Method for efficiently extracting solanesol in waste and inferior tobacco leaves

Abstract

The invention provides a method for efficiently extracting solanesol in waste and inferior tobacco leaves, which comprises the following steps of: 1, sufficiently grinding and mixing the crushed waste and inferior tobacco leaves and an organic porous polymer modified by alkaline ionic liquid to obtain a mixture; 2, the mixture is poured into an organic solvent and heated, solanesol ester is subjected to a hydrolysis reaction, after the reaction is finished, the organic solvent is removed through slow volatilization, and a solid mixture is obtained; and 3, putting the obtained solid mixture into a Soxhlet extractor, carrying out reflux extraction by using a low-boiling-point non-polar solvent, and removing the organic solvent from the extracting solution under reduced pressure to obtain the solanesol extract. According to the method, the solanesol ester is efficiently hydrolyzed and the solanesol in plants is enriched by using the alkaline ionic liquid organic porous polymer, so that the use of conventional micromolecular inorganic alkali is avoided, convenience is provided for subsequent separation, the extraction rate of the solanesol reaches 90% or above, and the content of the solanesol in the extract is 50% or above.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of fine chemical industry, and particularly relates to a method for efficiently extracting solanesol from waste tobacco leaves. BACKGROUND

[0002] A large amount of tobacco waste is generated in the planting and production of tobacco, and the tobacco waste contains a large amount of high-value components such as nicotine, solanesol, sugars and proteins. If the tobacco waste is not effectively utilized, not only the environment will be polluted, but also the resources will be wasted. At present, the functional components in the tobacco are mostly extracted by using an acid or alkaline water or an alcohol solution. Although the functional components can be extracted by using the method, the extraction efficiency is low and the extracted components are complex. When a solution with large polarity is used for extraction, the components such as sugars and proteins in the solution are dissolved, which causes difficulty in subsequent separation.

[0003] Solanesol is a high-value pharmaceutical intermediate and is mainly used for synthesizing coenzyme Q10 and vitamin K2. Waste tobacco leaves, as by-products of the tobacco industry, contain a large amount of solanesol (content: about 0.5%-3%) and are important raw materials for extracting solanesol. However, in the waste tobacco leaves, solanesol mainly exists in the form of combined state (solanesol ester), and the proportion of the combined state is significantly higher than that of the free state, which leads to extremely low efficiency of the traditional non-polar solvent direct extraction method.

[0004] The mainstream process for extracting solanesol from waste tobacco leaves in the industry is an alkali lye saponification-organic solvent extraction method. First, the waste tobacco leaves are crushed and mixed with an alcohol solution (such as methanol or ethanol) of high-concentration sodium hydroxide or potassium hydroxide, and then a saponification reaction is performed under heating reflux conditions to hydrolyze the combined-state solanesol ester into free solanesol. After the reaction, the residual alkali needs to be neutralized by using an acid (such as hydrochloric acid), and the generated soap and salt impurities need to be removed through multiple water washing. Finally, the free solanesol is extracted by using a non-polar solvent (such as petroleum ether or n-hexane), and the extract is obtained after concentration. The technology needs to use a large amount of strong acid and strong alkali, generates wastewater with high salinity and high chemical oxygen demand (COD), has high treatment cost and is easy to cause ecological damage; the neutralization, water washing and other post-processing steps are complicated, are easy to cause product loss and emulsification, and prolong the production cycle; the product purity and the extraction rate are both low, and the technology cannot meet the industrial production requirements.

[0005] Therefore, it is urgent to develop a green, simple and efficient method for extracting solanesol from waste tobacco leaves. SUMMARY

[0006] The solanesol in tobacco exists in a free state or a solanesol ester form, wherein the proportion of the solanesol ester form is relatively large, which is not conducive to separation of the solanesol from the tobacco by using a nonpolar solvent, and therefore it is necessary to develop an efficient separation process for recycling of waste tobacco leaves. In view of the problems in the above background art, the present application provides a method for efficiently extracting solanesol from waste tobacco leaves. The present application uses a supported basic ionic liquid organic porous polymer as a catalyst to efficiently hydrolyze solanesol ester, avoids the use of conventional small-molecule inorganic bases, and provides convenience for subsequent separation, and at the same time, the organic porous polymer contains a large number of nonpolar benzene ring groups and rich pore structures, and this type of organic porous polymer can enrich solanesol from plants to further improve the extraction efficiency of solanesol. The method can make the extraction rate of solanesol reach more than 90%, and the content of solanesol in the extract is more than 50%.

[0007] In a first aspect, the present application provides a method for efficiently extracting solanesol from waste tobacco leaves, comprising: Step 1: grinding and mixing: grinding and mixing the crushed waste tobacco leaves and the basic ionic liquid modified organic porous polymer to obtain a mixture; Step 2: hydrolysis reaction: pouring the mixture into an organic solvent and heating to make the solanesol ester undergo a hydrolysis reaction, and then slowly volatilizing to remove the organic solvent to obtain a solid mixture; Step 3: reflux extraction: placing the obtained solid mixture into a Soxhlet extractor and extracting with a low-boiling-point nonpolar solvent, and then removing the organic solvent from the extract under reduced pressure to obtain a solanesol extract.

[0008] In some embodiments, the preparation process of the basic ionic liquid modified organic porous polymer comprises: S1: polymerization reaction: preparing a vinyl modified organic porous polymer from a terephthaldehyde monomer and an aldehyde monomer; S2: imidazole modification: reacting the organic porous polymer, an initiator and a vinyl imidazole monomer in a polymerization solvent to obtain an imidazole modified organic porous polymer; S3: alkalization treatment: after alkalization treatment of the imidazole modified organic porous polymer by a strong alkali solution, a basic ionic liquid modified organic porous polymer is obtained.

[0009] This invention utilizes a Knevengay reaction between terephthalonitrile monomers and aldehyde monomers to generate a vinyl-containing organic porous polymer. This organic porous polymer then undergoes a double-bond polymerization reaction with vinyl imidazole monomers, grafting imidazole groups onto the framework. Further alkalization in a strongly alkaline solution completes ion exchange, introducing an alkaline ionic liquid structure to prepare an alkaline ionic liquid-modified organic porous polymer. This invention constructs a rigid porous framework through the Knevengay reaction, and combined with the high catalytic activity of the ionic liquid, it achieves dual functions of catalysis and adsorption enrichment, facilitating the extraction of solanesol. The organic porous polymer prepared by this invention contains a large number of nonpolar benzene ring groups and abundant pore structures, enabling selective adsorption and enrichment of solanesol and its ester compounds.

[0010] In some embodiments, the aldehyde monomer is selected from at least one of pyromellitic methyl benzoate, 1,3,5-tris(4-formylphenyl)benzene, and tris(4-benzoyl)amine.

[0011] In some embodiments, the molar ratio of the terephthalonitrile monomer to the aldehyde monomer is (1-2):1, preferably 1:1, 1.5:1, 2:1, or any two of the above values ​​forming a range.

[0012] In some embodiments, the S1 reaction is carried out in an inert atmosphere at 80-120°C for 56-72 hours, preferably any one of the ranges consisting of 80°C, 90°C, 100°C, 110°C, 120°C, and any two of the above values; preferably any one of the ranges consisting of 56 hours, 57 hours, 60 hours, 65 hours, 70 hours, 71 hours, 72 hours, and any two of the above values. In some embodiments, the inert atmosphere is a nitrogen or argon atmosphere.

[0013] In some embodiments, an inorganic base and a reaction solvent are added to reaction S1. In some embodiments, the inorganic base is cesium carbonate or sodium carbonate. In some embodiments, the reaction solvent is N,N-dimethylformamide or mesitylene.

[0014] In some embodiments, the vinylimidazole monomer is 1-vinylmethylimidazole, 1-vinylethylimidazole, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate, or 1-vinyl-3-ethylimidazolium bromide.

[0015] In some embodiments, the amount of vinylimidazole monomer used is 5wt%-10wt% of the amount of organic porous polymer used, preferably 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, or any two of the above values ​​forming a range.

[0016] In some embodiments, S2 is performed at 60-80°C for 4-8 hours, preferably any one of any two values ​​from 60°C, 70°C, 80°C, and above; preferably any one of any two values ​​from 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, and above.

[0017] In some embodiments, the polymerization solvent is toluene. In some embodiments, the initiator is azobisisobutyronitrile (AIBN).

[0018] In some embodiments, the strong alkaline solution is a 20wt%-30wt% sodium hydroxide or potassium hydroxide solution. Preferably, it is any one of the ranges of 20wt%, 25wt%, 30wt%, or any two of the above values.

[0019] In some embodiments, the S3 alkalization treatment is carried out at 60-80°C for 4-8 hours, preferably any one of any two values ​​from 60°C, 70°C, 80°C, and above; preferably any one of any two values ​​from 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, and above.

[0020] In some embodiments, the amount of the alkaline ionic liquid-modified organic porous polymer used is 5wt%-10wt% of the amount of waste tobacco leaves, preferably 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, or any two of the above values ​​forming a range.

[0021] In some embodiments, the waste tobacco leaves are pulverized to 60-100 mesh, preferably 60 mesh, 70 mesh, 80 mesh, 90 mesh, 100 mesh, or any two of the above values ​​forming a range. Further, the amount of organic solvent used is 10-20 times the amount of the mixture. Further, the grinding time is 0.5-2 hours.

[0022] In some embodiments, the hydrolysis reaction takes 4-8 hours and the reaction temperature is the boiling point of the organic solvent; preferably, it is any one of the ranges consisting of 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or any two of the above values.

[0023] In some embodiments, the organic solvent is methanol or ethanol.

[0024] In some embodiments, the low-boiling-point nonpolar solvent is n-hexane, cyclohexane, or petroleum ether.

[0025] In some embodiments, reflux extraction is performed at 80-120°C for 8-12 hours, preferably any one of any two values ​​from 80°C, 90°C, 100°C, 110°C, 120°C, and above; preferably any one of any two values ​​from 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, and above.

[0026] Compared with the prior art, one of the above technical solutions has the following advantages or beneficial effects. This invention provides a method for extracting solanesol from waste tobacco leaves. It utilizes an organic porous polymer modified with an alkaline ionic liquid to achieve hydrolysis catalysis and adsorption enrichment of solanesol from waste tobacco leaves. Solanesol esters are released through catalysis, and then separated through adsorption enrichment via a porous framework. Simultaneously, the alkaline ionic liquid provides strongly alkaline sites, catalyzing the hydrolysis of solanesol esters. This method significantly improves the extraction efficiency of solanesol while retaining nicotine, sugars, proteins, and other components in tobacco.

[0027] This invention achieves full contact between waste tobacco leaves and an organic porous polymer modified with an alkaline ionic liquid through grinding pretreatment; and ensures efficient reaction by achieving effective hydrolysis catalysis and adsorption enrichment through hydrolysis and extraction processes.

[0028] This invention provides a method for extracting solanesol from waste tobacco leaves, overcoming the environmental pollution and complex process defects of the traditional alkaline saponification method, avoiding the discharge of strong alkaline wastewater, eliminating the need for acid-base neutralization steps in the extract, shortening the production cycle, reducing operational complexity, and allowing for catalyst recycling and solvent reuse, thereby effectively reducing overall costs.

[0029] Terminology Explanation Certain embodiments of the invention will now be described in detail, examples of which are illustrated by the accompanying structural and chemical formulas. The invention is intended to cover all alternatives, modifications, and equivalents, all of which are included within the scope of the invention as defined in the claims. Those skilled in the art will recognize that many similar or equivalent methods and materials can be used to practice the invention. The invention is by no means limited to the methods and materials described herein. In the event that one or more of the incorporated documents, patents, and similar materials differ from or contradict this application (including, but not limited to, defined terminology, application of terminology, described techniques, etc.), this application shall prevail.

[0030] It should be further appreciated that certain features of the invention, for clarity, have been described in multiple independent embodiments, but may also be provided in combination in a single embodiment. Conversely, various features of the invention, for brevity, have been described in a single embodiment, but may also be provided individually or in any suitable sub-combination.

[0031] Unless otherwise stated, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. All patents and publications related to this invention are incorporated herein by reference in their entirety.

[0032] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0033] In the following content, all numbers disclosed herein, whether or not they use words such as "approximately" or "about," are approximate values. The value of each number may vary by 1%, 2%, 5%, 7%, 8%, 10%, 15%, or 20%. Whenever a number with a value of N is disclosed, any numbers with values ​​of N+ / -1%, N+ / -2%, N+ / -3%, N+ / -5%, N+ / -7%, N+ / -8%, N+ / -10%, N+ / -15%, or N+ / -20% will be explicitly disclosed, where "+ / -" indicates addition or subtraction. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and techniques have also been described in many publications.

[0035] All reagents used in this invention are commercially available or can be prepared by the methods described herein. Trimethylbenzaldehyde, terephthalonitrile, tris(4-benzoyl)amine, 1-vinylmethylimidazolium, 1-vinylethylimidazolium, azobisisobutyronitrile, toluene, etc. can all be purchased from the market.

[0036] General detection methods High performance liquid chromatography (HPLC) analysis: Chromatographic conditions: C18 reversed-phase column (4.6×250 mm, 5 μm), mobile phase: methanol:water (95:5), flow rate: 1.0 mL / min, detection wavelength: 210 nm.

[0037] Examples 1-4 Step A: Vinyl modification: Aldehyde monomer (1 mmol) and terephthalonitrile monomer (1.5 mmol) were added to a reaction vessel, followed by cesium carbonate (0.05 mmol) and N,N-dimethylformamide (50 mL) as reaction solvents. The reaction vessel was sealed and placed in an oven at 120 °C under a nitrogen atmosphere for 72 hours. After the reaction was completed, the solvent was removed by filtration. The filter cake was repeatedly washed with ethanol (10 mL) and water (10 mL). After washing, it was dried to obtain the vinyl-modified organic porous polymer.

[0038] Step B: Imidazole modification: Dissolve vinylimidazolium monomer (0.1g) in toluene (10mL), add azobisisobutyronitrile (0.01g) and vinyl-modified organic porous polymer (1g), heat under reflux for 8 hours, filter to remove solvent after reaction, wash repeatedly with toluene (10mL) and dry filter cake to obtain imidazole-modified organic porous polymer.

[0039] Step C: Alkaline modification: Immerse the imidazole-modified organic porous polymer (1g) in a strongly alkaline solution (10mL) and heat to 80℃ for 4 hours. After the reaction is complete, filter to remove the solution and wash with water (10mL) and ethanol (10mL). Dry under vacuum at 80℃ for 12 hours to obtain the alkaline ionic liquid-modified organic porous polymer.

[0040] Step D Hydrolysis reaction: Take 10g of waste tobacco leaves from Chenzhou area, crush them to 80 mesh, add 0.5g of organic porous polymer modified with alkaline ionic liquid and grind for 1 hour. Mix thoroughly, pour the mixed powder into 100mL of low boiling point alcohol and heat under reflux for 4 hours. Filter to remove the low boiling point alcohol and dry the filter cake.

[0041] Step E: Extraction: The dried filter cake was then placed in a Soxhlet extractor and refluxed with 100 mL of extraction solvent for 8 hours. After extraction, the extract was concentrated under reduced pressure to obtain the solanesol extract. Quantitative analysis was performed using liquid chromatography to determine the solanesol purity and extraction rate.

[0042] Table 1 Screening of Reaction Conditions

[0043] Example 5 Step A: Vinyl modification: Trimethylolpropane (1 mmol) and terephthalonitrile (1.5 mmol) were added to the reaction vessel, followed by cesium carbonate (0.05 mmol) and N,N-dimethylformamide (50 mL) as reaction solvents. The reaction vessel was sealed and placed in an oven at 120 °C under a nitrogen atmosphere for 70 hours. After the reaction was completed, the solvent was removed by filtration. The filter cake was repeatedly washed with ethanol (10 mL) and water (10 mL). After washing, it was dried to obtain the vinyl-modified organic porous polymer.

[0044] Step B: Imidazole modification: Dissolve 0.05 g of 1-ethyl-3-methylimidazole in 10 mL of toluene, add 0.01 g of azobisisobutyronitrile (AIBN) and 1 g of vinyl-modified organic porous polymer, heat under reflux for 8 hours, filter to remove solvent after reaction, wash repeatedly with 10 mL of toluene and dry filter cake to obtain imidazole-modified organic porous polymer.

[0045] Step C: Alkaline modification: Immerse the imidazole-modified organic porous polymer (1g) in 30wt% sodium hydroxide solution (10mL) and heat to 80℃ for 4 hours for alkalization. After the reaction is completed, filter to remove the solution and wash with water (10mL) and ethanol (10mL). Dry under vacuum at 80℃ for 12 hours to obtain the alkaline ionic liquid-modified organic porous polymer.

[0046] Step D Hydrolysis reaction: Take 10g of waste tobacco leaves from Chenzhou area, crush them to 100 mesh, add 1g of organic porous polymer modified with alkaline ionic liquid, grind for 1 hour, mix thoroughly, pour the mixed powder into 100mL of ethanol, heat under reflux for 8 hours, filter to remove low boiling point alcohol, and dry the filter cake.

[0047] Step E: Extraction: The dried filter cake was then placed in a Soxhlet extractor and refluxed with petroleum ether (100 mL) for 12 hours. After extraction, the extract was concentrated under reduced pressure to obtain solanesol extract. Quantitative analysis by liquid chromatography showed that the solanesol purity was 82.8% and the solanesol extraction rate was 95.6%.

[0048] Comparative Example 1 The difference from Example 5 is that the imidazole-modified organic porous polymer was directly ground on waste tobacco leaves, omitting the impregnation process with a strong alkaline solution; the rest of the process was the same as in Example 5. Quantitative analysis by liquid chromatography showed that the solanesol purity was 46.1% and the solanesol extraction rate was 67.2%.

[0049] Comparative Example 2 The difference from Example 5 is that the vinyl-modified organic porous polymer was directly impregnated in a 30 wt% sodium hydroxide solution, and the imidazole group modification process was omitted; the rest of the process was the same as in Example 5. Quantitative analysis by liquid chromatography showed that the solanesol purity was 42.1% and the solanesol extraction rate was 72.3%.

[0050] Example 6 The solid obtained after the reaction in Example 5 was recovered, washed three times with ethanol, and dried at 60°C for 8 hours to obtain an organic porous polymer modified with an alkaline ionic liquid for later use.

[0051] The recovered catalyst was catalyzed according to the reaction process of Example 5. After being recycled and reused 5 times, the purity of the obtained solanesol was 42.6% and the yield was 85.7%.

[0052] Example 7 The difference from Example 5 is that the amount of alkaline ionic liquid-modified organic porous polymer was changed, and the extraction effect was tested as follows: Table 2. Optimization of the dosage of the organic porous polymer modified with alkaline ionic liquid.

[0053] The results show that increasing the amount of alkaline ionic liquid-modified organic porous polymer improves the extraction efficiency.

[0054] Example 8 The difference from Example 5 is that the hydrolysis reaction time was changed, and the extraction effect was tested as follows: Table 3 Optimization of hydrolysis time

[0055] It is evident that extending the hydrolysis time has little impact on the extraction effect; considering cost, 4-6 hours is preferable.

[0056] The method of this invention has been described through preferred embodiments. Those skilled in the art will readily be able to modify or appropriately alter and combine the methods and applications described herein within the scope, spirit, and context of this invention to implement and apply the technology of this invention. Those skilled in the art can refer to the content herein to appropriately improve process parameters. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the scope of this invention.

Claims

1. A method for efficiently extracting solanesol from waste tobacco leaves, characterized in that, include: Step 1: Grinding and mixing: The pulverized waste tobacco leaves and the organic porous polymer modified with alkaline ionic liquid are thoroughly ground and mixed to obtain a mixture; Step 2 Hydrolysis reaction: Pour the mixture into an organic solvent and heat to cause the solanesyl ester to undergo a hydrolysis reaction. After the reaction is complete, slowly evaporate the organic solvent to obtain a solid mixture. Step 3: Reflux extraction: Place the obtained solid mixture into a Soxhlet extractor and reflux with a low-boiling-point nonpolar solvent. Remove the organic solvent from the extract under reduced pressure to obtain solanesol extract.

2. The method according to claim 1, characterized in that, The preparation process of the alkaline ionic liquid-modified organic porous polymer includes: S1 polymerization reaction: preparation of vinyl-modified organic porous polymers from terephthalonitrile monomers and aldehyde monomers; S2 Imidazole Modification: An organic porous polymer modified with imidazole was prepared by reacting an organic porous polymer, an initiator, and a vinyl imidazole monomer in a polymerization solvent. S3 Alkali Treatment: The imidazole-modified organic porous polymer is alkali-modified with a strong alkaline solution to obtain an organic porous polymer modified with an alkaline ionic liquid.

3. The method according to claim 2, characterized in that, The aldehyde monomer is selected from at least one of pyromellitic methyl ether, 1,3,5-tris(4-formylphenyl)benzene, and tris(4-benzoyl)amine; The molar ratio of the terephthalonitrile monomer to the aldehyde monomer is (1-2):

1.

4. The method according to claim 2, characterized in that, The S1 reaction is carried out at 80-120°C for 56-72 hours under an inert atmosphere, wherein the inert atmosphere is a nitrogen or argon atmosphere. The S1 reaction is carried out by adding an inorganic base and a reaction solvent, wherein the inorganic base is cesium carbonate or sodium carbonate; and the reaction solvent is N,N-dimethylformamide or mesitylene.

5. The method according to claim 2, characterized in that, The vinylimidazole monomer is 1-vinylmethylimidazole or 1-vinylethylimidazole; the amount of the vinylimidazole monomer is 5wt%-10wt% of the amount of the organic porous polymer.

6. The method according to claim 2, characterized in that, S2 is carried out at 60-80℃ for 4-8 hours; The polymerization solvent is toluene; the initiator is azobisisobutyronitrile.

7. The method according to claim 2, characterized in that, The strong alkaline solution is a 20wt%-30wt% sodium hydroxide or potassium hydroxide solution; S3 alkalization treatment is carried out at 60-80℃ for 4-8 hours.

8. The method according to claim 1, characterized in that, The waste tobacco leaves are pulverized to 60-100 mesh, the amount of the alkaline ionic liquid-modified organic porous polymer is 5wt%-10wt% of the amount of waste tobacco leaves, and the grinding time is 0.5-2 hours.

9. The method according to claim 1, characterized in that, The amount of organic solvent used is 10-20 times the amount of the mixture, the hydrolysis reaction time is 4-8 hours, and the reaction temperature is the boiling point temperature of the organic solvent. The organic solvent is methanol or ethanol.

10. The method according to claim 1, characterized in that, The reflux extraction is carried out at 80-120℃ for 8-12 hours; the low-boiling-point non-polar solvent is n-hexane, cyclohexane or petroleum ether.

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