A method for separating cyclohexanol and cyclohexene

Abstract

The present invention discloses a method for separating cyclohexanol and cyclohexene. Using mesotrione ethoxy pillar[6]arene crystal material as an adsorbent, the adsorbent is contacted with a mixture containing cyclohexanol and cyclohexene. The adsorbent selectively adsorbs cyclohexanol to achieve the separation of cyclohexanol and cyclohexene. The mesotrione ethoxy pillar[6]arene crystal material has the chemical structural formula as shown below. The separation process of cyclohexanol and cyclohexene in the present invention is simple in operation and has low equipment requirements; the separation process does not require rectification operation, has low energy consumption, no waste liquid or waste gas is generated during the production process, reducing the production cost of cyclohexanol; the crystal material used has high stability and can be recycled.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorption separation, and particularly relates to a method for separating cyclohexanol and cyclohexene. Background Art

[0002] Cyclohexanol is an important chemical raw material, mainly used in the production of adipic acid, hexamethylenediamine, cyclohexanone, caprolactam, and can also be used as a stabilizer for soaps, in the manufacture of disinfectant soaps and detergents, as a solvent for rubber, resins, nitrocellulose, metal soaps, oils, esters, ethers, as an admixture for coatings, a degreaser and demolding agent for leather, a dry cleaner, and a polishing agent. Cyclohexanol is also a raw material for fiber finishing agents, pesticides, and plasticizers, and is widely used in the synthesis field of fine chemicals such as pharmaceuticals and pesticides, with a large market demand.

[0003] There are two main production methods for cyclohexanol. The first is the phenol hydrogenation method, which is prepared using metallic nickel as a catalyst under the conditions of a temperature of 150°C and a pressure of 2.5 MPa. Due to the factor of the raw material price of this method, the second production method for cyclohexanol, the cyclohexene hydration method, has gradually replaced the phenol hydrogenation method. This method is green and economical, and the raw materials can be recycled because cyclohexene is a widely existing and easily obtainable chemical, which is more cost-saving than the relatively expensive phenol. Moreover, this method is carried out in the presence of a catalyst and does not require the use of hydrogen as a reducing agent like the phenol hydrogenation method. Therefore, in terms of environmental protection, the cyclohexene hydration method may be more favored. The cyclohexene hydration method can achieve high selectivity and yield by adjusting the reaction conditions and catalyst selection, which means fewer by-products and impurities, thus simplifying the subsequent purification steps. Compared with the phenol hydrogenation method, the process of the cyclohexene hydration method is relatively simple and does not require complex equipment and process conditions, which reduces the production cost and improves the production efficiency to a certain extent. Since the cyclohexene hydration method is a reversible reaction, the reaction equilibrium can be controlled by adjusting the reaction conditions and catalyst to achieve a higher cyclohexanol yield. In summary, compared with the phenol hydrogenation method, the cyclohexene hydration method has the advantages of low raw material cost, environmental friendliness, high reaction selectivity, simple process, and strong controllability. These advantages make the cyclohexene hydration method considered a more attractive and economically viable method for producing cyclohexanol in some cases. However, in the process of producing cyclohexanol, a mixture of cyclohexene and cyclohexanol will inevitably be produced. Separating the two by the traditional method of distillation is a very energy-consuming and uneconomical and environmentally unfriendly separation method.

[0004] The patent specification with the publication number CN112479808B discloses a method for directly hydrating cyclohexene to prepare cyclohexanol. In this method, o-cresol is used as a co-solvent, and under the action of an HZSM-5 molecular sieve catalyst, cyclohexene and water undergo a liquid-liquid two-phase hydration reaction to produce cyclohexanol. The obtained liquid-liquid two-phase is separated in a separator, and the aqueous phase carrying the catalyst and part of the co-solvent is returned to the reaction kettle. The oil phase is separated by a dividing-wall distillation column, while unreacted cyclohexene and the co-solvent o-cresol are recovered, and cyclohexanol is purified. The method for directly hydrating cyclohexene to prepare cyclohexanol provided by this patented technology has a short reaction time, a high cyclohexanol yield, good economy, and can be used for industrial production. Under preferred conditions, the cyclohexanol yield can reach 44.76%.

[0005] The patent specification with the publication number CN108997081A discloses a reactive distillation apparatus and separation method for hydrating cyclohexene to cyclohexanol. This apparatus includes four parts: a reactive distillation column, a settling separator, a separation column, and a liquid storage tank. In the reactive distillation column, steam and slurry contact reversely and generate intense agitation, thus realizing the cyclohexene hydration reaction process. The reaction products are separated by settling, and only the organic phase is added to the stripping section to inhibit the reverse reaction of cyclohexanol; in the settling separator, the aqueous phase and the organic phase are separated, and water and the catalyst can be recycled; in the separation column, cyclohexene, the co-solvent, and cyclohexanol are separated to obtain high-purity cyclohexanol, and cyclohexene and the co-solvent can be recycled; high-purity cyclohexanol is stored in the liquid storage tank. Using the apparatus and method of this invention can solve problems such as low single-pass conversion rate of cyclohexene and high reaction energy consumption in the cyclohexene hydration reaction. At the same time, it also has advantages such as the entire process can be continuously and stably operated, water and the catalyst can be recycled, and cyclohexene and the co-solvent can be recycled and utilized. Although this method optimizes the problem of high separation energy consumption in the past, the final separation effect of this method is not satisfactory. Summary of the Invention

[0006] The present invention provides a separation method for cyclohexanol and cyclohexene, which uses mesotrione ethoxy pillar[6]arene crystal material (P3QA) to adsorb and separate a mixture containing cyclohexanol and cyclohexene. This method has low energy consumption and a simple process, and can overcome problems existing in the separation technology of cyclohexanol and cyclohexene, such as high energy consumption, complicated process, and generation of waste liquid and waste gas during the production process.

[0007] The specific technical solution is as follows:

[0008] A separation method for cyclohexanol and cyclohexene, using mesotrione ethoxy pillar[6]arene crystal material as an adsorbent, contacting the adsorbent with a mixture containing cyclohexanol and cyclohexene, and the adsorbent selectively adsorbs cyclohexanol to achieve the separation of cyclohexanol and cyclohexene;

[0009] The mesotrione ethoxy pillar[6]arene crystal material has the following chemical structural formula:

[0010]

[0011] Due to the difference in the molecular structures of cyclohexanol and cyclohexene, the mesotrione ethoxylated pillar[6]arene crystal material (P3QA) can form a host-guest complex with cyclohexanol with a stoichiometric ratio of 1:1. This host-guest complex is unstable and will gradually desorb upon heating, releasing the adsorbed cyclohexanol. The mesotrione ethoxylated pillar[6]arene crystal material (P3QA) is stable at the desorption temperature and can be reused after the desorption process is completed.

[0012] The mesotrione ethoxylated pillar[6]arene and its preparation method used in the present invention have been disclosed in the prior art. For example, see the prior art Commun Chem 3, 117 (2020). https: / / doi.org / 10.1038 / s42004-020-00363-4.

[0013] The present invention provides a method for preparing the mesotrione ethoxylated pillar[6]arene crystal material, including: under a nitrogen atmosphere, placing diethoxylated pillar[6]arene in a mixed solution of dichloromethane and tetrahydrofuran, dropping ammonium cerium nitrate, after the reaction is completed, the reaction solution is extracted multiple times with dichloromethane and water to remove ammonium cerium nitrate in the aqueous phase, the organic phase is rotary evaporated, purified by column chromatography, and the obtained pure product is heated under vacuum for activation after rotary evaporation to obtain the mesotrione ethoxylated pillar[6]arene crystal material. The activated mesotrione ethoxylated pillar[6]arene crystal material (P3QA) can be directly used for the adsorption separation of a mixture containing cyclohexanol and cyclohexene.

[0014] In the method for preparing the mesotrione ethoxylated pillar[6]arene crystal material, the following one or more combinations of technical solutions can be preferably carried out:

[0015] The molar ratio of the diethoxylated pillar[6]arene to the ammonium cerium nitrate is 1:6.5 - 7;

[0016] The polar solvent used for the column chromatography purification is a mixed solvent of ethyl acetate and petroleum ether with a volume ratio of 1:4;

[0017] The temperature of the heating under vacuum for activation is not lower than 100 °C, and the time can be determined according to the situation, for example, it can be not less than 12 hours.

[0018] In one embodiment, the method for separating cyclohexanol and cyclohexene of the present invention is specifically as follows: placing the mesotrione ethoxylated pillar[6]arene crystal material in a mixed vapor atmosphere containing cyclohexanol and cyclohexene, with the temperature not higher than 30°C. The adsorption time can be changed with factors such as the sample amount, adsorption temperature, and the proportion of cyclohexanol in the mixture. During the adsorption process, the crystal form of the mesotrione ethoxylated pillar[6]arene crystal material (P3QA) does not change. Due to weak interactions such as CH-π interaction and π-π stacking, cyclohexanol in the mixed vapor will form a host-guest complex with the mesotrione ethoxylated pillar[6]arene, and the stoichiometric ratio of this host-guest complex is 1:1.

[0019] In one embodiment, after the adsorbent contacts the mixture containing cyclohexanol and cyclohexene, the method for separating cyclohexanol and cyclohexene of the present invention further includes removing the mixture adsorbed on the surface of the adsorbent by heating under normal pressure.

[0020] The temperature of the heating under normal pressure may not exceed 60°C, and the time can be adjusted according to the sample amount. Under the condition of not exceeding 60°C, the host-guest complex still exists stably, while the mixture containing cyclohexanol and cyclohexene adsorbed on the surface can be gradually removed. By removing the mixture adsorbed on the surface, the purity of the cyclohexanol separated by adsorption is improved.

[0021] In one embodiment, after removing the mixture adsorbed on the surface of the adsorbent by heating under normal pressure, the method for separating cyclohexanol and cyclohexene of the present invention further includes heating and desorbing the cyclohexanol adsorbed and complexed by the adsorbent to regenerate the adsorbent.

[0022] The temperature of the heating desorption may not be lower than 100°C, and the time can be adjusted according to the sample amount. At this temperature, the host-guest complex is unstable, and the cyclohexanol molecules adsorbed and complexed will be gradually released, while the mesotrione ethoxylated pillar[6]arene crystal material (P3QA) is stable and its crystal form does not change during the desorption process. After the desorption is completed, the regenerated mesotrione ethoxylated pillar[6]arene crystal material (P3QA) is obtained, which can be used to adsorb and separate cyclohexanol and cyclohexene again for the next cycle.

[0023] As a general inventive concept, the present invention also provides the application of the mesotrione ethoxylated pillar[6]arene crystal material as an adsorbent to selectively adsorb cyclohexanol from a mixture containing cyclohexanol and cyclohexene to achieve the separation of cyclohexanol and cyclohexene. The optional or preferred solutions in the application can refer to the relevant introduction of the above method for separating cyclohexanol and cyclohexene.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: The separation process of cyclohexanol and cyclohexene is simple in operation and has low equipment requirements; the separation process does not require rectification operation, has low energy consumption, no waste liquid or waste gas is generated during the production process, and the production cost of cyclohexanol is reduced; the crystal material used has high stability and can be recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 1H NMR spectrum of P3QA prepared in Example 1; 1 H NMR

[0026] Figure 2 High-resolution mass spectrum (HRMS) of P3QA prepared in Example 1;

[0027] Figure 3 Powder X-ray diffraction (PXRD) patterns of the meta-trisquinone ethoxylated pillar[6]arene crystal material (P3QA) in Examples 1 to 5. In the figure, line a is the single crystal simulation diagram of P3QA after adsorbing cyclohexanol;

[0028] Figure 4 Gas chromatography characterization result diagram of the adsorption separation of cyclohexanol and cyclohexene by the meta-trisquinone ethoxylated pillar[6]arene crystal material (P3QA) in Example 4;

[0029] Figure 5 Effect diagram of the adsorption separation of cyclohexanol and cyclohexene when the meta-trisquinone ethoxylated pillar[6]arene crystal material (P3QA) in Example 5 is recycled. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0031] The operating methods not specified in the following embodiments are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0032] Example 1

[0033] Preparation of mesotrione ethoxycalix[6]arene crystal material (P3QA): Weigh 0.5 g of diethoxycalix[6]arene and place it in a 150 mL mixed solution of dichloromethane / tetrahydrofuran = 1:1 (volume ratio). Under the condition of nitrogen atmosphere at room temperature, add dropwise 15 mL of an aqueous solution of ammonium cerium nitrate (3.08 mmol, 6.6 equiv) until the solution turns into a dark red oily substance. Let the solution react overnight at room temperature and perform TLC detection. If there are a large number of product spots, extract the reaction solution with dichloromethane and water multiple times to remove ammonium cerium nitrate in the aqueous phase. Spin-dry the organic phase, purify it by column chromatography (the polar solvent is a mixed solvent of ethyl acetate and petroleum ether with a volume ratio of 1:4), spin-dry the obtained pure product, and then dry it under vacuum at 100 °C to obtain an orange-red powder, denoted as P3QA.

[0034] The characterization data of the product prepared in this example are as follows:

[0035] See Figure 1 , P3QA, 1 H NMR (600 MHz, Chloroform-d) δ 6.66 (s, 6H), 6.51 (s, 6H), 3.90 (q, J = 7.0 Hz, 12H), 3.60 (d, J = 1.3 Hz, 12H), 1.32 (t, J = 6.9 Hz, 18H).

[0036] See Figure 2 , HRMS (ESI) m / z [P3QA·Na + Calculated for C 54 H 54 O 12 Na is 917.3513, and the actually measured result is 917.3506 (error: 0.0007 ppm).

[0037] The PXRD detection result is as shown by the e line in Figure 3 . The obtained mesotrione ethoxycalix[6]arene crystal material (P3QA) has good crystallinity.

[0038] Example 2

[0039] Adsorption of mesotrione ethoxycalix[6]arene crystal material (P3QA) on cyclohexanol or cyclohexene alone: Take two 20 mL culture bottles, add 1 mL of cyclohexanol and 1 mL of cyclohexene respectively, and name them P3QA-chun and P3QA-xi. Take 10 mg of the mesotrione ethoxycalix[6]arene crystal material (P3QA) prepared in Example 1 and place it in two 5 mL culture bottles respectively. Place the two open 5 mL culture bottles in the two 20 mL culture bottles respectively, seal the 20 mL culture bottles well, and place them in an oven at 30 °C for 24 hours.

[0040] The characterization data of the product prepared in this example are as follows:

[0041] P3QA-chun, 1 H NMR(400MHz,Chloroform-d)δ6.66(s,6H),6.51(s,6H),3.90(q,J=7.0Hz,12H),3.60(d,J=1.3Hz,12H),1.89(d,J=8.3Hz,5H),1.73(d,J=4.9Hz,7H),1.32(t,J=6.9Hz,18H).

[0042] P3QA-xi, 1 H NMR(500MHz,Chloroform-d)δ6.66(s,6H),6.51(s,6H),5.67(t,J=1.7Hz,1H),3.90(q,J=7.0Hz,12H),3.60(d,J=1.3Hz,12H),1.32(t,J=6.9Hz,18H).

[0043] 1 The H NMR results indicate that the mesotrione ethoxy column [6]arene crystal material (P3QA) adsorbed cyclohexanol in a stoichiometric ratio of 1:1, and adsorbed very little cyclohexene.

[0044] The PXRD test results of P3QA-xi are as Figure 3 shown by the d line in. The PXRD test results of P3QA-chun are as Figure 3 shown by the c line in. The spectrum of the mesotrione ethoxy column [6]arene crystal material (P3QA) after being placed in cyclohexanol vapor for a period of time did not change, indicating that its unit cell parameters did not change, meaning that the crystal structure of the mesotrione ethoxy column [6]arene crystal material (P3QA) did not change after adsorbing cyclohexanol.

[0045] Example 3

[0046] Adsorption of the 1:1 mixture of cyclohexanol and cyclohexene by the mesotrione ethoxy column [6]arene crystal material (P3QA): Take a 20 mL culture bottle, add 0.5 mL of cyclohexanol and 0.5 mL of cyclohexene, name it P3QA-hunhe, take 10 mg of the mesotrione ethoxy column [6]arene crystal material (P3QA) prepared in Example 1 and place it in a 5 mL culture bottle, place the open 5 mL culture bottle in the above 20 mL culture bottle, seal the 20 mL culture bottle, place it in an oven at 30 °C for 24 hours, and place the obtained powder in an oven at 60 °C for 30 minutes.

[0047] The characterization data of the product prepared in this example are as follows:

[0048] P3QA-mixture, 1 H NMR (400 MHz, Chloroform-d) δ 6.66 (s, 6H), 6.51 (s, 6H), 3.90 (q, J = 7.0 Hz, 12H), 3.60 (d, J = 1.3 Hz, 12H), 1.89 (d, J = 8.3 Hz, 5H), 1.73 (d, J = 4.9 Hz, 7H), 1.32 (t, J = 6.9 Hz, 18H).

[0049] In 1 the 1H NMR spectrum, only the signals of the hydrogen atoms corresponding to cyclohexanol were found, indicating that the mesotrione ethoxycalix[6]arene crystal material (P3QA) can selectively adsorb cyclohexanol.

[0050] The PXRD test results are as Figure 3 shown by line b in the figure. Compared with the PXRD spectrum of the initially activated mesotrione ethoxycalix[6]arene crystal material (P3QA), the PXRD spectrum of the mesotrione ethoxycalix[6]arene crystal material (P3QA) after being placed in the mixed vapor of cyclohexanol and cyclohexene for a period of time did not change, indicating that the crystal structure of the mesotrione ethoxycalix[6]arene crystal material (P3QA) did not change after selectively adsorbing cyclohexanol.

[0051] The results of headspace gas chromatography are as Figure 4 , and the results show that the mesotrione ethoxycalix[6]arene crystal material (P3QA) can selectively adsorb cyclohexanol, and its selectivity is 95.2%.

[0052] Example 4

[0053] Regeneration of the mesotrione ethoxycalix[6]arene crystal material (P3QA): 10 mg of the mesotrione ethoxycalix[6]arene crystal material (P3QA) saturated with cyclohexanol in Example 3 was heated in a vacuum oven at 100 °C for 12 hours, and the sample was denoted as P3QA-ZK.

[0054] The characterization data of the product prepared in this example are as follows:

[0055] P3QA-ZK, 1H NMR (600 MHz, Chloroform-d) δ 6.66 (s, 6H), 6.51 (s, 6H), 3.90 (q, J = 7.0 Hz, 12H), 3.60 (d, J = 1.3 Hz, 12H), 1.32 (t, J = 6.9 Hz, 18H).

[0056] In 1In the ¹H NMR spectrum, the signal of the hydrogen atoms corresponding to cyclohexanol has disappeared, indicating that the desorption regeneration of the mesotrione ethoxy column[6]arene crystal material (P3QA) has been completed and all cyclohexanol molecules have been released.

[0057] Example 5

[0058] Reuse of the mesotrione ethoxy column[6]arene crystal material (P3QA): Repeat Examples 3 and 4 with 10 mg of the regenerated mesotrione ethoxy column[6]arene crystal material (P3QA) from Example 4.

[0059] The results of headspace gas chromatography show that, as Figure 5 , the mesotrione ethoxy column[6]arene crystal material (P3QA) can selectively adsorb cyclohexanol with a selectivity as high as 95.2%. The selectivity can still be maintained above 85% after being reused 5 times.

[0060] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A method for separating cyclohexanol and cyclohexene, characterized in that, Using the 1,3,5-tris(quinone-ethoxy)calix[6]arene crystal material as an adsorbent, contacting the adsorbent with a mixture containing cyclohexanol and cyclohexene, and the adsorbent selectively adsorbs cyclohexanol to achieve the separation of cyclohexanol and cyclohexene; The 1,3,5-tris(quinone-ethoxy)calix[6]arene crystal material has the chemical structural formula shown as follows: The preparation method of the 1,3,5-tris(quinone-ethoxy)calix[6]arene crystal material includes: under a nitrogen atmosphere, placing diethoxycalix[6]arene in a mixed solution of dichloromethane and tetrahydrofuran, dropping ammonium cerium nitrate, after the reaction ends, extracting the reaction solution with dichloromethane and water for multiple times to remove ammonium cerium nitrate in the aqueous phase, rotary evaporating the organic phase, purifying by column chromatography, and heating and evacuating the obtained pure product under vacuum for activation to obtain the 1,3,5-tris(quinone-ethoxy)calix[6]arene crystal material; the temperature of the heating and evacuating activation is not lower than 100 °C; The specific separation method is: placing the 1,3,5-tris(quinone-ethoxy)calix[6]arene crystal material in a mixed vapor atmosphere containing cyclohexanol and cyclohexene, and the temperature is not higher than 30 °C; After the adsorbent contacts with the mixture containing cyclohexanol and cyclohexene, the separation method further includes removing the mixture adsorbed on the surface of the adsorbent by heating under atmospheric pressure; the temperature of the heating under atmospheric pressure does not exceed 60 °C; After removing the mixture adsorbed on the surface of the adsorbent by heating under atmospheric pressure, the separation method further includes heating and desorbing the cyclohexanol adsorbed and complexed by the adsorbent to realize the regeneration of the adsorbent; the temperature of the heating and desorbing is not lower than 100 °C.

2. The separation method according to claim 1, wherein In the preparation method of the 1,3,5-tris(quinone-ethoxy)calix[6]arene crystal material: The molar ratio of the diethoxycalix[6]arene to the ammonium cerium nitrate is 1:6.5 - 7; The polar solvent used for the column chromatography purification is a mixed solvent of ethyl acetate and petroleum ether with a volume ratio of 1:

4.

3. Application of mesotrione ethoxylated pillar[6]arene crystal material as an adsorbent to selectively adsorb cyclohexanol from a mixture containing cyclohexanol and cyclohexene to achieve the separation of cyclohexanol and cyclohexene, characterized in that, The 1,3,5-tris(quinone-ethoxy)calix[6]arene crystal material has the chemical structural formula shown as follows:

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