CN106519063B - A kind of preparation method of high esterification degree alginic acid methyl esters - Google Patents
A kind of preparation method of high esterification degree alginic acid methyl esters Download PDFInfo
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- CN106519063B CN106519063B CN201610871104.9A CN201610871104A CN106519063B CN 106519063 B CN106519063 B CN 106519063B CN 201610871104 A CN201610871104 A CN 201610871104A CN 106519063 B CN106519063 B CN 106519063B
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- alginic acid
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B37/00—Preparation of polysaccharides not provided for in groups C08B1/00 - C08B35/00; Derivatives thereof
- C08B37/006—Heteroglycans, i.e. polysaccharides having more than one sugar residue in the main chain in either alternating or less regular sequence; Gellans; Succinoglycans; Arabinogalactans; Tragacanth or gum tragacanth or traganth from Astragalus; Gum Karaya from Sterculia urens; Gum Ghatti from Anogeissus latifolia; Derivatives thereof
- C08B37/0084—Guluromannuronans, e.g. alginic acid, i.e. D-mannuronic acid and D-guluronic acid units linked with alternating alpha- and beta-1,4-glycosidic bonds; Derivatives thereof, e.g. alginates
Abstract
The present invention discloses a kind of preparation method of high esterification degree alginic acid methyl esters, preparation method includes the following steps: in anhydrous methanol, alginic acid is added, start stirring, it is added and the equimolar dehydrating agent of alginic acid water content, catalyst is added, stirring is warming up to reflux, after reaching reflux temperature, start that remaining dehydrating agent is added dropwise, after being dropped evenly in 2-4 hours, continue back flow reaction 6 ~ 20 hours, reaction was completed, after being cooled to room temperature, with lye pH adjustment=6.5 ~ 7.0, filtering, methanol aqueous solution of the filter cake with mass concentration higher than 60% washs, and it is dry at 40 DEG C, obtain alginic acid methyl esters；Using the preparation method of alginic acid methyl esters of the present invention, the esterification degree of prepared alginic acid methyl esters is higher than 70%, hence it is evident that higher than the esterification degree of the linear alcohols alginic acid ester of prior art preparation.
Description
Technical field
The present invention relates to a kind of preparation methods of alginic acid ester, more particularly to a kind of system of high esterification degree alginic acid methyl esters
Preparation Method.
Background technique
Alginic acid is mainly derived from brown alga plant and bacterium, and molecular formula is (C6H7O6Na)n, relative molecular weight is in 32000-
Between 200000, it is one that molecule, which is formed by beta-D-mannuronic acid and α-L- guluronic acid by (1 → 4) glycosidic bond links,
The linear polyanion water soluble carbohydrates of kind.Alginic acid is white or pale yellow powder insoluble in methanol, ethyl alcohol, DMF etc.
Organic solvent.Degradation reaction can all occur under acid, alkalinity and hot conditions, lead to the quick reduction of molecular weight.Therefore exist
Low temperature should be placed on during storage, in environment drying, divulged information, be protected from light.
The higher alginic acid derivative of commercialization degree mainly includes sodium alginate and polyetylene glycol alginate at present.As
A kind of biodegradable fully natural green high molecular material, and there is nontoxic, tasteless, gelation, stability, thickening property, cream
The features such as property changed, suspension and film forming, is widely used to the neck such as food, medicine, weaving, agricultural and wastewater treatment at present
Domain.
Though alginic acid is insoluble in the organic solvents such as alcohol, ethylene oxide and propylene oxide, to it with certain swellability,
Because intramolecular contains carboxyl, therefore in the presence of acid or basic catalyst, can same alkylol, propylene oxide or ethylene oxide etc.
Esterifying reagent directly occurs esterification and generates alginic acid ester.Propylene oxide and reacting ethylene oxide activity are higher, in Tong Hai
Alginic acid occurs not generate hydrone in esterification reaction process, is conducive to balanced reaction and carries out to positive direction, therefore esterification degree is higher,
For example, carrying out esterification using propylene oxide and alginic acid prepares propylene glycol alginate (PGA), esterification degree can reach 90% or more.
However, since esterification can generate hydrone, and hydrone and small-molecule starting material alcohol have for alkanol direct-connected for small molecule
There are compatibility or compatibility higher, it is difficult to be separated from each other, therefore even if promote esterification to positive direction using excessive alcohol
It carries out, esterification is also difficult to obtain high esterification degree alginic acid ester, and esterification degree is usually less than 20%.Such as Broderick
(Broderick E, Lyons H, Pembroke T, the et al. The characterization of a such as Eilish
novel, covalently modified, amphiphilic alginate derivative, which retains
gelling and non-toxic properties[J]. Journal of colloid and interface
Science, 2006,298 (1): 154-161.) sulphur acid as catalyst is used, it is anti-using alginic acid and excessive butanol direct esterification
Seaweed acid butyl ester should be prepared, when esterification reaches balance, esterification degree is lower than 20%；For long chain alkanol, due to seaweed
The compatibility of acid is poor, and reactivity is lower, therefore even if being easy to the hydrone separation that same esterification generates, esterification journey
Degree is relatively low.Preparation for alginic acid long-chain alcohol ester generallys use Ugi reaction (Ugi I. The α-at present
Addition of Immonium Ions and Anions to Isonitriles Accompanied by Secondary
Reactions[J]. Angewandte Chemie International Edition in English, 1962, 1(1):
It 8-21) prepares, but the esterification degree of alginic acid ester prepared by this method is also usually less than 20%.Just at present it has been reported that
It directlys adopt alginic acid and linear alcohols carries out esterification to prepare alginic acid ester, esterification degree is usually less than 50%.
Trimethyl orthoformate also known as trimethoxy-methane are a kind of colourless liquids, inflammable, can be dissolved in methanol, ethyl alcohol, second
The important organic synthesis intermediate of one kind of the organic solvents such as ether, the synthesis for a variety of medicine, dyestuff and fragrance etc..Orthoformic acid
Trimethyl is met water and is decomposed, and generates methanol and methyl formate, therefore can be used as dehydrating agent in the preparation process of alginic acid ester to make
With.
It is an object of the invention to provide a kind of high esterification degree alginic acid methyl esters and preparation method thereof, are easy to get for raw material, can
Biodegradable fully natural green macromolecule polysaccharide alginic acid opens up new space.
Compared with existing linear alcohols alginic acid ester technology of preparing, the esterification degree of alginic acid methyl esters prepared by the present invention is reachable
To 70% or more.
Summary of the invention
A kind of preparation method of high esterification degree alginic acid methyl esters, it is characterised in that implement as follows: in anhydrous methanol
In, alginic acid is added, starts stirring, is added and the equimolar dehydrating agent of alginic acid water content, addition catalyst, stirring is warming up to
Reflux, after reaching reflux temperature, starts that remaining dehydrating agent is added dropwise, and after dropping evenly in 2-4 hours, continues back flow reaction
6 ~ 20 hours, reaction was completed, and after being cooled to room temperature, with lye pH adjustment=6.5 ~ 7.0, filtering, filter cake are higher than 60% with mass concentration
Methanol aqueous solution washing, and it is dry at 40 DEG C, obtain alginic acid methyl esters；Alginic acid dosage and methanol usage described above
Mass ratio is 1:2 ~ 6；Dehydrating agent described above is trimethyl orthoformate；Dropwise addition residue dehydrating agent described above is to be added dropwise
The molar ratio of remaining trimethyl orthoformate, dripping quantity and alginic acid dosage is 1:0.5-1；Catalyst described above is quality
The concentrated sulfuric acid or p-methyl benzenesulfonic acid that concentration is 98%, dosage are the mass percent 0.2-3% of alginic acid dosage；It is described above
Lye be sodium carbonate liquor or sodium hydroxide solution.
Using the preparation method of alginic acid methyl esters of the present invention, the esterification degree of prepared alginic acid methyl esters is higher than 70%, hence it is evident that
Higher than the esterification degree of the linear alcohols alginic acid ester of prior art preparation.The present invention is further illustrated below by specific example.
Specific embodiment
Embodiment 1
200g anhydrous methanol is added in 500ml four-hole boiling flask, the alginic acid 50g that water content is 6% is added, stirs evenly,
The 0.4g concentrated sulfuric acid is added at room temperature and makees catalyst, is warming up to reflux temperature, back flow reaction 12h after mixing evenly, reaction terminates cold
But to room temperature, pH to 6.5 ~ 7.0, filtering, filter cake mass concentration 65% are adjusted with the aqueous sodium carbonate that mass concentration is 5%
Methanol aqueous solution washing is dried under the conditions of 40 DEG C, and alginic acid methyl esters sample is made.It is tested by national standard GB25533-2010, sea
The esterification degree of alginic acid methyl esters is 55.29%；Use rotational viscometer difference test temperature for 25 DEG C, mass concentration 3%, pH=7
Alginic acid and alginic acid methyl esters aqueous solution apparent viscosity, the apparent viscosity for obtaining sodium alginate soln is 156mPa.s；Alginic acid first
The apparent viscosity of ester solution is 50mPa.s.
Embodiment 2
200g anhydrous methanol is added in 500ml four-hole boiling flask, the alginic acid 50g that water content is 6% is added, stirs evenly,
The trimethyl orthoformate 17.67g with alginic acid water content equimolar amounts is added at room temperature, adds the 0.4g concentrated sulfuric acid and is catalyzed
Agent is warming up to reflux temperature after mixing evenly, is dropped evenly again in 2 hours into trimethyl orthoformate 15.9g.Continue after adding
It reacts 12 hours at reflux, reaction terminates to be cooled to room temperature, and adjusts pH with the aqueous sodium carbonate that mass concentration is 5 %
To 6.5 ~ 7.0, filtering, filter cake are washed with the methanol aqueous solution of mass concentration 65%, are dried under the conditions of 40 DEG C, and alginic acid is made
Methyl esters sample.The esterification degree of alginic acid methyl esters is 72.21% after tested.Temperature is 25 DEG C, mass concentration 3%, the seaweed of pH=7
Sour methyl esters aqueous solution apparent viscosity is 71mPa.s.
Embodiment 3
With embodiment 1,0.4g concentrated sulfuric acid catalyst is only changed to 1.40g p-methyl benzenesulfonic acid and makees catalyst.Obtain alginic acid
Methyl esters.The esterification degree of alginic acid methyl esters is 58.29% after tested.Temperature is 25 DEG C, mass concentration 3%, the alginic acid first of pH=7
Aqueous solution of ester apparent viscosity is 77mPa.s.
Embodiment 4
With embodiment 1,0.4g concentrated sulfuric acid catalyst is only changed to 0.6g concentrated sulfuric acid catalyst.Obtain alginic acid methyl esters.Through
The esterification degree for testing alginic acid methyl esters is 55.85%.Temperature is 25 DEG C, mass concentration 3%, the alginic acid methyl esters aqueous solution of pH=7
Apparent viscosity is 48mPa.s.
Embodiment 5
With embodiment 2,0.4g concentrated sulfuric acid catalyst is only changed to 1.4g p-methyl benzenesulfonic acid and makees catalyst.Obtain alginic acid first
Ester.The esterification degree of alginic acid methyl esters is 74.23% after tested.Temperature is 25 DEG C, mass concentration 3%, the alginic acid methyl esters of pH=7
Aqueous solution apparent viscosity is 81mPa.s.
Embodiment 6
With embodiment 2, only trimethyl orthoformate 15.9g will be dropped evenly again in 2 hours and be changed in 2 hours again
It drops evenly into trimethyl orthoformate 21.2g.Obtain alginic acid methyl esters.The esterification degree of alginic acid methyl esters is 72.86% after tested.Temperature
Degree is 25 DEG C, mass concentration 3%, and the alginic acid methyl esters aqueous solution apparent viscosity of pH=7 is 74mPa.s.
Embodiment 7
With embodiment 2,0.4g concentrated sulfuric acid catalyst is only changed to 1.2g p-methyl benzenesulfonic acid and makees catalyst.Obtain alginic acid first
Ester.The esterification degree of alginic acid methyl esters is 72.89% after tested.Temperature is 25 DEG C, mass concentration 3%, the alginic acid methyl esters of pH=7
Aqueous solution apparent viscosity is 78mPa.s.
As can be seen from the above-described embodiment, it under acid catalysis, is reacted by alginic acid with the direct refuxing esterification of methanol, preparation
The esterification degree of alginic acid methyl esters is below 60%, and under identical enzymatic synthesis condition, dehydrating agent trimethyl orthoformate, alginic acid is added
The esterification degree of methyl esters is improved significantly, and esterification degree is above 70% or more；Catalyst is done using p-methyl benzenesulfonic acid and relatively uses dense sulphur
The esterification degree of acid as catalyst, alginic acid methyl esters is improved.By the solution viscosity of alginic acid methyl esters prepared in the above embodiments
It is all larger than 48mPa.s, is higher than commodity pectin solution viscosity (low ester: 37mPa.s；High ester: 18mPa.s), add alginic acid first
The structure of ester structure and propylene glycol alginate and pectin has similarity, therefore alginic acid methyl esters is expected to prepare in milk beverage
The pectin of fictitious hosts valuableness uses in journey.
Certainly, the above description is not a limitation of the present invention, and the present invention is also not limited to the example above, the art
Those of ordinary skill, within the essential scope of the present invention, variation, addition or the replacement made all should belong to guarantor of the invention
Protect range.
Claims (1)
1. a kind of preparation method of high esterification degree alginic acid methyl esters, it is characterised in that implement as follows: in anhydrous methanol,
Alginic acid is added, starts stirring, is added and stirs and be warming up to back with the equimolar dehydrating agent of alginic acid water content, addition catalyst
Stream, after reaching reflux temperature, starts that remaining dehydrating agent is added dropwise, after being dropped evenly in 2-4 hours, continuation back flow reaction 6 ~
20 hours, reaction was completed, and after being cooled to room temperature, with lye pH adjustment=6.5 ~ 7.0, filtering, filter cake are higher than 60% with mass concentration
Methanol aqueous solution washing, and it is dry at 40 DEG C, obtain alginic acid methyl esters；The matter of alginic acid dosage and methanol usage described above
Amount is than being 1:2 ~ 6；Dehydrating agent described above is trimethyl orthoformate；Dropwise addition residue dehydrating agent described above is to be added dropwise to remain
The molar ratio of remaining trimethyl orthoformate, dripping quantity and alginic acid dosage is 1:0.5-1；Catalyst described above is that quality is dense
The concentrated sulfuric acid or p-methyl benzenesulfonic acid that degree is 98%, dosage are the mass percent 0.2-3% of alginic acid dosage；Described above
Lye is sodium carbonate liquor or sodium hydroxide solution.
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| CN116396324B (en) * | 2023-03-17 | 2024-01-02 | 南雄志一精细化工有限公司 | Preparation method of light-colored diphenyl phosphite |
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Non-Patent Citations (2)
| Title |
|---|
| The characterisation of a novel, covalently modified, amphiphilic alginate derivative, which retains gelling and non-toxic properties;Eilish Broderick等;《Journal of Colloid and Interface Science》;20060118;第298卷;第154-161页 * |
| The α-Addition of Immonium Ions and Anions to Isonitriles Accompanied by Secondary Reactions;DOZ. DR. IVAR UGI;《Angew. Chem. internat. Edit.》;19620127;第1卷(第1期);第8-21页 * |
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