CN110240715B - Method for quickly dissolving gelatin in Bronsted acidic ionic liquid at low temperature - Google Patents

Method for quickly dissolving gelatin in Bronsted acidic ionic liquid at low temperature Download PDF

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CN110240715B
CN110240715B CN201910571277.2A CN201910571277A CN110240715B CN 110240715 B CN110240715 B CN 110240715B CN 201910571277 A CN201910571277 A CN 201910571277A CN 110240715 B CN110240715 B CN 110240715B
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王国伟
孙钰
秦梦漪
庄玲华
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Nanjing Tech University
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    • C—CHEMISTRY; METALLURGY
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    • C07D215/00—Heterocyclic compounds containing quinoline or hydrogenated quinoline ring systems
    • C07D215/02—Heterocyclic compounds containing quinoline or hydrogenated quinoline ring systems having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen atoms or carbon atoms directly attached to the ring nitrogen atom
    • C07D215/04—Heterocyclic compounds containing quinoline or hydrogenated quinoline ring systems having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen atoms or carbon atoms directly attached to the ring nitrogen atom with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, directly attached to the ring carbon atoms
    • C07D215/06—Heterocyclic compounds containing quinoline or hydrogenated quinoline ring systems having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen atoms or carbon atoms directly attached to the ring nitrogen atom with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, directly attached to the ring carbon atoms having only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, attached to the ring nitrogen atom
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Abstract

The invention discloses a method for quickly dissolving gelatin by acidic ionic liquid at low temperature; in order to realize the purpose, the invention prepares the acid ionic liquid containing the sulfonate, uses the water solution of the acid ionic liquid containing the sulfonate as a solvent, and quickly dissolves the gelatin at low temperature; the acidic ionic liquid is as follows: an acidic ionic liquid containing sulfonate derived from an alkylbenzimidazole or (alkyl) quinoline compound; the acidic ionic liquid only dissolves the gelatin, and the hydrolysis of the gelatin cannot be caused; the method has the advantages of simple operation, no pollution, low dissolving temperature, high dissolving speed and obviously improved solubility of the gelatin compared with the common ionic liquid; the invention provides a new scheme for extracting collagen and treating collagen fiber, gelatin and hide powder, and can realize the full and efficient utilization of biomass resources.

Description

Method for quickly dissolving gelatin in Bronsted acidic ionic liquid at low temperature
Technical Field
The invention belongs to the field of collagen extraction and processing of gelatin, collagen fiber and skin powder, and particularly relates to a method for quickly dissolving gelatin by a Bronsted acidic ionic liquid at a low temperature and preparation of the Bronsted acidic ionic liquid.
Background
Gelatin (Gelatin) is degraded from collagen in connective tissues such as animal skin, ligaments, cartilage and tendons. Collagen (Collagen) is the most abundant and widely distributed protein in animals, approximately 1/3 of total protein in animals, and plays physiological actions such as supporting organs, protecting organisms and tissues, forming, maturing, differentiating cells and calcifying. The gelatin is widely applied to the fields of biomembrane materials, medical fibers, industrial gelatin and the like. The gelatin molecule contains a repeating sequence of the tripeptides glycine (Gly) -X-Y, where X and Y are typically proline (Pro) and hydroxyproline (Hyp). This tripeptide structure determines the triple helix conformation and typical physicochemical properties of gelatin. The application of the gelatin is limited because a large number of hydrogen bonds, ionic bonds, van der waals forces, hydrophobic bonds and the like exist between inner chains and among chains of the gelatin polypeptide chains, so that the gelatin is difficult to dissolve in common organic solvents (such as ethanol, acetone and the like), and therefore, the search for a proper solvent is vital to the expansion of the application of the gelatin.
Ionic Liquids (ILs) are excellent solvents with great application prospects, and have been developed into novel solvents of many biological macromolecules. Since the first time that Swatloski reported the solubility of ionic liquids to cellulose in 2002, the study of the solubility modification of ionic liquids to biomacromolecules (cellulose, collagen or gelatin, chitosan) was very hot (Journal of the American Chemical Society, 2002, 124: 4974-.
In 2010, Toyayaxu was first applied [ Bmim ] Cl to dissolve pigskin collagen (Toyayaxu, leather science and engineering, 2010, 20 (1): 5-8). Thereafter, many conventional imidazolyl ionic liquids, such as [ Amim ] Cl, [ Emim ] Cl, [ Etmim ] Cl, [ Emim ] Ac and [ Bmim ] Ac, were Applied to dissolution studies of collagen materials (collagen, collagen fibers, gelatin, skin powder) of different sources (Singh T.et al.J.Phys.chem.B, 2010, 114: 8441 8448; Elaeagnus, Chinese leather, 2011, 40 (19): 27-29; Hu Y.et al.journal of Applied Polymer Science, 2013, 130: 2245-.
Chinese patent application No. CN201010173659.9 (collagen dissolving and regenerating method) takes imidazole ionic liquid (BmimCl, BmimBr, EmimCl, EmimBr, AmimCl, AmimBr and the like) as a solvent, and collagen raw materials (collagen fibers, hide powder fibers and animal raw hide) can be completely dissolved in the ionic liquid to form a homogeneous system by heating and stirring for 0.5-6h at 85-140 ℃. Adding coagulator (deionized water, ethanol, methanol, acetone), and regenerating collagen material (fiber, film, microsphere and powder) with various forms. Chinese patent ZL201110073127.2 (a method for preparing collagen-based composite material) is prepared by dissolving imidazole ionic liquid (BmimCl, BmimBr, EmimCl, EmimBr, AmimCl and AmimBr) serving as a main solvent, dimethyl sulfoxide serving as a cosolvent and glycerol serving as a plasticizer at 85-140 ℃ for 0.5-6h under heating and stirring. Chinese patent ZL201310521634.7 (a method for preparing collagen microfibers by using ionic liquid mixed solvent) is prepared by heating and stirring fresh animal skins or leather waste materials subjected to dechromization at 90-130 ℃ for 2-12h by using imidazole ionic liquid/dimethyl sulfoxide as mixed solvent to obtain suspension, and centrifuging to obtain collagen microfibers. The imidazole ionic liquid is AmimCl, BmimCl, EmimCl, BmimAC or EmimAc. Chinese granted patent ZL201710078848.X (a preparation method of a flexible pressure sensor based on a regenerated collagen film) takes collagen-rich skin powder (cow leather or sheep skin) as a raw material, and adopts conventional imidazole ionic liquid to dissolve, spin-coat to prepare the film, soak and wash with deionized water, and prepare the regenerated collagen film.
The ionic liquid mentioned above is imidazole conventional halide salt or acetate ionic liquid, and has the advantages of low dissolution efficiency, high dissolution temperature (more than or equal to 85 ℃), long dissolution time, and easy collagen hydrolysis and protein denaturation; in addition, deionized water is used as a coagulant to dissolve the ionic liquid, so that the aim of regenerating collagen is fulfilled.
Acidic Ionic Liquids (AILs) are a branch of functionalized ionic liquids, and have both Acidic and ionic liquid properties. However, strong acids such as sulfuric acid, methanesulfonic acid, hydrochloric acid, nitric acid, etc. are often used in the preparation of acidic ionic Liquids, and the presence of strong acid components inevitably causes problems such as hydrolysis, degradation, and oxidative carbonization of solutes (gelatin, collagen, cellulose, chitosan, etc.) (Journal of Molecular Liquids, 2016, 218: 95-105; ChemSumschem, 2015, 8: 947-.
Therefore, the invention provides a method for rapidly dissolving gelatin at low temperature by using Bronsted acidic ionic liquid, wherein the cation part of the acidic ionic liquid is prepared by derivation of alkyl benzimidazole or (alkyl) quinoline compound, and the anion is provided by acetate with weaker acidity, so that side reactions such as hydrolysis, denaturation and degradation, carbonization and the like of solutes (gelatin, collagen and hide powder) can be avoided. A novel and efficient environment-friendly solvent system is screened out, rapid dissolution of gelatin is realized at a lower temperature, and industrialization of collagen and gelatin is greatly promoted.
Disclosure of Invention
A method for rapidly dissolving gelatin at low temperature by using an acidic ionic liquid comprises the steps of taking an aqueous solution containing a sulfonate acidic ionic liquid as a solvent, dissolving gelatin at 20-40 ℃ for 30-120min, wherein the gelatin accounts for 1-10% of the solvent by mass percent, the sulfonate acidic ionic liquid comprises an alkyl benzimidazole acidic ionic liquid or an alkyl quinoline acidic ionic liquid,
the structural formula is as follows:
alkyl benzimidazole acidic ionic liquids
Figure GSB0000196787700000041
Alkyl quinoline acidic ionic liquid
Figure GSB0000196787700000042
Wherein R is1Methyl, ethyl, propyl, butyl, hexyl, octyl, decyl;
R22-methyl, 3-methyl, 4-methyl, 5-methyl, 6-methyl, 8-methyl, 4-methoxy, 6-methoxy, 2-ethyl, 3-ethyl, 6-ethyl.
Preferably, the preparation of the sulfonate-containing acidic ionic liquid comprises two steps:
(1) preparation of sulfonic acid inner salt:
taking alkyl benzimidazole and sultone as raw materials, and reacting for 4-12h in a low-polarity aprotic organic solvent at the reaction temperature of 40-90 ℃ to prepare alkyl benzimidazole sulfonic acid inner salt;
taking alkyl quinoline and sultone as raw materials, reacting for 4-12h in a low-polarity aprotic organic solvent at the reaction temperature of 40-90 ℃ to prepare alkyl quinoline sulfonic acid inner salt;
(2) preparing the acidic ionic liquid containing the sulfonate:
mixing the alkyl benzimidazole sulfonic acid inner salt obtained in the step with acetic acid, and reacting for 2-6h to obtain alkyl benzimidazole acidic ionic liquid;
and mixing the alkyl quinoline sulfonic acid inner salt obtained in the step with acetic acid, and reacting for 2-6h to obtain the alkyl quinoline acidic ionic liquid.
Preferably, the low-polarity aprotic organic solvent is one or two mixed solvents of petroleum ether, n-hexane, cyclohexane, 1, 4-dioxane, toluene and xylene.
Preferably, the molar ratio of the alkyl benzimidazole sulfonic acid inner salt to the acetic acid is 1 to (1-9), and the molar ratio of the alkyl quinoline benzimidazole sulfonic acid inner salt to the acetic acid is 1 to (1-9).
Preferably, the mass ratio of the sulfonate acidic ionic liquid to the water in the solvent is (5-50) to (50-95).
The invention has the following remarkable advantages:
(1) the preparation process of the sulfonate-containing acidic ionic liquid is simple, and the yield is high;
(2) the aqueous solution of the acidic ionic liquid containing the sulfonate has low viscosity and proper pH value;
(4) the method is simple to operate, free of pollution, low in gelatin dissolving temperature and high in dissolving speed, and the solubility of gelatin is remarkably improved compared with that of common ionic liquid;
(5) the solvent system only realizes the dissolution of the gelatin, does not cause the hydrolysis (degradation) of the gelatin, and has small change of the molecular weight of the regenerated gelatin.
Drawings
FIG. 1 is a schematic diagram of the structure of an acidic ionic liquid containing sulfonate;
FIG. 2 Nuclear magnetic Hydrogen Spectrum (left side mBmPSO)3Right side mBmPSac);
FIG. 3 metallographic microscope photograph of gelatin dissolution (20X magnification, left before dissolution, right after mBmPSAC dissolution);
FIG. 4 Infrared Spectrum of raw or regenerated gelatin (a is raw gelatin and b is mBmPSAC dissolved and regenerated gelatin).
Detailed Description
The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.
Example 1
1-methyl-3- (propyl-3-sulfonic acid) benzimidazole salt (mBmPSO)3) Synthesis of (2)
Adding 80mL of petroleum ether (boiling point of 60-90 ℃) into a 100mL four-neck flask, adding 0.01moL of 1-methylbenzimidazole and 0.01moL of propane sultone, stirring, reacting at 80 ℃ for 6h, cooling to separate out a white solid, performing suction filtration, washing the white solid with ethyl acetate, and drying at 80 ℃ for 4h to obtain the white solid, namely mBmPSO3To obtain the 1-methyl-3- (propyl-3-sulfonic) benzimidazole salt, wherein the yield is 98 percent, and the melting point is 298 ℃. Confirming the structure by nuclear magnetic hydrogen spectrum;
the reaction equation is as follows:
Figure GSB0000196787700000061
synthesis of 1-methyl-3- (propyl-3-sulfonic) benzimidazole acetate (mBmPSAC)
The product of the first step (mBmPSO)3) Adding acetic acid (molar ratio is 1: 4) into a four-mouth bottle, stirring at 30 ℃, and gradually forming a homogeneous viscous liquid, namely acidic ionic liquid (mBmPSAC), wherein the raw material composition of the acidic ionic liquid is shown in Table 1, the yield is 100%, and the nuclear magnetic hydrogen spectrum confirms the structure; the product has the following structural formula:
Figure GSB0000196787700000062
mBmPSO3nuclear magnetic hydrogen spectrum (D)2O)：
2.35ppm(m，2H，CH2)，2.90ppm(t，2H，CH2)，4.02ppm(s，3H，-NCH3)，4.58ppm(t，2H，CH2)，7.61ppm(m，2H，ArH)，7.77ppm(m，1H，ArH)，7.83ppm(m，1H，ArH)，9.20ppm(s，1H，-NCHN-)；
Nuclear magnetic hydrogen spectrum (D) of mBmPSAC2O)：
1.99ppm(s，12H，CH3COO-)，2.35ppm(m，2H，CH2)，2.90ppm(t，2H，CH2)，4.01ppm(s，3H，-NCH3)，4.58ppm(t，2H，CH2)，7.62ppm(m，2H，ArH)，7.78ppm(m，1H，ArH)，7.84ppm(m，1H，ArH)，9.20ppm(s，1H，NCH)
Weighing 5g of mBmPSAC and 95g of deionized water, dissolving to form 5% acidic ionic liquid aqueous solution, weighing 3.02g (3% by mass) of gelatin, stirring and mixing at 25 ℃, observing by a metallographic microscope (figure 3), and stirring for 37min to form homogeneous solution, wherein the gelatin is completely dissolved in the acidic ionic liquid aqueous solution;
weighing 40g of gelatin-ionic liquid solution (gelatin is dissolved in mBmPSAC aqueous solution), adding the gelatin-ionic liquid solution into a three-mouth bottle, stirring at normal temperature, adding about 40mL of 0.36mol/L NaOH solution to adjust the pH value to be approximately 7, continuously stirring for 30min, filtering through filter cloth, washing for 3 times by deionized water, detecting the pH value to be approximately 7 by test paper, drying the regenerated gelatin for 2h at 80 ℃, weighing, testing the infrared spectrum of the regenerated gelatin, comparing, and calculating amide III (1240 cm)-1) And 1470cm-1Ratio of (A)1240/A1470Judging the degree of conformational damage of the gelatin before and after regeneration; before and after the ionic liquid dissolves gelatin, A1240And A1470The infrared absorption ratio of (A) is shown in Table 2;
example 2
1-butyl-3- (propyl-3-sulfonic acid) benzimidazole salt (bBmPSO)3) Synthesis of (2)
Adding 80mL of 1, 4-dioxane into a 100mL four-neck flask, adding 0.01moL of 1-butyl benzimidazole and 0.01moL of propane sultone, stirring, reacting at 90 ℃ for 6h, cooling to separate out a large amount of white solid, performing suction filtration, washing the white solid with ethyl acetate, performing suction filtration, and drying at 80 ℃ for 2h to obtain the white solid, namely bBmPSO3To obtain the 1-butyl-3- (propyl-3-sulfonic group) benzimidazole salt, wherein the yield is 97 percent, and the melting point is 267 ℃; confirming the structure by nuclear magnetic hydrogen spectrum;
Figure GSB0000196787700000071
synthesis of 1-butyl-3- (propyl-3-sulfonic) benzimidazole acetate (bBmPSAC)
The product of the first step (bBmPSO)3) Adding acetic acid (molar ratio is 1: 4) into a four-mouth bottle, stirring at normal temperature, and gradually forming a homogeneous viscous liquid, namely acidic ionic liquid (bBmPSAC), wherein the yield is 100%, and the structure is confirmed by nuclear magnetic hydrogen spectroscopy;
the reaction equation is as follows:
Figure GSB0000196787700000081
bBmPSO3nuclear magnetic hydrogen spectrum (D)2O)：
0.89ppm(t，3H，CH3)，1.37ppm(m，2H，CH2)，1.92ppm(m，2H，CH2)，2.28ppm(m，2H，CH2)，2.63ppm(t，2H，CH2)，4.54ppm(s，2H，-NCH2)，4.71ppm(t，2H，CH2)，7.67-7.85ppm(m，4H，ArH)，9.88ppm(s，1H，NCHN-)；
Nuclear magnetic hydrogen spectrum (D) of bBmPSAC2O)：
0.92ppm(t，3H，CH3)，1.35ppm(m，2H，CH2)，1.90ppm(m，2H，CH2)，1.96ppm(s，12H，CH3COO-)，2.25ppm(m，2H，CH2)，2.60ppm(t，2H，CH2)，4.51ppm(s，2H，-NCH2)，4.66ppm(t，2H，CH2)，7.65-7.83ppm(m，4H，ArH)，9.85ppm(s，1H，-NCHN-)；
Weighing 5g of bBmPSAC and 95g of deionized water, dissolving to form a 5% acidic ionic liquid aqueous solution, weighing 3.02g (3% by mass) of gelatin, stirring and mixing at 25 ℃, observing by a metallographic microscope (figure 3), and stirring for 42min to form a homogeneous solution, wherein the gelatin is completely dissolved in the acidic ionic liquid aqueous solution;
weighing 40g of gelatin-ionic liquid solution (gelatin is dissolved in bBmPSAC aqueous solution) and adding the gelatin-ionic liquid solution into a three-mouth bottle, stirring at normal temperature, adding about 40mL of 0.36mol/L NaOH solution to adjust the pH value to be approximately 7, continuously stirring for 30min, filtering through filter cloth, washing for 3 times with deionized water, and detecting through test paperMeasuring pH to about 7, drying regenerated gelatin at 80 deg.C for 2 hr, weighing, measuring infrared spectrum of regenerated gelatin, comparing with infrared spectrum of original gelatin, and calculating amide III (1240 cm)-1) And 1470cm-1Ratio of (A)1240/A1470Judging the degree of conformational damage of the gelatin before and after regeneration; before and after the ionic liquid dissolves gelatin, A1240And A1470The infrared absorption ratio of (A) is shown in Table 2;
example 3
1-methyl-3- (butyl-4-sulfonic acid) benzimidazole salt (mBmBSO)3) Synthesis of (2)
Adding 0.01moL of 1-methylbenzimidazole and 0.01moL of butane sultone into a 100mL four-neck flask, stirring, reacting at 90 ℃ for about 6 hours to generate a large amount of white solid, washing the white solid with ethyl acetate, filtering, and drying in vacuum at 80 ℃ for 2 hours to obtain the white solid, namely mBmPSO3To obtain the 1-methyl-3- (butyl-4-sulfonic) benzimidazole salt, wherein the yield is 98 percent, and the melting point is 229 ℃. Confirming the structure by nuclear magnetic hydrogen spectrum;
the reaction equation is as follows:
Figure GSB0000196787700000091
synthesis of 1-methyl-3- (butyl-4-sulfo) benzimidazole acetate (mBmBSAc)
The product of the first step (mBmBSO)3) Adding acetic acid (molar ratio is 1: 3) into a four-mouth bottle, stirring at 30 ℃, and gradually forming a homogeneous viscous liquid, namely acidic ionic liquid (mBmBSAc), wherein the raw material composition of the acidic ionic liquid is shown in Table 1, the yield is 100%, and the nuclear magnetic hydrogen spectrum confirms the structure;
the product has the following structural formula:
Figure GSB0000196787700000092
mBmBSO3nuclear magnetic hydrogen spectrum (D)2O)：2.08ppm(m，2H，CH2)，2.39ppm(m，2H，CH2)，2.92ppm(t，2H，-CH2SO3)，4.04ppm(s，3H，-NCH3)，4.59ppm(t，2H，-NCH2)，7.67-7.83ppm(m，4H，ArH)，9.25ppm(s，1H，-NCHN)；
Nuclear magnetic hydrogen spectrum (D) of mbmsbsac2O)：1.87ppm(s，12H，CH3COO-)，2.04ppm(m，2H，CH2)，2.13ppm(m，2H，CH2)，3.02ppm(t，2H，-CH2SO3)，3.96ppm(s，3H，-NCH3)，4.52ppm(t，2H，-NCH2)，7.68-7.85ppm(m，4H，ArH)，9.31ppm(s，1H，-NCHN)；
Weighing 5g of mBmBSAc and 95g of deionized water, dissolving to form 5% acidic ionic liquid aqueous solution, weighing 3.02g (3% by mass) of gelatin, stirring and mixing at 20 ℃, observing by a metallographic microscope (figure 3), and stirring for 40min to form homogeneous solution, which shows that the gelatin is completely dissolved in the acidic ionic liquid aqueous solution;
weighing 40g of gelatin-ionic liquid solution (gelatin is dissolved in mBmBSAc aqueous solution), adding the gelatin-ionic liquid solution into a three-mouth bottle, stirring at normal temperature, adding about 40mL of 0.36mol/L NaOH solution to adjust the pH value to be approximately 7, continuously stirring for 30min, filtering through filter cloth, washing for 3 times by deionized water, detecting the pH value to be approximately 7 by test paper, drying the regenerated gelatin for 2h at 80 ℃, weighing, testing the infrared spectrum of the regenerated gelatin and comparing the infrared spectrum with the infrared spectrum of the original gelatin, and calculating amide III 1240 (cm BSAc)-1) And 1470cm-1Ratio of (A)1240/A1470Judging the degree of conformational damage of the gelatin before and after regeneration; before and after the ionic liquid dissolves gelatin, A1240And A1470The infrared absorption ratio of (A) is shown in Table 2;
example 4
1-butyl-3- (butyl-4-sulfonic acid) benzimidazole salt (bBmBSO)3) Synthesis of (2)
Adding 0.01moL of 1-butyl benzimidazole and 0.01moL of butane sultone into a 100mL four-neck flask, stirring, reacting at 90 ℃ for about 6 hours to generate a large amount of white solid, washing the white solid with ethyl acetate, filtering, and drying in vacuum at 80 ℃ for 2 hours to obtain the white solid which is bBmBSO3Obtaining the 1-methyl-3- (butyl-4-sulfonic group) benzimidazole salt, wherein the yield is 96 percent, and the melting point is 208 ℃; nuclear magnetic hydrogen spectrum confirmation structure；
The reaction equation is as follows:
Figure GSB0000196787700000101
synthesis of 1-butyl-3- (butyl-4-sulfo) benzimidazole acetate (bBmBSAc)
The product of the first step (bBmBSO)3) Adding acetic acid (molar ratio is 1: 4) into a four-mouth bottle, stirring at normal temperature, and gradually forming a homogeneous viscous liquid, namely acidic ionic liquid (bBmBSAc), wherein the yield is 100 percent, and the nuclear magnetic hydrogen spectrum confirms the structure;
the product has the following structural formula:
Figure GSB0000196787700000111
bBmBSO3nuclear magnetic hydrogen spectrum (D)2O)：0.79ppm(t，3H，CH3)，1.20ppm(m，2H，CH2)，1.68ppm(m，2H，CH2)，1.80ppm(m，2H，CH2)，2.05ppm(m，2H，CH2)，2.84ppm(t，2H，CH2)，4.35ppm(t，2H，-NCH2)，4.42ppm(t，2H，CH2)，7.58-7.73ppm(m，4H，ArH)，9.23ppm(s，1H，-NCHN-)；
Nuclear magnetic hydrogen spectrum (D) of bbmbbsac2O)：0.81ppm(t，3H，CH3)，1.22ppm(m，2H，CH2)，1.71ppm(m，2H，CH2)，1.83ppm(m，2H，-NCH2)，1.97ppm(s，12H，CH3COO-)，2.28ppm(m，2H，CH2)，2.87ppm(t，2H，CH2)，4.39ppm(t，2H，-NCH2)，4.46ppm(t，2H，CH2)，7.63-7.76ppm(m，4H，ArH)，9.27ppm(s，1H，-NCHN-)；
Weighing 5g of bBmBSAc and 95g of deionized water, dissolving to form 5% acidic ionic liquid aqueous solution, weighing 3.02g (3% by mass) of gelatin, stirring and mixing at 25 ℃, observing by a metallographic microscope (figure 3), and stirring for 51min to form homogeneous solution, which shows that the gelatin is completely dissolved in the acidic ionic liquid aqueous solution;
weighing 40g of gelatin-ionic liquid solution (gelatin is dissolved in bBmBSAc aqueous solution), adding the gelatin-ionic liquid solution into a three-mouth bottle, stirring at normal temperature, adding about 40mL of 0.36mol/L NaOH solution to adjust the pH value to be approximately 7, continuously stirring for 30min, filtering through filter cloth, washing for 3 times by deionized water, detecting the pH value to be approximately 7 by test paper, drying the regenerated gelatin for 2h at 80 ℃, weighing, testing the infrared spectrum of the regenerated gelatin and comparing the infrared spectrum with the infrared spectrum of the original gelatin, and calculating amide III 1240 (cm BSAc)-1) And 1470cm-1Ratio of (A)1240/A1470Judging the degree of conformational damage of the gelatin before and after regeneration; before and after the ionic liquid dissolves gelatin, A1240And A1470The infrared absorption ratio of (A) is shown in Table 2;
table 1 preparation examples of acidic ionic liquids of alkylbenzimidazoles
Figure GSB0000196787700000121
Example 5
Preparation of 1-methyl-3- (propyl-3-sulfonic) benzimidazole acetate (mBmPSAC) according to example 1; weighing 10g of mBmPSAC and 90g of deionized water, dissolving to form 10% acidic ionic liquid aqueous solution, weighing 3.02g (3% by mass) of gelatin, stirring and mixing at 25 ℃, observing by a metallographic microscope (figure 3), and stirring for 32min to form homogeneous solution, wherein the gelatin is completely dissolved in the acidic ionic liquid aqueous solution;
weighing 40g of gelatin-ionic liquid solution (gelatin is dissolved in mBmPSAC aqueous solution), adding the gelatin-ionic liquid solution into a three-mouth bottle, stirring at normal temperature, adding about 40mL of 0.36mol/L NaOH solution to adjust the pH value to be approximately 7, continuously stirring for 30min, filtering through filter cloth, washing for 3 times by deionized water, detecting the pH value to be approximately 7 by test paper, drying the regenerated gelatin for 2h at 80 ℃, weighing, testing the infrared spectrum of the regenerated gelatin and comparing the infrared spectrum with the infrared spectrum of the original gelatin, and calculating amide III 1240 (cm III) by calculation-1) And 1470cm-1Ratio of (A)1240/A1470The degree of conformational damage to the gelatin before and after regeneration was determined. TABLE 2 Ionic liquid dissolved gelatin A1240And A1470Infrared absorption ratio of；
Example 6
Preparation of 1-methyl-3- (propyl-3-sulfonic) benzimidazole acetate (mBmPSAC) according to example 1; weighing 15g of mBmPSAC and 85g of deionized water, dissolving to form a 15% acidic ionic liquid aqueous solution, weighing 3.02g (3% by mass) of gelatin, stirring and mixing at 25 ℃, observing by a metallographic microscope (figure 3), and stirring for 30min to form a homogeneous solution, wherein the gelatin is completely dissolved in the acidic ionic liquid aqueous solution;
weighing 40g of gelatin-ionic liquid solution (gelatin is dissolved in mBmPSAC aqueous solution), adding the gelatin-ionic liquid solution into a three-mouth bottle, stirring at normal temperature, adding about 40mL of 0.36mol/L NaOH solution to adjust the pH value to be approximately 7, continuously stirring for 30min, filtering through filter cloth, washing for 3 times by deionized water, detecting the pH value to be approximately 7 by test paper, drying the regenerated gelatin for 2h at 80 ℃, weighing, testing the infrared spectrum of the regenerated gelatin and comparing the infrared spectrum with the infrared spectrum of the original gelatin, and calculating amide III 1240 (cm III) by calculation-1) And 1470cm-1Ratio of (A)1240/A1470The degree of conformational damage to the gelatin before and after regeneration was determined. TABLE 2 Ionic liquid dissolved gelatin A1240And A1470The infrared absorption ratio of (a);
dissolving gelatin with different mass ratios by adopting 1-methyl-3- (propyl-3-sulfonic group) benzimidazole acetate (mBmPSAC) acid ionic liquid aqueous solutions (5% -50%) with different mass ratios, dissolving the gelatin at 25 ℃, recording the dissolving time (min), regenerating the gelatin by adopting a sodium hydroxide solution, and testing the infrared spectrum of the regenerated gelatin; other conditions and operations were the same as in example 1; the results of the experiments of examples 5-13 are shown in Table 2.
Table 2 dissolution regeneration performance of acidic ionic liquid aqueous solution with different mass ratios for gelatin
Figure GSB0000196787700000131
Example 14
Preparation of 1-butyl-3- (propyl-3-sulfonic) benzimidazole acetate (bBmPSAc) according to example 2; weighing 10g of bBmPSAC and 90g of deionized water, dissolving to form 10% acidic ionic liquid aqueous solution, weighing 3.02g (3% by mass) of gelatin, stirring and mixing at 25 ℃, observing by a metallographic microscope (figure 3), and stirring for 40min to form homogeneous solution, wherein the gelatin is completely dissolved in the acidic ionic liquid aqueous solution;
weighing 40g of gelatin-ionic liquid solution (gelatin is dissolved in bBmPSAC aqueous solution), adding the gelatin-ionic liquid solution into a three-mouth bottle, stirring at normal temperature, adding about 40mL of 0.36mol/L NaOH solution to adjust the pH value to be approximately 7, continuously stirring for 30min, filtering through filter cloth, washing for 3 times by deionized water, detecting the pH value to be approximately 7 by test paper, drying the regenerated gelatin for 2h at 80 ℃, weighing, testing the infrared spectrum of the regenerated gelatin and comparing the infrared spectrum with the infrared spectrum of the original gelatin, and calculating amide III 1240 (cm III) by calculation-1) And 1470cm-1Ratio of (A)1240/A1470The degree of conformational damage to the gelatin before and after regeneration was determined. TABLE 2 Ionic liquid dissolved gelatin A1240And A1470The infrared absorption ratio of (a);
dissolving gelatin with different mass ratios by adopting 1-butyl-3- (propyl-3-sulfonic group) imidazole acetate (bBmPSAC) acid ionic liquid aqueous solutions (5% -50%) with different mass ratios, dissolving the gelatin at 25 ℃, recording the dissolving time (min), regenerating the gelatin by adopting a sodium hydroxide solution, and testing the infrared spectrum of the regenerated gelatin; other conditions and operations were the same as in example 2; the results of the experiments for examples 14-22 are set forth in Table 3.
TABLE 3 dissolution regeneration performance of acidic ionic liquid aqueous solution with different mass ratios on gelatin
Figure GSB0000196787700000141
Figure GSB0000196787700000151
Example 23
1-Ethyl-3- (propyl-3-sulfonic acid) benzimidazolate (eBmPSO)3) Synthesis of (2)
80mL of 1, 4-dioxane was added to a 100mL four-necked flask, O.01mol of 1-ethylbenzimidazole and 0.01moL of propane sultone were added thereto, and stirring was carried outStirring, reacting at 90 deg.C for 6h, cooling to separate out a large amount of white solid, vacuum filtering, washing with ethyl acetate, vacuum filtering, and drying at 80 deg.C for 2h to obtain white solid, i.e. eBmPSO3Obtaining 1-ethyl-3- (propyl-3-sulfonic group) benzimidazole salt, wherein the yield is 95 percent, and the melting point is 203 ℃; confirming the structure by nuclear magnetic hydrogen spectrum;
synthesis of 1-hexyl-3- (propyl-3-sulfonic) benzimidazole acetate (eBmPSAC)
The product of the first step (eBmPSO)3) Adding acetic acid (molar ratio is 1: 4) into a four-mouth bottle, stirring at normal temperature, and gradually forming a homogeneous viscous liquid, namely the acidic ionic liquid (eBmPSAC), wherein the yield is 100 percent, and the structure is confirmed by nuclear magnetic hydrogen spectrum;
weighing 5g of eBmPSAC and 95g of deionized water, dissolving to form a 5% acidic ionic liquid aqueous solution, weighing 3.02g (3% by mass) of gelatin, stirring and mixing at 25 ℃, observing by a metallographic microscope (figure 3), and stirring for 46min to form a homogeneous solution, wherein the gelatin is completely dissolved in the acidic ionic liquid aqueous solution;
weighing 40g of gelatin-ionic liquid solution (gelatin is dissolved in eBmPSAC aqueous solution), adding the gelatin-ionic liquid solution into a three-mouth bottle, stirring at normal temperature, adding about 40mL of O.36mol/L NaOH solution to adjust the pH value to be approximately 7, continuously stirring for 30min, filtering through filter cloth, washing for 3 times by deionized water, detecting the pH value to be approximately 7 by test paper, drying the regenerated gelatin for 2h at 80 ℃, weighing, testing the infrared spectrum of the regenerated gelatin and comparing the infrared spectrum with the infrared spectrum of the original gelatin, and calculating amide III 1240 (cm III) by calculation-1) And 1470cm-1Ratio of (A)1240/A1470Judging the degree of conformational damage of the gelatin before and after regeneration;
different alkyl benzimidazoles (raw material 1) and sultones (raw material 2) are adopted to prepare a series of alkyl benzimidazole acidic ionic liquids, and other conditions and operations are the same as those in example 23; the results of the preparations of examples 23 to 32 are shown in Table 4.
Table 4 preparation examples of acidic ionic liquids of alkylbenzimidazoles
Figure GSB0000196787700000161
Example 33
2-methyl-1- (propyl-3-sulfonic acid) quinoline salt (2-mQPSO)3) Synthesis of (2)
Adding 80mL of 1, 4-dioxane into a 100mL four-neck flask, adding 0.01moL of 2-methylquinoline and 0.01moL of propane sultone, stirring, reacting at 90 ℃ for 6h, cooling to separate out a large amount of white solid, performing suction filtration, washing the white solid with ethyl acetate, performing suction filtration, and drying at 80 ℃ for 2h to obtain the white solid, namely 2-mQPSO3Obtaining 2-methyl-3- (propyl-3-sulfonic group) quinoline salt, wherein the yield is 96 percent, and the melting point is 257 ℃; confirming the structure by nuclear magnetic hydrogen spectrum;
synthesis of 2-methyl-1- (propyl-3-sulfonic) quinoline acetate (2-mQPSAc)
The product of the first step (2-mQPSO)3) Adding acetic acid (molar ratio is 1: 4) into a four-mouth bottle, stirring at normal temperature, and gradually forming a homogeneous viscous liquid, namely the acidic ionic liquid (2-mQPSAc), wherein the yield is 100%, and the nuclear magnetic hydrogen spectrum confirms the structure;
weighing 5g of 2-mQPSAc and 95g of deionized water, dissolving to form a 5% acidic ionic liquid aqueous solution, weighing 3.02g (3% by mass) of gelatin, stirring and mixing at 25 ℃, observing by a metallographic microscope (figure 3), and stirring for 56min to form a homogeneous solution, wherein the gelatin is completely dissolved in the acidic ionic liquid aqueous solution;
weighing 40g of gelatin-ionic liquid solution (gelatin is dissolved in 2-mQPSAc aqueous solution), adding the gelatin-ionic liquid solution into a three-mouth bottle, stirring at normal temperature, adding about 40mL of 0.36mol/L NaOH solution to adjust the pH value to be approximately 7, continuously stirring for 30min, filtering by using filter cloth, washing by using deionized water for 3 times, detecting the pH value to be approximately 7 by using test paper, drying the regenerated gelatin for 2h at the temperature of 80 ℃, weighing, testing the infrared spectrum of the regenerated gelatin and comparing the infrared spectrum with the infrared spectrum of the original gelatin, and calculating amide III (1240 cm)-1) And 1470cm-1Ratio of (A)1240/A1470Judging the degree of conformational damage of the gelatin before and after regeneration;
different alkyl quinolines (raw material 1) and sultone (raw material 2) are adopted to prepare a series of alkyl quinoline acidic ionic liquid, and other conditions and operations are the same as those of the example 33; the results of the preparations of examples 33 to 54 are shown in Table 5.
Table 5 preparation examples of (alkyl) quinoline acidic ionic liquids
Figure GSB0000196787700000181

Claims (5)

1. A method for quickly dissolving gelatin at low temperature by using acidic ionic liquid is characterized by comprising the following steps: dissolving gelatin at 20-40 ℃ for 30-120min by taking an aqueous solution containing a sulfonate acidic ionic liquid as a solvent, wherein the gelatin accounts for 1-10% of the solvent by mass percent, the sulfonate acidic ionic liquid comprises an alkyl benzimidazole acidic ionic liquid or an alkyl quinoline acidic ionic liquid,
the structural formula is as follows:
alkyl benzimidazole acidic ionic liquids
Figure FSB0000196787690000011
Alkyl quinoline acidic ionic liquid
Figure FSB0000196787690000012
Wherein R is1Methyl, ethyl, propyl, butyl, hexyl, octyl, decyl;
R22-methyl, 3-methyl, 4-methyl, 5-methyl, 6-methyl, 8-methyl, 4-methoxy, 6-methoxy, 2-ethyl, 3-ethyl, 6-ethyl.
2. The method for rapidly dissolving gelatin at low temperature by using acidic ionic liquid as claimed in claim 1, wherein: the preparation of the acidic ionic liquid containing the sulfonate comprises two steps:
(1) preparation of sulfonic acid inner salt:
taking alkyl benzimidazole and sultone as raw materials, and reacting for 4-12h in a low-polarity aprotic organic solvent at the reaction temperature of 40-90 ℃ to prepare alkyl benzimidazole sulfonic acid inner salt;
taking alkyl quinoline and sultone as raw materials, reacting for 4-12h in a low-polarity aprotic organic solvent at the reaction temperature of 40-90 ℃ to prepare alkyl quinoline sulfonic acid inner salt;
(2) preparing the acidic ionic liquid containing the sulfonate:
mixing the alkyl benzimidazole sulfonic acid inner salt obtained in the step with acetic acid, and reacting for 2-6h to obtain alkyl benzimidazole acidic ionic liquid;
and mixing the alkyl quinoline sulfonic acid inner salt obtained in the step with acetic acid, and reacting for 2-6h to obtain the alkyl quinoline acidic ionic liquid.
3. The method for rapidly dissolving gelatin at low temperature by using acidic ionic liquid as claimed in claim 2, wherein: the low-polarity aprotic organic solvent is one or two mixed solvents of petroleum ether, n-hexane, cyclohexane, 1, 4-dioxane, toluene and xylene.
4. The method for rapidly dissolving gelatin at low temperature by using acidic ionic liquid as claimed in claim 2, wherein: the molar ratio of the alkyl benzimidazole sulfonic acid inner salt to the acetic acid is 1: 1-9, and the molar ratio of the alkyl quinoline benzimidazole sulfonic acid inner salt to the acetic acid is 1: 1-9.
5. The method for rapidly dissolving gelatin at low temperature by using acidic ionic liquid as claimed in claim 1, wherein: the mass ratio of the sulfonate acidic ionic liquid to the water in the solvent is (5-50) to (50-95).
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008000045A1 (en) * 2006-06-30 2008-01-03 University Of Wollongong Nanostructured composites
CN101463137A (en) * 2009-01-16 2009-06-24 四川大学 Method for preparing natural polymer blended membrane with ion liquid as solvent
CN103263694A (en) * 2013-05-14 2013-08-28 北京华信佳音医疗科技发展有限责任公司 Collagen-based dura and preparation method thereof
CN109498485A (en) * 2018-12-31 2019-03-22 中吉亚科技(广州)有限公司 A kind of water-based nail polish

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008000045A1 (en) * 2006-06-30 2008-01-03 University Of Wollongong Nanostructured composites
CN101463137A (en) * 2009-01-16 2009-06-24 四川大学 Method for preparing natural polymer blended membrane with ion liquid as solvent
CN103263694A (en) * 2013-05-14 2013-08-28 北京华信佳音医疗科技发展有限责任公司 Collagen-based dura and preparation method thereof
CN109498485A (en) * 2018-12-31 2019-03-22 中吉亚科技(广州)有限公司 A kind of water-based nail polish

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