Method for preparing aryl anisole from phenolic compound

Abstract

The invention discloses a preparation method for preparing aryl anisole from a phenolic compound, and the preparation method comprises the following steps: reacting a mixture containing the phenolic compound, dimethyl carbonate and a catalyst in a closed reactor to obtain aryl anisole, the phenolic compound is selected from at least one of phenol, m-cresol, o-cresol, p-cresol, o-diphenol, resorcinol, o-chlorophenol, m-chlorophenol and p-chlorophenol. The preparation method disclosed by the invention can improve the atom utilization rate and reduce impurities brought by organic alkali decomposition in the reaction process, and has a certain industrialization prospect.

Description

Technical Field

[0001] The present application relates to a preparation method of aryl phenyl ether from phenolic compounds, belonging to the technical field of chemical industry catalysts. Background Art

[0002] The most common reaction in alkylation is methylation reaction, and the O-methylation reaction of phenolic compounds is particularly important. In this process, the methyl carbon of the methylation reagent is attacked by nucleophiles, the alkoxy bond is broken, and aryl methyl ether is formed. And aryl methyl ether is an important intermediate for preparing valuable fine chemicals such as dyes, agricultural chemicals, and fragrances.

[0003] Chinese invention patents CN107311938A, CN106916055A, and CN1546448A respectively disclose methods for preparing aryl methyl imidazole from phenolic compounds using catalysts with K 2 CO 3 , Y-type zeolite, and X-type molecular sieve as active centers. The reaction is carried out at 130-295 °C for 3-5 h, and the yield of aryl methyl ether can reach up to 99%. These methods have relatively high reaction temperatures, long reaction times, and high requirements for reaction equipment.

[0004] The literature (Chemical Engineering Research & Design. 2021, 168, 202-213.) reported that aryl methyl ether was synthesized from phenolic compounds using dimethyl carbonate as a methylation reagent in the presence of 1-butyl-3-methylimidazolium chloride. The reaction was carried out at 120 °C under atmospheric pressure for 1.5 h, and the selectivity and yield of aryl methyl ether in this method were both greater than 99%.

[0005] The literature (Chemsuschem. 2022, 15(3).) reported an aryl methyl ether synthesis route using dimethyl carbonate as a methylation reagent in the presence of dimethyl sulfide. The reaction was carried out in a high-pressure reactor at 220 °C for 4-6 h, and the selectivity and yield of the O-methylation product of aryl methyl ether in this method were both greater than 99%.

[0006] The literature (Applied Catalysis a-General. 2001, 211(1), 41-46.) reported an aryl methyl ether synthesis route using dimethyl carbonate as a methylation reagent in the presence of calcined Mg-Al hydrotalcite. The reaction was carried out in a fixed-bed reactor at 325 °C for 2 h, and the selectivity and yield of the O-methylation product of aryl methyl ether in this method were both greater than 95%.

[0007] Currently, for the problem that the reaction temperature for the O-methylation reaction of phenolic compounds catalyzed by a single-component catalyst is relatively high or the required reaction time is relatively long, the requirements for the reaction equipment are relatively high, increasing the time cost. Summary of the Invention

[0008] In view of the above technical problems, the present invention uses a catalyst composed of an organic base and an inorganic base, and proposes a method to significantly reduce the reaction temperature and reaction time on the premise of the same conversion rate and yield. The optional substrates are also more diverse, providing a method for efficiently preparing aryl anisole.

[0009] According to one aspect of the present application, there is provided a preparation method for preparing aryl anisole from phenolic compounds, and the preparation method includes:

[0010] In a closed reactor, a mixture containing a phenolic compound, dimethyl carbonate, and a catalyst is reacted to obtain aryl anisole;

[0011] The catalyst includes an organic base and an inorganic base;

[0012] The organic base is selected from at least one of ethylamine, piperidine, piperazine, 4-dimethylaminopyridine, 4-methylmorpholine, pyridine, lithium diisopropylamide (LDA), lithium hexamethyldisilazide (LiHMDS), 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU), sodium methoxide, potassium ethoxide, and potassium tert-butoxide;

[0013] The inorganic base is selected from at least one of LiOH, NaOH, KOH, RbOH, Mg(OH) 2 , Ca(OH) 2 , Sr(OH) 2 , Ba(OH) 2 and at least one of them.

[0014] Optionally, the molar ratio of the organic base to the inorganic base is 10:1 to 1:10.

[0015] Optionally, the molar ratio of the phenolic compound to the catalyst is 100:1 to 5:1.

[0016] Optionally, the molar ratio of the phenolic compound to the catalyst independently selects any value from 100:1, 90:1, 80:1, 60:1, 50:1, 20:1, 10:1, 5:1 or the range value between any two of the above.

[0017] Optionally, the molar ratio of the phenolic compound to dimethyl carbonate is 1:1 to 1:10.

[0018] Optionally, the phenolic compound is selected from at least one of phenol, m-cresol, o-cresol, p-cresol, o-dihydroxybenzene, m-dihydroxybenzene, o-chlorophenol, m-chlorophenol, and p-chlorophenol.

[0019] Optionally, the temperature of the reaction is 100 - 300 °C.

[0020] Optionally, the temperature of the reaction is independently selected from any value among 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 180 °C, 190 °C, 200 °C, 220 °C, 280 °C, 300 °C or the range value between any two of the above.

[0021] Optionally, the temperature of the reaction is 120 - 280 °C.

[0022] Optionally, the temperature of the reaction is independently selected from any value among 120 °C, 140 °C, 160 °C, 180 °C, 200 °C, 220 °C, 240 °C, 260 °C, 280 °C or the range value between any two of the above.

[0023] Optionally, the temperature of the reaction is 120 - 160 °C.

[0024] Optionally, the time of the reaction is 0.1 - 5 h.

[0025] Optionally, the time of the reaction is selected from any value among 0.1 h, 0.2 h, 0.4 h, 0.5 h, 1 h, 1.5 h, 2 h, 3 h, 4 h, 4.5 h, 5 h or the range value between any two of the above.

[0026] Optionally, the time of the reaction is 0.2 - 4.5 h.

[0027] Optionally, the time of the reaction is 0.4 - 2 h.

[0028] Optionally, the closed reactor is a batch autoclave reactor.

[0029] As an optional technical solution, the present application is achieved through the following technical solutions:

[0030] A method for preparing aryl anisole from a phenolic compound, a raw material containing a phenolic compound, under the condition of a catalyst, undergoes an O-methylation reaction with dimethyl carbonate to generate aryl anisole; the reaction system of the reaction is a homogeneous system.

[0031] In a batch reactor, the molar ratio of the organic base to the inorganic base is 10:1 to 1:10, and the molar ratio of the phenolic compound to dimethyl carbonate is 1:1 to 1:10. The reaction is carried out at a reaction temperature of 100 to 300 °C for 0.2 to 4.5 h to produce aryl anisole. The raw materials used are one of phenol, m-cresol, o-cresol, p-cresol, o-dihydroxybenzene, m-dihydroxybenzene, o-chlorophenol, m-chlorophenol, and p-chlorophenol. Preferably, the reaction temperature is 120 to 160 °C, and the reaction time is 0.4 to 2 h.

[0032] The beneficial effects that this application can produce include:

[0033] The reaction raw materials provided by this application are rich in source and the preparation process is mature; it improves the atom utilization rate, reduces the impurities brought by the decomposition of the organic base during the reaction, and only requires a relatively mild reaction temperature and a short time, and has good industrialization prospects. Therefore, the present invention provides a method for efficiently producing aryl anisole. Detailed Embodiments

[0034] The following describes this application in detail with reference to the embodiments, but this application is not limited to these embodiments.

[0035] Unless otherwise specified, the raw materials in the embodiments of this application are all purchased through commercial channels.

[0036] In the embodiments of the present invention, the gas chromatography internal standard calibration method is used to quantitatively analyze the raw material conversion rate and product composition in the system after the reaction ends.

[0037] Calculation methods for conversion rate and selectivity:

[0038]

[0039]

[0040] Yield of Product A = Conversion Rate × Selectivity of Product A

[0041] Product A in the above calculation method refers to aryl anisole.

[0042] Comparative Example 1

[0043] O-methylation of p-cresol to p-methyl anisole: In a batch reactor, 20 mmol of p-cresol, 120 mmol of dimethyl carbonate, and 6 mmol of 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) were added; after replacing the air in the reactor with nitrogen, the reaction was carried out at a reaction temperature of 160 °C for 60 min, and then cooled to room temperature in an ice bath. Finally, the composition of the substances in the reaction system was analyzed.

[0044] Comparative Examples 2 to 9

[0045] Ethylamine, piperidine, piperazine, 4-dimethylaminopyridine, 4-methylmorpholine, pyridine, sodium methoxide, and potassium ethoxide were used to replace 1,8-diazabicyclo[5.4.0]undec-7-ene, respectively, and the other processes were the same as those in Comparative Example 1.

[0046] Table 1 Results of Comparative Examples 1-9

[0047]

[0048]

[0049] As can be seen from Table 1, when a single organic base was used as the catalyst, the conversion rate and yield of p-cresol O-methylation were both low, and among them, 1,8-diazabicyclo[5.4.0]undec-7-ene had the highest yield for the reaction of p-cresol O-methylation to p-methylanisole.

[0050] Example 1

[0051] Preparation of p-methylanisole by p-cresol O-methylation: In a batch autoclave reactor, 50 mmol of p-cresol, 200 mmol of dimethyl carbonate, 4 mmol of 1,8-diazabicyclo[5.4.0]undec-7-ene, and 1.25 mmol of NaOH were added; after purging the air in the autoclave with nitrogen, the reaction was carried out at a reaction temperature of 160 °C for 60 min, and then cooled to room temperature in an ice bath. Finally, the composition of the substances in the reaction system was analyzed.

[0052] Example 2

[0053] The substrate composition was the same as that in Example 1. The reaction time of p-cresol O-methylation was 30 min, and the other conditions were the same as those in Example 1.

[0054] Examples 3-7

[0055] LiOH, KOH, RbOH, Mg(OH) 2 , Sr(OH) 2 were used to replace NaOH, respectively, and the other processes were the same as those in Example 1.

[0056] Table 2 Results of Examples 1-7

[0057] Example Organic base Inorganic base Conversion rate (%) Yield (%) 1 DBU NaOH 100 100 2 DBU NaOH 51 51 3 DBU LiOH 78 78 4 DBU KOH 45 44 5 DBU RbOH 39 39 6 DBU <![CDATA[Mg(OH) 2 > 56 55 7 DBU <![CDATA[Sr(OH) 2 > 78 77

[0058] As can be seen from Table 2, the highest yield for the reaction of p-cresol O-methylation to p-methylanisole was obtained by the synergistic catalysis of 1,8-diazabicyclo[5.4.0]undec-7-ene and NaOH.

[0059] Examples 8-12

[0060] Phenol, m-cresol, resorcinol, o-dihydroxybenzene, and o-chlorophenol were used to replace p-cresol respectively, and other processes were the same as those in Example 1.

[0061] Table 3 Results of Examples 8-12

[0062] Example Raw material Conversion rate (%) Selectivity (%) Yield (%) 8 Phenol 53 100 52 9 m-Cresol 46 100 41 10 Resorcinol 78 89 78 11 Catechol 62 100 61 12 o-Chlorophenol 59 100 59

[0063] As can be seen from Table 3, the selectivity and yield of the reaction of synthesizing aryl anisole by the O-methylation of phenolic compounds with 1,8-diazabicyclo[5,4,0]undec-7-ene and NaOH as the co-catalyst are both relatively high.

[0064] Example 13

[0065] The reaction temperature for the O-methylation of p-cresol to p-methylanisole was 110 °C, and other conditions were the same as those in Example 1.

[0066] Example 14

[0067] The reaction temperature for the O-methylation of p-cresol to p-methylanisole was 120 °C, and other conditions were the same as those in Example 1.

[0068] Example 15

[0069] The reaction temperature for the O-methylation of p-cresol to p-methylanisole was 130 °C, and other conditions were the same as those in Example 1.

[0070] Example 16

[0071] The reaction temperature for the O-methylation of p-cresol to p-methylanisole was 133 °C, and other conditions were the same as those in Example 1.

[0072] Example 17

[0073] The reaction temperature for the O-methylation of p-cresol to p-methylanisole was 137 °C, and other conditions were the same as those in Example 1.

[0074] Example 18

[0075] The reaction temperature for the O-methylation of p-cresol to p-methylanisole was 140 °C, and other conditions were the same as those in Example 1.

[0076] Example 19

[0077] The reaction temperature for the O-methylation of p-cresol to p-methylanisole was 150 °C, and other conditions were the same as those in Example 1.

[0078] Example 20

[0079] The reaction temperature for the O-methylation of p-cresol to p-methylanisole was 170 °C, and other conditions were the same as those in Example 1.

[0080] Table 4 Results of Examples 13 - 20

[0081] Example Reaction temperature (°C) Conversion rate (%) Yield (%) 13 110 2 2 14 120 16 16 15 130 23 23 16 133 43 43 17 137 61 61 18 140 75 74 19 150 85 84 1 160 100 100 20 170 100 100

[0082] Note: The corresponding conversion rates and yields in Table 4 are the reaction results after reacting alone for 60 min at the corresponding reaction temperature, rather than the reaction results of sampling during continuous reaction.

[0083] It can be seen from Table 4 that when the reaction temperature rises to 160 °C, p - cresol is basically completely converted, and the yield of anisole is 99%; when the temperature rises to 170 °C, p - cresol is completely converted, the yield of anisole remains unchanged, and no other by - products are produced. Therefore, considering from the perspective of the yield of anisole, the preferred reaction temperature for the O - methylation of p - cresol is 160 °C.

[0084] Example 21

[0085] The reaction time for the O - methylation of p - cresol to produce anisole is 10 min, and other conditions are the same as those in Example 1.

[0086] Example 22

[0087] The reaction time for the O - methylation of p - cresol to produce anisole is 20 min, and other conditions are the same as those in Example 1.

[0088] Example 23

[0089] The reaction time for the O - methylation of p - cresol to produce anisole is 30 min, and other conditions are the same as those in Example 1.

[0090] Example 24

[0091] The reaction time for the O - methylation of p - cresol to produce anisole is 40 min, and other conditions are the same as those in Example 1.

[0092] Example 25

[0093] The reaction time for the O - methylation of p - cresol to produce anisole is 50 min, and other conditions are the same as those in Example 1.

[0094] Table 5 Results of Examples 21 - 25

[0095]

[0096]

[0097] Note: The corresponding conversion rates and yields in Table 5 are the reaction results at the corresponding reaction time, rather than the reaction results of sampling during continuous reaction.

[0098] As can be seen from Table 5, the conversion rate of p-cresol increased rapidly after the reaction time reached 30 min. When the reaction time was 60 min, p-cresol was basically completely converted, the selectivity of p-methylanisole was 99.5%, and the yield was 99.1%. Therefore, from the perspective of the yield of p-methylanisole, the preferred O-methylation reaction time of p-cresol was 60 min.

[0099] The above are only several embodiments of the present application, and do not impose any form of limitation on the present application. Although the present application is disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, makes some changes or modifications using the technical content disclosed above, which are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A preparation method of aryl phenyl ether from phenolic compounds, characterized in that, the preparation method includes: In a closed reactor, reacting a mixture containing phenolic compounds, dimethyl carbonate, and a catalyst to obtain aryl phenyl ether; the catalyst includes an organic base and an inorganic base; the organic base is selected from at least one of ethylamine, piperidine, piperazine, 4-dimethylaminopyridine, 4-methylmorpholine, pyridine, lithium diisopropylamide, lithium hexamethyldisilazide, 1,8-diazabicyclo[5,4,0]undec-7-ene, sodium methoxide, potassium ethoxide, potassium tert-butoxide; The inorganic base is selected from at least one of LiOH, NaOH, KOH, RbOH, Mg(OH) 2 , Ca(OH) 2 , Sr(OH) 2 , Ba(OH) 2 .

2. The preparation method according to claim 1, characterized in that, the molar ratio of the organic base to the inorganic base is 10:1 to 1:

10.

3. The preparation method according to claim 1, characterized in that, the molar ratio of the phenolic compound to the catalyst is 100:1 to 5:

1.

4. The preparation method according to claim 1, characterized in that, the molar ratio of the phenolic compound to dimethyl carbonate is 1:1 to 1:10; Preferably, the phenolic compound is selected from at least one of phenol, m-cresol, o-cresol, p-cresol, o-dihydroxybenzene, m-dihydroxybenzene, o-chlorophenol, m-chlorophenol, p-chlorophenol.

5. The preparation method according to claim 1, characterized in that, the temperature of the reaction is 100 - 300 °C.

6. The preparation method according to claim 1, characterized in that, the temperature of the reaction is 120 - 280 °C.

7. The preparation method according to claim 1, characterized in that, the temperature of the reaction is 120 - 160 °C.

8. The preparation method according to claim 1, characterized in that, the reaction time is 0.1 - 5 h.

9. The preparation method according to claim 1, characterized in that, the reaction time is 0.2 - 4.5 h.

10. The preparation method according to claim 1, characterized in that, the reaction time is 0.4 - 2 h.

Images