CN104311407A - Environmental-friendly preparation process of 3,5,5-trimethyl-3-cyclohexene-1-ketone - Google Patents

Abstract

A kind of synthetic technique of 3,5,5-trimethyl-3-cyclohexen-1-ketone, it is characterized in that: with 3,5,5-trimethyl-2-cyclohexen-1-ketone ( α-IP) is a raw material, with alkaline ionic liquid as a catalyst, adopts reactive distillation technology to carry out isomerization reaction, and prepares a kind of 3,5,5-trimethyl-3-cyclohexene-1-ketone (β -IP), the reaction absolute pressure is 0.2-2Bar, the reaction temperature is 150-230°C, the purity of the product β-IP can reach 99.5wt%-99.8wt%, and the reaction selectivity can reach 99.2%-99.9%. The process has the advantages of high selectivity, no alkali precipitation, and easy recovery of the catalyst, and is a green and environmentally friendly synthesis process.

Description

A green preparation process of 3,5,5-trimethyl-3-cyclohexen-1-one

technical field

The invention relates to a green preparation process of 3,5,5-trimethyl-3-cyclohexen-1-one (β-IP), in particular to a preparation process of alkaline ionic liquid catalyzed synthesis of β-IP.

Background technique

3,5,5-Trimethyl-3-cyclohexen-1-one (β-IP) is an important intermediate for the synthesis of vitamin E, carotenoids, astaxanthin and other natural products and spices, especially The main raw material for the preparation of tea aroma ketone (2,6,6-trimethyl-2-cyclohexene-1,4-dione, KIP), tea aroma ketone is also the main raw material for the preparation of trimethylhydroquinone (VE main ring ) precursor.

β-IP and 3,5,5-trimethyl-2-cyclohexen-1-one (α-IP) are a pair of isomers, there is isomerism equilibrium under acid or base catalysis, β- IP can be prepared by isomerization of α-IP. However, since β-IP is an unstable structure, its equilibrium concentration is very low, and continuous extraction is required to break the equilibrium. At present, many documents have reported on the isomerization reaction. The catalytic types are mainly divided into two types: acid catalysis and base catalysis. The main processes are as follows:

German published patent DE 2457157 discloses the use of triethanolamine as a catalyst to carry out isomerization reaction with α-IP as a raw material, and the reaction solution is washed with tartaric acid and salt solution to prepare β-IP. The main disadvantage of this method is the reaction yield Low, complex post-treatment, more waste liquid, etc.

The U.S. published patent US 4845303 utilizes transition metal catalysts such as iron acetylacetonate and aluminum acetylacetonate to realize isomerization reaction. The main disadvantages of this process are: 1) low space-time yield of β-IP; 2) massive accumulation of by-products; 3) difficult separation of the catalyst from the homogeneous catalyst system.

French published patent FR 1446246, U.S. published patent US 5929285 and German published patent DE2508779 etc. respectively disclose a kind of isomerization reaction with organic acid as catalyst, which is used to prepare β-IP, and the solid acid involved is: teredipic acid , toluenesulfonic acid, amino acids, etc. The main disadvantages of this process are: 1) the conversion rate is low, 2) by-products are generated more, and 3) the equipment is severely corroded.

U.S. published patent US 6005147 reports the isomerization reaction catalyzed by Co ₃ 0 ₄ , the reaction temperature is 216-217 ° C, and the method for obtaining β-IP by vacuum distillation. The main disadvantages of this process are: 1) There are many by-products in the reaction , the self-condensation product of isophorone is obvious; 2) the conversion rate is low; 3) the catalyst is not easy to recycle.

Chinese published patent CN 1235954 and US published patent US 6265617 use alkali metal or alkaline earth metal compounds as catalysts to synthesize β-IP, and the catalysts involved mainly include NaOH, Na ₂ CO ₃ and the like. The main disadvantages of this process are: 1) because the catalyst used is alkali metal or alkaline earth metal hydroxide, carbonate and bicarbonate, etc., such strong alkali or strong alkali salt is easy to salt out, which seriously corrodes the reaction equipment; 2) the reaction There are many scraps produced in the process, and the catalyst is easily poisoned, and it is not easy to regenerate and recycle, and the formed by-products are also relatively serious for environmental pollution.

Chinese patent CN 1660752A takes α-IP as raw material, uses acidic ceramic material as separating agent and catalyst material, and carries out isomerization reaction in multistage reactor. high.

Under the synergistic effect of catalytic amount of FeCl ₃ and Grignard reagent RMgX, the isomerization reaction can also be promoted to synthesize β-IP. The main disadvantages of this process are: 1) the reaction conditions are relatively harsh, 2) the catalyst is expensive , 3) The post-processing is more complicated.

Most of the existing processes have the following disadvantages: 1) the catalyst cannot be recycled or used too much; 2) the space-time yield is not high; 3) the by-products accumulate more; 4) inorganic alkali catalysts are prone to alkali analysis, and equipment Serious corrosion; 5) transition metal catalysts are serious to environmental pollution.

Therefore, a new process needs to be found to solve various deficiencies in the prior art.

Contents of the invention

The object of the present invention is to provide a green preparation process of 3,5,5-trimethyl-3-cyclohexen-1-one (β-IP). The process uses alkaline ionic liquid as a catalyst, which has the advantages of high product yield, easy catalyst recovery, green environmental protection, and easy realization of industrial production. There are many by-products, serious equipment corrosion, and large environmental pollution.

For realizing above object of the invention, the technical scheme that the present invention adopts is as follows:

A kind of preparation technology of 3,5,5-trimethyl-3-cyclohexen-1-one, with 3,5,5-trimethyl-2-cyclohexen-1-one (α-IP) As raw material, using alkaline ionic liquid as catalyst, using reactive distillation technology, to prepare 3,5,5-trimethyl-3-cyclohexen-1-one (β-IP) by isomerizing α-IP .

In the present invention, the structural formula of the basic ionic liquid catalyst is A ⁺ B ⁻ , wherein, A ⁺ is a cationic unit, including but not limited to pyrrolidine cations, alkyl quaternary ammonium salt cations, quaternary phosphonium salt cations, Pyridine cations and imidazole cations, the structural formulas are B ^- is a basic anion unit, including but not limited to OH ^- , CO ₃ ^2- , HCO ₃ ^- , H ₂ PO ₄ ^- , HPO ₄ ^2- , carboxylic acid anion RCOO ^- and pyrrole anion Wherein, R, R', R", and R"' may be the same or different, each independently representing H, a chain alkyl group containing 1-20 carbon atoms or a cycloalkyl group containing 3-20 carbon atoms, It is preferably a chain alkyl group having 4 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms.

Preferably, in the preparation process of the present invention, the basic anion unit of the basic ionic liquid catalyst is OH ⁻ , carboxylic acid anion RCOO ⁻ or pyrrole anion Wherein, R, R', R", and R"' may be the same or different, each independently representing H, a chain alkyl group containing 1-20 carbon atoms or a cycloalkyl group containing 3-20 carbon atoms, It is preferably a chain alkyl group having 4 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms.

More preferably, in the present invention, the basic ionic liquid catalyst is selected from One or two or more of them, wherein Bu is n-butyl.

In the present invention, the amount of the catalyst is 0.001wt%-5wt%, preferably 0.01wt%-1wt% of the raw material 3,5,5-trimethyl-2-cyclohexen-1-one (α-IP) .

The reactive distillation process of the present invention is carried out in a tower reactor, the theoretical plate number of the reactor is 25-50, preferably 30-40, and the reflux ratio is 10:1-2:1. At room temperature, pre-mix the basic ionic liquid and the raw material α-IP, enter the tower reactor from the tower reactor, and then raise the temperature of the tower reactor to 150°C-230°C, α-IP is catalyzed by the alkaline ionic liquid, The isomerization reaction occurs, and since the boiling point of the generated product β-IP is 190°C, which is lower than that of the raw material α-IP at 215°C, the β-IP generated by the reaction is continuously distilled from the top of the tower, thereby making the isomerization The equilibrium of the constitutive reaction shifts towards the formation of β-IP.

During the reactive distillation process, the absolute pressure of the tower reactor is 0.2Bar-2Bar, preferably 0.5Bar-1Bar, the reactive distillation temperature is 150°C-230°C, preferably 170°C-220°C, and the reaction residence time is 24-150h. Preferably 50-100h. Collect and obtain the β-IP crude product that purity is 93wt%-95wt% at tower top,

The β-IP crude product collected at the top of the reaction distillation column reactor is further vacuum distillation product β-IP, the absolute pressure of vacuum distillation is 1.5KPa, and the theoretical plate number of vacuum distillation column is 25- 40, the reflux ratio is 3:1-5:1, and the tower top temperature is 62-69°C. In the preparation process of the present invention, the purity of the product β-IP can reach 99.5%-99.8% by weight, and the reaction selectivity can reach 99.2%-99.9%.

The present invention applies alkaline ionic liquid to the isomerization reaction of catalyzed α-IP, compared with the prior art, has the following advantages:

1) The basic ionic liquid is dispersed in the liquid phase in a homogeneous form. The basic ionic liquid can be dissolved in α-IP without adding other solvents, so it overcomes the problem of easy alkali precipitation of inorganic bases, and the product selectivity is high;

2) Alkaline ionic liquids have the characteristics of high temperature resistance, easy recycling, and environmental friendliness;

3) By changing the structure of the anion and cation units, the alkalinity and selectivity of the catalyst can be regulated. Compared with ordinary inorganic bases, the organic cation of this type of catalyst has greater steric hindrance, and the reaction intermediate of the catalyst is: Among them, the large steric hindered cation A ⁺ acts as a wall, blocking the combination of IP anion intermediates and other IP molecules, thereby inhibiting the formation of self-polymerization products, so it has high isomerization selectivity;

4) Reactive distillation technology is used to carry out the reaction, the operation process is simple, and the reaction can be carried out continuously;

5) The catalyst is quickly and efficiently recovered from the reaction system through water washing and extraction, which can realize the rapid separation of the alkaline ionic liquid catalyst and the reaction solution, and effectively solve the problem of separation of the catalyst. At the same time, the catalyst can be regenerated and used, so as to achieve the purpose of catalyst recycling and reuse, reduce the consumption of chemical reagents, and reduce the generation of "three wastes", which is a green and environmentally friendly preparation process.

Description of drawings

Figure 1 is a gas chromatographic analysis spectrum

Detailed ways

Gas phase analysis conditions: Agilent gas chromatography online determination, chromatographic column: polysiloxane column HP-5, gasification chamber temperature: 250°C, detector temperature: 250°C, temperature program: 50°C, 1min; 80°C, 1min ; 10°C/min to 250°C, 10min.

Example 1

The preparation method of basic ionic liquid used in the present invention

Anion potassium salt (K ⁺ B ^— , purchased from Bailingwei Technology) was added to the dichloromethane solution of ionic liquid bromide salt (A ⁺ Br ^— , purchased from Shanghai Chengjie Chemical Co., Ltd.), and vigorously stirred at room temperature for 10 hours, and then the precipitated potassium bromide (KBr) was removed by filtration. The filtrate was evaporated to remove the solvent, washed three times with ether, and finally dried at 90°C for 10 h to obtain the corresponding ionic liquid (A ⁺ B ^— ).

Example 2

Add the α-IP raw material containing 0.05wt% alkaline ionic liquid catalyst IL-A to the tower reactor of the tower reactor, carry out rectification reaction under the conditions of 210°C and 0.9Bar, α-IP isomerization reaction occurs, and stay After 24 hours, the reaction selectivity was 99.7%, and the crude product β-IP (purity 94wt%) was collected from the top of the tower. The crude product β-IP is subjected to further vacuum distillation under the conditions of 1.5KPa pressure, 30 trays, and 3:1 reflux ratio to obtain product β-IP with a purity of 99.5wt%. The gas phase analysis spectrum is shown in Figure 1 .

Example 3-10

On the basis of example 2, change catalyst type and consumption, temperature, pressure, reaction time, the results are shown in Table 1.

Among them, the structural formulas of the catalysts IL-F, IL-G, and IL-H are respectively

Example 11

For the catalyst IL-D in example 6, after utilizing water to carry out extraction recovery, remove water through decompression, repeat the condition of example 6: in the column reactor, add the α- The IP raw material stayed for 100 hours under the conditions of 230°C and 2.0 Bar, and the reaction selectivity was 99.6%. The selectivity did not change after the catalyst was recovered. The results are shown in Table 1.

Table 1 Example 2-11

The above specific implementation methods are not intended to limit the technical solution of the present invention in any form. All simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention fall within the protection scope of the present invention.

Claims (7)

1. A preparation process for 3,5,5-trimethyl-3-cyclohexen-1-one, using 3,5,5-trimethyl-2-cyclohexen-1-one as raw material, 3,5,5-trimethyl-3 is prepared by isomerizing 3,5,5-trimethyl-2-cyclohexen-1-one with alkaline ionic liquid as catalyst and reactive distillation technology - cyclohexen-1-one. 2. The preparation process according to claim 1, wherein the structural formula of the alkaline ionic liquid is A ^{+ B-} , wherein A ⁺ is a cationic unit selected from pyrrolidine cations, alkyl quaternary ammonium salts Cationoids, quaternary phosphonium salt cations, pyridine cations and imidazole cations, the structural formulas are B ^- is a basic anion unit, selected from OH ^- , CO ₃ ^2- , HCO ₃ ^- , H ₂ PO ₄ ^- , HPO ₄ ^2- , carboxylic acid anion RCOO ^- and pyrrole anion Wherein, R, R', R", R"' are the same or different, each independently represents H, a chain alkyl group containing 1-20 carbon atoms or a cycloalkyl group containing 3-20 carbon atoms, preferably A chain alkyl group containing 4-8 carbon atoms or a cycloalkyl group containing 5-8 carbon atoms. 3. preparation technique according to claim 2, is characterized in that, the basic anion unit of described alkaline ionic liquid is carboxylic acid anion ^RCOO- , ^OH- or pyrrole anion Wherein, R, R', R", R"' are the same or different, each independently represents H, a chain alkyl group containing 1-20 carbon atoms or a cycloalkyl group containing 3-20 carbon atoms, preferably A chain alkyl group containing 4-8 carbon atoms or a cycloalkyl group containing 5-8 carbon atoms. 4. preparation technology according to claim 3, is characterized in that, described alkaline ionic liquid catalyst is One or two or more of them, wherein Bu is n-butyl. 5. according to the preparation technology described in any one of claim 1-4, it is characterized in that, the consumption of described catalyst is 0.001wt of raw material 3,5,5-trimethyl-2-cyclohexen-1-one %-5wt%, preferably 0.01wt%-1wt%. 6. preparation technology according to claim 1 is characterized in that, described reactive distillation is carried out in tower reactor, and reactor theoretical plate number is 25-50, preferred 30-40; Reflux ratio is 10: 1-2:1. 7. The preparation process according to claim 1 or 6, characterized in that, the absolute pressure of the reactive distillation is 0.2Bar-2Bar, preferably 0.5Bar-1Bar; the reaction temperature is 150°C-230°C, preferably 170°C -220°C; the reaction residence time is 24-150h, preferably 50-100h.