times (i.e., used as a methylating agent for the next methylation reaction), and that it is industrially very useful to quantitatively obtain o-dimethyl ether even if the number of times of reuse can reach 30 or more, for example.

The number of times of recycling of the dimethyl carbonate obtained as described above is preferably 25 or less, and more preferably 20 or less.

According to the present invention, preferably, the conditions of the reduced pressure distillation include: the temperature of the reduced pressure distillation is 60-180 ℃, and the pressure of the reduced pressure distillation is-0.01 to-0.1 Mpa; more preferably, the conditions of the reduced pressure distillation include: the temperature of the reduced pressure distillation is 80-160 ℃, and the pressure of the reduced pressure distillation is-0.01 to-0.1 MPa; more preferably, the conditions of the reduced pressure distillation include: the temperature of the reduced pressure distillation is 80-160 ℃, and the pressure of the reduced pressure distillation is-0.01 to-0.1 MPa.

The present inventors have also surprisingly found that the residue after distillation can be used as a catalyst, and the obtained residue after distillation can be reused many times (that is, used as a catalyst for the next methylation reaction), and that even if the number of reuse can reach 30 or more, for example, it is possible to quantitatively obtain o-dimethyl ether, and therefore, the present invention is industrially very useful.

The number of times of recycling the residue after distillation is preferably 25 or less, and more preferably 20 or less.

Therefore, in the present invention, it is preferred that the process of the present invention further comprises using dimethyl carbonate obtained by distillation as a methylating agent.

In the present invention, it is also preferable that the method of the present invention further comprises using the residue after distillation as a catalyst.

According to the invention, a methylation reagent dimethyl carbonate which is green and environment-friendly is used, a specific raw material and a catalyst are used for methylation reaction, the dimethyl carbonate is used as a methylation reagent and also used as a solvent in the reaction, after the reaction is finished, the dimethyl carbonate can be recovered by distillation, the dimethyl carbonate obtained by distillation can be used as the methylation reagent for continuous use, and after the dimethyl carbonate is recovered by distillation, a target product dimethyl phthalate can be obtained quantitatively and at high purity by reduced pressure distillation, and the distillation residue can be used as the catalyst for continuous use.

The invention also provides the o-dimethyl ether prepared by the method.

The present invention will be described in detail below by way of examples, but the present invention is not limited to the following examples.

Example 1

1) Adding 11 g (100mmol) of catechol, 63 g (700mmol) of dimethyl carbonate and 12.2 g (80mmol) of DBU into a 100 ml stainless steel autoclave, replacing twice by nitrogen, heating to 160 ℃ for reaction, slowly opening a vent valve (connected with a condenser in front) when a pressure gauge is increased to 4MPa, releasing the pressure to 2MPa, circulating in the way, finishing the reaction after 8 hours, cooling to room temperature, venting, and performing post-treatment.

2) Distilling the reaction liquid obtained in the step 1) at normal pressure, wherein the distillation temperature is 150 ℃, and obtaining 45 g of front cut fraction; after atmospheric distillation, the reaction mixture was further subjected to vacuum distillation to obtain o-dimethyl ether (purity: 99%, weight: 13.7 g, yield: 98.5%), the temperature of vacuum distillation was 130 ℃ and the pressure of vacuum distillation was-0.098 MPa, and the residue in the autoclave after vacuum distillation was used as a catalyst and recycled to the next reaction.

3) Rectifying 51 g of front cut fraction obtained in the step 2) (the rectifying temperature is 110 ℃), recycling 6.1 g of methanol extracted from the top of the tower to prepare dimethyl carbonate, and recycling the rest dimethyl carbonate in the kettle to the next batch of reaction (adding new dimethyl carbonate to the insufficient part).

The methylation reaction was performed for the next batch in the same manner as in the above steps 1), 2) and 3), and 29 times of methylation reactions were repeated, wherein the methylation reaction performed for the first time and 29 times of methylation reactions were repeated, and the yield and purity of the o-dimethylether obtained in the reduced pressure distillation were as shown in table 1.

TABLE 1

Example 2

1) 11 g (100mmol) of catechol, 54 g (600mmol) of dimethyl carbonate and 10.7 g (70mmol) of DBU are added into a 100 ml stainless steel autoclave, nitrogen is replaced twice, the temperature is increased to 180 ℃, the reaction is carried out for 8 hours, and after the reaction is finished, the temperature is reduced to room temperature for post-treatment.

2) Distilling the reaction liquid obtained in the step 1) at normal pressure, wherein the distillation temperature is 150 ℃ to obtain 40 g of front cut (rectifying the front cut at the rectification temperature of 110 ℃, recycling methanol extracted from the top of the tower to prepare dimethyl carbonate, and recycling the rest dimethyl carbonate in the kettle to the next batch of reaction); after atmospheric distillation, the reaction mixture was further subjected to vacuum distillation to obtain o-dimethyl ether (purity: 99.1%, weight: 13.7 g, yield: 98.2%), the temperature of vacuum distillation was 130 ℃ and the pressure of vacuum distillation was-0.098 MPa, and the residue in the autoclave after vacuum distillation was used as a catalyst and recycled for the next reaction.

3) The dimethyl carbonate obtained in step 2) was used as a partial methylating agent (fresh dimethyl carbonate was used for the other part), and the residue after vacuum distillation was used as a catalyst, and the methylation reaction was carried out in the next batch by the methods of the above steps 1) and 2) and was repeated 29 times, and the yield and purity of the obtained phthalic ether by vacuum distillation were as shown in table 2.

TABLE 2

Number of times	Yield (%)	Purity (% by weight)
			1	98.2	99.1
2	98.5	99.2
			3	98.8	99.1
4	98.7	99.3
			5	98.8	99.2
6	98.7	99.1
			7	98.6	99.3
8	98.8	99.2
			9	98.6	99.1
10	98.7	99.1
			11	98.2	99.3
12	98.5	99.1
			13	98.8	99.0
14	98.6	99.1
			15	98.3	99.2
16	98.1	99.3
			17	98.2	99.2
18	98.1	99.0
			19	98.4	99.1
20	98.2	99.1
			21	98.0	98.8
22	98.1	98.9
			23	97.8	98.7
24	97.9	98.8
			25	97.3	98.5
26	97.4	98.1
			27	97.1	98.2
28	97.2	98.0
			29	97.5	97.9
30	97.2	97.8

Example 3

1) 11 g (100mmol) of catechol, 45 g (500mmol) of dimethyl carbonate and 6.1 g (40mmol) of DBU are added into a 100 ml stainless steel autoclave, nitrogen is replaced twice, the temperature is increased to 190 ℃, the reaction is carried out for 8 hours, and after the reaction is finished, the temperature is reduced to room temperature for post-treatment.

2) Distilling the reaction liquid obtained in the step 1) at normal pressure, wherein the distillation temperature is 150 ℃ to obtain 38 g of front cut fraction (rectifying the front cut fraction at the rectification temperature of 110 ℃, recycling methanol extracted from the top of the tower to prepare dimethyl carbonate, and recycling the rest dimethyl carbonate in the kettle to the next batch of reaction); after atmospheric distillation, the reaction mixture was further subjected to vacuum distillation to obtain o-dimethyl ether (purity: 99.2%, weight: 13.6 g, yield: 97.5%), the temperature of vacuum distillation was 130 ℃ and the pressure of vacuum distillation was-0.098 MPa, and the residue in the autoclave after vacuum distillation was used as a catalyst and recycled for the next reaction.

3) The yield and purity of the phthalic ether obtained by the reduced pressure distillation were as shown in table 3, wherein the dimethyl carbonate obtained in step 2) was used as a partial methylating agent (fresh dimethyl carbonate was used for the other portions), and the residue obtained by the reduced pressure distillation was used as a catalyst, and the methylation reaction was performed in the next batch by the methods of the above steps 1) and 2) and was repeated 29 times.

TABLE 3

Comparative example 1

The procedure was followed in step 1) of example 1, except that the catalyst was diisopropylethylamine and the yield of o-dimethylether was 18.5%.

Comparative example 2

The procedure was followed in step 1) of example 1, except that the methylating agent was dimethyl sulfate and the yield of o-dimethyl ether was 46.2%.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.