CN115873008A - Method for purifying isosorbide and purified isosorbide - Google Patents
Method for purifying isosorbide and purified isosorbide Download PDFInfo
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Abstract
The invention provides an isosorbide purification method and purified isosorbide. The purification method comprises the following steps: preparing a layered double-metal hydroxide precursor by adopting a nucleation/crystallization isolation method and assisting in microwave treatment; roasting the layered double hydroxide precursor to obtain a mixed metal oxide adsorbent; and (3) circularly flowing the solution containing the isosorbide to be purified into an adsorption column filled with the mixed metal oxide adsorbent by adopting reduced pressure column chromatography, performing adsorption treatment, and at least crystallizing the solution after the adsorption treatment to obtain the purified isosorbide. The purified isosorbide provided by the invention is prepared by the method. The purification method can reduce the content of impurities such as acidic substances, metal ions and the like in the isosorbide, avoids introducing new impurities and improves the purity of the isosorbide.
Description
Technical Field
The invention relates to a method for purifying isosorbide and the purified isosorbide, belonging to the technical field of chemical separation.
Background
At present, the shortage of petrochemical resources and the increasing environmental pollution make biobased materials get more and more attention. The bio-based material is a chemical product developed on the basis of biomass, wherein isosorbide is widely applied to the fields of medicine, food, polycarbonate and other high polymers as the only sugar diol produced in an industrial scale-up manner. In the medical field, isosorbide and its derivatives have good curative effects in dehydration, diuresis and treatment of cerebral edema; in addition, isosorbide can be used as an organic synthesis intermediate for synthesizing finished medicines with specific efficacies. Isosorbide is composed of rigid furan dicyclo, is a chiral symmetric bicyclic diol, can be used as a polymerization monomer for synthesizing polycarbonate, polyether, polyester, polyurethane and the like, improves the high-temperature performance and the impact performance of a polymer, and endows the material with optical transparency and biodegradability.
The synthesis of isosorbide is essentially divided into two steps, as shown below:
firstly, reducing glucose by hydrogenation to obtain sorbitol, and dehydrating the sorbitol twice to obtain the isosorbide. The catalyst for catalyzing the dehydration reaction of sorbitol is generally an acidic catalyst, for example, sulfuric acid, phosphoric acid, p-toluenesulfonic acid, heteropolyacid, metal salt solid acid, or the like. After sorbitol is dehydrated for the second time under the action of an acid catalyst to obtain a crude product of isosorbide, the isosorbide product with high purity is usually obtained through the steps of reduced pressure distillation, organic solvent extraction, recrystallization and the like. At present, although the purity of the isosorbide product can reach 98% or more, the residual acidic substances, metal ions and the like in the isosorbide product still have certain adverse effects on the application of the isosorbide. Especially when the isosorbide is used as a polymerization monomer in the synthesis process of polycarbonate, polyether, polyester, polyurethane and the like, the polymer is easy to yellow and discolor, which limits the further development of the polymer field. Therefore, the search for suitable purification methods for isosorbide is important to expand the applications of isosorbide.
Conventionally, a method for removing acids from isosorbide solution is generally to add an alkaline compound such as sodium hydroxide to neutralize the isosorbide solution. Although this method neutralizes the isosorbide solution, it introduces new impurities that have some adverse effects on later applications (e.g., participation in polymer synthesis).
Therefore, the development of a novel method for purifying isosorbide has become one of the problems to be solved in the art.
Disclosure of Invention
In order to solve the above technical problems, the present invention aims to provide a method for purifying isosorbide and a purified isosorbide. The purification method of the invention can reduce the content of impurities such as acidic substances, metal ions and the like in the isosorbide, avoid the introduction of new impurities and improve the purity of the isosorbide.
In order to achieve the above object, the present invention provides, in a first aspect, a method for purifying isosorbide, comprising the steps of:
(1) Preparation of Mixed Metal oxide sorbents
Circularly stirring a solution containing divalent metal ions and trivalent metal ions in a full back-mixing rotary liquid film nucleation reactor to form uniform crystal nuclei to obtain mixed slurry; carrying out crystallization reaction on the mixed slurry under the microwave condition to obtain a layered double hydroxide precursor; roasting the layered double hydroxide precursor to obtain a mixed metal oxide adsorbent;
(2) Purified isosorbide
And (2) filling the mixed metal oxide adsorbent obtained in the step (1) into an adsorption column, circularly flowing a solution containing the isosorbide to be purified into the adsorption column filled with the mixed metal oxide adsorbent from top to bottom by adopting reduced pressure column chromatography, and performing adsorption treatment to at least crystallize the solution after the adsorption treatment to obtain the purified isosorbide.
In the above method, preferably, in the step (1), the divalent metal ion includes Mg 2+ 、Zn 2+ 、Cu 2+ 、Fe 2+ And Ni 2+ And the like, or combinations thereof.
In the above method, preferably, in the step (1), the trivalent metal ion includes Al 3+ 、Cr 3+ And Fe 3+ And the like, or combinations of several thereof.
According to a specific embodiment of the present invention, in step (1) of the above method, the divalent metal ion and the trivalent metal ion in the solution containing the divalent metal ion and the trivalent metal ion may be provided by a divalent metal salt and a trivalent metal salt, respectively, and the specific kinds of the divalent metal salt and the trivalent metal salt are not particularly limited as long as they are soluble salts of the divalent metal and the trivalent metal, such as but not limited to nitrates of the divalent metal and the trivalent metal, and the like.
In the above method, preferably, in step (1), the molar ratio of the divalent metal ion and the trivalent metal ion in the solution containing the divalent metal ion and the trivalent metal ion is 2.
In the above method, preferably, in the step (1), the concentration of the divalent metal ion in the solution containing the divalent metal ion and the trivalent metal ion is 1 to 2mol/L, and the concentration of the trivalent metal ion is 0.5 to 1mol/L.
In the above method, in the step (1), the rotation speed of the circulating stirring in the complete back-mixing rotary liquid film nucleation reactor is preferably 1000 to 2500rpm for 3 to 10min.
In the above method, preferably, in the step (1), the crystallization reaction is carried out under microwave conditions at a temperature of 110 to 130 ℃, a microwave power of 390W, and a time of 50 to 70min. More preferably, the crystallization reaction is carried out under stirring, and the rotation speed of the stirring is 150 to 350rpm. More specifically, the crystallization reaction under microwave conditions may be performed using a microwave reaction vessel.
According to an embodiment of the present invention, after the crystallization reaction in step (1) of the above method is performed under microwave conditions, conventional washing, filtering, drying, grinding, etc. steps may be further included to obtain the layered double hydroxide precursor. The washing can adopt deionized water and/or ethanol and the like, the filtration can adopt centrifugal filtration, and the drying temperature can be 60-80 ℃.
In the above method, preferably, in the step (1), the layered double hydroxide precursor includes Zn 2 + 2 Al 3+ 1 -LDHs precursor, mg 2+ 2 Al 3+ 1 -LDHs precursor and Zn 2+ 2 Fe 3+ 1 One or a combination of a plurality of precursors of LDHs and the like.
In the above method, the baking temperature is preferably 450 to 700 ℃ for 6 to 12h in the step (1). According to the embodiment of the present invention, the temperature of the firing may be 450 ℃, 500 ℃, 600 ℃ or 700 ℃, but is not limited thereto.
According to an embodiment of the present invention, step (1) of the above method may further include a conventional grinding step after firing.
In the above-mentioned aspectIn the method, preferably, in the step (1), the mixed metal oxide adsorbent has a particle size of 400 to 800nm and a specific surface area of 170 to 330m 2 g -1 The pore diameter is 3 to 10nm, and the pore volume is 0.120 to 0.531cm 3 g -1 。
In the above method, preferably, in the step (1), the layered double hydroxide precursor is Mg 2+ 2 Al 3+ 1 LDHs precursor, the roasting temperature is 500 ℃, and the prepared mixed metal oxide adsorbent is Mg 2+ 2 Al 3 + 1 -MMO-500。
The invention creatively adopts a nucleation/crystallization isolation method and a microwave treatment assisted method to synthesize the nano-scale layered double hydroxide (preferably M) with good crystallinity and uniform size 2+ 2 M 3+ 1 LDHs) precursor, and regulating the roasting temperature of the layered double hydroxide precursor by adjusting the type of metal ions to regulate the prepared mixed metal oxide (preferably M) 2+ 2 M 3+ 1 MMO) adsorbent, and makes it suitable for purifying isosorbide, with excellent adsorption decoloration and purification effect. The mixed metal oxide adsorbent is an inorganic alkaline adsorbent, can adsorb impurities such as acidic substances, metal ions and the like in the isosorbide, avoids introducing new impurities, and can be recycled for multiple times.
According to the specific embodiment of the present invention, the isosorbide to be purified according to the present invention may include commercially available isosorbide products, or may include crude isosorbide products obtained by industrially subjecting sorbitol to secondary dehydration, and the present invention does not specifically limit the source of the isosorbide to be purified.
In the above method, preferably, in the step (2), the solution containing isosorbide to be purified is a mixed solution of isosorbide to be purified and ethyl acetate. More preferably, the mixing mass ratio of the isosorbide to be purified to the ethyl acetate is 1. More preferably, the mixing temperature of the isosorbide to be purified and the ethyl acetate is 55 to 70 ℃.
In the above method, preferably, in the step (2), the solution containing isosorbide to be purified is circulated by a peristaltic pump from top to bottom into the adsorption column packed with the mixed metal oxide adsorbent.
In the above method, preferably, in the step (2), the operating conditions of the reduced pressure column chromatography include: the pressure is 60000 to 90000Pa, the flow rate of the solution is 1.5 to 5mL/min, and the adsorption treatment time is 5 to 7h.
In the above method, preferably, in the step (2), the temperature of the crystallization is from-20 ℃ to 4 ℃ for 4 to 7h.
According to a specific embodiment of the present invention, step (2) of the above method may comprise a conventional filtration step before crystallization, and may further comprise conventional filtration, drying and the like after crystallization, to obtain the purified isosorbide. Wherein, centrifugal filtration can be carried out before crystallization, and cold filtration with a filter membrane can be carried out after crystallization, and the filter membrane used is preferably an organic phase filter membrane with the pore diameter of 0.22 μm.
In a second aspect, the invention provides a purified isosorbide, which is prepared by the above method for purifying isosorbide.
According to an embodiment of the present invention, it is preferable that the acid value of the purified isosorbide is 0.30mgKOH/g or less.
According to an embodiment of the present invention, the purified isosorbide preferably has a conductivity of 95 μ s/cm or less.
According to an embodiment of the present invention, preferably, the purified isosorbide has an APHA color value of 30 or less.
According to an embodiment of the present invention, the purity of the purified isosorbide is preferably 99% or more.
The invention provides an isosorbide purification method and purified isosorbide. The invention combines the nuclear/crystallization isolation method and the microwave method for the first time to synthesize the junctionNanoscale M with good crystallinity and uniform size 2+ 2 M 3+ 1 LDHs precursor, regulating and controlling the M prepared by adjusting the metal ion species and the roasting temperature 2+ 2 M 3+ 1 The specific surface area and the structure of the MMO adsorbent optimize the adsorption, decoloration and purification effects of the MMO adsorbent. The present invention utilizes the M 2+ 2 M 3+ 1 Purification of isosorbide by means of an MMO adsorbent which is first subjected to adsorptive separation and then to recrystallization, the M 2+ 2 M 3+ 1 The MMO adsorbent was able to reduce the acid number of commercial isosorbide products from 2.2 to 0.10mgKOH/g, the conductivity from 7000 to 15 μ s/cm, the APHA color value to 17, and the purity from 98% to 99.65%. M of the invention 2+ 2 M 3+ 1 The MMO adsorbent can adsorb impurities such as acidic substances, metal ions and the like in the isosorbide, avoids introducing new impurities, and can be recycled for multiple times. Purification method of the invention M prepared by the invention is used 2+ 2 M 3+ 1 The purification effect of the adsorbent, namely the MMO adsorbent, on the isosorbide is obviously better than that of adsorbents such as activated carbon, ion exchange resin and the like. The purified isosorbide provided by the invention reduces the influence of acidic substances and metal ions remained in the preparation of isosorbide by sorbitol on later-stage application, can be used as an organic intermediate synthetic drug in the medical field, can also be applied in the polymer synthesis field, can produce colorless and transparent polymers, and greatly expands the application range of isosorbide.
Detailed Description
The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention.
According to an embodiment of the present invention, preferably, the method for purifying isosorbide provided by the present invention comprises the following steps:
(1) Preparation of Mixed Metal oxide sorbents
Simultaneously adding a solution containing divalent metal ions and a solution containing trivalent metal ions into a full back-mixing rotary liquid film nucleation reactor, and circularly stirring at the rotating speed of 1000-2500 rpm (preferably 2000 rpm) for 3-10min (preferably 3 min) to form uniform crystal nuclei to obtain mixed slurry; adding the mixed slurry into a microwave reaction kettle, stirring (the rotation speed is 150 to 350rpm, preferably 250 rpm) for 50 to 70min (preferably 50 min) under the conditions of 110 to 130 ℃ (preferably 120 ℃) and 390W for crystallization reaction, then fully washing a product obtained by the crystallization reaction by using deionized water and/or ethanol, centrifugally filtering, carrying out vacuum drying at 60 to 80 ℃, and then grinding to obtain a layered double-metal hydroxide precursor;
placing the layered double-metal hydroxide precursor into a muffle furnace, heating to 450-700 ℃ at a speed of 10 ℃/min by adopting a programmed heating method, then roasting at a constant temperature for 6-12h, and grinding a roasted product to obtain a mixed metal oxide adsorbent; the mixed metal oxide adsorbent has the particle size of 400-800nm and the specific surface area of 170-330m 2 g -1 The pore diameter is 3 to 10nm, and the pore volume is 0.120 to 0.531cm 3 g -1 ；
Wherein the divalent metal ion comprises Mg 2+ 、Zn 2+ 、Cu 2+ 、Fe 2+ And Ni 2+ And the like; the trivalent metal ion comprises Al 3+ 、Cr 3+ And Fe 3+ And the like; the molar ratio of the divalent metal ion to the trivalent metal ion is 2; simultaneously adding a solution containing divalent metal ions and a solution containing trivalent metal ions into a mixed solution formed in a full back-mixing rotary liquid film nuclear reactor, wherein the concentration of the divalent metal ions is 1-2mol/L, and the concentration of the trivalent metal ions is 0.5-1mol/L;
(2) Purified isosorbide
Filling the mixed metal oxide adsorbent obtained in the step (1) into an adsorption column, uniformly mixing isosorbide to be purified and ethyl acetate at 55 to 70 ℃ (preferably 70 ℃) according to the mass ratio of 1.
Example 1
This example provides a method for the purification of isosorbide comprising the steps of:
(1) Preparation of Mixed Metal oxide adsorbent (Zn) 2+ 2 Al 3+ 1 -MMO-450）
0.4 mol of Zn (NO) 3 ) 2 ·6H 2 O and 0.2 mol Al (NO) 3 ) 3 ·9H 2 O (purchased from Chinese medicine) was dissolved in 120 mL of CO-removed solution 2 Respectively marking solution A and solution B in deionized water, simultaneously adding solution A and solution B into a full back-mixing rotary liquid film nucleation reactor, circularly stirring at the rotating speed of 2000rpm for 3min to form uniform crystal nuclei, and obtaining mixed slurry; adding the mixed slurry into a microwave reaction kettle, stirring at the rotation speed of 250rpm for 50min under the conditions of 120 ℃ and 390W for crystallization reaction, then fully washing a product obtained by crystallization reaction by using deionized water and ethanol, centrifugally filtering, carrying out vacuum drying at 60 ℃, and then grinding to obtain a layered double hydroxide precursor Zn 2+ 2 Al 3+ 1 -LDH；
Taking 100g of Zn 2+ 2 Al 3+ 1 Placing the-LDH in a muffle furnace, heating to 450 ℃ at the speed of 10 ℃/min by adopting programmed heating, roasting at constant temperature for 10h, grinding the roasted product to obtain the mixed metal oxide adsorbent Zn 2+ 2 Al 3+ 1 -MMO-450；Zn 2+ 2 Al 3+ 1 MMO-450 has an average particle diameter of 600nm and a specific surface area of 200m 2 g -1 Pore diameter of 7nm and pore volume of 0.197cm 3 g -1 ；
(2) Purified isosorbide
Zn obtained in the step (1) 2+ 2 Al 3+ 1 Filling MMO-450 into an adsorption column, uniformly mixing isosorbide (purchased from Shanghai leaves) and ethyl acetate (purchased from Chinese medicaments) to be purified according to the mass ratio of 1 to 6 at 70 ℃ to obtain a mixed solution of isosorbide and ethyl acetate to be purified, performing reduced pressure column chromatography, and circularly pumping the mixed solution of isosorbide and ethyl acetate to be purified into a column filled with Zn from top to bottom by using a peristaltic pump 2+ 2 Al 3+ 1 And (2) performing vacuum column chromatography in an adsorption column of MMO-450 at 90000Pa, performing cyclic adsorption treatment for 5h, performing centrifugal filtration (2000rpm, 5 min) on the adsorption-treated mixed solution, then performing recrystallization for 5h in a refrigerator at the temperature of 4 ℃, filtering with a filter membrane (cold filtration with a 0.22 mu m organic phase filter membrane), and performing vacuum drying to obtain the purified isosorbide.
The purity, acid value, conductivity and APHA color value of isosorbide to be purified and isosorbide after purification were tested using the following methods:
1. purity: measuring by using a high performance liquid chromatograph;
2. acid value: measuring by using a KOH titration method;
3. conductivity: measuring by using a DDS-11A type conductivity meter;
4. APHA color values: measured by a yellow index meter.
The purified isosorbide provided in this example had a purity of 99.03%, an acid value of 0.29mgKOH/g, an electrical conductivity of 53. Mu.s/cm, and an APHA color value of 30.
Example 2
This example provides a method for the purification of isosorbide comprising the steps of:
(1) Preparation of Mixed Metal oxide adsorbent (Zn) 2+ 2 Al 3+ 1 -MMO-500）
0.4 mol of Zn (NO) 3 ) 2 ·6H 2 O and 0.2 mol Al (NO) 3 ) 3 ·9H 2 O (purchased from Chinese medicine) is dissolved in 120 mL of CO respectively 2 Respectively marking solution A and solution B in deionized water, simultaneously adding the solution A and the solution B into a full back-mixing rotary liquid film nucleation reactor, and circularly stirring at the rotating speed of 2000rpm for 3min to form uniform crystal nuclei to obtain mixed slurry; adding the mixed slurry into a microwave reaction kettle, stirring at the rotation speed of 250rpm for 50min under the conditions of 120 ℃ and 390W for crystallization reaction, then fully washing a product obtained by crystallization reaction by using deionized water and ethanol, centrifugally filtering, carrying out vacuum drying at 60 ℃, and then grinding to obtain a layered double hydroxide precursor Zn 2+ 2 Al 3+ 1 -LDH；
Taking 100g of Zn 2+ 2 Al 3+ 1 Placing the-LDH in a muffle furnace, raising the temperature to 500 ℃ at the speed of 10 ℃/min by adopting programmed temperature raising, roasting at constant temperature for 10 hours, grinding the roasted product to obtain the mixed metal oxide adsorbent Zn 2+ 2 Al 3+ 1 -MMO-500；Zn 2+ 2 Al 3+ 1 MMO-500 has an average particle diameter of 500nm and a specific surface area of 189 m 2 g -1 Pore diameter of 6nm and pore volume of 0.187cm 3 g -1 ；
(2) Purified isosorbide
Zn obtained in the step (1) 2+ 2 Al 3+ 1 Filling MMO-500 into an adsorption column, uniformly mixing isosorbide (purchased from Shanghai leaves) and ethyl acetate (purchased from Chinese medicaments) to be purified according to the mass ratio of 1 to 6 at 70 ℃ to obtain a mixed solution of isosorbide and ethyl acetate to be purified, performing reduced pressure column chromatography, and circularly pumping the mixed solution of isosorbide and ethyl acetate to be purified into a column filled with Zn from top to bottom by using a peristaltic pump 2+ 2 Al 3+ 1 In an adsorption column of MMO-500, the pressure of reduced pressure column chromatography is 90000Pa, the flow rate of the mixed solution is 2mL/min, the cyclic adsorption treatment is carried out for 5h, and the adsorption treatment is carried outAnd carrying out centrifugal filtration (2000rpm, 5 min) on the obtained mixed solution, then putting the mixed solution into a refrigerator, recrystallizing for 5h at the temperature of 4 ℃, filtering the obtained product through a filter membrane (cold filtration of a 0.22-micron organic phase filter membrane), and drying the obtained product in vacuum to obtain purified isosorbide.
The purity, acid number, conductivity, and APHA color values of the purified isosorbide provided in this example were tested using the test methods of example 1.
The purified isosorbide provided in this example had a purity of 99.11%, an acid value of 0.21mgKOH/g, an electrical conductivity of 60 μ s/cm, and an APHA color value of 23.
Example 3
This example provides a method for the purification of isosorbide comprising the steps of:
(1) Preparation of Mixed Metal oxide adsorbent (Zn) 2+ 2 Al 3+ 1 -MMO-600）
0.4 mol of Zn (NO) 3 ) 2 ·6H 2 O and 0.2 mol Al (NO) 3 ) 3 ·9H 2 O (purchased from Chinese medicine) is dissolved in 120 mL of CO respectively 2 Respectively marking solution A and solution B in deionized water, simultaneously adding solution A and solution B into a full back-mixing rotary liquid film nucleation reactor, circularly stirring at the rotating speed of 2000rpm for 3min to form uniform crystal nuclei, and obtaining mixed slurry; adding the mixed slurry into a microwave reaction kettle, stirring at the rotation speed of 250rpm for 50min under the conditions of 120 ℃ and 390W for crystallization reaction, then fully washing a product obtained by the crystallization reaction by using deionized water and ethanol, carrying out centrifugal filtration, carrying out vacuum drying at 60 ℃, and then grinding to obtain a layered double hydroxide precursor Zn 2+ 2 Al 3+ 1 -LDH；
Taking 100g of Zn 2+ 2 Al 3+ 1 Placing LDH in a muffle furnace, raising the temperature to 600 ℃ at the speed of 10 ℃/min by adopting temperature programming, roasting at constant temperature for 10h, grinding the roasted product to obtain the mixed metal oxide adsorbent Zn 2+ 2 Al 3+ 1 -MMO-600；Zn 2+ 2 Al 3+ 1 MMO-600 having an average particle diameter of 800nm and a specific surface area of 170m 2 g -1 The pore diameter is 7nm, and the pore volume is 0.169cm 3 g -1 ；
(2) Purified isosorbide
Zn obtained in the step (1) 2+ 2 Al 3+ 1 Filling the MMO-600 into an adsorption column, uniformly mixing isosorbide (purchased from Shanghai leaves) and ethyl acetate (purchased from Chinese medicaments) to be purified according to the mass ratio of 1 to 6 at 70 ℃ to obtain a mixed solution of isosorbide and ethyl acetate to be purified, performing reduced pressure column chromatography, and circularly pumping the mixed solution of isosorbide and ethyl acetate to be purified into a column filled with Zn from top to bottom by using a peristaltic pump 2+ 2 Al 3+ 1 In an adsorption column of MMO-600, performing reduced pressure column chromatography at 90000Pa, performing cyclic adsorption treatment for 5h, performing centrifugal filtration (2000rpm, 5 min) on the adsorption-treated mixed solution, then recrystallizing for 5h in a refrigerator at 4 ℃, filtering with a filter membrane (cold filtration with a 0.22-micron organic phase filter membrane), and performing vacuum drying to obtain the purified isosorbide.
The purified isosorbide provided in this example was tested for purity, acid number, conductivity, and APHA color value using the test method of example 1.
The purified isosorbide provided in this example had a purity of 99.08%, an acid number of 0.30mgKOH/g, a conductivity of 95 μ s/cm, and an APHA color value of 29.
Example 4
This example provides a method for the purification of isosorbide comprising the steps of:
(1) Preparation of Mixed Metal oxide adsorbent (Zn) 2+ 2 Al 3+ 1 -MMO-700）
0.4 mol of Zn (NO) 3 ) 2 ·6H 2 O and 0.2 mol Al (NO) 3 ) 3 ·9H 2 O (purchased from Chinese medicine) is dissolved in 120 mL of CO respectively 2 Respectively marking solution A and solution B in deionized water, simultaneously adding solution A and solution B into the full back-mixing rotating liquid film nucleation reactionIn the reactor, circularly stirring for 3min at the rotating speed of 2000rpm to form uniform crystal nuclei to obtain mixed slurry; adding the mixed slurry into a microwave reaction kettle, stirring at the rotation speed of 250rpm for 50min under the conditions of 120 ℃ and 390W for crystallization reaction, then fully washing a product obtained by crystallization reaction by using deionized water and ethanol, centrifugally filtering, carrying out vacuum drying at 60 ℃, and then grinding to obtain a layered double hydroxide precursor Zn 2+ 2 Al 3+ 1 -LDH；
Taking 100g of Zn 2+ 2 Al 3+ 1 Placing the-LDH in a muffle furnace, heating to 700 ℃ at the speed of 10 ℃/min by adopting programmed heating, roasting at constant temperature for 10h, grinding the roasted product to obtain the mixed metal oxide adsorbent Zn 2+ 2 Al 3+ 1 -MMO-700；Zn 2+ 2 Al 3+ 1 The average particle diameter of MMO-700 is 688nm, the specific surface area is 270 m 2 g -1 Pore diameter of 10nm and pore volume of 0.401cm 3 g -1 ；
(2) Purified isosorbide
Zn obtained in the step (1) 2+ 2 Al 3+ 1 Filling MMO-700 into an adsorption column, uniformly mixing isosorbide (purchased from Shanghai leaves) and ethyl acetate (purchased from Chinese medicaments) to be purified according to the mass ratio of 1 to 6 at 70 ℃ to obtain a mixed solution of isosorbide and ethyl acetate to be purified, performing reduced pressure column chromatography, and circularly pumping the mixed solution of isosorbide and ethyl acetate to be purified into a column filled with Zn from top to bottom by using a peristaltic pump 2+ 2 Al 3+ 1 And (2) performing vacuum column chromatography in an adsorption column of MMO-700 at 90000Pa, performing cyclic adsorption treatment for 5h, performing centrifugal filtration (2000rpm, 5 min) on the adsorption-treated mixed solution, then performing recrystallization for 5h in a refrigerator at the temperature of 4 ℃, filtering with a filter membrane (cold filtration with a 0.22 mu m organic phase filter membrane), and performing vacuum drying to obtain the purified isosorbide.
The purified isosorbide provided in this example was tested for purity, acid number, conductivity, and APHA color value using the test method of example 1.
The purified isosorbide provided in this example had a purity of 99.24%, an acid value of 0.20mgKOH/g, an electrical conductivity of 68 μ s/cm, and an APHA color value of 20.
Example 5
This example provides a method for the purification of isosorbide comprising the steps of:
(1) Preparation of Mixed Metal oxide adsorbent (Mg) 2+ 2 Al 3+ 1 -MMO-500）
0.4 mol of Mg (NO) 3 ) 2 ·6H 2 O and 0.2 mol Al (NO) 3 ) 3 ·9H 2 O (purchased from Chinese medicine) was dissolved in 120 mL of CO-removed solution 2 Respectively marking solution A and solution B in deionized water, simultaneously adding the solution A and the solution B into a full back-mixing rotary liquid film nucleation reactor, and circularly stirring at the rotating speed of 2000rpm for 3min to form uniform crystal nuclei to obtain mixed slurry; adding the mixed slurry into a microwave reaction kettle, stirring at the rotation speed of 250rpm for 50min under the conditions of 120 ℃ and 390W for crystallization reaction, then fully washing a product obtained by the crystallization reaction by using deionized water and ethanol, carrying out centrifugal filtration, carrying out vacuum drying at 60 ℃, and then grinding to obtain a layered double hydroxide precursor Mg 2+ 2 Al 3+ 1 -LDH；
100g of Mg are taken 2+ 2 Al 3+ 1 Placing LDH in a muffle furnace, raising the temperature to 500 ℃ at the speed of 10 ℃/min by adopting temperature programming, roasting at constant temperature for 10h, grinding the roasted product to obtain the mixed metal oxide adsorbent Mg 2+ 2 Al 3+ 1 -MMO-500；Mg 2+ 2 Al 3+ 1 MMO-500 having an average particle diameter of 456nm and a specific surface area of 330m 2 g -1 The pore diameter is 6nm, and the pore volume is 0.531cm 3 g -1 ；
(2) Purified isosorbide
Mg obtained in the step (1) 2+ 2 Al 3+ 1 Loading of MMO-500 to adsorptionIn the column, isosorbide (purchased from Shanghai leaves) and ethyl acetate (purchased from Chinese medicine) to be purified are uniformly mixed at 70 ℃ according to the mass ratio of 1 2+ 2 Al 3+ 1 And in an adsorption column of MMO-500, performing reduced pressure column chromatography at 90000Pa, performing cyclic adsorption treatment for 5h at a flow rate of 2mL/min on the mixed solution, performing centrifugal filtration (2000rpm, 5 min) on the adsorbed mixed solution, then recrystallizing for 5h in a refrigerator at 4 ℃, filtering with a filter membrane (cold filtration with a 0.22 mu m organic phase filter membrane), and performing vacuum drying to obtain the purified isosorbide.
The purified isosorbide provided in this example was tested for purity, acid number, conductivity, and APHA color value using the test method of example 1.
The purified isosorbide provided in this example had a purity of 99.65%, an acid number of 0.10mgKOH/g, a conductivity of 15 μ s/cm, and an APHA color value of 17.
Example 6
This example provides a method for the purification of isosorbide comprising the steps of:
(1) Preparation of Mixed Metal oxide adsorbent (Zn) 2+ 2 Fe 3+ 1 -MMO-500）
0.4 mol of Zn (NO) 3 ) 2 ·6H 2 O and 0.2 mol Fe (NO) 3 ) 3 ·9H 2 O (purchased from Chinese medicine) is dissolved in 120 mL of CO respectively 2 Respectively marking solution A and solution B in deionized water, simultaneously adding the solution A and the solution B into a full back-mixing rotary liquid film nucleation reactor, and circularly stirring at the rotating speed of 2000rpm for 3min to form uniform crystal nuclei to obtain mixed slurry; adding the mixed slurry into a microwave reaction kettle, stirring at the rotation speed of 250rpm for 50min at the temperature of 120 ℃ and the power of 390W for crystallization reaction, fully washing a product obtained by the crystallization reaction by using deionized water and ethanol, centrifuging and filtering, and performing vacuum filtration at the temperature of 60 DEG CDrying in air, and grinding to obtain layered double hydroxide precursor Zn 2+ 2 Fe 3+ 1 -LDH；
Taking 100g of Zn 2+ 2 Fe 3+ 1 Placing the-LDH in a muffle furnace, raising the temperature to 500 ℃ at the speed of 10 ℃/min by adopting programmed temperature raising, roasting at constant temperature for 10 hours, grinding the roasted product to obtain the mixed metal oxide adsorbent Zn 2+ 2 Fe 3+ 1 -MMO-500；Zn 2+ 2 Fe 3+ 1 MMO-500 has an average particle diameter of 650nm and a specific surface area of 210 m 2 g -1 The aperture is 4nm, and the pore volume is 0.340cm 3 g -1 ；
(2) Purified isosorbide
Zn obtained in the step (1) 2+ 2 Fe 3+ 1 Filling MMO-500 into an adsorption column, uniformly mixing isosorbide (purchased from Shanghai leaves) and ethyl acetate (purchased from Chinese medicaments) to be purified according to the mass ratio of 1 to 6 at 70 ℃ to obtain a mixed solution of isosorbide and ethyl acetate to be purified, performing reduced pressure column chromatography, and circularly pumping the mixed solution of isosorbide and ethyl acetate to be purified into a column filled with Zn from top to bottom by using a peristaltic pump 2+ 2 Fe 3+ 1 And (2) in an adsorption column of MMO-500, performing reduced pressure column chromatography at 90000Pa, performing cyclic adsorption treatment for 5h at the flow rate of 2mL/min, performing centrifugal filtration (2000rpm, 5 min) on the adsorption-treated mixed solution, then recrystallizing in a refrigerator at 4 ℃ for 5h, filtering with a filter membrane (cold filtration with a 0.22-micron organic phase filter membrane), and performing vacuum drying to obtain the purified isosorbide.
The purity, acid number, conductivity, and APHA color values of the purified isosorbide provided in this example were tested using the test methods of example 1.
The purified isosorbide provided in this example had a purity of 99.32%, an acid value of 0.23mgKOH/g, an electrical conductivity of 53. Mu.s/cm, and an APHA color value of 21.
Comparative example 1
This comparative example provides a method for the purification of isosorbide by neutralization crystallization with NaOH, comprising the steps of:
the isosorbide to be purified (purchased from Shanghai leaves) and ethyl acetate (purchased from Chinese medicine) are uniformly mixed at 70 ℃ according to the mass ratio of 1.
The purified isosorbide provided in this comparative example was tested for purity, acid number, conductivity, and APHA color value using the test methods of example 1.
The purified isosorbide provided in this comparative example had a purity of 98.10%, an acid number of 0.20mgKOH/g, an electrical conductivity of 7100. Mu.s/cm, and an APHA color value of 56.
Comparative example 2
This comparative example provides a method for the purification of isosorbide using the layered double hydroxide precursor Zn prepared in example 1 2+ 2 Al 3+ 1 -LDH purification of isosorbide, the process comprising the following steps:
the layered double hydroxide precursor Zn prepared in example 1 was added 2+ 2 Al 3+ 1 Loading LDH into an adsorption column, uniformly mixing isosorbide (purchased from Shanghai source leaves) and ethyl acetate (purchased from Chinese medicaments) to be purified at 70 ℃ according to the mass ratio of 1 2+ 2 Al 3+ 1 And (3) performing cyclic adsorption treatment for 5h in an adsorption column of LDH under the pressure of 90000Pa in reduced pressure column chromatography, performing centrifugal filtration (2000rpm, 5 min) on the adsorption-treated mixed solution, then placing the mixture in a refrigerator for recrystallization for 5h at the temperature of 4 ℃, and then performing filter membrane filtration (cold filtration of a 0.22 mu m organic phase filter membrane) and vacuum drying to obtain the purified isosorbide.
The purified isosorbide provided in this comparative example was tested for purity, acid number, conductivity, and APHA color value using the test methods of example 1.
The purified isosorbide provided in this comparative example had a purity of 98.86%, an acid number of 0.47 mgKOH/g, an electrical conductivity of 1000 μ s/cm, and an APHA color value of 32.
Comparative example 3
This comparative example provides a process for the purification of isosorbide using activated carbon as adsorbent, comprising the steps of:
filling powdered activated carbon (AR, shanghai test) into an adsorption column, uniformly mixing isosorbide to be purified (purchased from Shanghai leaves) and ethyl acetate (purchased from national medicine) at 70 ℃ according to the mass ratio of 1.
The purified isosorbide provided in this comparative example was tested for purity, acid number, conductivity, and APHA color value using the test methods of example 1.
The purified isosorbide provided in this comparative example had a purity of 98.85%, an acid number of 1.29 mgKOH/g, an electrical conductivity of 60 μ s/cm, and an APHA color value of 23.
Comparative example 4
This comparative example provides a process for the purification of isosorbide using a strong cation exchange resin as adsorbent, comprising the steps of:
filling strong cation exchange resin (Tianjin Kaiyu resin YKR-1) into an adsorption column, uniformly mixing isosorbide to be purified (purchased from Shanghai leaves) and ethyl acetate (purchased from Chinese medicaments) at 70 ℃ according to the mass ratio of 1.
The purified isosorbide provided in this comparative example was tested for purity, acid number, conductivity, and APHA color value using the test methods of example 1.
The purified isosorbide provided in this comparative example had a purity of 99.10%, an acid value of 0.79mgKOH/g, an electrical conductivity of 100 μ s/cm, and an APHA color value of 43.
The isosorbide to be purified, which was used in the above examples and comparative examples, was the same commercial isosorbide product, and the purity, acid number, conductivity, and APHA color values of the isosorbide to be purified and the purified isosorbide provided in examples 1-6 and comparative examples 1-4 are shown in table 1.
TABLE 1 parameters of isosorbide to be purified, isosorbide obtained by purification in examples 1-6 and comparative examples 1-4
From the above data, it can be seen that the present invention utilizes M 2+ 2 M 3+ 1 Purification of isosorbide by means of an MMO adsorbent, the M being first subjected to adsorptive separation and then to recrystallization 2+ 2 M 3+ 1 The MMO adsorbent is capable of reducing the acid value of commercial isosorbide products from 2.2mgKOH/g to 0.10mgKOH/g, the conductivity from 7000 mus/cm to 15 mus/cm, the APHA color value to17, the purity is improved from 98 percent to 99.65 percent, and the purification effect of the isosorbide is obviously better than that of adsorbents such as activated carbon, ion exchange resin and the like.
Claims (10)
1. A method for the purification of isosorbide comprising the steps of:
(1) Preparation of Mixed Metal oxide sorbents
Circularly stirring a solution containing divalent metal ions and trivalent metal ions in a full back-mixing rotary liquid film nucleation reactor to form uniform crystal nuclei to obtain mixed slurry; carrying out crystallization reaction on the mixed slurry under the microwave condition to obtain a layered double hydroxide precursor; roasting the layered double hydroxide precursor to obtain a mixed metal oxide adsorbent;
(2) Purified isosorbide
And (2) filling the mixed metal oxide adsorbent obtained in the step (1) into an adsorption column, circularly flowing a solution containing the isosorbide to be purified into the adsorption column filled with the mixed metal oxide adsorbent from top to bottom by adopting vacuum column chromatography, and performing adsorption treatment to at least crystallize the solution after the adsorption treatment to obtain the purified isosorbide.
2. The method for purifying isosorbide according to claim 1, wherein in step (1), the divalent metal ion comprises Mg 2+ 、Zn 2+ 、Cu 2+ 、Fe 2+ And Ni 2+ One or a combination of several of them;
the trivalent metal ion comprises Al 3+ 、Cr 3+ And Fe 3+ One or a combination of several of them;
the molar ratio of the divalent metal ions to the trivalent metal ions in the solution containing the divalent metal ions and the trivalent metal ions is 2;
the concentration of the divalent metal ions in the solution containing the divalent metal ions and the trivalent metal ions is 1 to 2mol/L, and the concentration of the trivalent metal ions is 0.5 to 1mol/L.
3. The method for purifying isosorbide according to claim 1, wherein in the step (1), the rotation speed of the circulating stirring in the full back-mixing rotary liquid film nucleation reactor is 1000 to 2500rpm for 3 to 10min;
in the step (1), the crystallization reaction is carried out under the microwave condition at the temperature of 110-130 ℃, the microwave power of 390W and the time of 50-70min.
4. The method for purifying isosorbide according to claim 1, wherein in step (1), the layered double hydroxide precursor comprises Zn 2+ 2 Al 3+ 1 -LDHs precursor, mg 2+ 2 Al 3+ 1 -LDHs precursor and Zn 2+ 2 Fe 3+ 1 -one or a combination of several of LDHs precursors.
5. The method for purifying isosorbide according to claim 1, wherein in the step (1), the baking temperature is 450 to 700 ℃ for 6 to 12h.
6. The method for purifying isosorbide according to claim 1, wherein in the step (1), the mixed metal oxide adsorbent has a particle diameter of 400 to 800nm and a specific surface area of 170 to 330m 2 g -1 The pore diameter is 3 to 10nm, and the pore volume is 0.120 to 0.531cm 3 g -1 。
7. The method for purifying isosorbide according to claim 1, wherein, in step (2), the solution containing isosorbide to be purified is a mixed solution of isosorbide to be purified and ethyl acetate;
the mixing mass ratio of the isosorbide to be purified to the ethyl acetate is 1;
the mixing temperature of the isosorbide to be purified and the ethyl acetate is 55 to 70 ℃.
8. The method for purifying isosorbide according to claim 1, wherein in step (2), a solution containing isosorbide to be purified is circulated by a peristaltic pump from top to bottom into an adsorption column packed with the mixed metal oxide adsorbent;
in the step (2), the operating conditions of the reduced pressure column chromatography comprise: the pressure is 60000 to 90000Pa, the flow rate of the solution is 1.5 to 5mL/min, and the adsorption treatment time is 5 to 7h.
9. The process for the purification of isosorbide according to claim 1 wherein in step (2) the crystallization temperature is between-20 ℃ and 4 ℃ and the time is between 4 and 7h.
10. A purified isosorbide produced by the method for purifying isosorbide according to any one of claims 1 to 9;
the acid value of the purified isosorbide is below 0.30 mgKOH/g;
the electric conductivity of the purified isosorbide is below 95 mu s/cm;
the purified isosorbide has an APHA color value of 30 or less;
the purity of the purified isosorbide is more than 99%.
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