Preparation method of alcohol compound
By using a manganese complex catalyst and alkaline substances to react with polymers under an inert atmosphere, efficient generation of alcohol compounds was achieved under mild conditions, solving the problem of high reaction conditions for plastic depolymerization in existing technologies and improving the yield.
Patent Information
- Application Number
- CN202511681395.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-17
- Publication Date
- 2026-02-24
AI Technical Summary
In existing technologies, the depolymerization reaction conditions for plastics are relatively high, making it difficult to carry out under mild conditions, and the yield is low.
Using a manganese complex as a catalyst, combined with an alkaline substance and a hydrogen source, the polymer reacts under an inert atmosphere to generate alcohol compounds through depolymerization and hydrogenation. The specific steps include adding the polymer, hydrogen source, alkaline substance, and catalyst to a solvent, where depolymerization and hydrogenation reactions occur under catalysis to generate alcohol compounds.
The reaction yield was improved under mild conditions, and the efficiency of generating alcohol compounds was increased, especially in the temperature range of 60°C to 100°C, where the yield was significantly improved.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of degradation technology, and more specifically to a method for preparing alcohol compounds. Background Technology
[0002] Plastics are synthetic polymers made from fossil fuels such as petroleum and coal. Their widespread use and low cost make them indispensable in industry and daily life. However, plastics are difficult to degrade naturally, and their massive use has led to a dramatic increase in global plastic waste, posing a significant threat to the global ecosystem. Polyethylene terephthalate (PET) is the most produced and widely used type of polyester plastic. Recently developed hydrogenation depolymerization technology has brought new hope for the treatment of PET plastic waste.
[0003] However, the depolymerization reaction conditions for plastics are currently too high, and milder conditions are needed for depolymerization. Summary of the Invention
[0004] This invention provides a method for preparing alcohol compounds, which enables the reaction to be carried out under relatively mild conditions and can effectively improve the yield.
[0005] The present invention provides a method for preparing alcohol compounds, comprising:
[0006] Provide polymers;
[0007] Under an inert atmosphere, a polymer, a hydrogen source, an alkaline substance, and a catalyst are added to a solvent, and a depolymerization and hydrogenation reaction occurs under catalysis to generate alcohol compounds. The catalyst includes a compound represented by formula A.
[0008]
[0009] In this invention, the polymer includes polymers having ester groups and similar structures, such as at least one of polyester, polycarbonate, and polylactic acid. Under the catalytic action of a catalyst, the above materials can yield the desired alcohol compound. In some embodiments, the molecular weight of the polymer can be from 20,000 to 150,000 g / mol.
[0010] This invention uses a manganese complex as a catalyst. The alkaline substance can remove the chlorine atoms coordinated in the catalyst and the hydrogen atoms bonded to nitrogen, thereby activating the catalyst. The catalyst catalyzes the decomposition of the polymer to generate depolymerized monomers.
[0011] Manganese complexes react with basic substances to form Mn complexes with empty coordination sites. These complexes then react further with a hydrogen source, such as ammonia borane (H3NBH3), cleaving the ammonia borane through metal-ligand synergistic action to generate Mn-H complexes. These complexes can reduce ester groups in hydrogenolytic monomers such as DMT to produce alcohol products.
[0012] In some embodiments, the polyester includes one or more of polyethylene terephthalate, polybutylene terephthalate, or polycaprolactone.
[0013] In some embodiments, the molar ratio of catalyst to polymer is 0.02 to 0.1.
[0014] When the molar ratio of catalyst to polymer is within the above range, the catalyst can more fully catalyze the depolymerization of the polymer and improve the reaction yield of the final product, alcohol compounds.
[0015] In some embodiments, the alkaline substance includes at least one selected from potassium tert-butoxide, sodium methoxide, sodium hydroxide, or potassium hydride. The alkaline substance can both activate the catalyst and cooperate with it to catalyze the reaction.
[0016] In some embodiments, the molar ratio of the alkaline substance to the polymer is 0.01 to 0.2.
[0017] When the molar ratio of alkaline substances to polymers is within the above range, they can work in conjunction with catalysts to more fully catalyze the depolymerization of polymers and improve the reaction yield of the final product, alcohol compounds.
[0018] In some embodiments, the hydrogen source includes at least one of ammonia borane, ethanol, or formic acid. These hydrogen sources provide hydrogen for the reaction, which is beneficial for the production of alcohol compounds.
[0019] In some embodiments, the molar ratio of hydrogen source to polymer is from 1 to 3.5. A molar ratio of hydrogen source to polymer within this range can improve the reaction yield.
[0020] In some embodiments, the depolymerization and hydrogenation reaction is carried out at temperatures ranging from 20°C to 100°C. At these temperatures, the reaction conditions are relatively mild, and the reaction yield is relatively high.
[0021] In some embodiments, the step of adding the polymer, hydrogen source, alkaline substance, and catalyst to a solvent under an inert atmosphere, and then catalyzing a depolymerization and hydrogenation reaction to generate an alcohol compound, includes:
[0022] In step S100, the polymer, hydrogen source, alkaline substance and catalyst are added to the solvent under an inert atmosphere, and a depolymerization reaction occurs under catalysis to generate depolymerized monomers;
[0023] In step S200, the depolymerized monomer, hydrogen source, alkaline substance and catalyst are added to the solvent under an inert atmosphere, and a hydrogenation reaction occurs through catalysis to generate alcohol compounds.
[0024] In this invention, steps S100 and S200 can be performed sequentially or simultaneously. For example, the polymer, hydrogen source, alkaline substance and catalyst are added to the solvent together under an inert atmosphere, and a depolymerization reaction and a hydrogenation reaction occur through catalysis to generate alcohol compounds. This operation method can simplify the reaction and increase the reaction rate.
[0025] In some embodiments, the depolymerization reaction temperature is between 20°C and 100°C, optionally between 60°C and 90°C. When the depolymerization reaction temperature is within the above range, the reaction yield can be further improved.
[0026] In some embodiments, the hydrogenation reaction temperature is between 20°C and 100°C, and optionally between 55°C and 70°C. When the hydrogenation reaction temperature is within the above range, the reaction yield can be further improved. Detailed Implementation
[0027] The following embodiments describe the contents of the present invention in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of the present invention. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.
[0028] Example 1: Preparation of Catalyst
[0029] Provides 2,2'-dipyridinemethylamine and manganese dichloride;
[0030] Under an inert atmosphere such as nitrogen, 2,2'-dipyridinylmethylamine and manganese dichloride were added sequentially to a reaction flask. The solution turned pale yellow. The temperature was heated to 70°C and refluxed for 5 hours. A catalyst was obtained through chemical reaction. The catalyst included the compound shown in formula A.
[0031]
[0032] The molar ratio of manganese dichloride to 2,2'-dipyridinemethylamine is 0.5 to 3, for example, the molar ratio of manganese dichloride to 2,2'-dipyridinemethylamine is 1.5.
[0033] Example 2: Treatment of polyethylene terephthalate (PET)
[0034] Step 1: The compound represented by Formula A catalyzes the depolymerization reaction of PET.
[0035] For example, experiment group 7 in Table 1:
[0036] In a glove box under N2 atmosphere, PET (0.5 mmol, calculated based on the molecular weight of the PET monomer DMT of 194.18 g / mol. For example, if the mass of PET is mg, its molar amount is (m / 194.18) mol), H3N·BH3 (1.1 mmol, the molar ratio of H3N·BH3 to PET in step 1 is 2.2), the compound shown in Formula A (2.0 mol% (calculated based on the molar amount of PET, the molar ratio of the catalyst to PET in step 1 is 0.02), KO t Bu (5mol% (calculated based on the amount of substance of PET), KO t The molar ratio of Bu to PET in step 1 is 0.05. The mixture is stirred in methanol (2.0 ml) in a 25 ml pressure tube at 80 °C for 12 hours to obtain the depolymerized monomer.
[0037] The reaction principle is as follows:
[0038]
[0039] In the reaction principle, Mn represents the compound shown in formula A.
[0040] Experiments were conducted by changing the type of alkaline substance (Base), the type of solvent (Solvent), and the reaction temperature (T). Specific parameters are shown in Table 1.
[0041] Alkaline substances include potassium tert-butoxide (KO). t Bu, sodium hydroxide NaOH, sodium methoxide NaOMe, potassium hydride KH; the solvent includes at least one of 1,4-dioxane, methanol MeOH, toluene and tetrahydrofuran THF.
[0042] Table 1
[0043]
[0044] In Table 1, RT represents room temperature, and Yield... [b] Indicates yield.
[0045] The yields were obtained by column chromatography. NMR spectroscopy showed that the product DMT, obtained in group 7 at 80 °C, had a high yield of 97%.
[0046] No catalyst was added in group 10, and no alkaline substance was added in group 11. The control experiments of groups 10 and 11 showed that the compound represented by formula A and the alkaline substance such as KOtBu are responsible for catalyzing the reaction, and that no reaction occurs in the absence of the compound represented by formula A or the alkaline substance.
[0047] By controlling the reaction temperature within a range of 20°C to 100°C, the catalytic reaction rate increased and the yield increased with increasing temperature; the yield was highest at 80°C. Further experiments revealed that at excessively high temperatures, such as above 100°C, the stability of the hydrogen source, such as ammonia borane, decreased, leading to thermal decomposition and a drop in yield. Therefore, a higher yield was achieved at temperatures between 60°C and 90°C.
[0048] For groups 3 through 6, the alkaline substance was adjusted; compared to other alkaline substances, potassium tert-butoxide KO was used. t Bu has a higher yield.
[0049] For groups 7 through 9, the solvent was adjusted. Compared to other solvents, methanol (MeOH) yielded higher yields. Methanol can be activated by forming hydrogen bonds with the catalyst. Subsequently, the hydroxyl group (-OH) of methanol undergoes nucleophilic attack with the carbonyl carbon atom in the ester bond, forming a tetrahedral intermediate. The intermediate then decomposes to generate the corresponding monomer, increasing the yield. Optionally, based on 1 mmol of polymer, the volume of methanol is 2 mL to 10 mL.
[0050] Next, the scope of subsequent transfer hydrogenation reactions will be explored under optimized reaction conditions (i.e., the conditions of experiment group 7, with a yield of 97%).
[0051] Step 2: The compound shown in Formula A catalyzes the transfer hydrogenation reaction of DMT to produce an alcohol.
[0052] For example, the fourth group of experiments in Table 2:
[0053] In a glove box under N2 atmosphere, DMT (5 mmol, 700 mg) and H3N·BH3 (5.5 mmol, 172 mg; the molar ratio of H3N·BH3 to DMT in step 2 is 1.1, so the molar ratio of the total molar amount of H3N·BH3 to the polymer in steps 1 and 2 should be 3.3) were added to a round-bottom flask (equipped with a magnetic stirrer). Then, compound A (50 mg, 0.1 mmol; the molar ratio of the catalyst to DMT in step 2 is 0.02, so the molar ratio of the total molar amount of the catalyst to the polymer in steps 1 and 2 should be 0.04) and KO were added. t Bu (20mg, 5mol%, KO) tThe molar ratio of Bu to DMT in step 2 is 0.05. Therefore, in steps 1 and 2, KO t The total molar amount of Bu should be 0.1 (the molar ratio of the polymer to the total amount of Bu should be 0.1) and THF (2 ml). The mixture was stirred at 60 °C. After 6 hours, the reaction mixture was separated by silica gel chromatography and eluted with ethyl acetate / petroleum ether to give the product, 4-benzyldiethanol.
[0054] The reaction principle is as follows:
[0055]
[0056] Experiments were conducted with different solvents and reaction temperatures. Specific parameters are shown in Table 2.
[0057] The solvent includes at least one of toluene, tetrahydrofuran (THF), methanol (MeOH), and 1,4-dioxane.
[0058] Table 2
[0059]
[0060] In Table 2,
[0061] By controlling the reaction temperature within a range of 20°C to 100°C (e.g., groups 1 to 3), the catalytic reaction rate increased and the yield increased with increasing temperature; the yield was relatively high at 60°C. Further experiments revealed that at excessively high temperatures, such as above 100°C, the stability of the hydrogen source, such as ammonia borane, decreased, making it prone to thermal decomposition and leading to a decrease in yield. Therefore, a higher yield was achieved at temperatures between 55°C and 70°C.
[0062] Groups 3 through 6 involved controlling the type of solvent. Using tetrahydrofuran (THF) as the solvent resulted in higher product yields. The high solubility of catalysts, depolymerizing monomers, and basic substances in THF is beneficial for improving the completeness of the reaction and increasing product yield. Optionally, based on 1 mmol of depolymerizing monomer, the volume of tetrahydrofuran was 0.1 mL to 2 mL.
[0063] The amount of catalyst added to groups 1 through 6 was the same, while the amount of catalyst added to group 7 was 5% mol, which was higher than that of group 4. The catalyst could effectively catalyze the reaction and improve the reaction rate and reaction yield.
[0064] Example 3 Treatment of polybutylene terephthalate (PBT)
[0065] The steps for treating PET are basically the same as in Example 2, except that the reaction raw materials are adjusted, as shown in the following reaction principle:
[0066]
[0067] The yield of the final product was 85%.
[0068] Example 4: Treatment of polycaprolactone (PCL)
[0069] The steps for treating PET are basically the same as in Example 2, except that the reaction raw materials are adjusted, as shown in the following reaction principle:
[0070]
[0071] The yield of the final product was 73%.
[0072] Example 5: Treatment of Polylactic Acid (PLA)
[0073] The steps for treating PET are basically the same as in Example 2, except that the reaction raw materials are adjusted, as shown in the following reaction principle:
[0074]
[0075] The yield of the final product was 79%.
[0076] Example 6: Treatment of Polycarbonate (PC)
[0077] The steps for treating PET are basically the same as in Example 2, except that the reaction raw materials are adjusted, as shown in the following reaction principle:
[0078]
[0079] The yield of the final product was 87%.
[0080] The above experiments showed that adding only catalysts or alkaline substances did not produce any products.
[0081] In the example, both a catalyst and an alkaline substance are added to the system simultaneously to complete the reaction; the catalyst and the alkaline substance work together for catalysis.
[0082] The catalyst reacts with a basic substance to generate a Mn complex with empty coordination sites. This complex then reacts further with ammonia borane (H3NBH3), cleaving the ammonia borane through metal-ligand synergy to generate a Mn-H complex. This complex can reduce ester groups in hydrogenated DMT and other compounds to produce alcohol products.
[0083] Compared to sodium hydroxide, potassium tert-butoxide (KPO) is used as an alkaline substance. t The catalytic reaction is more complete and the yield is higher when Bu is used. The solvent is an organic solvent; the yield is higher when tetrahydrofuran (THF) is used.
[0084] Under specific preferred component systems, the present invention can achieve high yields, for example, with basic compounds such as potassium tert-butoxide (KO). t Bu, the solvent chosen is tetrahydrofuran (THF).
[0085] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the invention, and that changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the invention.
Claims
1. A method for preparing an alcohol compound, characterized in that, include: Provide polymers; Under an inert atmosphere, the polymer, hydrogen source, alkaline substance, and catalyst are added to a solvent, and a depolymerization and hydrogenation reaction occurs under catalysis to generate alcohol compounds. The catalyst includes compounds represented by formula A.
2. The preparation method according to claim 1, characterized in that, The molar ratio of the catalyst to the polymer is 0.02 to 0.
1.
3. The preparation method according to claim 1 or 2, characterized in that, The alkaline substance includes at least one of potassium tert-butoxide, sodium methoxide, sodium hydroxide, or potassium hydride.
4. The preparation method according to any one of claims 1 to 3, characterized in that, The molar ratio of the alkaline substance to the polymer is 0.01 to 0.
2.
5. The preparation method according to any one of claims 1 to 4, characterized in that, The hydrogen source includes at least one of ammonia borane, ethanol, or formic acid; and / or the molar ratio of the hydrogen source to the polymer is 1 to 3.
5.
6. The preparation method according to any one of claims 1 to 5, characterized in that, The reaction temperature for the depolymerization and hydrogenation reaction is 20°C to 100°C.
7. The preparation method according to any one of claims 1 to 6, characterized in that, The step of adding the polymer, hydrogen source, alkaline substance and catalyst to a solvent under an inert atmosphere, and conducting a depolymerization and hydrogenation reaction to generate alcohol compounds through catalysis, includes: The polymer, hydrogen source, alkaline substance and catalyst are added to a solvent under an inert atmosphere, and a depolymerization reaction occurs under catalysis to generate depolymerized monomers; Under an inert atmosphere, the depolymerized monomer, hydrogen source, alkaline substance and catalyst are added to a solvent, and a hydrogenation reaction occurs through catalysis to generate alcohol compounds.
8. The preparation method according to claim 7, characterized in that, The reaction temperature for the depolymerization reaction is between 20°C and 100°C.
9. The preparation method according to claim 7 or 8, characterized in that, The reaction temperature for the hydrogenation reaction is between 20°C and 100°C.
10. The preparation method according to any one of claims 1 to 9, characterized in that, The polymer includes ester groups.