Preparation method of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol with high cis-trans ratio

Abstract

The present invention provides a high cis-trans ratio 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol preparation method, which comprises: mixing 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanedione, a catalyst and a mixed solvent, and carrying out a hydrogenation reaction to obtain the high cis-trans ratio 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol, the mixed solvent comprises a first solvent and a second solvent; the first solvent comprises any one of diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, anisole, neopentyl glycol or 1, 2-butanediol or a combination of at least two of the diethylene glycol dimethyl ether, the triethylene glycol dimethyl ether, the anisole, the neopentyl glycol and the 1, 2-butanediol. According to the method, 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanedione is used as a raw material and is subjected to a hydrogenation reaction in a catalyst and mixed solvent system, and on the premise that the high conversion rate of TMCD and the high selectivity of the CBDO product are ensured, the CBDO product with the high cis-trans ratio can be prepared through a one-step method.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic chemical synthesis and relates to a method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol with a high cis / trans ratio. Background Art

[0002] As an important aliphatic monomer, 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) is an important raw material for the production of high-performance copolyester products. This polymer has the advantages of high transparency, high impact strength, high glass transition temperature, and good toughness. In addition, due to the release of bisphenol A during the degradation of polycarbonate (PC) resin, which causes environmental hazards such as endocrine system disorders in humans, PC resin is restricted or prohibited in some regions. The copolyester product based on CBDO is an important substitute for polycarbonate (PC) resin, which is green and environmentally friendly and has a broad market prospect.

[0003] At present, the industrial production technology of CBDO mainly uses the route of isobutyric anhydride as the raw material. In the first stage, isobutyric anhydride undergoes thermal cracking to produce dimethylketene, and then dimerizes into 2,2,4,4-tetramethyl-1,3-cyclobutanedione (TMCD). TMCD is catalytically hydrogenated to obtain CBDO.

[0004] CBDO has a symmetric structure, namely cis and trans isomers. Cis-CBDO has a non-planar structure with a dihedral angle of 17.5°, and trans-CBDO is a planar structure with a dihedral angle of 0° (as shown in the following formula). The raw material composition of CBDO with different cis / trans molar ratios affects the polymerization reaction process of copolyester products and the physical and chemical properties of resin products to a certain extent.

[0005]

[0006] US20080132739A1 and US7524994B2 disclose cobalt-based and cobalt-iridium modified alumina-supported catalysts, 10% TMCD / isobutyl isobutyrate, with a selectivity of CBDO above 88%, and a CBDO product with a cis / trans ratio of 0.4 - 1.2 is obtained. CN105732329B discloses a Cu-Zn-Cr-based alumina-supported catalyst, 7.3% TMCD / dimethyl 1,4-cyclohexanedicarboxylate, with a selectivity of CBDO of 85.8% and a CBDO product with a cis / trans ratio of 0.5 - 1.5 is obtained. CN114349596A discloses a Ru-In-based alumina-supported catalyst, 10% TMCD / methanol, with a selectivity of CBDO of about 99% in a batch high-pressure reaction. However, most of the cis / trans ratios of the above-prepared CBDO products are within 0.4 - 2.

[0007] CN107001198A and CN107001204A disclose that the hydrogenated CBDO mixture after the hydrogenation reaction is used as the raw material (the cis / trans ratio is about 1), dissolved in a light alkane or isoparaffin solvent and an aqueous solvent, and then a Ru-based catalyst is added, and the hydrogenation reaction is carried out in a autoclave reactor to obtain a CBDO product with a cis / trans ratio of 2-25. CN112023919A discloses a dual-catalyst combination method of a hydrogenation catalyst and an isomerization catalyst. The hydrogenation catalyst and the isomerization catalyst are respectively filled in the middle positions of a fixed-bed hydrogenation reactor and an isomerization reactor. The selectivity of CBDO is more than 99%, and a CBDO product with a cis / trans ratio of 32.18 is obtained. CN112023919B discloses a catalyst Ru / BINAP-POP catalyst constructed with a low metal loading (0.01-1%), the size controlled at the atomic level (0.01 -1 nm), and the carrier being a porous organic polymer. For 10% TMCD / (isobutyl isobutyrate + 2-methyl-heptane), the selectivity of CBDO in the autoclave high-pressure reaction is more than 99%, and a CBDO product with a cis / trans ratio of 31.03 is obtained.

[0008] Although the method of combining a hydrogenation catalyst and an isomerization catalyst can significantly increase the molar ratio of cis / trans CBDO products in the reaction material, adding an isomerization reaction unit requires an increase in equipment investment and catalyst cost; in addition, a CBDO product with a high cis / trans ratio can also be obtained by preparing an atomic-level catalyst, but the carrier of its catalyst is difficult to obtain, which potentially restricts its industrial application.

[0009] In summary, providing a preparation method of a high cis / trans ratio CBDO product with low raw material cost, simple operation and economic efficiency is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0010] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a preparation method of 2,2,4,4-tetramethyl-1,3-cyclobutanediol with a high cis / trans ratio. Using 2,2,4,4-tetramethyl-1,3-cyclobutanedione as the raw material, the hydrogenation reaction is carried out under a catalyst and a mixed solvent system. On the premise of ensuring a high conversion rate of TMCD and a high selectivity of the CBDO product, a CBDO product with a high cis / trans ratio can be obtained by a one-step method.

[0011] To achieve the purpose of the present invention, the following technical solutions are adopted:

[0012] The present invention provides a preparation method of 2,2,4,4-tetramethyl-1,3-cyclobutanediol with a high cis / trans ratio, characterized in that the preparation method includes:

[0013] Mix 2,2,4,4 - tetramethyl - 1,3 - cyclobutanedione, a catalyst, and a mixed solvent, and carry out a hydrogenation reaction to obtain 2,2,4,4 - tetramethyl - 1,3 - cyclobutanediol with a high cis - to - trans ratio;

[0014] The mixed solvent includes a first solvent and a second solvent; the first solvent includes any one or a combination of at least two of diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, anisole, neopentyl glycol, or 1,2 - butanediol.

[0015] The preparation method provided by the present invention uses TMCD as a raw material to carry out a hydrogenation reaction under a catalyst and a mixed solvent system. On the premise of ensuring a high conversion rate of TMCD and a high selectivity of the CBDO product, it not only realizes the rapid hydrogenation of cis - CBDO, but also obtains a CBDO product with a high cis - to - trans ratio through only one - step method. Compared with the traditional two - step method of hydrogenation catalysis and isomerization catalysis, the preparation method is simple in operation, low in raw material cost, economically efficient, and easy to scale up production.

[0016] It should be noted that through the synergistic compounding of the first solvent and the second solvent and the specific screening of the components of the first solvent, the dielectric constant of the mixed solvent is adjusted, and then the polarity of the mixed solvent is changed. Through the principle of similar - phase solubility, the cis - structured CBDO product is rapidly detached from the catalyst surface, obtaining a higher cis - structured CBDO product and improving the cis - to - trans ratio in the CBDO product.

[0017] As a preferred technical solution of the present invention, the mass ratio of 2,2,4,4 - tetramethyl - 1,3 - cyclobutanedione to the mixed solvent is 1:(18 - 22), for example, it can be 1:18.5, 1:19, 1:19.5, 1:20, 1:20.5, 1:21, or 1:21.5, etc., but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0018] As a preferred technical solution of the present invention, the second solvent includes any one or a combination of at least two of other alcohols, alkanes, or esters.

[0019] Preferably, the other alcohols include any one or a combination of at least two of methanol, ethanol, ethylene glycol, propanol, butanol, or 1,6 - hexanediol.

[0020] Preferably, the alkane includes cyclohexane and / or an alkane having at least 5 carbon atoms.

[0021] In the present invention, the alkane having at least 5 carbon atoms includes, but is not limited to, pentane, hexane, or heptane, etc.

[0022] Preferably, the esters include any one or a combination of at least two of ethyl acetate, butyl acetate, isobutyl isobutyrate, or isobutyl acetate.

[0023] As a preferred technical solution of the present invention, based on the total mass of the mixed solvent being 100 wt%, the content of the first solvent is 50 - 100 wt% and does not include 100 wt%, for example, it can be 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt% or 95 wt% etc., but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable, preferably 70 - 90 wt%.

[0024] It is worth noting that using a mixed solvent system with the first solvent as the main solvent and the second solvent as the auxiliary solvent is not only beneficial to the rapid hydrogenation of cis-CBDO, but also beneficial to improving the cis-trans ratio in the CBDO product.

[0025] As a preferred technical solution of the present invention, the catalyst includes a carrier and an active component supported on the carrier.

[0026] Preferably, the active component includes any one or a combination of at least two of Pt, Pd, Au or Ru, preferably Pt.

[0027] In the present invention, the raw materials of the active component include any one or a combination of at least two of chlorides, nitrates, chlorates, acetates or oxalates of Pt, Pd, Au or Ru.

[0028] Preferably, the carrier includes any one or a combination of at least two of γ-Al2O3, activated carbon, carbon nanotubes, titanium dioxide, silicon dioxide, zirconium dioxide, molecular sieves or porous polymers, preferably activated carbon.

[0029] Preferably, based on the total mass of the catalyst being 100 wt%, the content of the active component is 0.1 - 30 wt%, for example, it can be 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 10 wt%, 15 wt%, 20 wt% or 25 wt% etc., but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable, preferably 3 - 8 wt%.

[0030] Preferably, the preparation method of the catalyst includes an impregnation reduction method or a wet adsorption reduction method, preferably the wet adsorption reduction method.

[0031] In the present invention, the relevant parameters of the catalyst preparation method are not specifically limited, and those skilled in the art can adjust according to their own experience as long as the content of the active component in the prepared catalyst is 0.1 - 30 wt%.

[0032] As a preferred technical solution of the present invention, after mixing and before the hydrogenation reaction, it further includes: alternately introducing nitrogen and hydrogen to displace air, and then continuously introducing hydrogen to a set pressure value.

[0033] In the present invention, the displacement needs to be carried out at least 3 times to ensure that the air in the reaction kettle is completely displaced.

[0034] As a preferred technical solution of the present invention, the hydrogenation reaction is carried out under stirring.

[0035] Preferably, the temperature of the hydrogenation reaction is 50-180 °C, for example, it can be 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C or 170 °C, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable, preferably 80-120 °C.

[0036] Preferably, the pressure of the hydrogenation reaction is 1-10 MPa, for example, it can be 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa or 9 MPa, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable, preferably 3-5 MPa.

[0037] Preferably, the heat preservation time of the hydrogenation reaction is 0.1-10 h, for example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h or 9 h, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable, preferably 1-3 h.

[0038] As a preferred technical solution of the present invention, post-treatment is also carried out after the hydrogenation reaction.

[0039] Preferably, the post-treatment includes: cooling the reaction solution after the reaction ends to room temperature, then performing a first separation, and performing a second separation on the filtrate obtained from the first separation to obtain 2,2,4,4-tetramethyl-1,3-cyclobutanediol with a high cis-trans ratio.

[0040] Preferably, the method of the first separation includes filtration.

[0041] In the present invention, the catalyst in the reaction solution can be separated by filtration.

[0042] Preferably, the method of the second separation includes freeze crystallization or distillation, preferably freeze crystallization.

[0043] Preferably, the temperature of the freeze crystallization is -50 to 0 °C, for example, it can be -45 °C, -40 °C, -35 °C, -30 °C, -25 °C, -20 °C, -15 °C, -10 °C or -5 °C, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable, preferably -20 to -10 °C.

[0044] In the present invention, the rapid separation of the mixed solvent and the CBDO product can be achieved by means of freeze crystallization.

[0045] As a preferred technical solution of the present invention, the cis / trans ratio of the 2,2,4,4-tetramethyl-1,3-cyclobutanediol is ≥8, for example, it can be 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or 22, etc., but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0046] In the present invention, on the premise of ensuring a high conversion rate of TMCD and a high selectivity of the CBDO product, the purpose of cis / trans ratio ≥8 in the CBDO product can still be achieved.

[0047] As a preferred technical solution of the present invention, the preparation method includes:

[0048] Mix 2,2,4,4-tetramethyl-1,3-cyclobutanedione, a catalyst and a mixed solvent, and successively carry out a hydrogenation reaction and a post-treatment to obtain 2,2,4,4-tetramethyl-1,3-cyclobutanediol with a cis / trans ratio ≥8;

[0049] The mass ratio of the 2,2,4,4-tetramethyl-1,3-cyclobutanedione to the mixed solvent is 1:(18 - 22);

[0050] The mixed solvent includes a first solvent and a second solvent; the first solvent includes any one or a combination of at least two of diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, anisole, neopentyl glycol or 1,2-butanediol; the second solvent includes any one or a combination of at least two of other alcohols, alkanes or esters; based on the total mass of the mixed solvent being 100 wt%, the content of the first solvent is 50 - 100 wt% and does not include 100 wt%;

[0051] The catalyst includes a carrier and an active component supported on the carrier; the active component includes any one or a combination of at least two of Pt, Pd, Au or Ru; the carrier includes any one or a combination of at least two of γ-Al2O3, activated carbon, carbon nanotubes, titanium dioxide, silicon dioxide, zirconium dioxide, molecular sieve or porous polymer; based on the total mass of the catalyst being 100 wt%, the content of the active component is 0.1 - 30 wt%;

[0052] After the mixing, before the hydrogenation reaction, it further includes: alternately introducing nitrogen and hydrogen to displace air, and then continuously introducing hydrogen to a set pressure value;

[0053] The hydrogenation reaction is carried out under stirring; the temperature of the hydrogenation reaction is 50 - 180 °C, the pressure is 1 - 10 MPa, and the heat preservation time is 0.1 - 10 h;

[0054] The post-treatment includes: cooling the reaction solution after the reaction ends to room temperature, then performing a first separation, and performing a second separation on the filtrate obtained from the first separation;

[0055] The method of the second separation includes freeze crystallization or distillation; the temperature of the freeze crystallization is -50 - 0 °C.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] (1) The preparation method provided by the present invention uses TMCD as a raw material to carry out a hydrogenation reaction under a catalyst and a mixed solvent system. On the premise of ensuring a high conversion rate of TMCD and a high selectivity of the CBDO product, it not only realizes the rapid hydrogenation of cis-CBDO, but also can obtain a CBDO product with a high cis / trans ratio through a one-step method. Compared with the traditional two-step method of hydrogenation catalysis and isomerization catalysis, the preparation method is simple to operate, has a low raw material cost, is economical and efficient, and is easy to scale up production; among them, the conversion rate of TMCD ≥ 94%, the selectivity of CBDO ≥ 90%, and the cis / trans ratio of the CBDO product ≥ 8;

[0058] (2) The preparation method provided by the present invention adjusts the dielectric constant of the mixed solvent and then changes the polarity of the mixed solvent by the synergistic compounding of the first solvent and the second solvent and the specific screening of the first solvent component. Through the principle of similar solubility, the cis-CBDO product with a cis structure is rapidly separated from the catalyst surface, improving the cis / trans ratio in the CBDO product. Specific Embodiments

[0059] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0060] The materials used in the specific embodiments of the present invention can all be obtained by purchasing commercially, or prepared by conventional methods in the prior art.

[0061] Metal mass = Metal salt mass × Metal atomic mass / Metal salt molecular weight × 100%;

[0062] Theoretical metal loading = Metal mass / (Metal mass + Carrier mass) × 100%.

[0063] Preparation Example 1

[0064] This preparation example provides a method for preparing a catalyst. The preparation method includes:

[0065] Add 5 g of activated carbon and 150 g of deionized water to a three-necked flask and stir at room temperature to obtain an activated carbon slurry;

[0066] Dissolve 0.55 g of H2PtCl6·xH2O (purity ≥ 99%) in 50 mL of deionized water, then add it dropwise to the activated carbon slurry, adsorb for 5 h, then adjust the pH value of the aforementioned solution to 9 with sodium hydroxide solution, and then reduce it with 20 g of a sodium borohydride solution with a mass concentration of 20% for 3 h. Finally, filter, wash, and dry in sequence to obtain a 5% Pt / C catalyst.

[0067] Preparation Example 2

[0068] This preparation example provides a method for preparing a catalyst. Except for using 0.65 g of RuCl3·3H2O to replace 0.55 g of H2PtCl6·xH2O, other conditions are the same as those in Preparation Example 1.

[0069] In this preparation example, the obtained catalyst is denoted as a 5% Ru / C catalyst.

[0070] Preparation Example 3

[0071] This preparation example provides a method for preparing a catalyst. Except for using 0.9 g of chloroauric acid to replace 0.55 g of H2PtCl6·xH2O, other conditions are the same as those in Preparation Example 1.

[0072] In this preparation example, the obtained catalyst is denoted as a 5% Au / C catalyst.

[0073] Preparation Example 4

[0074] This preparation example provides a method for preparing a catalyst. Except for using ZSM-5 molecular sieve to replace activated carbon, other conditions are the same as those in Preparation Example 1.

[0075] In this preparation example, the obtained catalyst is denoted as a 5% Pt / ZSM-5 catalyst.

[0076] Preparation Example 5

[0077] This preparation example provides a method for preparing a catalyst. Except for using γ-Al2O3 to replace activated carbon, other conditions are the same as those in Preparation Example 1.

[0078] In this preparation example, the obtained catalyst is denoted as a 5% Pt / γ-Al2O3 catalyst.

[0079] Preparation Example 6

[0080] This preparation example provides a method for preparing a catalyst. Except for using ZrO2 to replace activated carbon, other conditions are the same as those in Preparation Example 1.

[0081] In this preparation example, the obtained catalyst is denoted as 5% Pt / ZrO2 catalyst.

[0082] Preparation Example 7

[0083] This preparation example provides a method for preparing a catalyst. Except for using 0.52 g of zinc chloride to replace 0.55 g of H2PtCl6·xH2O, other conditions are the same as those in Preparation Example 1.

[0084] In this preparation example, the obtained catalyst is denoted as 5% Zn / C catalyst.

[0085] Example 1

[0086] This example provides a method for preparing high cis / trans ratio 2,2,4,4 - tetramethyl - 1,3 - cyclobutanediol. The preparation method includes the following steps:

[0087] (1) Dissolve 5.3 g of TMCD crystals in 100.7 g of a mixed solvent, and then add 1.5 g of 5% Pt / C catalyst thereto to obtain a mixed slurry. Then transfer the mixed slurry to a high - pressure reactor and seal the reactor;

[0088] The mixed solvent includes a first solvent and a second solvent with a mass ratio of 3:1; the first solvent is anisole, and the second solvent is ethanol;

[0089] (2) Alternately introduce nitrogen and hydrogen to displace air for 5 times, and then continuously introduce hydrogen to a pressure of 4 MPa, and then carry out a hydrogenation reaction to obtain a reaction solution;

[0090] The hydrogenation reaction is carried out under stirring, and the stirring speed is 200 rpm / min;

[0091] The temperature of the hydrogenation reaction is 100 °C, the pressure is 4 MPa, and the heat - preservation time is 2 h;

[0092] (3) Cool the reaction solution obtained in step (2) to room temperature, and then filter to obtain a filtrate containing CBDO. Subsequently, freeze - crystallize the filtrate at - 15 °C for 3 h, and filter to obtain high cis / trans ratio 2,2,4,4 - tetramethyl - 1,3 - cyclobutanediol.

[0093] Example 2

[0094] This example provides a method for preparing high cis / trans ratio 2,2,4,4 - tetramethyl - 1,3 - cyclobutanediol. The preparation method includes the following steps:

[0095] (1) Dissolve 5.3 g of TMCD crystals in 100.7 g of a mixed solvent, and then add 1.5 g of 5% Pt / C catalyst thereto to obtain a mixed slurry. Then transfer the mixed slurry to a high-pressure reactor and seal the reactor.

[0096] The mixed solvent comprises a first solvent and a second solvent with a mass ratio of 3:1; the first solvent is anisole, and the second solvent is butyl acetate.

[0097] (2) Alternately introduce nitrogen and hydrogen to displace air for 5 times, and then continuously introduce hydrogen to a pressure of 4 MPa. Then carry out a hydrogenation reaction to obtain a reaction solution.

[0098] The hydrogenation reaction is carried out under stirring, and the stirring speed is 200 rpm / min.

[0099] The temperature of the hydrogenation reaction is 100 °C, the pressure is 4 MPa, and the heat preservation time is 2 h.

[0100] (3) Cool the reaction solution obtained in step (2) to room temperature, and then filter to obtain a filtrate containing CBDO. Subsequently, carry out rotary evaporation on the filtrate under a vacuum of 10 KPa and a temperature of 130 °C, and cool down to obtain 2,2,4,4-tetramethyl-1,3-cyclobutanediol with a high cis / trans ratio.

[0101] Examples 3-28 and Comparative Examples 1-3

[0102] Except for changing the raw materials, the ratio of the mixed solvent, and the conditions such as the hydrogenation reaction and freeze crystallization used in Example 1, the specific changed parameters are shown in Table 1; other conditions are carried out with reference to Example 1.

[0103] Table 1

[0104]

[0105]

[0106]

[0107]

[0108] In the above examples and comparative examples, the content and purity of substances in the materials after the hydrogenation reaction were analyzed by gas chromatography.

[0109] Among them, the product analysis and test conditions are as follows: Agilent GC-8890 gas chromatograph; DB-FFAP chromatographic column, hydrogen flame detector; the initial temperature is 100 °C, the temperature is raised to 230 °C at a heating rate of 10 °C / min, and maintained at this temperature for 3 min; the temperature of the detector is 250 °C.

[0110] Among them, the conversion rate of TMCD, the selectivity of CBDO, and the cis / trans ratio of the CBDO product are all calculated according to the following formula.

[0111]

[0112] Among them, m0 is the feeding amount of TMCD, m is the mass of the collected liquid (the filtrate containing CBDO), m1 is the mass of the crystalline substance, w TMCD % is the percentage content of TMCD in the sample after the reaction, w CBDO % is the purity of CBDO in the crystalline substance, A Cis is the peak area of cis-CBDO on the chromatogram, A Tran is the peak area of trans-CBDO on the chromatogram.

[0113] The test and calculation results in the above-mentioned examples and comparative examples are shown in Table 2.

[0114] Table 2

[0115]

[0116]

[0117] It can be seen from Table 2 that:

[0118] (1) For the preparation methods provided in Examples 1-25 of the present invention, using TMCD as the raw material to carry out the hydrogenation reaction under a hydrogenation catalyst and a mixed solvent system, on the premise of ensuring a high conversion rate of TMCD and a high selectivity of the CBDO product, a CBDO product with a high cis / trans ratio is obtained by a one-step method; among them, the conversion rate of TMCD ≥ 94%, the selectivity of CBDO ≥ 90%, and the cis / trans ratio of the CBDO product ≥ 8;

[0119] (2) By comprehensively comparing Example 1 and Examples 26-27, it can be seen that when the proportion of the first solvent in the mixed solvent is too small, due to the relatively large dielectric constant of the mixed solvent and the strong polarity of the solvent, the matching with the cis-CBDO product is inconsistent, resulting in the cis product being unable to quickly detach from the catalyst surface, which is not conducive to improving the cis / trans ratio of the CBDO product;

[0120] (3) By comprehensively comparing Example 1 and Example 28, it can be seen that when the active component in the catalyst used is Zn element, since the cracking ability of Zn for adsorbing hydrogen is weaker than that of Pt for hydrogen, the hydrogenation reaction ability is insufficient, resulting in a low conversion rate. At the same time, the insufficient hydrogenation performance also causes the cis product to be unable to quickly detach from the catalyst surface, indirectly affecting the selectivity, resulting in both the reaction performance and the cis / trans ratio of the CBDO product being low;

[0121] (4) It can be seen from the comparison between Example 1 and Comparative Examples 1-2 that when the mixed solvent contains only the first solvent or the second solvent, the cis / trans ratio of the CBDO product is too low;

[0122] (5) It can be seen from the comparison between Example 1 and Comparative Example 3 that when two second solvents are compounded, since the strongly polar solvent is the main component, the mixed solvent shows strong polarity, which is inconsistent with the matching of the cis-CBDO product, resulting in the inability of the cis product to quickly detach from the catalyst surface; moreover, the proportion of the low-boiling solvent is too high, resulting in gasification during the reaction, which poses a certain obstacle to the removal of the product into the solvent; due to the above two factors, the cis / trans ratio of the CBDO product is too low.

[0123] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol with a high cis-trans ratio, characterized in that: The preparation method comprises: Mixing 2,2,4,4-tetramethyl-1,3-cyclobutanedione, a catalyst and a mixed solvent, and performing a hydrogenation reaction to obtain 2,2,4,4-tetramethyl-1,3-cyclobutanediol with a high cis-trans ratio; The mixed solvent comprises a first solvent and a second solvent; the first solvent comprises any one of diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, anisole, neopentyl glycol or 1,2-butanediol, or a combination of at least two thereof.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the 2,2,4,4-tetramethyl-1,3-cyclobutanedione to the mixed solvent is 1:(18-22).

3. The preparation method according to claim 1 or 2, characterized in that: The second solvent includes any one or a combination of at least two of other alcohols, alkanes or esters; Preferably, the other alcohols include any one or a combination of at least two of methanol, ethanol, ethylene glycol, propanol, butanol or 1,6-hexanediol; Preferably, the alkane comprises cyclohexane and / or an alkane containing at least 5 carbon atoms; Preferably, the esters include any one of ethyl acetate, butyl acetate, isobutyl isobutyrate or isobutyl acetate, or a combination of at least two thereof.

4. The preparation method according to any one of claims 1 to 3, characterized in that Based on the total mass of the mixed solvent being 100 wt %, the content of the first solvent is 50 to 100 wt % (excluding 100 wt %), preferably 70 to 90 wt %.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The catalyst comprises a carrier and an active component supported on the carrier; Preferably, the active component comprises any one or a combination of at least two of Pt, Pd, Au or Ru, preferably Pt; Preferably, the carrier comprises any one or a combination of at least two of γ-Al2O3, activated carbon, carbon nanotubes, titanium dioxide, silicon dioxide, zirconium dioxide, molecular sieves or porous polymers, preferably activated carbon; Preferably, based on the total mass of the catalyst being 100 wt%, the content of the active component is 0.1 to 30 wt%, preferably 3 to 8 wt%; Preferably, the preparation method of the catalyst comprises an impregnation reduction method or a wet adsorption reduction method, preferably a wet adsorption reduction method.

6. The preparation method according to any one of claims 1 to 5, characterized in that: After the mixing, before the hydrogenation reaction, the method further comprises: alternately introducing nitrogen and hydrogen to replace the air, and then continuously introducing hydrogen to a set pressure value.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The hydrogenation reaction is carried out under stirring; Preferably, the temperature of the hydrogenation reaction is 50 to 180°C, preferably 80 to 120°C; Preferably, the pressure of the hydrogenation reaction is 1 to 10 MPa, preferably 3 to 5 MPa; Preferably, the holding time of the hydrogenation reaction is 0.1 to 10 hours, preferably 1 to 3 hours; Preferably, after the hydrogenation reaction, cooling and solid-liquid separation are sequentially performed before separation.

8. The preparation method according to any one of claims 1 to 7, characterized in that: After the hydrogenation reaction, post-treatment is also performed; Preferably, the post-treatment comprises: cooling the reaction solution after the reaction to room temperature, and then performing a first separation, and performing a second separation on the filtrate obtained from the first separation to obtain 2,2,4,4-tetramethyl-1,3-cyclobutanediol with a high cis-trans ratio; Preferably, the first separation method comprises filtration; Preferably, the second separation method comprises freeze crystallization or distillation, preferably freeze crystallization; Preferably, the temperature of the freeze crystallization is -50 to 0°C, preferably -20 to -10°C.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The cis / trans ratio of the 2,2,4,4-tetramethyl-1,3-cyclobutanediol is ≥8.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The preparation method comprises: Mixing 2,2,4,4-tetramethyl-1,3-cyclobutanedione, a catalyst and a mixed solvent, and sequentially performing a hydrogenation reaction and a post-treatment to obtain 2,2,4,4-tetramethyl-1,3-cyclobutanediol having a cis / trans ratio of ≥8; The mass ratio of the 2,2,4,4-tetramethyl-1,3-cyclobutanedione to the mixed solvent is 1:(18-22); The mixed solvent includes a first solvent and a second solvent; the first solvent includes any one of diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, anisole, neopentyl glycol or 1,2-butanediol or a combination of at least two; the second solvent includes any one of other alcohols, alkanes or esters or a combination of at least two; based on the total mass of the mixed solvent being 100wt%, the content of the first solvent is 50-100wt% but not including 100wt%; The catalyst comprises a carrier and an active component supported on the carrier; the active component comprises any one of Pt, Pd, Au or Ru or a combination of at least two thereof; the carrier comprises any one of γ-Al2O3, activated carbon, carbon nanotubes, titanium dioxide, silicon dioxide, zirconium dioxide, molecular sieve or porous polymer or a combination of at least two thereof; the content of the active component is 0.1 to 30 wt% based on the total mass of the catalyst being 100 wt%; After the mixing, before the hydrogenation reaction, the method further comprises: alternately introducing nitrogen and hydrogen to replace the air, and then continuously introducing hydrogen to a set pressure value; The hydrogenation reaction is carried out under stirring; the temperature of the hydrogenation reaction is 50 to 180° C., the pressure is 1 to 10 MPa, and the insulation time is 0.1 to 10 h; The post-treatment includes: cooling the reaction solution after the reaction to room temperature, and then performing a first separation, and performing a second separation on the filtrate obtained from the first separation; The second separation method includes freezing crystallization or distillation; the temperature of the freezing crystallization is -50 to 0°C.

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