A method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis by-product

Abstract

The invention discloses a method for preparing trimethylhydroquinone by using trimethylhydroquinone synthesis byproducts. The dimerized byproducts of the reaction of preparing trimethylhydroquinone from trimethylphenol are used as raw materials, and the dimerized byproducts are catalyzed by CuO / SiO2 catalysts and catalyzed by palladium carbon for hydrogenation, so that the dimerized byproducts can be converted into trimethylhydroquinone. The method comprises the following steps: step 1: ethyl acetate, dimerized byproducts, and CuO / SiO2 catalysts are sequentially added into a three-necked flask, and ozone is introduced for reaction; step 2: after the reaction is completed, CuO / SiO2 is filtered and removed. The beneficial effect of the invention is that the dimerized byproducts of the reaction of preparing trimethylhydroquinone from trimethylphenol are used as raw materials, and the dimerized byproducts are catalyzed by CuO / SiO2 catalysts and catalyzed by palladium carbon for hydrogenation, so that the dimerized byproducts can be converted into trimethylhydroquinone. This method realizes the conversion of byproducts into main products in the preparation process of trimethylhydroquinone, significantly reduces the cost of three wastes treatment, and improves the process economy.

Description

Technical Field

[0001] The invention relates to a method for preparing trimethylhydroquinone, in particular to a method for preparing trimethylhydroquinone by utilizing a by-product of trimethylhydroquinone synthesis, and belongs to the field of fine chemicals. Background Art

[0002] Trimethylhydroquinone (2,3,5-trimethylbenzoquinone, TMHQ) is a white or off-white crystal and an important intermediate for the industrial synthesis of vitamin E. It can be condensed with isophytol to produce vitamin E. Trimethylhydroquinone is an important intermediate for the synthesis of vitamin E.

[0003] The current industrial method for synthesizing trimethylhydroquinone uses trimethylphenol as a raw material and oxidizes it with oxygen or hydrogen peroxide to generate trimethylbenzoquinone. In the process of preparing trimethylhydroquinone from trimethylphenol, a certain amount of dimerization by-product will be generated. Relevant patents include: CN116874361, CN116102414, CN115894204, WO2021122437, WO2015000767. Trimethylbenzoquinone is further hydrogenated and reduced to obtain trimethylhydroquinone (detailed processes can be seen in the following patents: CN115784860, CN114100627, WO2021135443, WO2021122437, WO2020035600).

[0004]

[0005] The prior art does not have a method for effectively utilizing the dimerization by-products. Therefore, in the existing production process, the dimerization by-products separated during the product purification process are treated as solid waste. Not only are the materials not effectively utilized, but additional solid waste treatment fees are also added. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis by-products in order to solve the above-mentioned problems, effectively utilizing the dimerized by-products formed in the process of preparing trimethylhydroquinone from trimethylphenol, and using the dimerized by-products as raw materials to prepare trimethylhydroquinone. This method realizes the conversion of by-products in the preparation process of trimethylhydroquinone into main products, significantly reduces the cost of three wastes treatment and improves the process economy.

[0007]

[0008] The present invention achieves the above-mentioned purpose through the following technical scheme, a method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis byproducts, using the dimerization byproduct of the reaction of preparing trimethylhydroquinone from trimethylphenol as a raw material, catalyzing ozone oxidation with a CuO / SiO2 catalyst, and catalyzing hydrogenation with palladium carbon, so that the dimerization byproducts can be converted into trimethylhydroquinone, comprising the following steps:

[0009] Step 1: Add ethyl acetate, dimerization byproduct, and CuO / SiO2 catalyst in a three-necked flask in sequence, and introduce ozone to react;

[0010] Step 2: After the reaction is completed, filter and remove CuO / SiO2;

[0011] Step 3: Transfer the filtrate to a stainless steel reactor, add a palladium-carbon catalyst, and react after filling with hydrogen. After the reaction is completed, filter and remove the palladium-carbon to obtain a trimethylhydroquinone ethyl acetate solution.

[0012] As a further feasible solution, the catalyst used in the ozone generation is CuO / SiO2.

[0013] As a further feasible scheme, the catalyst used when passing hydrogen is palladium carbon.

[0014] As a further feasible solution, the mass ratio of CuO / SiO2 to the dimerization by-product is 0.5:100-1:5.

[0015] As a further feasible scheme, the mass ratio of the palladium carbon to the dimerization by-product is 0.1:100-1:10.

[0016] As a further feasible solution, the ozone reaction temperature is between -20°C and 20°C.

[0017] As a further feasible solution, it is characterized in that the hydrogen reduction temperature is between 30-100°C.

[0018] As a further feasible solution, the hydrogen reduction pressure is between 0.5-5 MPa.

[0019] As a further feasible scheme, after the reaction is completed, the CuO / SiO2 and palladium carbon recovered by filtration can be directly used for the next batch of reactions.

[0020] The beneficial effects of the present invention are as follows: the present invention effectively utilizes the dimerization by-product formed in the process of preparing trimethylhydroquinone from trimethylphenol, and uses the dimerization by-product as a raw material to prepare trimethylhydroquinone. This method realizes the conversion of the by-product in the process of preparing trimethylhydroquinone into the main product, significantly reduces the cost of three wastes treatment, and improves the process economy. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1

[0023] A method for preparing trimethylhydroquinone by utilizing trimethylhydroquinone synthesis byproducts, which uses the dimerization byproducts of the reaction of preparing trimethylhydroquinone from trimethylphenol as raw materials, catalyzes ozone oxidation with a CuO / SiO2 catalyst, and performs palladium-carbon catalytic hydrogenation to convert the dimerization byproducts into trimethylhydroquinone, cools the reaction solution to 0°C, and introduces ozone for 8 hours.

[0024] The preparation steps are as follows:

[0025] Step 1: Add 200.0g ethyl acetate, 40.0g dimerization byproduct, and 2.0g CuO / SiO2 catalyst in a 500ml three-necked flask, cool the reaction solution to 0°C, maintain this temperature, and introduce ozone for reaction for 8 hours under vigorous stirring;

[0026] Step 2: After the reaction is completed, filter and remove CuO / SiO2;

[0027] Step 3: Transfer the filtrate to a 1000 ml stainless steel reactor, add 0.4 g of palladium carbon catalyst, fill with 2.0 MPa hydrogen, raise the temperature to 80°C, and maintain this condition for 4 hours;

[0028] Step 4: After the reaction is completed, the palladium carbon is removed by filtration. The obtained trimethylhydroquinone ethyl acetate solution is subjected to chromatographic analysis, which shows that the conversion rate of the dimerization byproduct is 92.2% and the selectivity of trimethylhydroquinone is 98.1%.

[0029] Example 2

[0030] Based on the method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis by-product provided in Example 1 of the present invention, the method for preparing trimethylhydroquinone in Example 2 of the present invention is different in that the reaction solution is cooled to -10°C and ozone is introduced for a reaction time of 10 hours.

[0031] The preparation steps are as follows:

[0032] Step 1: Add 200.0g ethyl acetate, 40.0g dimerization byproduct, and 2.0g CuO / SiO2 catalyst in a 500ml three-necked flask, cool the reaction solution to -10°C, maintain this temperature, and introduce ozone for reaction for 10 hours under vigorous stirring;

[0033] Step 2: After the reaction is completed, filter and remove CuO / SiO2;

[0034] Step 3: Transfer the filtrate to a 1000 ml stainless steel reactor, add 0.4 g of palladium carbon catalyst, fill with 2.0 MPa hydrogen, raise the temperature to 80°C, and maintain this condition for 4 hours;

[0035] Step 4: After the reaction is completed, the palladium carbon is removed by filtration. The obtained trimethylhydroquinone ethyl acetate solution is subjected to chromatographic analysis, which shows that the conversion rate of the dimerization byproduct is 96.3% and the selectivity of trimethylhydroquinone is 97.9%.

[0036] Embodiment 3-10

[0037] Based on the method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis byproduct provided in Example 1 of the present invention, the methods for preparing trimethylhydroquinone in Examples 3 to 10 of the present invention are different in that different CuO / SiO2 and palladium carbon addition amounts are used, and the results obtained are shown in Table 1:

[0038] Table 1. Reaction results of different catalyst addition amounts

[0039]

[0040] Examples 11-16

[0041] Similar to Example 1, different temperature reactions were used, and the results are shown in Table 2:

[0042] Table 2. Reaction results at different temperatures

[0043]

[0044]

[0045] Examples 17-19

[0046] Similar to Example 1, different hydrogen pressures were used for the reaction, and the results are shown in Table 3:

[0047] Table 3. Reaction results at different hydrogen pressures

[0048]

[0049] The preparation steps are as follows:

[0050] Step 1: Add 200.0g ethyl acetate, 40.0g dimerization byproduct, and 2.0g CuO / SiO2 catalyst in a 500ml three-necked flask, cool the reaction solution to 0°C, maintain this temperature, and introduce ozone for reaction for 8 hours under vigorous stirring;

[0051] Step 2: After the reaction is completed, filter and remove CuO / SiO2;

[0052] Step 3: Transfer the filtrate to a 1000 ml stainless steel reactor, add 0.4 g of palladium carbon catalyst, fill with 0.5 MPa / 1 MPa / 5 MPa hydrogen, heat to 80 ° C, and maintain this condition for 4 hours;

[0053] Step 4: After the reaction is completed, the palladium carbon is removed by filtration. The chromatographic analysis of the obtained trimethylhydroquinone ethyl acetate solution shows that the conversion rates of dimerization byproducts are 91.7% / 92.3% / 92.1% and the selectivities of trimethylhydroquinone are 87.7% / 93.5% / 99.1%.

[0054] Embodiment 20

[0055] Catalyst recovery: 200.0g ethyl acetate, 40.0g dimerization byproduct, and 2.0g CuO / SiO2 catalyst were added to a 500ml three-necked flask in sequence, the reaction solution was cooled to 0°C, maintained at this temperature, ozone was introduced under vigorous stirring for 8 hours, after the reaction was completed, CuO / SiO2 (recovery) was filtered, the filtrate was transferred to a 1000ml stainless steel reactor, 0.4g palladium carbon catalyst was added, 2.0MPa hydrogen was charged, the temperature was raised to 80°C, the reaction was maintained under this condition for 4 hours, after the reaction was completed, palladium carbon (recovery) was filtered;

[0056] Catalyst application: 200.0g ethyl acetate, 40.0g dimerization by-product, and 2.0g CuO / SiO2 (recovery) catalyst were added to a 500ml three-necked flask in sequence, the reaction solution was cooled to 0°C, maintained at this temperature, and ozone was introduced under vigorous stirring for 8 hours. After the reaction was completed, CuO / SiO2 was filtered out, the filtrate was transferred to a 1000ml stainless steel reactor, and 0.4g palladium carbon (recovery) catalyst was added, 2.0MPa hydrogen was charged, the temperature was raised to 80°C, and the reaction was maintained under this condition for 4 hours. After the reaction was completed, palladium carbon was filtered out, and the obtained trimethylhydroquinone ethyl acetate solution was analyzed by chromatography, showing a dimerization by-product conversion rate of 92.1% and a trimethylhydroquinone selectivity of 97.8%.

[0057] When the present invention is used, ethyl acetate, dimerization byproduct and CuO / SiO2 catalyst are sequentially added into a three-necked flask, ozone is introduced to react, after the reaction is finished, CuO / SiO2 is filtered out, the filtrate is transferred into a stainless steel reactor, palladium carbon catalyst is added, hydrogen is introduced to react, after the reaction is finished, palladium carbon is filtered out to obtain trimethylhydroquinone ethyl acetate solution.

[0058] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

[0059] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing trimethylhydroquinone using a by-product of trimethylhydroquinone synthesis, characterized in that: The dimerized byproduct of the reaction of preparing trimethylhydroquinone from trimethylphenol is used as the raw material, and the dimerized byproduct is converted into trimethylhydroquinone by catalytic ozone oxidation with CuO / SiO2 catalyst and palladium-carbon catalytic hydrogenation. The chemical formula of the dimerized byproduct is The following steps are involved: Step 1: Add ethyl acetate, dimerization byproduct, and CuO / SiO2 catalyst in a three-necked flask in sequence, and introduce ozone to react; Step 2: After the reaction is completed, filter and remove CuO / SiO2; Step 3: Transfer the filtrate to a stainless steel reactor, add a palladium-carbon catalyst, and react after filling with hydrogen. After the reaction is completed, filter and remove the palladium-carbon to obtain a trimethylhydroquinone ethyl acetate solution.

2. The method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis by-product according to claim 1, characterized in that: The catalyst used in the ozone flow is CuO / SiO2.

3. The method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis by-product according to claim 1, characterized in that: The catalyst used when passing hydrogen is palladium carbon.

4. The method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis by-product according to claim 1, characterized in that: The mass ratio of the CuO / SiO2 to the dimerization byproduct is 0.5:100-1:

5.

5. The method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis by-product according to claim 1, characterized in that: The mass ratio of the palladium carbon to the dimerization by-product is 0.1:100-1:

10.

6. The method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis by-product according to claim 1, characterized in that: The ozone reaction temperature is between -20 and 20°C.

7. The method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis by-product according to claim 1, characterized in that: The hydrogen reduction temperature is between 30-10°C.

8. The method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis by-product according to claim 1, characterized in that: The hydrogen reduction pressure is between 0.5-5 MPa.

9. The method for preparing trimethylhydroquinone using trimethylhydroquinone synthesis by-product according to claim 1, characterized in that: After the reaction is completed, the CuO / SiO2 and palladium carbon recovered by filtration can be directly used for the next batch of reactions.

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