JPH052681B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to acetyl curdlan, a novel curdlan (β-1,3-glucan) derivative. Curdlan is a soil bacterium Alcaligenes
Produced by Faecalisvra.myxogenes, having the following chemical structure: It is a water-insoluble polysaccharide that was first discovered by some of the present inventors (Agric.Biol.
Chem., 30 , 196 (1966); Arch.Biochem.
Biophys., 124 , 292 (1968) et al.), but later it was discovered that it can also be obtained from other bacterial species such as Agrobacterium and certain species of Rhizobium, and has continued to this day. Curdlan has unique properties such as the ability to form a heat-irreversible gel when its suspension is heated, and is therefore expected to be used in a variety of applications. That is, for example, it is attracting attention for its use as a carrier for gel filtration, affinity chromatography, or immobilized enzyme carrier, starch jelly for food, low-calorie food, and solidifying material for industrial use. It is of interest as an optimal material for studying gelation mechanisms and as a basic substance for antitumor polysaccharides. Although curdlan is such a useful compound, it has some difficulties in forming a film, and
Since the specificity of the membrane is also slightly inferior, it is extremely difficult to use this to form a membrane that is strong and has separation properties that can be used as a separation membrane. The present inventors have made extensive research to compensate for the drawbacks of curdlan and to find new possibilities for curdlan, and have arrived at a new curdlan derivative, acetyl curdlan, and completed the present invention. I reached it. That is, the present invention provides curdlan (β-1,3-glucan) having the following structure. General formula obtained by acetylating the hydroxyl group [] [C ₆ H ₇ O ₂ (OCOCH ₃ ) _x (OH) _3-x ] _o [] [In the formula, x represents 1 to 3, and n is approximately 200 ~2000
represents an integer. ) is acetyl curdlan. In the acetyl curdlan of the present invention represented by the general formula [], x representing the degree of substitution of the acetyl group is usually 1 to 3, more preferably 2 to 3, and n representing the degree of polymerization is usually It is about 200-2000, more preferably 300-700. Acetyl curdlan of the present invention is generally synthesized by the following method. That is, for example, curdlan is heated in an acetic acid solvent in the presence of a dehydrating agent such as p-toluenesulfonic acid using 1 to 3 times the theoretical amount of acetic anhydride, usually at 40 to 50°C.
The acetylation reaction is carried out for 1 to 5 hours (adjust the amount of acetic anhydride, reaction temperature, reaction time, etc. as appropriate depending on the desired degree of substitution and viscosity), and then the reaction solution is poured into a large amount of water using a conventional method. The target acetyl curdlan can be easily obtained by injecting water into the reaction solution or by injecting water into the reaction solution to cause crystallization, which is collected, washed with water, and dried. Furthermore, if necessary, the acetyl group can be partially hydrolyzed by adding, for example, an aqueous sulfuric acid solution or the like to the reaction solution after the reaction and heat-treating it, thereby adjusting the degree of acetyl substitution as appropriate. It is expected that the acetyl curdlan of the present invention can be used in roughly the same applications as curdlan itself, for example, as a carrier for gel filtration and a carrier for affinity chromatography, with unique effects. However, it can also be used in similar applications to acetylcellulose, such as plastics, paint lacquers, and electrical insulation. Furthermore,
As an effect that cannot be obtained from the card run itself,
These include its coating properties and membrane specificity. That is,
The separation membrane made of acetyl curdlan of the present invention can be used very effectively as a separation membrane for ultrafiltration. The separation membrane made of acetyl curdlan of the present invention is preferably used for fractionation of substances having a molecular weight within the range of about 200 to 20,000, and is particularly excellent in the region of small molecular weight cutoff (1,000 or less). Demonstrates fractional separation. The separation membrane made of acetyl curdlan of the present invention is capable of separating, for example, organic acids and sugars with similar molecular weights, such as glycol and lactic acid, sucrose and malic acid (or tartaric acid), It is possible to effectively separate raffinose (or molasses) and citric acid. Therefore, the present invention can be used to separate and purify organic acids from a mixture of organic acids and saccharides in the production of lower organic acids by fermentation of saccharides, and to remove organic acids contained as impurities in saccharides. This can be accomplished extremely effectively by using a separation membrane made of acetylcurdlan. Unlike, for example, polymer electrolyte complex membranes, the separation membrane made of acetyl curdlan of the present invention has high physical and mechanical strength as a membrane, is resistant to pollution, is resistant to electrolytes, and is stable. Because of its good properties, it can be used repeatedly, is very easy to use from both an equipment and operational standpoint, and is extremely economical. As described above, the present invention provides a novel curdlan derivative that is useful as a material for ultrafiltration separation membranes, etc., and makes a great contribution to this industry. Examples and reference examples are shown below, but the present invention is not limited to these examples and reference examples in any way. In addition, the water flux in the reference example
is a batch-type ultrafiltration device (effective membrane area 12.13
cm ² ), water permeation was measured using distilled water at 20° C. under an operating pressure of 4 Kg/cm ² , and calculated using the formula below. Permeation flux [/m ² · hr] = Water permeation rate [ml] / Effective membrane area [cm ² ] × 60 / Required time (minutes) × 10 In addition, the rejection rate is calculated using the following formula (a). It was expressed using the true rejection rate obtained by correcting the concentration factor using equation (b) from the rejection rate (Rj). Apparent rejection rate (Rj) = 1 - solute concentration in permeated water / solute concentration in stock solution... (
b) True blocking rate = log [Rj (A-1) + 1] / logA × 100...
(b) Here, A represents the concentration ratio (=volume of stock solution [ml]/volume of concentrated solution [ml]). Example 1 308 g (1.85 glucose units) of curdlan (β-1,3-glucan, n = approximately 500) and 48 g (0.252 mol) of p-toluenesulfonic acid were dissolved in 1.88 acetic acid, and the mixture was heated at 45 to 50°C. Acetic anhydride 1.08 (11.42
mol) was added dropwise over a period of 1 hour. Approximately 50℃ after dropping
After carrying out the acetylation reaction for 4 hours at
It was diluted with water and filtered by suction. The liquid was poured into 60 g of water to cause crystallization, and the precipitate was collected, washed with water, and dried to obtain 376 g of acetyl curdlan (yield: 2.4%).
Acetyl content: 43.35% (degree of acetyl substitution (DS) = 2.83), viscosity (1.8% formic acid solution, 20°C):
12.8cps, IR (Film): ν2960 (-CH), 1740~1760
(-CO-), 1370 (-O-CO- _CH3 ), 1200-1240
(-CO-O-), 1030-1070 (C-O-C), 890cm
^-1 (−CH−). Example 2 308 g (1.85 glucose units) of curdlan (β-1,3-glucan, n = approximately 500) and 48 g (0.252 mol) of p-toluenesulfonic acid were dissolved in 1.88 acetic acid, and the mixture was heated at 45 to 50°C. Acetic anhydride 1.08 (11.42
mol) was added dropwise over a period of 1 hour. Approximately 50℃ after dropping
After carrying out the acetylation reaction, the mixture was treated in the same manner as in Reference Example 1 to obtain 380 g of acetylcurdlan. Acetyl content: 44.65% (degree of acetyl substitution (DS)
= 2.98), viscosity (1.8% formic acid solution, 20°C): 59 cps. Example 3 308 g (1.85 glucose units) of curdlan (β-1,3-glucan, n = approx. 500) and 48 g (0.252 mol) of p-toluenesulfonic acid were dissolved in 1.88 acetic acid and heated at 45 to 50°C. Acetic anhydride 1.08 (11.42
mol) was added dropwise over a period of 2 hours. Approximately 50℃ after dropping
After carrying out the acetylation reaction for 4 hours at
It was diluted with water and filtered by suction. Next, 78.9 g of concentrated sulfuric acid and 1.26 g of water were added to the solution, and the mixture was treated at 50° C. for 8 hours to partially hydrolyze the acetyl groups. After the reaction, add 60 g of water to crystallize, collect the precipitated crystals, wash with water and dry to obtain 328 g of acetyl curdlan.
I got it. Acetyl content: 37.30% (degree of acetyl substitution (DS) = 2.2), viscosity (1.8% formic acid solution, 20
℃): 27cps. Reference Example 1 2 parts of the acetyl curdlan synthesized in Example 1 were dissolved in 11.3 parts of formic acid, and the prepared casting liquid was cast onto a horizontally held glass plate to a thickness of 0.2 mm, and then heated at 20°C for 4 hours. The solvent was partially evaporated for minutes. Next, a membrane was obtained by immersing it in water at 20°C. Membrane performance is shown in Table 1.

[Table] Reference example 2 2 parts of acetyl curdlan synthesized in Example 1,
A cast solution consisting of 8.2 parts of formic acid and 3.4 parts of methylene dichloride was cast onto a horizontally held glass plate to a thickness of 0.2 mm, and the solvent was partially evaporated at 20° C. for 2 minutes. Next, it was immersed in water at 20°C to form a gel, thereby obtaining a separation membrane. Membrane performance is shown in Table 2.

[Table] Reference Example 3 A casting solution prepared by dissolving 2 parts of the acetyl curdlan synthesized in Example 2 in 18 parts of formic acid was cast onto a horizontally held glass plate to a thickness of 0.2 mm. The solvent was partially evaporated for 5 minutes at 20°C. Next, a separation membrane was obtained by immersing it in water at 20°C. Membrane performance is shown in Table 3.

[Table] Reference Example 4 Two parts of the acetyl curdlan synthesized in Example 3 were dissolved in 18 parts of formic acid, and the prepared casting solution was cast onto a horizontally held glass plate to a thickness of 0.2 mm. The solvent was partially evaporated for 1 minute at °C. Next, it was immersed in water at 20°C to form a gel, thereby obtaining a separation membrane. Membrane performance is shown in Table 4.

[Table] Reference example 5 2 parts of acetyl curdlan synthesized in Example 1,
A casting solution consisting of 8.2 parts of formic acid and 3.4 parts of methylene dichloride was cast to a thickness of 0.2 mm on a horizontally held glass plate, and the solvent was partially evaporated at 20° C. for 2 minutes. Next, it was immersed in water at 20°C to form a gel, thereby obtaining a separation membrane. The water permeation flux of the resulting separation membrane at an operating pressure of 4 kg/cm ² was 4.26/m ² ·hr. This membrane was used to treat a 1:1 mixture of 1000 ppm lactic acid and 1000 ppm glucose. The results are shown in Table 5.

[Table] However, the degree of separation was calculated using the following formula. Separation degree = Lactic acid concentration in permeated liquid / Glucose concentration in permeated liquid / Lactic acid concentration in stock solution / Glucose concentration in stock solution Reference example 6 Prepared by dissolving 2 parts of acetyl curdlan synthesized in Example 1 in 11.3 parts of formic acid. The resulting casting solution was cast onto a horizontally held glass plate to a thickness of 0.2 mm, and the solvent was partially evaporated at 20° C. for 4 minutes. Next, a separation membrane was obtained by immersing it in water at 20°C. The water permeation flux of the obtained separation membrane at an operating pressure of 4 kg/cm ² was 6.6/m ² ·hr. Using this membrane, 1000ppm malic acid and 1000ppm
A 1:1 mixture with sucrose was treated. The results are shown in Table 6.

[Table] Reference example 7 2 parts of acetyl curdlan synthesized in Example 1,
A cast solution consisting of 8.2 parts of formic acid and 3.4 parts of methylene dichloride was cast onto a horizontally held glass plate to a thickness of 0.2 mm, and the solvent was partially evaporated at 20° C. for 2 minutes. Next, it was immersed in water at 20°C to form a gel, thereby obtaining a separation membrane. The permeation flux of water through this separation membrane at an operating pressure of 4 kg/cm ² was 4.26/m ² ·hr. When this membrane was used as an ultrafiltration membrane, the rejection rates of various solutes were as shown in Table 7.

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Claims (1)

[Claims] 1 Curdlan (β-1,3-
glucan) General formula obtained by acetylating the hydroxyl group [] [C ₆ H ₇ O ₂ (OCOCH ₃ ) _x (OH) _3-x ] _o [] [In the formula, x represents 1 to 3, and n is approximately 200 ~2000
represents an integer. ) acetylcurdlan.