CN116891536A - Method for realizing surface esterification of cellulose in aqueous solution - Google Patents
Method for realizing surface esterification of cellulose in aqueous solution Download PDFInfo
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- 229920002678 cellulose Polymers 0.000 title claims abstract description 89
- 239000001913 cellulose Substances 0.000 title claims abstract description 87
- 238000005886 esterification reaction Methods 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 30
- 230000032050 esterification Effects 0.000 title claims abstract description 24
- 239000007864 aqueous solution Substances 0.000 title claims abstract description 13
- 239000003054 catalyst Substances 0.000 claims abstract description 18
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 18
- 229920001567 vinyl ester resin Polymers 0.000 claims abstract description 18
- 238000001035 drying Methods 0.000 claims abstract description 14
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- 235000010980 cellulose Nutrition 0.000 claims description 81
- 238000006243 chemical reaction Methods 0.000 claims description 50
- VHYFNPMBLIVWCW-UHFFFAOYSA-N 4-Dimethylaminopyridine Chemical compound CN(C)C1=CC=NC=C1 VHYFNPMBLIVWCW-UHFFFAOYSA-N 0.000 claims description 30
- 239000002994 raw material Substances 0.000 claims description 23
- 238000001914 filtration Methods 0.000 claims description 14
- 150000007530 organic bases Chemical class 0.000 claims description 11
- 239000007788 liquid Substances 0.000 claims description 10
- 229920000168 Microcrystalline cellulose Polymers 0.000 claims description 9
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims description 9
- 235000019813 microcrystalline cellulose Nutrition 0.000 claims description 9
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- 230000035484 reaction time Effects 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 7
- MEGHWIAOTJPCHQ-UHFFFAOYSA-N ethenyl butanoate Chemical compound CCCC(=O)OC=C MEGHWIAOTJPCHQ-UHFFFAOYSA-N 0.000 claims description 4
- 230000008569 process Effects 0.000 claims description 4
- 238000003756 stirring Methods 0.000 claims description 4
- 229920000742 Cotton Polymers 0.000 claims description 3
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 claims description 3
- 238000004064 recycling Methods 0.000 claims description 3
- 229920001046 Nanocellulose Polymers 0.000 claims description 2
- CMDXMIHZUJPRHG-UHFFFAOYSA-N ethenyl decanoate Chemical compound CCCCCCCCCC(=O)OC=C CMDXMIHZUJPRHG-UHFFFAOYSA-N 0.000 claims description 2
- GLVVKKSPKXTQRB-UHFFFAOYSA-N ethenyl dodecanoate Chemical compound CCCCCCCCCCCC(=O)OC=C GLVVKKSPKXTQRB-UHFFFAOYSA-N 0.000 claims description 2
- LZWYWAIOTBEZFN-UHFFFAOYSA-N ethenyl hexanoate Chemical compound CCCCCC(=O)OC=C LZWYWAIOTBEZFN-UHFFFAOYSA-N 0.000 claims description 2
- QBDADGJLZNIRFQ-UHFFFAOYSA-N ethenyl octanoate Chemical compound CCCCCCCC(=O)OC=C QBDADGJLZNIRFQ-UHFFFAOYSA-N 0.000 claims description 2
- UIWXSTHGICQLQT-UHFFFAOYSA-N ethenyl propanoate Chemical compound CCC(=O)OC=C UIWXSTHGICQLQT-UHFFFAOYSA-N 0.000 claims description 2
- 230000001502 supplementing effect Effects 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims 2
- 230000004048 modification Effects 0.000 abstract description 9
- 238000012986 modification Methods 0.000 abstract description 9
- 239000003513 alkali Substances 0.000 abstract description 6
- 238000005580 one pot reaction Methods 0.000 abstract description 3
- 239000002904 solvent Substances 0.000 abstract description 2
- 125000004185 ester group Chemical group 0.000 description 8
- 239000007787 solid Substances 0.000 description 8
- 238000005406 washing Methods 0.000 description 8
- 239000003960 organic solvent Substances 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 description 6
- 150000008064 anhydrides Chemical group 0.000 description 6
- -1 polysaccharide compound Chemical class 0.000 description 5
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 4
- IMROMDMJAWUWLK-UHFFFAOYSA-N Ethenol Chemical compound OC=C IMROMDMJAWUWLK-UHFFFAOYSA-N 0.000 description 4
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 4
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 4
- 238000009776 industrial production Methods 0.000 description 4
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- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N acetone Substances CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 2
- PCLIMKBDDGJMGD-UHFFFAOYSA-N N-bromosuccinimide Chemical compound BrN1C(=O)CCC1=O PCLIMKBDDGJMGD-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 150000001735 carboxylic acids Chemical class 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
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- AMXOYNBUYSYVKV-UHFFFAOYSA-M lithium bromide Chemical compound [Li+].[Br-] AMXOYNBUYSYVKV-UHFFFAOYSA-M 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
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- 238000012360 testing method Methods 0.000 description 2
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 2
- 238000005809 transesterification reaction Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 2
- NGNBDVOYPDDBFK-UHFFFAOYSA-N 2-[2,4-di(pentan-2-yl)phenoxy]acetyl chloride Chemical compound CCCC(C)C1=CC=C(OCC(Cl)=O)C(C(C)CCC)=C1 NGNBDVOYPDDBFK-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000001157 Fourier transform infrared spectrum Methods 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- IKHGUXGNUITLKF-XPULMUKRSA-N acetaldehyde Chemical compound [14CH]([14CH3])=O IKHGUXGNUITLKF-XPULMUKRSA-N 0.000 description 1
- 150000008065 acid anhydrides Chemical class 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000009471 action Effects 0.000 description 1
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- 230000009286 beneficial effect Effects 0.000 description 1
- 239000002551 biofuel Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 210000002421 cell wall Anatomy 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
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- 239000008103 glucose Substances 0.000 description 1
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- 230000002427 irreversible effect Effects 0.000 description 1
- 230000003780 keratinization Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B3/00—Preparation of cellulose esters of organic acids
- C08B3/06—Cellulose acetate, e.g. mono-acetate, di-acetate or tri-acetate
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B3/00—Preparation of cellulose esters of organic acids
- C08B3/08—Preparation of cellulose esters of organic acids of monobasic organic acids with three or more carbon atoms, e.g. propionate or butyrate
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Biochemistry (AREA)
- Materials Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Polysaccharides And Polysaccharide Derivatives (AREA)
Abstract
The application belongs to the technical field of cellulose modification, and particularly relates to a method for realizing cellulose surface esterification in an aqueous solution. The method utilizes an organic alkali catalyst and a vinyl ester esterifying agent to prepare the surface esterification product of cellulose in an aqueous solution by a one-pot method, is simple, quick and easy to implement, solves the problem that cellulose cannot be directly esterified in the aqueous solution, ensures that the cellulose can be directly subjected to surface esterification without drying or solvent replacement, and can directly recycle the reacted solution, thereby obviously improving the efficiency.
Description
Technical Field
The application belongs to the technical field of cellulose modification, and particularly relates to a method for realizing cellulose surface esterification in an aqueous solution.
Background
Cellulose is a natural polysaccharide compound, and is formed by connecting glucose molecules through beta-1, 4-glycosidic bonds, so as to form a long-chain structure. Is widely existing in plant cell walls, accounts for more than 50% of the carbon content in plant kingdom, and has good reproducibility and biodegradability, and structural support and stability are provided for plants. In industry, cellulose is useful for the preparation of paper, textiles, food additives, biofuels, and the like. In scientific research, cellulose is used as biomedical materials, tissue engineering scaffolds, and the like. However, cellulose has some limitations in its natural morphology, such as hydrophilicity, low mechanical strength, susceptibility to agglomeration, and the like. To overcome these limitations and expand the field of application, cellulose esterification modifications have been widely studied and applied.
In particular, the surface esterification modification of cellulose can improve the hydrophobic property of the cellulose under the condition of not changing the internal structure of the cellulose, and effectively improve the compatibility between the cellulose and a hydrophobic matrix. Side chain structure can be introduced to enhance the interaction force between cellulose molecules, thereby improving the mechanical strength and durability of the cellulose material; different functional groups are introduced to impart new chemical properties and functions to cellulose.
The cellulose esterification reaction is a chemical reaction in which cellulose is reacted with an acid anhydride (acid anhydride compound or acid anhydrating agent) to form a cellulose ester. This reaction is accomplished by reacting the anhydride groups in the anhydride with the hydroxyl groups in the cellulose to form ester linkages. Anhydride compounds commonly used in the esterification reaction include inorganic anhydrides (e.g., acid chloride, acid anhydride chloride) and organic anhydrides (e.g., acetic anhydride, acetone anhydride, etc.). Anhydrides such as N, N-dimethylacetamide, N-bromosuccinimide (DMAc/LiBr) and the like may also be used to catalyze the cellulose esterification reaction.
In current cellulose esterification studies, dry cellulosic materials are predominantly used in organic solvents. Cetin, NS. and the like are prepared by transesterification of vinyl acetate in DMF organic solvent (Cetin, NS.et al., macromol. Biosci.2009,9, 997-1003.). Organic solvents commonly used for cellulose esterification modification, such as dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), N-Dimethylformamide (DMF) and the like, volatilize in the atmosphere and pollute the environment; the cost is usually high, and certain limitation is caused on the large-scale application of cellulose esterification modification; recovery and disposal of the discarded solvent also faces some technical and cost challenges. Tripathi et al, using dried fiber samples, exchanging with acetone, adding a mixed solvent of toluene, acetic acid and sulfuric acid, and finally adding acetic anhydride to react to obtain esterified cellulose (Anurodh Tripathi, marko ago et al, ACS appliedmaterials & interfaces.2018,10, 51:44776-44786.). The drying of the raw material requires the removal of a large amount of water from the cellulose, which results in irreversible destruction of the chemical bonds between the fibrils, a phenomenon also known as "keratinization", which eventually reduces the dispersibility, reactivity and performance of the cellulose in use.
Therefore, developing a method for esterifying the surface of cellulose, which does not require an organic solvent and has reaction conditions more suitable for industrial production, is a technical problem that needs to be solved by those skilled in the art.
Disclosure of Invention
In view of the above, a first object of the present application is to provide a method for surface esterification of cellulose, which does not need organic solvents and has reaction conditions suitable for industrial production, wherein the method has mild reaction conditions, and the reaction system can be used for subsequent production, so as to promote the development of cellulose esterification modification in a simple, environment-friendly, green and sustainable direction.
In order to achieve the above purpose, the present application adopts the following technical scheme:
a method for effecting surface esterification of cellulose in an aqueous solution comprising the steps of:
(I) Adding cellulose raw materials into the aqueous solution to enable the concentration mass fraction of the mixed solution to be 0.1-30%, and uniformly stirring;
(II) adding an organic base catalyst and a vinyl ester esterifying agent into the mixed solution obtained in the step (I), stirring vigorously, reacting at constant temperature for a period of time, standing after the reaction is finished, filtering, and drying to obtain a cellulose surface esterification product;
(III) the liquid obtained by filtering in the step (II) is used for recycling the subsequent surface esterification reaction of cellulose.
It is worth noting that, although the prior art discloses a technical scheme for preparing surface esterified microcrystalline cellulose by using an esterification method of mixed acid in aqueous solution, the reaction temperature is higher, and the reaction time is 3-20 times of that of the application at the same reaction temperature. Further, the use of a mixed acid results in neutralization of the product in the post-treatment, and no post-treatment method of the reaction system is mentioned. In principle, surface esterification of microcrystalline cellulose in mixed acids is essentially a reaction of carboxylic acids with hydroxyl groups, which is devoid of water, and therefore the reactivity of carboxylic acids with hydroxyl groups is much lower than that of anhydrides. According to the application, vinyl esters are used as an esterifying agent, under the action of an alkaline catalyst, the vinyl esters and cellulose hydroxyl groups form cellulose ester and vinyl alcohol through transesterification, the structure of the vinyl alcohol is unstable, and once the vinyl alcohol is generated, the vinyl alcohol is immediately converted into acetaldehyde, so that the forward reaction is accelerated, and the rapid esterification of the cellulose surface is realized.
Compared with the prior art, the method has the advantages that the cellulose surface esterification product is prepared by using the organic alkali catalyst and the vinyl ester esterifying agent in the aqueous solution through a one-pot method, and the method does not need to dry cellulose raw materials, so that the internal structure transformation caused by raw material drying is avoided, and the reaction efficiency is improved; and the reaction system does not need an organic solvent, so that the environmental hazard is reduced, the reaction cost is reduced, and the operation threshold is lowered.
Further, the cellulose in step (I) comprises one or more of pulp, cotton, microcrystalline cellulose, nanocellulose, lignocellulosic.
Further, the organic base catalyst in the step (II) comprises 4-dimethylaminopyridine or diethanolamine, and the addition amount of the organic base catalyst is 1-100% of the mass of the cellulose raw material.
Further, the vinyl ester esterifying agent in the step (II) comprises one or more of vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate and vinyl laurate, and the vinyl ester esterifying agent.
Further, the reaction temperature in the step (II) is 0-70 ℃ and the reaction time is 5min-5h.
Further, the reaction temperature in the step (II) is room temperature, and the reaction time is 1h-5h.
The application is worth to be explained, the reaction temperature is set to be room temperature, heating is not needed, the energy consumption and the dangerous degree of the reaction are reduced, and the amplification and the industrial production of the reaction system are facilitated.
Further, the reaction temperature in the step (II) is 60-70 ℃ and the reaction time is 5-30 min. Considering that the improvement of the reaction temperature is helpful for the rapid reaction, the improvement of the reaction temperature increases the energy consumption to a certain extent, and compared with the synthesis process in the prior art, the application can effectively reduce the energy consumption and improve the process cost control capability by controlling the high-temperature reaction time.
Further, the step (III) comprises detecting, calibrating and filtering to obtain the contents of vinyl ester esterifying agent and organic alkali catalyst in the liquid, and supplementing cellulose raw material or cellulose raw material mixed solution, vinyl ester esterifying agent and organic alkali catalyst to ensure that the concentration mass fraction of the cellulose raw material mixed solution in the reaction solution is 0.1-30%, the mass of the organic alkali catalyst is not less than 1% of the mass of the cellulose raw material, and the mass of the vinyl ester esterifying agent is not less than 5% of the mass of the cellulose raw material.
It is worth to say that the esterification reaction is used as a reversible reaction, the complete reaction of the reaction raw materials cannot be realized, and the concentration ratio of the reactant to the product in the reaction system has great influence on the reaction speed and the reaction efficiency of the esterification reaction. Therefore, in industrial production, the production cost and the production efficiency are comprehensively considered, and the concentration of reactants in a reaction system needs to be controlled. According to the application, through recycling of the reaction solution, waste of esterification raw materials is avoided, and the post-reaction treatment procedure is simplified, so that a more environment-friendly solution is provided for industrialized development of cellulose surface esterification.
Compared with the prior art, the application has the remarkable advantages that:
(1) The application discloses a method for preparing an esterification product on the surface of cellulose by using an organic base catalyst and a vinyl ester esterifying agent in an aqueous solution through a one-pot method, so that raw materials do not need to be dried and can react in an aqueous system, the internal structure transformation caused by the drying of the raw materials is avoided, and the reaction efficiency is improved; and organic solvents are not needed to be added, so that the harm to the environment is reduced, and the reaction cost and the operation difficulty are greatly reduced.
(2) The reaction temperature can be carried out at room temperature without heating, so that the energy consumption and the hazard degree are reduced greatly; the organic alkali catalyst and the vinyl ester esterifying agent can be recycled, so that the cost of raw materials is reduced.
(3) The preparation process provided by the application is simple and convenient to operate, quick in reaction, low in cost, free of complex reaction equipment, and extremely beneficial to industrialized mass production, and the practical application potential of the modified cellulose is improved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for the description of the embodiments or the prior art will be briefly described below, it will be apparent that the drawings in the following description are only embodiments of the present application, and other drawings can be obtained from the provided drawings without inventive effort for a person skilled in the art
FIG. 1 is a FT-IR spectrum of modified cellulose measured in example 1 of the present application.
Detailed Description
The following description of the technical solutions in the embodiments of the present application will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The word "embodiment" as used herein does not necessarily mean that any embodiment described as "exemplary" is preferred or advantageous over other embodiments. Performance index testing in the examples of the present application, unless otherwise specified, was performed using conventional testing methods in the art. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure.
Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; other test methods and techniques not specifically mentioned in the present application are those commonly used by those skilled in the art.
Numerous specific details are set forth in the following examples in order to provide a better understanding of the present application. It will be understood by those skilled in the art that the present application may be practiced without some of these specific details. In the examples, some methods, means, instruments, devices, etc. well known to those skilled in the art are not described in detail in order to highlight the gist of the present application. On the premise of no conflict, the technical features disclosed by the embodiment of the application can be combined at will, and the obtained technical scheme belongs to the disclosure of the embodiment of the application.
The present application will be further specifically illustrated by the following examples, which are not to be construed as limiting the application, but rather as falling within the scope of the present application, for some non-essential modifications and adaptations of the application that are apparent to those skilled in the art based on the foregoing disclosure.
Example 1
(1) Into a 100mL Erlenmeyer flask was added 50mL of water, 2g of microcrystalline cellulose, 1.0g of 4-Dimethylaminopyridine (DMAP), 20mL of vinyl acetate.
(2) The conical flask was stoppered with a stopper, stirred vigorously at room temperature, and reacted for 1h. After the reaction is completed, standing, filtering, washing the solid, and drying to obtain the cellulose with esterified surface. The surface of the surface-modified cellulose was measured with an infrared spectrometer to have a large number of ester groups (FIG. 1).
(3) The filtered liquid can be recycled, and the esterification reaction of the cellulose surface can be continued.
Example 2
(1) Into a 100mL Erlenmeyer flask was added 50mL of water, 2g of microcrystalline cellulose, 0.2g of 4-Dimethylaminopyridine (DMAP), 20mL of vinyl acetate.
(2) The conical flask was stoppered with a stopper, stirred vigorously at room temperature, and reacted for 1h. After the reaction is completed, standing, filtering, washing the solid, and drying to obtain the cellulose with esterified surface. The surface of the surface-modified cellulose was measured with an infrared spectrometer to have a large number of ester groups (FIG. 1).
(3) The filtered liquid can be recycled, and the esterification reaction of the cellulose surface can be continued.
Example 3
(1) A100 mL Erlenmeyer flask was charged with 20mL of a 3.5% suspension of cellulose nanocrystals, 0.014g of 4-Dimethylaminopyridine (DMAP), 5mL of vinyl acetate.
(2) The conical flask was stoppered with a stopper, stirred vigorously at room temperature, and reacted for 5 hours. After the reaction is completed, standing, filtering, washing the solid, and drying to obtain the cellulose with esterified surface. The surface of the surface-modified cellulose was measured with an infrared spectrometer to have a large number of ester groups (FIG. 1).
(3) The filtered liquid can be recycled, and the esterification reaction of the cellulose surface can be continued.
Example 4
(1) 50mL of 30% strength pulp, 1.5g of 4-Dimethylaminopyridine (DMAP), 20mL of vinyl acetate were added to a 100mL Erlenmeyer flask.
(2) The conical flask was stoppered with a stopper, stirred vigorously at 60℃and reacted for 30min. After the reaction is completed, standing, filtering, washing the solid, and drying to obtain the cellulose with esterified surface. The surface of the surface-modified cellulose was measured with an infrared spectrometer to have a large number of ester groups.
(3) The filtered liquid can be recycled, and the esterification reaction of the cellulose surface can be continued.
Example 5
The solution obtained in step (3) of example 1 was filtered in a 100mL Erlenmeyer flask, and the residual amount of 4-Dimethylaminopyridine (DMAP) was measured and calibrated to be 0.7g, the residual amount of vinyl acetate was 19mL, and 2g of microcrystalline cellulose and 0.3g of DMAP were added. The conical flask was stoppered with a stopper, stirred vigorously at room temperature, and reacted for 1h. After the reaction is completed, standing, filtering, washing the solid, and drying to obtain the cellulose with esterified surface. The surface of the surface-modified cellulose was measured with an infrared spectrometer to have a large number of ester groups (FIG. 1).
Example 6
(1) Into a 100mL Erlenmeyer flask was added 50mL of water, 2g of cotton linter, 1g of diethanolamine, 20mL of vinyl butyrate.
(2) The conical flask was stoppered with a stopper, stirred vigorously at 60℃and reacted for 30min. After the reaction is completed, standing, filtering, washing the solid, and drying to obtain the cellulose with esterified surface. The surface of the surface-modified cellulose was measured with an infrared spectrometer to have a large number of ester groups.
(3) The filtered liquid can be recycled, and the esterification reaction of the cellulose surface can be continued.
Example 7
(1) Into a 100mL Erlenmeyer flask was added 50mL of water, 2g of microcrystalline cellulose, 2g of 4-Dimethylaminopyridine (DMAP), 20mL of vinyl butyrate.
(2) The conical flask was stoppered with a stopper, stirred vigorously at 60℃and reacted for 5min. After the reaction is completed, standing, filtering, washing the solid, and drying to obtain the cellulose with esterified surface. The surface of the surface-modified cellulose was measured with an infrared spectrometer to have a large number of ester groups.
(3) The filtered liquid can be recycled, and the esterification reaction of the cellulose surface can be continued.
In order to further demonstrate the advantages of the present application for a better understanding thereof, the technical advances of the application are determined by the following comparative examples, which are not to be construed as limiting the application, and the nature of the products obtained by other determination experiments made by those skilled in the art based on the above summary of the application and the use thereof based on the above-described nature are also considered to fall within the scope of the application.
Comparative example 1
(1) Into a 100mL Erlenmeyer flask was added 50mL of water, 2g of microcrystalline cellulose, no organic base catalyst, and 20mL of vinyl acetate.
(2) The conical flask was stoppered with a stopper, stirred vigorously at 60℃and reacted for 5min. After the reaction is completed, standing, filtering, washing and drying the solid. The structure of the sample was measured by infrared spectrometer, and it was found that the surface of cellulose was not successfully modified with ester groups (FIG. 1).
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
1. A method for effecting surface esterification of cellulose in an aqueous solution, comprising the steps of:
(I) Adding cellulose raw materials into an aqueous solution to form a mixed solution, controlling the concentration mass fraction of the mixed solution to be 0.1-30%, and uniformly stirring;
(II) adding an organic base catalyst and a vinyl ester esterifying agent into the mixed solution obtained in the step (I), stirring vigorously, reacting at constant temperature for a period of time, standing after the reaction is finished, filtering, and drying to obtain a cellulose surface esterification product;
(III) the liquid obtained by filtering in the step (II) is used for recycling the subsequent surface esterification reaction of cellulose.
2. The method of claim 1, wherein the cellulose in step (I) comprises one or more of pulp, cotton, microcrystalline cellulose, nanocellulose, lignocellulosic.
3. The method according to claim 1, wherein the organic base catalyst in the step (II) comprises 4-dimethylaminopyridine or diethanolamine, and the organic base catalyst is added in an amount of 1 to 100% by mass of the cellulose raw material.
4. The method according to claim 1, wherein the vinyl ester esterifying agent in the step (II) comprises one or more of vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, and vinyl laurate, and the vinyl ester esterifying agent is added in an amount of not less than 5% by mass of the cellulose raw material.
5. The process according to claim 1, wherein the reaction temperature in step (II) is 0 ℃ to 70 ℃ and the reaction time is 5min to 5h.
6. The method of claim 5, wherein the reaction temperature in step (II) is room temperature and the reaction time is 1h to 5h.
7. The process of claim 5, wherein the step (II) is carried out at a reaction temperature of 60 ℃ to 70 ℃ for a reaction time of 5min to 30min.
8. The method of claim 1, wherein the step (III) includes detecting, calibrating and filtering to obtain the contents of the vinyl ester esterifying agent and the organic base catalyst in the liquid, and supplementing the cellulose raw material or the cellulose raw material mixture, the vinyl ester esterifying agent and the organic base catalyst to make the concentration mass fraction of the cellulose raw material mixture in the reaction solution be 0.1% -30%, the mass of the organic base catalyst be not less than 1% of the mass of the cellulose raw material, and the mass of the vinyl ester esterifying agent be not less than 5% of the mass of the cellulose raw material.
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| CN117343204A (en) * | 2023-12-04 | 2024-01-05 | 北京林业大学 | Cellulose surface esterification product and preparation method and application thereof |
| CN117343204B (en) * | 2023-12-04 | 2024-03-12 | 北京林业大学 | Cellulose surface esterification product and preparation method and application thereof |
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