High esterification degree ethyl alginate preparation method

A technology of ethyl alginate and high degree of esterification, applied in the field of preparation of ethyl alginate with high degree of esterification, can solve the problem of low degree of esterification, poor compatibility, difficulty in obtaining high degree of esterification alginate, etc. question

Active Publication Date: 2017-03-22
QINGDAO UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, for small-molecular direct alkanols, since the esterification reaction will generate water molecules, and the water molecules have compatibility or high compatibility with small-molecular raw material alcohols, it is difficult to separate each other, so even if an excessive amount of alcohol is used To promote the positive direction of the esterification reaction, the esterification reaction is also difficult to obtain alginate with a high degree of esterification, and the degree of esterification is usually less than 20%.
For example Broderick Eilish et al. (Broderick E, Lyons H, Pembroke T, et al. The characterization of novel, covalently modified, amphiphilic alginate derivative, which retainsgelling and non-toxic properties[J]. Journal of colloid and interfacescience, 2006, 298(1 ): 154-161.) Using sulfuric acid as a catalys...

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0011] Add 200g of absolute ethanol to a 500ml four-necked flask, add 50g of alginic acid with a water content of 6%, stir evenly, add 0.4g of concentrated sulfuric acid as a catalyst at room temperature, stir evenly and then raise the temperature to reflux temperature, reflux for 8 hours, and the reaction is over , cooled to room temperature, adjusted the pH to 6.5~7.0 with 5% sodium carbonate aqueous solution, filtered, washed the filter cake with 70% ethanol aqueous solution, and dried at 40°C to obtain ethyl alginate . The degree of esterification of the product was tested according to the national standard GB25533-2010, and the degree of esterification of the prepared ethyl alginate was 52.34%; the alginic acid with a temperature of 25°C, a mass concentration of 3%, and a pH of 7 was tested using a rotational viscometer. and the apparent viscosity of the ethyl alginate aqueous solution, the apparent viscosity of the sodium alginate solution is 157 mPa.s; the apparent visc...

Embodiment 2

[0013] Add 200g of absolute ethanol to a 500ml four-neck flask, add 50g of alginic acid with a water content of 6%, stir evenly, add 24.67g of triethyl orthoformate at room temperature with an equimolar amount to the water content of alginic acid, and then add 0.4g Concentrated sulfuric acid was used as a catalyst, and after stirring evenly, the temperature was raised to reflux temperature, and 23 g of triethyl orthoformate was evenly added dropwise within 2 hours. After adding, continue to react under reflux state for 8 hours, and after the reaction is finished, cool to room temperature, adjust the pH to 6.5~7.0 with a 5% sodium carbonate aqueous solution with a mass concentration, filter, and wash the filter cake with an ethanol aqueous solution with a mass concentration of 70%. Dry at 40°C to prepare ethyl alginate samples. The degree of esterification of ethyl alginate was tested to be 70.68%. The temperature is 25°C, the mass concentration is 3%, and the apparent viscosi...

Embodiment 3

[0015] With embodiment 1, just change 0.4g concentrated sulfuric acid catalyst into 1.40g p-toluenesulfonic acid as catalyst. Ethyl alginate was obtained. After testing, the degree of esterification of ethyl alginate was 54.67%. The temperature is 25°C, the mass concentration is 3%, and the apparent viscosity of ethyl alginate aqueous solution with pH=7 is 73mPa.s.

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Abstract

The invention discloses a high esterification degree ethyl alginate preparation method, which comprises: adding alginic acid to anhydrous ethanol, stirring, adding a dehydrating agent having the same molar water content as the alginic acid, adding a catalyst, carrying out stirring heating to achieve a reflux state, adding the remaining dehydrating agent in a dropwise manner when the reflux temperature is achieved, continuously carrying out a reflux reaction for 6-18 h after the remaining dehydrating agent is uniformly added in the dropwise manner within 2-4 h, completing the reaction, cooling to a room temperature, adjusting the pH to 6.5-7.0 with an alkali liquid, filtering, washing the filter cake by using an ethanol aqueous solution with a mass concentration of higher than 60%, and drying at a temperature of 40 DEG C to obtain the ethyl alginate. According to the present invention, with the ethyl alginate preparation method, the esterification degree of the prepared ethyl alginate is higher than 68% and is significantly higher than the esterification degree of the straight chain alkanol ethyl alginate prepared by using the existing technology.

Description

technical field [0001] The invention relates to a method for preparing alginate, in particular to a method for preparing ethyl alginate with a high degree of esterification. Background technique [0002] Alginic acid is mainly derived from brown algae plants and bacteria, and its molecular formula is (C 6 h 7 o 6 Na) n , the relative molecular weight is between 32000-200000, the molecule is composed of β-D-mannuronic acid and α-L-guluronic acid linked by (1→4) glycosidic bonds, it is a linear polyanion water-soluble carbohydrate. Alginic acid is white or light yellow powder, insoluble in methanol, ethanol, DMF and other organic solvents. Degradation reactions occur under acidic, alkaline and high temperature conditions, resulting in a rapid decrease in molecular weight. Therefore, it should be placed in a low temperature, dry, ventilated, and dark environment during storage. [0003] Alginic acid derivatives with a high degree of commercialization currently mainly inc...

Claims

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Application Information

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IPC IPC(8): C08B37/04
CPCC08B37/0084
Inventor 刘馨张晓东陈照军杜辉夏凯
Owner QINGDAO UNIV
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