A preparation method of 2,2,4,4-tetramethyl-1,3-cyclobutanediol

Abstract

The present invention relates to a method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol. The method comprises (1) the synthesis of 3-hydroxy-2,2,4,4-tetramethylcyclobutanone: dissolving 2,2,4-trimethyl-3-oxopentanal in an alcohol solvent to prepare a solution, and cyclizing 3-hydroxy-2,2,4,4-tetramethylcyclobutanone solution under the catalysis of ruthenium / calcium / aluminum-hydrotalcite solid catalyst; (2) the synthesis of CBDO: adding a reactor equipped with an activated carbon-supported ruthenium-indium metal catalyst to the solution obtained in step (1), introducing hydrogen, and hydrogenating to obtain CBDO. The starting raw material of the present invention is obtained by oxidation of 2,2,4-trimethyl-1,3-pentanediol, a byproduct of dodecanol ester, which not only has low raw material cost, but also can reduce the solid waste treatment cost of dodecanol ester manufacturers and reduce the emission of greenhouse gas CO2; the reaction steps are reduced to 3 steps, saving device investment and manual operation costs.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical engineering, and particularly relates to a method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol. Background Art

[0002] 2,2,4,4-Tetramethyl-1,3-cyclobutanediol (CBDO) is an important aliphatic diol polyester monomer. Due to the rigidity of the special four-membered ring in the structure, it can be used to produce high-performance copolyester products with high impact strength, high glass transition temperature, high transparency and good toughness. For example, Tritan, a new generation of polyester currently widely used in baby bottles, high-end water cups and electronic cigarette mouthpieces, is copolymerized by CBDO, terephthalic acid and 1,4-cyclohexanedimethanol. Tritan has a high glass transition temperature, high transparency, and does not contain bisphenol A. Compared with polycarbonate PC, it has significant advantages in the field of food contact. However, due to the long synthesis route of CBDO and the high manufacturing cost, Tritan is not widely used in the market.

[0003] At present, the industrial production route of CBDO is to use isobutyraldehyde as the starting material, oxidize it to produce isobutyric acid, then dehydrate it to produce isobutyric anhydride, and then pyrolyze it at high temperature to produce dimethyl isobutyl ketone (DMK), and then produce 2,2,4,4-tetramethyl-1,3-cyclobutanedione (CBDK) through intermolecular dimerization, and finally obtain CBDO through hydrogenation. The production process is relatively long, and the total yield is less than 50%.

[0004]

[0005] Therefore, it is of great significance to develop a preparation process with low raw material cost and short synthetic route. Summary of the invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a new CBDO synthesis method. The method uses 2,2,4-trimethyl 1,3-pentanediol (currently, most alcohol ester companies treat this byproduct by incineration) as a starting material, an oxidation reaction to obtain 2,2,4-trimethyl-3-oxopentanal, and then catalyzed by a ruthenium / calcium / aluminum-hydrotalcite solid catalyst to obtain 3-hydroxy-2,2,4,4-tetramethylcyclobutanone through intramolecular cyclization, followed by hydrogenation to obtain CBDO.

[0007]

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for preparing CBDO comprises the following steps:

[0010] (1) Synthesis of 3-hydroxy-2,2,4,4-tetramethylcyclobutanone: 2,2,4-trimethyl-3-oxopentanal is dissolved in an alcohol solvent to prepare a solution, and cyclization is performed to synthesize a 3-hydroxy-2,2,4,4-tetramethylcyclobutanone solution under the catalysis of a ruthenium / calcium / aluminum-hydrotalcite solid catalyst;

[0011] (2) Synthesis of CBDO: Add the solution obtained in step (1) into a reaction kettle containing an activated carbon-supported ruthenium-indium metal catalyst, introduce hydrogen, and hydrogenate to obtain CBDO.

[0012] Preferably, the 2,2,4-trimethyl-3-oxopentanal is obtained by oxidation reaction of 2,2,4-trimethyl-1,3-pentanediol, a byproduct of dodecanol ester.

[0013] Synthesis of 2,2,4-trimethyl-3-oxopentanal: Referring to the literature (J.AM.CHEM.SOC.2006,128,8412-8413), 2,2,4-trimethyl-1,3-pentanediol was dissolved in dichloromethane solvent to prepare a solution of a certain concentration, and oxidized to 2,2,4-trimethyl-3-oxopentanal under the catalysis of 1-Me-AZADO and NaOCl aqueous solution as an oxidant. The reaction solution was washed with water, concentrated to remove the solvent and used as a raw material for the cyclization reaction.

[0014] The catalyst in step (1) of the present invention is a ruthenium / calcium / aluminum-hydrotalcite solid catalyst, the general formula of which is Ru x Ca4Al-LDH. The molar ratio of calcium:aluminum is 4, the molar ratio of ruthenium:aluminum is 0.5-1.5, and x=0.5-1.5.

[0015] As a preferred solution, the preparation of ruthenium / calcium / aluminum-hydrotalcite solid catalyst comprises the following steps:

[0016] A certain proportion of Ca(NO3)2-4H2O, Al(NO3)3-9H2O and RuCl3-3H2O is added to deionized water, and the pH value is adjusted to a certain value using an alkali solution, preferably an aqueous solution of LiOH, NaOH or KOH, and the solution is filtered and washed after stirring at room temperature for a certain period of time, and then dried at 60-100°C for 12-48 hours. The obtained solid is calcined at high temperature in an air environment for a certain period of time, cooled to room temperature, and then dispersed in an alkali solution with a certain pH value, preferably a LiOH, NaOH or KOH solution, stirred for 1-3 hours, filtered and washed, and dried at 60-100°C for 12-48 hours.

[0017] Preferably, the pH value of the stirring and mixing before calcination is 12.6-13.2, and the time is 5-10 hours.

[0018] Preferably, the calcination temperature is 450-500° C., the calcination time is 2-6 h, and the pH value of the stirred mixture after calcination is 13.0-13.5.

[0019] Preferably, step (1) of the present invention is carried out according to the following steps:

[0020] Under N2, add 0.04 mol of Ca(NO3)2-4H2O, 0.01 mol of Al(NO3)3-9H2O and 0.005-0.015 mol of RuCl3-3H2O to 100 mL of deionized water to prepare an aqueous solution. Then add LiOH, NaOH or KOH aqueous solution (100 mL, 1.1 M), stir the precipitate at room temperature for 5-10 hours at a pH of 12.6-13.2, then filter, wash with water, and dry at 60-100°C for 12-48 hours. The solid is heated in air at 450-500°C for 2-6 hours, calcined and cooled to room temperature, then dispersed in LiOH, NaOH or KOH solution at pH 13.0-13.5 and stirred for 1-3 hours. Filter, wash with water, and finally dry at 60-100°C for 12-48 hours to obtain a cyclization catalyst.

[0021] The reaction equation of step (1) of the present invention is as follows:

[0022]

[0023] The alcohol solvent in step (1) of the present invention is methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol or butanediol, and the amount used is 20-100 times the mass of 2,2,4-trimethyl-3-oxopentanal, that is, the concentration of 2,2,4-trimethyl-3-oxopentanal is 1-5%. The purpose of the low concentration is to reduce the occurrence of intermolecular condensation reaction.

[0024] The ruthenium / calcium / aluminum-hydrotalcite solid catalyst in step (1) of the present invention is used in an amount of 0.1-1% of the mass of 2,2,4-trimethyl-3-oxopentanal.

[0025] The reaction temperature in step (1) of the present invention is 10-45°C.

[0026] The reaction time in step (1) of the present invention is 2-5h.

[0027] Preferably, step (1) of the present invention is carried out as follows: 2,2,4-trimethyl-3-oxopentanal is dissolved in ethanol at 15-30° C. to prepare a 2-4% solution, and a ruthenium / calcium / aluminum-hydrotalcite solid catalyst is added to react for 3-4 hours. The solution after filtering to remove the catalyst is directly subjected to the next step of reaction.

[0028] The reaction equation of step (2) of the present invention is as follows:

[0029]

[0030] The step (2) of the present invention is prepared by hydrogenation in the presence of a hydrogenation catalyst.

[0031] The hydrogenation catalyst in step (2) of the present invention is an activated carbon-supported ruthenium-indium metal catalyst, wherein the ruthenium loading is 5.0-10.0wt% and the indium loading is 1.0-6.0wt% based on the total mass of the catalyst; the preparation thereof can refer to patent CN114349596A. The amount of the catalyst used is 0.1-1% of the mass of 3-hydroxy-2,2,4,4-tetramethylcyclobutanone.

[0032] The reaction temperature of step (2) of the present invention is 120-150° C. and the pressure is 2Mpa-4Mpa.

[0033] Preferably, step (2) of the present invention is carried out according to the following steps: adding the solution prepared by reaction (2) into a reactor containing an activated carbon-supported ruthenium-indium metal catalyst, controlling the reactor temperature to 120-150°C, introducing hydrogen to 2Mpa-4Mpa, reacting for 5-10 hours, and then returning to normal temperature and pressure for sampling and analysis.

[0034] The positive effects of the present invention are: 1) 2,2,4-trimethyl 1,3-pentanediol, a byproduct of dodecanol ester, is used as a starting raw material. This byproduct is usually burned as solid waste by dodecanol ester manufacturers. The present invention uses this waste to synthesize CBDO, which not only reduces the cost of raw materials, but also reduces the three waste treatment costs of dodecanol ester manufacturers and reduces the emission of greenhouse gas CO2. 2) The reaction steps are significantly reduced, and the investment in industrial equipment will be greatly reduced: the current CBDO production process uses isobutyraldehyde as the initial raw material, and requires oxidation, dehydration, cracking, cyclization, and hydrogenation to obtain CBDO. The present invention only requires oxidation, condensation, and hydrogenation to obtain CBDO. 3) The cyclization step of the present invention uses ruthenium / calcium / aluminum-hydrotalcite solid catalyst, which has the advantages of high selectivity and easy separation. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with specific implementation methods. However, those skilled in the art will understand that the embodiments described below are only part of the embodiments of the present invention, rather than all of the embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention.

[0036] The main raw material 2,2,4-trimethyl 1,3-pentanediol was purchased from Inokai Chemical Reagent Co., Ltd., 1-Me-AZADO was purchased from McLean Reagent Co., Ltd., Ca(NO3)2-4H2O, Al(NO3)3-9H2O, RuCl3-3H2O and NaOH were purchased from Sigma-Aldrich.

[0037] <Test Method>

[0038] 1. The composition of ruthenium / calcium / aluminum-hydrotalcite solid catalyst was analyzed by inductively coupled plasma emission spectroscopy (ICP), model Thermo iCAP 7000; the reaction products were qualitatively analyzed by high-resolution mass spectrometer, model ThermoQ Exactive Focus; the selectivity of cyclization and hydrogenation reactions was determined by gas chromatography (Agilent 7820A), DB-5 chromatographic column, FID detector, vaporization temperature 260°C, detector temperature 260°C, carrier gas was high-purity nitrogen, and the flow rate was 30 ml / min.

[0039] 2. Synthesis of 2,2,4-trimethyl-3-oxopentanal: Reference literature (J.AM.CHEM.SOC.2006,128,8412-8413), prepared with 2,2,4-trimethyl-1,3-pentanediol as raw material: 1.5 mol 2,2,4-trimethyl-1,3-pentanediol was dissolved in 4 L dichloromethane solvent to prepare a solution, 1.5 mmol 1-Me-AZADO was added, and then a mixture of 1.4 L NaOCl aqueous solution (mass concentration 8%) and 1.9 L saturated NaHCO3 solution was added dropwise for 30 min, followed by stirring for 1 h, and the temperature was controlled at 0°C throughout the process. The reaction solution was then separated and washed once with 3 L water, and the oil phase was concentrated to remove the solvent and used as the raw material for the cyclization reaction.

[0040] 3. Hydrogenation catalyst: Activated carbon-supported ruthenium-indium metal catalyst, prepared with reference to patent CN114349596A, Example 2.

[0041] Example 1

[0042] (1) Preparation of Ru / Ca / Al-Hydrotalcite Solid Catalyst

[0043] Under N2 atmosphere, add 0.04 mol of Ca(NO3)2-4H2O, 0.01 mol of Al(NO3)3-9H2O and 0.005 mol of RuCl3-3H2O to 100 mL of deionized water. Then add LiOH aqueous solution (100 mL, 1.1 M), stir the precipitate at room temperature for 5 hours at pH 12.6, then filter, wash with water, and dry at 60°C for 12 hours. The solid is heated in air at 450°C for 2 hours, cooled to room temperature after calcination, and then dispersed in LiOH solution at pH 13.0 and stirred for 1 hour. Filter, wash with water, and finally dry at 60°C for 12 hours to obtain a cyclization catalyst (ruthenium / calcium / aluminum-hydrotalcite solid catalyst).

[0044] (2) Synthesis of 3-hydroxy-2,2,4,4-tetramethylcyclobutanone

[0045] At 10°C, 10 g of 2,2,4-trimethyl-3-oxopentanal was dissolved in 1000 g of methanol to prepare a 1% solution, and 0.01 g of the above-mentioned ruthenium / calcium / aluminum-hydrotalcite solid catalyst was added and reacted for 5 h. The solution after filtering out the catalyst was placed at room temperature. 3-Hydroxy-2,2,4,4-tetramethylcyclobutanone was qualitatively analyzed by high-resolution mass spectrometry, HRMS (ESI) m / z [M+1] + :[C8H 15 O2] + The calculated value is 143.1072 and the measured value is 143.1061.

[0046] (3) Synthesis of CBDO

[0047] The above solution was added to the reactor, and 0.01 g of activated carbon-supported ruthenium indium metal catalyst was added. The reactor temperature was controlled at 120°C, and hydrogen was introduced to 2 MPa. After reacting for 2 hours, the reaction was restored to normal temperature and pressure for sampling and analysis. The conversion rate of the raw material 2,2,4-trimethyl-3-oxopentanal was 90%, the selectivity of CBDO was 94%, and the cis-trans ratio was 1.15. CBDO was qualitatively analyzed by high-resolution mass spectrometry, HRMS (ESI) m / z [M+1] + :[C8H 17 O2] + The calculated value is 145.1229 and the measured value is 145.1245.

[0048] Example 2

[0049] (1) Preparation of Ru / Ca / Al-Hydrotalcite Solid Catalyst

[0050] Under N2 atmosphere, add 0.04mol of Ca(NO3)2-4H2O, 0.01mol of Al(NO3)3-9H2O and 0.01milRuCl3-3H2O to 100mL of deionized water. Then add NaOH aqueous solution (100mL, 1.1M), stir the precipitate at room temperature for 8 hours at pH 12.8, then filter, wash with water, and dry at 80°C for 24 hours. The solid is heated in air at 480°C for 4 hours, cooled to room temperature after calcination, and then dispersed in pH13.3 NaOH solution and stirred for 2 hours. Filter, wash with water, and finally dry at 80°C for 24 hours to obtain a cyclization catalyst (ruthenium / calcium / aluminum-hydrotalcite solid catalyst).

[0051] (2) Synthesis of 3-hydroxy-2,2,4,4-tetramethylcyclobutanone

[0052] At 30°C, 10 g of 2,2,4-trimethyl-3-oxopentanal was dissolved in 500 g of ethanol to prepare a 2% solution, and 0.05 g of the above-mentioned ruthenium / calcium / aluminum-hydrotalcite solid catalyst was added and reacted for 3 hours. The solution after filtering to remove the catalyst was left at room temperature.

[0053] (3) Synthesis of CBDO

[0054] The above solution was added to the reactor, and 0.05 g of activated carbon-supported ruthenium indium metal catalyst was added. The reactor temperature was controlled at 140°C, and hydrogen was introduced to 3 MPa. After the reaction was completed for 8 hours, the reaction was restored to normal temperature and pressure for sampling and analysis. The raw material had a 2,2,4-trimethyl-3-oxopentanal conversion rate of 95%, a CBDO selectivity of 95.3%, and a cis-trans ratio of 1.2.

[0055] Example 3

[0056] (1) Preparation of Ru / Ca / Al-Hydrotalcite Solid Catalyst

[0057] In N2 atmosphere, add 0.04mol of Ca(NO3)2-4H2O, 0.01mol of Al(NO3)3-9H2O and 0.015mol of RuCl3-3H2O to 100mL of deionized water. Then add KOH aqueous solution (100mL, 1.1M), stir the precipitate at room temperature for 10 hours at pH 13.2, then filter, wash with water, and dry at 100℃ for 48 hours. The solid is heated in air at 500℃ for 6 hours, cooled to room temperature after calcination, and then dispersed in pH13.5KOH solution and stirred for 3 hours. Filter, wash with water, and finally dry at 100℃ for 48 hours to obtain a cyclization catalyst (calcium-aluminum-ruthenium oxide composite solid phase catalyst).

[0058] (2) Synthesis of 3-hydroxy-2,2,4,4-tetramethylcyclobutanone

[0059] At 45°C, 10 g of 2,2,4-trimethyl-3-oxopentanal was dissolved in 200 g of ethylene glycol to prepare a 1% solution, and 0.1 g of the calcium-aluminum-ruthenium oxide composite solid phase catalyst was added. The reaction was continued for 5 hours. The solution after filtering to remove the catalyst was left at room temperature.

[0060] (3) Synthesis of CBDO

[0061] The above solution was added to the reactor, 0.1 g of activated carbon-supported ruthenium-indium metal catalyst was added, the reactor temperature was controlled at 150°C, hydrogen was introduced to 4 MPa, and after reacting for 10 hours, the temperature was restored to normal temperature and pressure for sampling and analysis. The raw material had a 2,2,4-trimethyl-3-oxopentanal conversion rate of 99.5%, a CBDO selectivity of 91.2%, and a cis-trans ratio of 1.11.

Claims

1. A method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol, comprising the following steps: (1) Synthesis of 3-hydroxy-2,2,4,4-tetramethylcyclobutanone: 2,2,4-trimethyl-3-oxopentanal is dissolved in an alcohol solvent to prepare a solution, and cyclization is performed to synthesize a 3-hydroxy-2,2,4,4-tetramethylcyclobutanone solution under the catalysis of a ruthenium / calcium / aluminum-hydrotalcite solid catalyst; (2) Synthesis of CBDO: Add the solution obtained in step (1) into a reaction kettle containing an activated carbon-supported ruthenium-indium metal catalyst, introduce hydrogen, and hydrogenate to obtain CBDO.

2. The preparation method according to claim 1, characterized in that: The 2,2,4-trimethyl-3-oxopentanal in step (1) of the present invention is obtained by oxidation reaction of 2,2,4-trimethyl-1,3-pentanediol, a byproduct of dodecanol ester.

3. The preparation method according to claim 1, characterized in that: The ruthenium / calcium / aluminum-hydrotalcite solid catalyst in step (1) of the present invention has the general formula Ru x Ca4Al-LDH, Among them, the molar ratio of calcium:aluminum is 4, and the molar ratio of ruthenium:aluminum is 0.5-1.5, that is, x=0.5-1.

5.

4. The preparation method according to claim 1 or 3, characterized in that: The preparation of the ruthenium / calcium / aluminum-hydrotalcite solid catalyst comprises the following steps: Add Ca(NO3)2-4H2O, Al(NO3)3-9H2O and RuCl3-3H2O into water, adjust the pH value with alkali solution, stir, filter, wash and dry at room temperature, disperse in alkali solution after calcination, stir, filter, wash and dry.

5. The preparation method according to claim 4, characterized in that: The alkali solution is an aqueous solution of LiOH, NaOH or KOH.

6. The preparation method according to claim 5, characterized in that: The pH value of alkali solution is adjusted to 12.6-13.2, and the pH value of dispersion in NaOH solution is 13.0-13.

5.

7. The preparation method according to claim 4, characterized in that: The calcination temperature is 450-500°C, the time is 2-6h, the drying temperature is 60-100°C, and the drying time is 12-48h.

8. The preparation method according to claim 1, characterized in that: The alcohol solvent in step (1) is methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol or butanediol, and the amount used is 20-100 times the mass of 2,2,4-trimethyl-3-oxopentanal.

9. The preparation method according to claim 1, characterized in that: The ruthenium / calcium / aluminum-hydrotalcite solid catalyst in step (1) is used in an amount of 0.1-1% of the mass of 2,2,4-trimethyl-3-oxopentanal.

10. The preparation method according to claim 1, characterized in that: The reaction temperature in step (1) is 10-45° C., and / or the reaction time is 2-5 h.

11. The preparation method according to claim 10, characterized in that: The reaction temperature in step (1) is 15-30°C.

12. The preparation method according to claim 10, characterized in that: The reaction time in step (1) is 3-4 h.

13. The preparation method according to claim 1, characterized in that: The hydrogenation catalyst in step (2) is an activated carbon-supported ruthenium-indium metal catalyst, wherein the ruthenium loading is 5.0-10.0wt% and the indium loading is 1.0-6.0wt% based on the total mass of the catalyst; and / or the catalyst dosage is 0.1-1% of the mass of 3-hydroxy-2,2,4,4-tetramethylcyclobutanone.

14. The preparation method according to claim 1, characterized in that: The reaction temperature of step (2) is 120-150° C., the pressure is 2Mpa-4Mpa, and the reaction time is 5-10h.

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