Preparation method of 2, 3, 5-trimethoxy hydroquinone diester

Abstract

The invention discloses a preparation method of 2, 3, 5-trimethylhydroquinone diester, which comprises the following steps: by taking 4-oxoisophorone KIP and acetic anhydride as raw materials, carrying out rearrangement reaction under the catalytic action of a solid acid catalyst, and carrying out light component removal and heavy component removal to obtain the 2, 3, 5-trimethylhydroquinone diester; wherein the content a% of key impurities o-KIP in 4-oxoisophorone KIP, the content b% of HIP and the content c% of DH-KIP meet the relation that b + c-a is larger than or equal to 0.05 and smaller than or equal to 0.1. The method provided by the invention is milder in process conditions, greatly improved in reaction selectivity, and capable of effectively reducing the production cost and the three-waste treatment capacity.

Description

Technical Field

[0001] The invention relates to a preparation method of 2,3,5-trimethylhydroquinone diester, and belongs to the technical field of organic synthesis. Background Art

[0002] 2,3,5-Trimethylhydroquinone diester is an important intermediate for the synthesis of the main ring of vitamin E. At the same time, its hydrolysis product 2,3,5-trimethylhydroquinone can be used as an antioxidant, dye and pharmaceutical intermediate, rubber antioxidant, inhibitor, developer, etc., and its industrialization prospects are very broad.

[0003] U.S. Patent No. 5,969,176A reports the use of a mixture of Lewis acid and Bronsted acid as a catalyst (e.g., a mixture of concentrated sulfuric acid and boric acid) to catalyze rearrangement acylation to prepare trimethylhydroquinone dialkanoate; U.S. Patent No. 6,350,897 reports the preparation of trimethylhydroquinone diester by reacting 4-oxoisophorone (KIP) in the presence of a sulfonating agent, a strong acid, and an acylating agent; Chinese Patent No. CN102180793A reports the use of α-isophorone as a raw material, reacting it with an acylating agent in the presence of a catalyst to obtain an ester of the enol isomer of isophorone, then adding a solvent DMSO, a heteropolyacid catalyst, and a base, blowing air, reacting to obtain a monoesterified product of ketoisophorone, and then reacting in the presence of acetic anhydride and a catalyst to obtain 2,3,5-trimethylhydroquinone diester.

[0004] The above patents and previous studies mainly focused on the optimization of the catalytic system and the screening of process routes, but the impact of key impurities in the raw materials on the rearrangement acylation reaction has not been studied in depth. Summary of the invention

[0005] The object of the present invention is to increase the selectivity of the reaction of KIP with acetic anhydride to prepare 2,3,5-trimethylhydroquinone diester in a simple manner.

[0006] The equation for the reaction of 4-oxoisophorone (KIP) with acetic anhydride to form 2,3,5-trimethylhydroquinone diester is as follows:

[0007]

[0008] The structural formula of the main impurities in KIP is as follows:

[0009]

[0010] The inventors have studied the above reaction and discovered the structure-activity relationship between the key impurities o-KIP, HIP, DH-KIP in the raw material KIP and the improvement of the selectivity and efficiency of the rearrangement acylation reaction.

[0011] To achieve the above invention objectives, the technical solutions of the present invention are as follows:

[0012] A method for preparing 2,3,5-trimethylhydroquinone diester, which uses 4-oxoisophorone (KIP) and acetic anhydride as raw materials, undergoes a rearrangement reaction under the catalytic action of a solid acid catalyst, and then undergoes light removal and heavy removal to obtain 2,3,5-trimethylhydroquinone diester;

[0013] Among them, the content of key impurity o-KIP a%, the content of HIP b%, and the content of DH-KIP c% in KIP must satisfy the following relationship:

[0014] 0.05≤b+ca≤0.1.

[0015] As an embodiment, preferably, the molar ratio of KIP to acetic anhydride is 1:2.5-10, preferably 1:3-5.

[0016] As an embodiment, preferably, the purity of KIP is above 99%, preferably 99.0%-99.5%.

[0017] As an embodiment, preferably, the type of solid acid catalyst can be carboxylic acid resin, sulfonic acid resin, phosphoric acid resin, phenolic resin, preferably sulfonic acid resin, preferably, the acid content in the sulfonic acid resin is 1%-4%, such as DuPont UP650, A1000, A1300, A2900, etc.

[0018] Preferably, the mass ratio of the solid acid catalyst to KIP is 1%-30%, preferably 5%-10%.

[0019] As an embodiment, preferably, the rearrangement reaction temperature is 25-100°C, preferably 40-70°C; the rearrangement reaction time is 4-12h, preferably 6-8h.

[0020] As an embodiment, preferably, the light removal of the reaction liquid is carried out in a light removal tower. The temperature of the bottom of the light removal tower is 90-150°C, the pressure of the top of the tower is 2-20 kPaA, the light components are extracted from the top of the tower, and the bottom liquid is then subjected to heavy removal treatment in a heavy removal tower.

[0021] Preferably, the temperature of the deweighting tower kettle is 150-200° C., the pressure at the top of the tower is 100-500 PaA, and 2,3,5-trimethylhydroquinone diester is obtained at the top of the tower.

[0022] As an implementation mode, preferably, the KIP satisfying 0.05≤b+ca≤0.1 is obtained by subjecting KIP to acid treatment, alkali treatment and distillation.

[0023] Preferably, the acid treatment uses a carboxylic acid resin (such as D113, D151, D152), the mass ratio of the carboxylic acid resin to KIP is 5-50:1, preferably 10-30:1; the acid treatment time is 2-10h, preferably 4-8h; the acid treatment temperature is 25-60°C, preferably 25-40°C.

[0024] Preferably, the alkali treatment uses a tertiary amine ion exchange resin (such as D301, D354, D370), the mass ratio of the tertiary amine ion exchange resin to KIP is 5-50:1, preferably 10-30:1; the alkali treatment time is 2-10h, preferably 4-8h; the alkali treatment temperature is 25-60°C, preferably 25-40°C.

[0025] Preferably, the temperature of the distillation tower bottom is 90-120°C, the pressure at the top of the tower is 10-20 hPaA, and the KIP at the top of the tower meets the requirements.

[0026] KIP raw materials that satisfy the above relationship can show better reaction selectivity under milder reaction conditions in the rearrangement acylation reaction. When b+ca is less than 0.05, the reaction selectivity remains basically unchanged, but the reaction efficiency deteriorates, and a higher reaction temperature is required; when b+ca is greater than 0.1, the reaction efficiency remains basically unchanged, but the reaction selectivity deteriorates.

[0027] The present invention adopts the above technical solution and has the following positive effects:

[0028] (1) The reaction selectivity is significantly improved, which can greatly reduce the amount of three wastes to be treated and reduce production costs;

[0029] (2) The reaction temperature is lower, which can significantly reduce the amount of public works and reduce production costs. DETAILED DESCRIPTION

[0030] In order to better understand the technical solution of the present invention, the following examples will further illustrate the method provided by the present invention, but the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the claims of the present invention.

[0031] The main raw materials used in the following examples and comparative examples are as follows:

[0032] Unpretreated KIP, produced by Wanhua, has a purity of 98.5%, including 0.45% o-KIP, 0.55% HIP, and 0.40% DH-KIP;

[0033] Acetic anhydride, analytical grade, Aladdin;

[0034] Sulfonic acid resin UP650, A1000, A1300, A2900, DuPont;

[0035] Carboxylic acid type resin D113, D151, D152, tertiary amine type resin D301, D354, D370, Purui Resin Company.

[0036] The gas chromatography reaction test conditions of the present invention are as follows:

[0037] (1) Chromatographic column: non-polar column, DB-5;

[0038] (2) Inlet temperature: 40°C;

[0039] (3) Split ratio: 1:10;

[0040] (4) Heating program: 40 °C for 0.5 min, then increase the temperature to 200 °C at a heating rate of 15 °C / min and hold for 2 min; then increase the temperature to 280 °C at a heating rate of 10 °C / min and hold for 2 min;

[0041] (5) Gas phase detector temperature: 220°C.

[0042] Example 1

[0043] 1) KIP pretreatment: Take the produced KIP (purity of 98.5%), the mass ratio of carboxylic acid resin D113 to KIP is 25:1, and the acid treatment operation is carried out at 30°C for 6 hours; the mass ratio of tertiary amine type D301 resin to KIP is 20:1, and the alkali treatment operation is carried out at 30°C for 5 hours. Then the acid-treated and alkali-treated KIP is distilled at 120°C and 20hPaA to obtain the pretreated KIP. The purity of the pretreated KIP is 99.41%, and the content of o-KIP, HIP and DH-KIP in the product is 0.22%, 0.20% and 0.10%. After calculation, b+ca=0.08.

[0044] 2) Rearrangement reaction and post-treatment: The pretreated KIP and acetic anhydride were added in a molar ratio of 1:3, and the amount of sulfonic acid solid acid catalyst UP650 was 5% of the mass of KIP. After reacting at 50°C for 7 hours, the light was removed at 150°C and 20kPaA, and the heavy was removed at 200°C and 500PaA to obtain the final trimethylhydroquinone diester product. Among them, the KIP conversion rate was 99.2%, the trimethylhydroquinone diester selectivity was 96.2%, and the product purity was 99.5%.

[0045] Example 2

[0046] 1) KIP pretreatment: Take the produced KIP (purity of 98.5%), the mass ratio of carboxylic acid resin D151 to KIP is 10:1, and the acid treatment operation is carried out at 25°C for 8 hours; the mass ratio of tertiary amine resin D354 to KIP is 30:1, and the alkali treatment operation is carried out at 50°C for 4 hours. Then the acid-treated and alkali-treated KIP is distilled at 90°C and 10hPaA to obtain the pretreated KIP. The purity of the pretreated KIP is 99.43%, and the content of o-KIP, HIP and DH-KIP in the product is 0.18%, 0.10% and 0.15%. After calculation, b+ca=0.07.

[0047] 2) Rearrangement reaction and post-treatment: The pretreated KIP and acetic anhydride were added in a molar ratio of 1:5, and the amount of sulfonic acid solid acid catalyst A1000 was 10% of the mass of KIP. After reacting at 40°C for 10 hours, the light residue was removed at 90°C and 2kPaA, and the heavy residue was removed at 150°C and 100PaA to obtain the final trimethylhydroquinone diester product. Among them, the conversion rate was 99.3%, the selectivity was 96.1%, and the product purity was 99.3%.

[0048] Example 3

[0049] 1) KIP pretreatment: Take the produced KIP (purity of 98.5%), the mass ratio of carboxylic acid resin D152 to KIP is 30:1, and the acid treatment operation is carried out at 50°C for 4 hours; the mass ratio of tertiary amine resin D370 to KIP is 10:1, and the alkali treatment operation is carried out at 25°C for 8 hours. Then the acid-treated and alkali-treated KIP is distilled at 100°C and 15hPaA to obtain the pretreated KIP. The purity of the pretreated KIP is 99.39%, and the content of o-KIP, HIP and DH-KIP in the product is 0.19%, 0.15% and 0.10%. After calculation, b+ca=0.06.

[0050] 2) Rearrangement reaction and post-treatment: The pretreated KIP and acetic anhydride were added in a molar ratio of 1:2.5, and the amount of sulfonic acid solid acid catalyst A1300 was 1% of the mass of KIP. After reacting at 70°C for 6 hours, the light residue was removed at 150°C and 20kPaA, and the heavy residue was removed at 180°C and 300PaA to obtain the final trimethylhydroquinone diester product. Among them, the conversion rate was 99.6%, the selectivity was 96.8%, and the product purity was 99.5%.

[0051] Example 4

[0052] 1) KIP pretreatment: Take the produced KIP (purity of 98.5%), add the carboxylic acid resin D151 and KIP in a mass ratio of 5:1, and perform acid treatment at 40°C for 10 hours; the mass ratio of tertiary amine resin D301 and KIP is 50:1, and perform alkali treatment at 60°C for 2 hours. Then distill the acid-treated and alkali-treated KIP at 120°C and 20hPaA to obtain the pretreated KIP. The purity of the pretreated KIP is 99.25%, and the content of o-KIP, HIP and DH-KIP in the product is 0.30%, 0.25% and 0.13%. After calculation, b+ca=0.08.

[0053] 2) Rearrangement reaction and post-treatment: The pretreated KIP and acetic anhydride were added in a molar ratio of 1:10, and the amount of sulfonic acid solid acid catalyst A2900 was 20% of the mass of KIP. After reacting at 25°C for 12 hours, the light fraction was removed at 90°C and 2kPaA, and the heavy fraction was removed at 150°C and 100PaA to obtain the final trimethylhydroquinone diester product. Among them, the conversion rate was 99.4%, the selectivity was 96.0%, and the product purity was 99.2%.

[0054] Example 5

[0055] 1) KIP pretreatment: Take the produced KIP (purity of 98.5%), the mass ratio of carboxylic acid resin D151 to KIP is 50:1, and the acid treatment operation is carried out at 60°C for 2h; the mass ratio of tertiary amine resin D301 to KIP is 5:1, and the alkali treatment operation is carried out at 40°C for 10h. Then the acid-treated and alkali-treated KIP is distilled at 90°C and 10hPaA to obtain the pretreated KIP. The purity of the pretreated KIP is 99.33%, and the content of o-KIP, HIP and DH-KIP in the product is 0.25%, 0.16% and 0.16%. After calculation, b+ca=0.07.

[0056] 2) Rearrangement reaction and post-treatment: The pretreated KIP and acetic anhydride were added in a molar ratio of 1:4, and the amount of sulfonic acid solid acid catalyst UP650 was 30% of the mass of KIP. After reacting at 100°C for 4 hours, the light product was removed at 100°C and 10kPaA, and the heavy product was removed at 180°C and 300PaA to obtain the final trimethylhydroquinone diester product. Among them, the conversion rate was 99.6%, the selectivity was 96.7%, and the product purity was 99.3%.

[0057] Example 6

[0058] 1) KIP pretreatment: Take the produced KIP (purity of 98.5%), add the carboxylic acid resin D152 and KIP in a mass ratio of 20:1, and perform acid treatment at 30°C for 5 hours; the mass ratio of tertiary amine resin D370 and KIP is 25:1, and perform alkali treatment at 30°C for 6 hours. Then distill the acid-treated and alkali-treated KIP at 100°C and 15hPaA to obtain the pretreated KIP. The purity of the pretreated KIP is 99.39%, and the content of o-KIP, HIP and DH-KIP in the product is 0.20%, 0.16% and 0.10%. After calculation, b+ca=0.06.

[0059] 2) Rearrangement reaction and post-treatment: The pretreated KIP and acetic anhydride were added in a molar ratio of 1:7, and the amount of sulfonic acid solid acid catalyst A1000 was 8% of the mass of KIP. After reacting at 80°C for 5 hours, the light residue was removed at 100°C and 10 kPaA, and the heavy residue was removed at 150°C and 100 PaA to obtain the final trimethylhydroquinone diester product. Among them, the reaction conversion rate was 99.1%, the reaction selectivity was 96.4%, and the product purity was 99.8%.

[0060] Comparative Example 1

[0061] Compared with Example 1, Comparative Example 1 did not pretreat KIP, and other conditions remained unchanged. The o-KIP content in the unpretreated KIP was 0.45%, the HIP content was 0.55%, and the DH-KIP content was 0.40%. After calculation, b+ca=0.50. The reaction conversion rate was 99.2%, the reaction selectivity was 85.1%, and the product purity was 96.2%.

[0062] Comparative Example 2

[0063] Compared with Example 1, in Comparative Example 2, KIP was not subjected to acid-base treatment, and other conditions remained unchanged. The purity of KIP after pretreatment was 99.12%. The o-KIP content, HIP content, and DH-KIP content in KIP without acid-base pretreatment were 0.20%, 0.30%, and 0.13%, respectively. After calculation, b+ca=0.23. The reaction conversion rate was 99.0%, the reaction selectivity was 90.1%, and the product purity was 97.2%.

[0064] Comparative Example 3

[0065] Compared with Example 1, in Comparative Example 3, only KIP was treated with alkali, and other conditions remained unchanged. The purity of KIP after pretreatment was 99.35%. The content of o-KIP, HIP and DH-KIP in KIP treated with alkali alone was 0.25%, 0.10% and 0.05%, respectively. After calculation, b+ca=-0.10. The reaction conversion rate was 96.2%, the reaction selectivity was 96.1% and the product purity was 98.2%.

[0066] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as limiting the present invention. Those skilled in the art will appreciate that, under the guidance of this specification, some modifications or adjustments may be made to the present invention. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A method for preparing 2,3,5-trimethylhydroquinone diester, which comprises taking KIP and acetic anhydride as raw materials, performing a rearrangement reaction under the catalytic action of a solid acid catalyst, and then removing the light and heavy components to obtain 2,3,5-trimethylhydroquinone diester; in, The content of impurity o-KIP a%, the content of HIP b%, and the content of DH-KIP c% in KIP satisfy the following relationship: 0.05≤b+ca≤0.

1.

2. The method according to claim 1, characterized in that The molar ratio of KIP to acetic anhydride is 1:2.5-10, preferably 1:3-5.

3. The method according to any one of claims 1 to 2, characterized in that: The purity of KIP is above 99%, preferably 99.0% to 99.5%.

4. The method according to any one of claims 1 to 2, characterized in that: The solid acid catalyst is selected from carboxylic acid resin, sulfonic acid resin, phosphoric acid resin, phenolic resin, preferably sulfonic acid resin.

5. The method according to claim 1 or 4, characterized in that: The mass ratio of the solid acid catalyst to KIP is 1%-30%, preferably 5%-10%.

6. The method according to any one of claims 1 to 5, characterized in that: The rearrangement reaction temperature is 25-100°C, preferably 40-70°C; the rearrangement reaction time is 4-12h, preferably 6-8h.

7. The method according to any one of claims 1 to 6, characterized in that: The temperature of the bottom of the tower for removing light components from the reaction liquid is 90-150°C, and the pressure at the top of the tower is 2-20kPaA. The light components are extracted from the top of the tower, and the bottom liquid is then subjected to heavy component removal treatment.

8. The method according to any one of claims 1 to 7, characterized in that: The temperature of the reactor of the reaction liquid deweighting tower is 150-200°C, the pressure at the top of the tower is 100-500 PaA, and 2,3,5-trimethylhydroquinone diester is obtained at the top of the tower.

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