CN103044574A - Process for preparing narrow-distribution chitosan with controllable molecular weight through microwave-H2O2 combined degradation method - Google Patents
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Abstract
The invention discloses a process for preparing narrow-distribution chitosan with controllable molecular weight through a microwave-H2O2 combined degradation method. The process comprises the following steps of: adding highly polymerized chitosan into a reactor, then stirring and dissolving by using an acetic acid solution, and standing for 10 minutes; adding 2-8 percent of H2O2 into the obtained solution; fixing the reactor in a microwave experimental instrument, simultaneously starting stirring, radiating for 3-8 minutes through a pulse mode to obtain a pale yellow solution; and regulating a pH value to be 7-8 by using an alkaline liquor, filtering, collecting the precipitation, performing vacuum drying to obtain water-soluble oligochitosan. Due to the adoption of the microwave-H2O2 combined degradation method, the narrow-distribution water-soluble oligochitosan is prepared under homogeneous-phase condition, According to the method, the operation is easy, environmental protection is realized, and secondary pollution is avoided; and moreover, the reaction is rapid during synergism of microwave and H2O2, a large quantity of energies and resources are saved, the molecular weight and distribution of the oligochitosan can be effectively controlled, and the repeatability is good.
Description
Technical field
The present invention relates to the preparation of water-soluble chitosan, specifically is to utilize microwave and H
2O
2Synergy is degraded to chitosan, obtains molecular weight controlled, the chitosan oligomer product of narrow molecular weight distributions.
Technical background
Chitosan is the positively charged ion alkaline polysaccharide of the unique existence of occurring in nature, is the high deacetylation product of chitin, has good biocompatibility, is widely used in the fields such as biological medicine, agricultural, chemical industry.Chitosan is as a kind of superpolymer, is formed by connecting through repeating many times by the glucosamine unit, and molecular weight does not wait to millions of from hundreds of thousands of.Along with the increase of molecular weight, the raising speed of the intensity of chitosan, modulus, toughness slows down, and is tending towards at last a certain ultimate value, when molecular weight is very high, that is to say when molecular chain is very long, and flow difficulties, and then be difficult to processing or application.Water insoluble and the organic solvent of chitosan can only be dissolved in the minority diluted acids such as acetic acid, hydrochloric acid, and this is so that the application of chitosan has been subject to more restriction, and application performance is not in full use.At present, the terms of settlement that generally adopts is that chitosan is carried out various modifications to adapt to the application requiring of different field, but still to face same problem in the modifying process, the molecular weight of its superelevation and the solubility property that brings thus are not good so that during modification the control of the selection of reaction system, reaction conditions and product the relatively difficulty that all becomes such as separate.Therefore carrying out the degraded of chitosan, especially by the control degradation condition, obtain the chitosan of desired molecule weight range, is very necessary, as to have an actual application value job.
The degradation method of chitosan is a lot, can be divided into chemical degradation method, mechanical degradation method, enzyme liberating method.Wherein chemical degradation method is a kind of degradation method that generally adopts in the present suitability for industrialized production, and the method is simple, cost is low, and is little on the subsequent disposal impact of reaction product.But this method degradation process is difficult to control, and the molecular weight ranges of gained degraded product is very wide, and the stability of reaction and repeatability are relatively poor, and the productive rate of product is lower, and the environmental pollution that causes is more serious; The mechanical degradation canonical is from random degradation kinetics, simple to operate, speed of response is fast, energy consumption is low, pollution-free.But this method easily causes some crosslinked and branching reactions, and aftertreatment is complicated, and yield is too low, causes production cost too high, be difficult to be applied on the suitability for industrialized production as the main body method, and can only be as the carrying out of supplementary means accelerated reaction; The enzyme liberating method does not need a large amount of reaction reagents than carrying out under the mild conditions, and the molecular weight of degraded product is easily controlled.But this edman degradation Edman is relatively harsher for the demand of dhdps enzyme, and different enzymes are different to the palliating degradation degree of chitosan, and simultaneously the obtaining of enzyme, the purifying of enzyme, the immobilization of enzyme etc. are difficulty relatively all, and cost is also very high.Also have different degradation method are united use, but can not solve still that operating process is partially long, energy consumption is high, productive rate is low and the problem such as complex process, be difficult to the molecular weight of final product is realized the control of standard, poor repeatability.Have indivedual methods can partly realize the molecular weight controlled degradation, but product is the water-insoluble chitosan, molecular weight is higher, then has no about the molecular weight distribution characteristic of degrading and mentions.
Summary of the invention
The objective of the invention is to utilize microwave-H
2O
2The combined degradation method prepares water-soluble chitosan under homogeneous phase condition, and the molecular weight of chitosan oligomer is measured, and can obtain specifying the chitosan oligomer of molecular weight ranges by the regulation and control degradation condition, and be narrow distribution of products.
Technical scheme of the present invention is:
A kind of microwave-H
2O
2The narrow distributed Chitosan poly sugar technique that the standby molecular weight of combined degradation legal system is controlled may further comprise the steps:
The first step is added to high chitosan in the reactor, then is 1% the lower dissolving of acetic acid solution stirring with mass concentration, places 10min; Material proportion is that every 2.00g chitosan adds the 30mL acetic acid solution;
Second step, the adding mass concentration is 2% ~ 8% H in the solution that obtains upward
2O
2, material proportion is that every 2.00g chitosan adds 30mLH
2O
2Solution stirs;
The 3rd step, be fixed in reactor in the microwave experiment instrument and assemble reflux, setting radiation temperature is 50 ℃ ~ 80 ℃, and the anodic current of radiation is adjusted to 40mA ~ 80mA;
The 4th step, open the microwave experiment instrument, start simultaneously stirring, by the pulse mode radiation, control effective radiated time 3min ~ 8min, obtain pale yellow solution;
In the 5th step, regulate pH to 7 ~ 8 with alkali lye;
In the 6th step, filter, with the dehydrated alcohol precipitation of filtrate with 2 ~ 3 times of volumes, collecting precipitation and 40 ℃ of lower vacuum-dryings, get water soluble oligo-chitosan, the molecular-weight average of described chitosan oligomer is 5000 ~ 20000, and polydispersity coefficient D is between 1.4～1.9.
Described high chitosan in the described the first step is that molecular-weight average is the chitosan between 500,000 ~ 2,000,000.
Alkali lye in described the 5th step is that mass concentration is 5% sodium hydroxide solution.
The present invention has advantages of:
Adopt microwave-H
2O
2The combined degradation method, the narrow distribution water soluble oligo-chitosan of preparation under homogeneous phase condition, this method is simple to operate, environmental protection, do not produce secondary pollution; Microwave and H
2O
2Be swift in response during synergy, save mass energy and resource, can effectively control molecular weight and the distribution thereof of chitosan oligomer simultaneously, good reproducibility; The present invention is to provide a kind of narrow distribution oligopolymerization chitosan sugar product, polydispersity coefficient D is 1.0 ~ 2.0, and molecular-weight average is below 20,000, and molecular weight distribution characteristic is clear and definite, for subsequent applications provides clear and definite selection foundation; In the implementation process, microwave radiation applies with pulse mode, while hierarchy of control temperature, so that the heat effect of microwave and non-thermal effect work simultaneously, take full advantage of the energy, also avoided because the long-time continuous radiation, so that the too high unsafe condition that produces of system temperature, met very much the controlled and controlled development trend of process of macromolecule chemical industry structure.
The most important innovative point of the present invention has two.The firstth, to the degraded system Choice and design: the present invention uses acetic acid aqueous solution to be solvent, add certain density hydrogen peroxide and be degraded reagent, thereby form the dielectric reaction system of a strong polarity, not only can dissolve chitosan fully, so that degradation process is carried out under homogeneous phase, and acetic acid is more conducive to the absorption of microwave as the proton type solvent, the regulation and control of favourable microwave, so that degradation process is carried out more evenly effectively, thereby the molecular weight distribution of product is effectively controlled, acidic conditions can promote the decomposition of hydrogen peroxide and formation and the transmission of free radical in addition, has strengthened the oxidation capacity of hydrogen peroxide, thereby effectively promotes the carrying out of DeR.The secondth, to the deep understanding of microwave action mechanism with rationally use: microwave radiation is to the effect of chemical reaction, the one, make the molecular motion aggravation, temperature raises; The 2nd, the specificity of electromagnetic energy and microwave makes it form special microenvironment field to effects such as the Lorentz force of polar molecule and ionic conduction, causes system character and active etc. change.Be connected with a large amount of polar functional groups on the chitosan molecule chain, these polar molecule fragments are subjected to the impact of microwave particularly outstanding, thereby form special little chemical environment, and further affect moment of dipole, hydrogen bond, chemical bonding state, degree of crystallinity of group etc., bring thus the variation of state of aggregation, molecular structure and reactive behavior and reaction kinetics performance, that is to say, microwave radiation is bound to cause the degraded of chitosan, and molecular weight and the distribution thereof of chitosan exerted an influence.Therefore, effective control of microwave radiation is emphasis of the present invention, using on the strong polar reaction system basis, by microwave irradiation power or anodic current, radiated time and microwave are applied mode and the isoparametric adjustment of temperature of reaction, intensity and the radiation amount of control microwave radiation, rationally utilize heat effect and the non-thermal effect of microwave, make it to add coupling and reach synergy with the medium of degrading is appropriate, the degraded that guarantees chitosan is carried out effectively reposefully, and realize the molecular weight of degraded product and the control of distribution thereof, mainly obtain narrow distribution of products.Operating process of the present invention is short, energy consumption is low, technique is simple, the control of the molecular weight of final product and the realization standard that distributes thereof, good reproducibility.
Description of drawings
Fig. 1 is the infrared spectrogram of chitosan among the embodiment 1 (A) and chitosan oligomer (B);
Fig. 2 is the X-ray diffraction spectrogram of chitosan among the embodiment 1 (A) and chitosan oligomer (B).
Embodiment
In following examples, used chitosan is that Jinan Haidebei Marine Organism Engineering Co., Ltd. or Chemical Reagent Co., Ltd., Sinopharm Group produce, and deacetylation is more than 90%, and molecular-weight average is about 900,000.
The present invention adopts the extrapolation one point method that the molecular weight of chitosan oligomer is measured, and the preparation HAc-NaCl aqueous solution is as solvent, by the fall time of Ubbelohde viscosimetry working sample, according to formula η=[(t/t
0-1)+3ln (t/t
0)]/4C=KM
αCalculate the molecular weight of chitosan oligomer.
The present invention is by calculating polydispersity coefficient D, and namely weight-average molecular weight is determined the distribution situation of molecular weight divided by number-average molecular weight.Weight-average molecular weight adopts light scattering determining, and number-average molecular weight adopts end-group analysis to measure.Generally, D was at 1.0 ~ 2.0 o'clock, and degree of scatter is lower, and the molecular weight distribution of product is narrow distribution; D was at 2.0 ~ 20 o'clock, and degree of scatter is higher, and the molecular weight distribution of product is wide distribution, and the D value is larger, distributed wider.
The below further specifies the present invention with embodiment, and embodiment only is used for describing the present invention in detail, is not considered as the restriction to claim protection domain of the present invention.
Embodiment 1:
Take by weighing chitosan 2.00g in reactor, add 30mL1%(w/w) the acetic acid stirring and dissolving, place after the 10min, add again 6%(w/w) H
2O
230mL places the microwave reaction instrument and assembles reflux, stirs; 65 ℃ of microwave radiation temperature are set, and radiation anodic current 80mA opens the radiation of microwave pulse formula; During from the beginning radiometer, control effective radiated time 3min.Be cooled to room temperature after the reaction, use 5%(w/w) sodium hydroxide solution regulate pH to 7 ~ 8, remove by filter a small amount of residue, the dehydrated alcohol of filtrate with 2.5 times of volumes precipitated, collecting precipitation, 40 ℃ of lower vacuum-dryings get water soluble oligo-chitosan; Recording productive rate is 55%, and the product molecular-weight average is 7255, and polydispersity coefficient D is 1.6, belongs to narrow distribution product.
The infrared spectrogram of chitosan, chitosan oligomer is seen Fig. 1, as can be seen from the figure, and 3400cm
-1About the peak be-NH
2Overlap to form with the absorption peak of-OH stretching vibration, it is because due to hydroxyl increases after the degraded that chitosan oligomer absorption herein strengthens.Chitosan is at 1625cm
-1About absorption peak be the absorption peak of acid amides I band, degradation process has been destroyed the hydrogen bond action of chitosan molecule chain so that-NH
2Flexural vibration absorb to strengthen, chitosan oligomer is at 1598cm
-1Absorption strengthen.1080cm
-1Near be the absorption peak of primary hydroxyl and secondary hydroxyl C-O stretching vibration, the degraded before and after peak shape similar.In the spectrogram of chitosan oligomer, still there is 1151cm
-1And 894cm
-1The charateristic avsorption band of two chitosan β-Isosorbide-5-Nitrae glycosidic links.By the contrast of the spectrogram before and after the degraded, can find out microwave-H
2O
2Degrade chitosan does not destroy the basic chemical structure of chitosan.The X-ray diffraction spectrogram of chitosan, chitosan oligomer is seen Fig. 2, as can be seen from the figure, chitosan two very sharp-pointed diffraction peaks occurred at 11 ° and 21 °, and the diffraction peak intensity of chitosan oligomer at this two place dies down, peak shape broadens, but new peak does not appear, illustrate that degradation process just destroyed the crystallizing field of chitosan, weakened in the molecule because hydrogen bond action amino and that hydroxyl brings, ordered structure changes to disordered structure, the molecule regularity descends, but its molecular chain basic chemical structure does not change.Can find out the degradation of chitosan success by above data.
The preparation process of the present embodiment repeats above operation at least five times, records productive rate 54%～55%, and the product molecular-weight average is between 7255～7618, and polydispersity coefficient D all belongs to narrow distribution product between 1.6～1.7.
Comparative Examples 1: other conditions are identical with embodiment 1, only use H
2O
2And obtain water soluble oligo-chitosan without microwave action; Repetitive operation at least five times records productive rate 15%～25%, and its molecular-weight average is 3855～9056, and polydispersity coefficient D is between 15.2～19.0.Can find out: the productivity ratio of products therefrom is lower; There is fluctuation in molecular weight of product, and is wayward; Molecular weight distribution is wider.
Comparative Examples 2: according to " microwave radiation prepares water-soluble chitosan fast " (Ding Yinghong etc., China's biochemical drug magazine, 2002,23(3): document operation 132-133): the hydrogen peroxide 25mL of adding 5% in beaker, 1.7g chitosan, so that the concentration of chitosan is 5%, soak placement 10mim(and note: this moment, reaction solution was heterogeneous suspension); Cover watch-glass and be placed in the microwave oven, 440W continuous gamma radiation 3min; Cooling, suction filtration after reaction finishes, filtrate is precipitated to get water-soluble chitosan with 4 times 95% ethanol, repeatedly repetitive operation, productive rate is 20%～26%; Molecular-weight average changes between 6225～17000, and fluctuation is obvious, and polydispersity coefficient D is significantly less than the numerical value of Comparative Examples 1 between 6.9～7.4, but still belongs to wide distribution of products.
It is pointed out that repetitive operation many times, this Comparative Examples does not obtain 50% above productive rate and repeatability such as bibliographical information yet, and the molecular-weight average of product is very unstable, fluctuates in a sizable scope; Also measure with regard to NM molecular weight distribution in the document in the contrast, what the result showed that this method obtains is wide distribution of products.Normally, the operation of this Comparative Examples is to carry out in the microwave reaction instrument more advanced than common microwave stove, if the method circulation ratio of bibliographical information is well talked about, it is just right that this Comparative Examples should obtain more preferably data.It is considered herein that above-mentioned situation appears and should be based on following reason: one, this Comparative Examples is actual adopt be that molecular weight is 900,000, deacetylation is at the chitosan more than 90%, and what adopt in the document is that molecular weight is 14.3 ten thousand chitosan, and its deacetylation is 75%.Its two, also be topmost reason, in the document setting of microwave parameters too simple, the comprehensively impact of reflected microwave in degradation of chitosan; Simultaneously, document uses too simple household microwave oven, and its accurate degree to the microwave regulation and control is not very strict, the fluctuation of the experiment condition that brings thus and the impact of reaction covered most probably or ignore, in a single day and use the microwave reaction instrument, these problems are just highlighted.This is actual be one to the problem of perception of microwave chemical.
Microwave action mechanism and reaction result are closely-related with control and the reaction medium of microwave radiation, described as preamble of the present invention, the control of microwave radiation, not only to comprise the adjustment of the overall flux of radiation, the appropriate mode that applies also will be arranged, be also noted that the variation of yield of radiation or density, be aided with simultaneously suitable medium and guarantee effective absorption of microwave and the performance of usefulness, these must be by regulating radiation power or the anode transmitter current of microwave, radiation applies mode, radiated time, the isoparametric setting of temperature of reaction realizes with the reaction medium rational Match again.Just holding the effect microwave irradiation time is example, under identical microwave power, it and microwave apply mode and have jointly determined microwave radiation total amount and microwave radiation density, reaction process and result there is very important impact, therefore, by changing simply microwave irradiation power or radiated time, only the microwave radiation total amount is controlled, such as the way of Comparative Examples 2, be to be difficult to accomplish the end in view, contrast the present embodiment 2, embodiment 3 and embodiment 4 are not difficult to find this point, unilaterally by prolonging radiated time, do not obtain better degradation results, but caused the crosslinking polymerization of chitosan oligomer, so that molecular weight of product transfers to raise.Comparative Examples 2 just is applied to microwave radiation in the hydrogen peroxide system simply: at first, the author does not design reaction system, just chitosan is simply mixed with hydrogen peroxide, what obtain is heterogeneous reaction system, not as acetic acid medium polarity among the embodiment strong, do not have whipping appts, even the body heating mode usefulness of microwave is higher, reaction effect also can be subject to certain impact in addition.Secondly, reaction in the normal domestic use microwave oven, open wide in the system and carry out, the backflow that there is no need and whipping appts can't carry out temperature control, hydrogen peroxide has certain loss; Simultaneously, the power setting of household microwave oven is divided into different gears, right and wrong are continuously adjustable, also can't carry out pulse operation, so the author can only adopt simple rated output continuous gamma radiation to apply microwave, is difficult to realize Effective Regulation and the utilization of microwave, although the author adopt obtained under different capacity and the radiated time closer like the product of molecular-weight average, but it is not tested molecular weight distribution, and it obviously is inadequate describing for the such molecular weight characteristics of macromolecular compound.Moreover the accuracy of household microwave oven power stage and stability are not high, can not satisfy well the requirement of microwave reaction, reaction easily occurs not thoroughly or excessively acute phenomenon, are difficult to realize that the standard of degradation process and product structure controls.In a word, because the author does not carry out deep research to the mechanism of action of microwave, so there are obvious gap in reaction result and embodiment; Simultaneously, there is certain danger in the process of reaction.
Comparative Examples 2 and the most important difference of embodiment are that the product molecular weight distribution characteristic that both obtain is different: the former obtains wide distribution of products, and this is the inevitable outcome of inhomogeneous reaction; Narrow distribution of products and embodiment obtains.
Embodiment 2:
Take by weighing chitosan 2.00g in reactor, add 30mL1%(w/w) the acetic acid stirring and dissolving, add again afterwards 2%(w/w) H
2O
230mL places the microwave reaction instrument and assembles reflux, stirs; The microwave radiation temperature 50 C is set, and radiation anodic current 40mA opens the radiation of microwave pulse formula; Control effective radiated time 3min.Be cooled to room temperature after the reaction, use 5%(w/w) sodium hydroxide solution regulate pH to 7 ~ 8, remove by filter a small amount of residue, the dehydrated alcohol of filtrate with 2 times of volumes precipitated, 40 ℃ of lower vacuum-dryings of collecting precipitation get water soluble oligo-chitosan; Recording productive rate is 49%, and the product molecular-weight average is 18229, and polydispersity coefficient D is 1.8, belongs to narrow distribution product.
The preparation process of the present embodiment repeats above operation at least five times, records productive rate between 48%～49%, and the product molecular-weight average is 18229～18560, and polydispersity coefficient D about 1.8, is narrow distribution product.
Comparative Examples 3: other conditions are identical with embodiment 2, only use H
2O
2And obtain water soluble oligo-chitosan without microwave action; Repetitive operation at least five times is surveyed its productive rate 10%～12%, and the product molecular-weight average is 6520～18156, and polydispersity coefficient D changes between 9.1～18.1.Can find out: the productive rate of products therefrom is very low; Molecular weight is fluctuating in a big way, and is wayward; Molecular weight distribution is wider.
Embodiment 3:
Step is with embodiment 2, and difference is to control effective radiated time 5min, gets water soluble oligo-chitosan; Recording productive rate is 52%, and the product molecular-weight average is 6560, and polydispersity coefficient D is 1.8, belongs to narrow distribution product.
The preparation process of the present embodiment repeats above operation at least five times, records productive rate all about 52%, and the product molecular-weight average is 6560～8407, and polydispersity coefficient D is narrow distribution product between 1.8～2.0.
Embodiment 4:
Step is with embodiment 2, and difference is to control effective radiated time 8min, gets water soluble oligo-chitosan; Recording productive rate is 49%, and the product molecular-weight average is 12618, and polydispersity coefficient D is 1.5, belongs to narrow distribution product.
The preparation process of the present embodiment repeats above operation at least five times, records productive rate 49%～50%, and the product molecular-weight average is 10260～12618, and polydispersity coefficient D all belongs to narrow distribution product between 1.5～1.9.
Embodiment 5:
Take by weighing chitosan 2.00g in reactor, add 30mL1%(w/w) the acetic acid stirring and dissolving, add again afterwards 8%(w/w) H
2O
230mL places the microwave reaction instrument and assembles reflux, stirs; The microwave radiation temperature 50 C is set, and radiation anodic current 80mA opens the radiation of microwave pulse formula; Control effective radiated time 5min.Be cooled to room temperature after the reaction, use 5%(w/w) sodium hydroxide solution regulate pH to 7 ~ 8, remove by filter a small amount of residue, the dehydrated alcohol of filtrate with 3 times of volumes precipitated, 40 ℃ of lower vacuum-dryings of collecting precipitation get water soluble oligo-chitosan; Recording productive rate is 55%, and the product molecular-weight average is 2618, and polydispersity coefficient D is 1.4, belongs to narrow distribution product.
The preparation process of the present embodiment repeats above operation at least five times, records productive rate 55%～58%, and the product molecular-weight average is 2618～2998, and polydispersity coefficient D all belongs to narrow distribution product between 1.4～1.7.
Comparative Examples 4: other conditions are identical with embodiment 5, only use H
2O
2And obtain water soluble oligo-chitosan without microwave action; Repetitive operation at least five times records productive rate 20%～25%, and the product molecular-weight average is 3520～10556, and polydispersity coefficient D belongs to wide distribution product between 6.8～8.5.Can find out: the productive rate of gained degraded product is still very low; The molecular weight fluctuation range is larger, and is wayward; Molecular weight distribution is wider.
Embodiment 6:
Take by weighing chitosan 2.00g in reactor, add 30mL1%(w/w) the acetic acid stirring and dissolving, add again afterwards 2%(w/w) H
2O
230mL places the microwave reaction instrument and assembles reflux, continues to stir 30min; 80 ℃ of microwave radiation temperature are set, and radiation anodic current 80mA opens the radiation of microwave pulse formula; Control effective radiated time 8min.Be cooled to room temperature after the reaction, use 5%(w/w) sodium hydroxide solution regulate pH to 7 ~ 8, remove by filter a small amount of residue, the dehydrated alcohol of filtrate with 2 times of volumes precipitated, 40 ℃ of lower vacuum-dryings of collecting precipitation get water soluble oligo-chitosan; Recording productive rate is 49%, and the product molecular-weight average is 11260, and polydispersity coefficient D is 1.5, belongs to narrow distribution product.
The preparation process of the present embodiment repeats above operation at least five times, records productive rate 49%～52%, and the product molecular-weight average is 11260～14618, and polydispersity coefficient D is narrow distribution product between 1.5～1.9.
Embodiment 7:
Take by weighing chitosan 2.00g in reactor, add 30mL1%(w/w) the acetic acid stirring and dissolving, add again afterwards 8%(w/w) H
2O
230mL places the microwave reaction instrument and assembles reflux, continues to stir 30min; 80 ℃ of microwave radiation temperature are set, and radiation anodic current 60mA opens the radiation of microwave pulse formula; Control effective radiated time 3min.Be cooled to room temperature after the reaction, use 5%(w/w) sodium hydroxide solution regulate pH to 7 ~ 8, remove by filter a small amount of residue, the dehydrated alcohol of filtrate with 2.5 times of volumes precipitated, 40 ℃ of lower vacuum-dryings of collecting precipitation get water soluble oligo-chitosan; Recording productive rate is 52%, and the product molecular-weight average is 5436, and polydispersity coefficient D is 1.6, belongs to narrow distribution product.
The preparation process of the present embodiment repeats above operation at least five times, records productive rate 52%～54%, and the product molecular-weight average is to change between 5436～7618, and polydispersity coefficient D is narrow distribution product between 1.6～1.8.
The present invention does not address part and is applicable to prior art.
Claims (3)
1. microwave-H
2O
2The narrow distributed Chitosan poly sugar technique that the standby molecular weight of combined degradation legal system is controlled is characterized by and may further comprise the steps:
The first step is added to high chitosan in the reactor, then is 1% the lower dissolving of acetic acid solution stirring with mass concentration, places 10min; Material proportion is that every 2.00g chitosan adds the 30mL acetic acid solution;
Second step, the adding mass concentration is 2% ~ 8% H in the solution that obtains upward
2O
2, material proportion is that every 2.00g chitosan adds 30mLH
2O
2Solution stirs;
The 3rd step, be fixed in reactor in the microwave experiment instrument and assemble reflux, setting radiation temperature is 50 ℃ ~ 80 ℃, and the anodic current of radiation is adjusted to 40mA ~ 80mA;
The 4th step, open the microwave experiment instrument, start simultaneously stirring, by the pulse mode radiation, control effective radiated time 3min ~ 8min, obtain pale yellow solution;
In the 5th step, regulate pH to 7 ~ 8 with alkali lye;
In the 6th step, filter, with the dehydrated alcohol precipitation of filtrate with 2 ~ 3 times of volumes, collecting precipitation and 40 ℃ of lower vacuum-dryings, get water soluble oligo-chitosan, the molecular-weight average of described chitosan oligomer is 5000 ~ 20000, and polydispersity coefficient D is between 1.4～1.9.
2. microwave-H
2O
2The narrow distributed Chitosan poly sugar technique that the standby molecular weight of combined degradation legal system is controlled, the described high chitosan that it is characterized by in the described the first step is that molecular-weight average is the chitosan between 500,000 ~ 2,000,000.
3. microwave-H
2O
2The narrow distributed Chitosan poly sugar technique that the standby molecular weight of combined degradation legal system is controlled, the alkali lye that it is characterized by in described the 5th step is that mass concentration is 5% sodium hydroxide solution.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103360514A (en) * | 2013-06-24 | 2013-10-23 | 广西民族大学 | Method for preparing water-soluble chitosan oligosaccharide by quick degradation |
| CN104629099A (en) * | 2015-03-06 | 2015-05-20 | 中国科学院海洋研究所 | Method for rapidly preparing ultrahigh-concentration chitosan solution |
| CN112194736A (en) * | 2020-09-24 | 2021-01-08 | 长春工业大学 | Method for preparing chitosan oligosaccharide by microwave-peroxide coupling degradation of chitosan |
| CN113637096A (en) * | 2021-09-15 | 2021-11-12 | 吴洪德 | Preparation method of chitosan oligosaccharide, chitosan oligosaccharide and chitosan oligosaccharide health-care product |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103360514A (en) * | 2013-06-24 | 2013-10-23 | 广西民族大学 | Method for preparing water-soluble chitosan oligosaccharide by quick degradation |
| CN104629099A (en) * | 2015-03-06 | 2015-05-20 | 中国科学院海洋研究所 | Method for rapidly preparing ultrahigh-concentration chitosan solution |
| CN112194736A (en) * | 2020-09-24 | 2021-01-08 | 长春工业大学 | Method for preparing chitosan oligosaccharide by microwave-peroxide coupling degradation of chitosan |
| CN113637096A (en) * | 2021-09-15 | 2021-11-12 | 吴洪德 | Preparation method of chitosan oligosaccharide, chitosan oligosaccharide and chitosan oligosaccharide health-care product |
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| CN103044574B (en) | 2015-05-06 |
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