JPH1112302A - Production of tricarboxypolysaccharide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a tricarboxypolysaccharide having a high carboxyl content by oxidizing a polysaccharide with a percarboxylic acid in the presence of a ruthenium compound at a temperature higher than a specific temperature. SOLUTION: This polysaccharide is obtained by oxidizing (A) a polysaccharide (e.g. starch, etc.), with (C) a percarboxylic acid (e.g. peracetic acids, etc.), as an oxidant in the presence of (B) a ruthenium compound (e.g. ruthenium chloride, etc.), at >=60 deg.C. It is preferable that the above reaction is carried out under the following conditions: the concentration of the component A in the oxidation reaction mixture is 1-80 wt.%; the use of the component B is in an amount of 0.00001-0.1 mol in terms of ruthenium atom based on 1 mol of the pyranose unit constituting the component A; and the use of the component C is 3-30 mol based on 1 mol of the pyranose unit. The produced tricarboxypolysaccharide has a high Ca-ion blocking performance and is suitable especially as a builder of a detergent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to highly carboxylated tricarboxypolysaccharides and salts thereof produced by the oxidation of polysaccharides. The tricarboxypolysaccharides and salts thereof obtained according to the present invention may be, in addition to a scale adhesion inhibitor, a pigment dispersant, a sizing agent, a concrete admixture,
Particularly, it can be suitably used as a detergent builder.

[0002]

2. Description of the Related Art Various attempts have been made to industrially utilize polysaccharides as renewable resources ubiquitous on the earth.
Japanese Patent Publication No. 49-1281 discloses a method of oxidizing a polysaccharide using a combination of periodic acid and chlorite or a hypochlorite, and oxidizing the second and third positions of the polysaccharide. It is described that the dicarboxy starch obtained by the above has a detergent builder function.

JP-A-60-2187 discloses a method for producing a dicarboxy polysaccharide by using a polysaccharide as sodium hypochlorite or chlorine or a combination of periodic acid and halogen. JP-A-4-175301 discloses a method for producing a dicarboxypolysaccharide using hypochlorite and / or hypoiodite.

[0004] As a method for producing a tricarboxypolysaccharide by oxidizing a polysaccharide, Japanese Patent Publication No. 47-40552 and Czechoslovakia Patent No. 235576 disclose that starch is treated with periodate and nitrous oxide. A method for oxidative carboxylation is disclosed. In EP Patent No. 542496,
A method for oxidatively carboxylating starch by adding vanadium salt and nitrite in a nitric acid / sulfuric acid solvent is disclosed.

[0005] However, Japanese Patent Publication No. 49-1281 and Japanese Patent Publication No. 47
-40552 and the method described in Czechoslovakia Patent 235576 require the use of expensive periodic acid, and the method described in EP Patent 542496 requires a high concentration of periodic acid. The reaction of the reaction solution is not easy because nitric acid oxidation of candy starch using sulfuric acid as a solvent,
Neither is suitable as an industrial production method.

Generally, in order to obtain an excellent detergent builder, a high Ca ion sequestering ability is required, and a polycarboxylic acid type structure containing a large number of carboxyl groups in a molecule is important. However, it has been extremely difficult to oxidatively carboxylate polysaccharides using the raw materials without excessive decomposition of the polymer structure inherent to the polysaccharides.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an industrial process for producing a polycarboxylic acid having a very high carboxyl group content. Another object of the present invention is to oxidize polysaccharides while maintaining a certain molecular weight,
The HOH- groups and -CH ₂ OH group is the provision of a method of converting the -COOH group.

[0008]

Means for Solving the Problems The present inventors have studied a method for producing a polycarboxylic acid having a high carboxyl group content by using a polysaccharide as a raw material. As a result, the present invention has been completed. That is, the present invention is a method for producing a water-soluble tricarboxypolysaccharide, which comprises oxidizing a polysaccharide with a percarboxylic acid in the presence of a ruthenium compound.

A feature of the present invention resides in that an oxidation reaction by a combination of a ruthenium compound and a percarboxylic acid is applied to a polysaccharide. The tricarboxypolysaccharide produced in the present invention is defined as (A) an average of 60% or more of the -CH2OH group at the 6-position of the pyranose unit, which is produced by oxidizing the polysaccharide, is -C
OOH groups or salts thereof are converted to (OH), and (a) at least 10% of the -CHOH- groups at the 2nd and 3rd positions of the pyranose unit have an average structure of at least 10% which is oxidatively cleaved and converted to a -COOH group or its salt. It is a polycarboxylic acid having a molecular weight of 600 to 100,000, and the present invention also includes a salt thereof.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Polysaccharides used in the present invention include starch and cellulose. Starch is preferred because of the ease of reaction. Examples of the starch include corn starch, potato starch, tapioca starch, wheat starch, sweet potato starch, rice starch, and the like, and low-molecular-weight water-soluble starch can also be used as a raw material.

[0011] Maize starch and tapioca starch are preferred for industrial practice. These ingredients are
The concentration in the oxidation reaction mixture is 1 to 80% by weight, preferably 3 to 80% by weight.
Used in the range of 50% by weight.

The ruthenium compounds used in the present invention include ruthenium metal; ruthenium oxides such as ruthenium dioxide and ruthenium tetroxide; ruthenates such as sodium ruthenate; ruthenium halides such as ruthenium chloride and ruthenium bromide; nitric acid Ruthenium; ruthenium sulfate; ruthenium carboxylate such as ruthenium acetate; ammonium hexachlororuthenate, potassium hexachlororuthenate, potassium pentachloroaquaruthenate, ammonium pentachloroaquaruthenate, potassium pentachloronitrosylruthenate, hexaammineruthenium chloride, Hexaammine ruthenium bromide, hexaammine ruthenium iodide, nitrosyl pentaammine ruthenium chloride, hydroxonitrosylte Raan Min ruthenium nitrate, ethylenediaminetetraacetic acid ruthenium, and ruthenium complexes such as ruthenium dodecacarbonyl carbonium.

A ruthenium metal carrier having ruthenium metal supported on various carriers can also be used. Specific examples include ruthenium metal / alumina, ruthenium metal / carbon, ruthenium metal / silica alumina, ruthenium metal / titania, and the like. Preferred ruthenium compounds are ruthenium chloride, ruthenium bromide, potassium pentachloroaquaruthenate, ammonium pentachloroaquaruthenate, sodium ruthenate, ruthenium nitrate, ruthenium acetate, hexaammineruthenium chloride, hexaammineruthenium bromide, ethylenediaminetetraacetic acid It is a water-soluble ruthenium compound exemplified by ruthenium.

The amount of the ruthenium compound used is such that the amount of ruthenium atoms is from 0.00001 to 0.1 times mol per mol of pyranose units constituting the polysaccharide as a raw material.

In the present invention, the percarboxylic acid used as the oxidizing agent includes formic acid, peracetic acid, perpropionic acid, perbenzoic acid, perchlorobenzoic acid, methylperbenzoic acid, dimethylperbenzoic acid and the like. It is also possible to use an equilibrium percarboxylic acid generated by a reaction between an acid anhydride and hydrogen peroxide, a percarboxylic acid generated by a reaction between an aldehyde and oxygen, and the like.

Of these percarboxylic acids, peracetic acid is particularly preferred from the viewpoint of economy and prevention of excessive decomposition of the polysaccharide. It is also possible to use a percarboxylic acid such as peracetic acid generated by the reaction of oxygen with an aldehyde such as equilibrated peracetic acid or acetaldehyde prepared from acetic anhydride and hydrogen peroxide. The amount of the percarboxylic acid used is in the range of 3 to 30 times mol per mol of pyranose units constituting the polysaccharide,
Preferably, it is selected from the range of 5 to 15 moles.

In the present invention, a reaction solvent which is chemically stable to percarboxylic acid is used, but a carboxylic acid corresponding to percarboxylic acid is preferable. Aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons and the like can also be used.

The oxidation of the polysaccharide with the percarboxylic acid is preferably carried out under heating conditions. The reaction temperature when oxidizing a polysaccharide with a percarboxylic acid in the presence of a ruthenium compound is preferably 60 ° C.
That is all. The upper limit of the oxidation reaction temperature is determined in consideration of the stability of the percarboxylic acid and the decomposition of the polysaccharide.
120 ° C. More preferred reaction temperature range is 65-100
° C, most preferably 70-90 ° C.

When the oxidation reaction temperature is low, a limited amount of polysaccharide undergoes oxidation, and the amount of polysaccharide left unreacted increases. When the oxidation reaction temperature is high, the molecular weight is reduced due to excessive decomposition of the polysaccharide.

The tricarboxypolysaccharide, which is a product in the present invention, has a high Ca ion sequestering ability and can be suitably used particularly as a detergent builder. That is, another object of the present invention is to provide an excellent detergent builder of the present invention.

The detergent builder of the present invention is characterized in that (a) the average of 60% or more of the —CH 2 OH group at the 6-position of the pyranose unit is oxidized to —COO
H group or a salt thereof, and (a) a pyranose unit
On average, 10% or more of the 2- and 3-position -CHOH- groups are polymers having a molecular weight of 600 or more and 100,000 or less consisting of a polycarboxylic acid structure which has been oxidatively cleaved and converted into -COOH groups or salts thereof.

In the present invention, the product tricarboxypolysaccharide is obtained as a reaction mixture of a ruthenium compound and a carboxylic acid. can do. Examples of the purification operation include solvent extraction, chelate extraction, ion exchange resin treatment, ultra-membrane treatment, dialysis membrane treatment, RO membrane treatment, ion selective membrane treatment, microfiltration, concentration, lyophilization and the like. Further, if necessary, the product may be dissolved in water, and then recrystallized by adding a lower alcohol or a lower ketone to purify the product.

In the present invention, since the by-product derived from the percarboxylic acid used as the oxidizing agent is a carboxylic acid generated by losing the oxygen atom of the percarboxyl group, it can be removed by distillation or drying.

[0024]

The present invention will be described below in more detail with reference to examples. In the examples, the molecular weight is 0.3 M NaCl / 0.1 M NaH2PO4 / 0.33 M
GPC (column: Shodex O) using KH2P04 aqueous solution as eluent
Hpack SB-G / Shodex OHpack SB-803HQ 8mmID × 300mmL, R
I detector) and the weight average molecular weight was measured using a polysaccharide as a sample. The structure of the product was analyzed by ¹³ C-NMR.

Example 1 In a 100 ml round bottom Pyrex flask equipped with a stirrer, thermometer and condenser, 2.16 g of corn starch (1.88 g dry), 30 mg of ruthenium chloride trihydrate and 12 g of acetic acid
And heated to a temperature of 80 ° C. with stirring. 34.62 g of 38% equilibrated peracetic acid (15 times mol of pyranose units)
Was added over 5.7 hours by pump. Six hours after the start of the addition, a part was collected and subjected to iodine titration analysis. As a result, the conversion of peracetic acid was 100%.

The purple reaction mixture was cooled to room temperature, and filtered with a precision filter (JAWP02500, manufactured by Nippon Millipore Co .; 1.0 μm
), Some of the insolubilized ruthenium compounds were filtered, and then concentrated under reduced pressure. Add aqueous sodium hydroxide solution to adjust pH
After adjusting to 7, a white precipitate was formed when 120 ml of methanol was added. The precipitate was separated by filtration with a filter paper, washed with methanol, and lyophilized to obtain 0.39 g of a white product.

The product was precisely weighed, dissolved in water, treated with an H-type cation exchange resin to obtain an acid form, and titrated with an N / 10 sodium hydroxide aqueous solution.
7.9 meq / g. The product was analyzed for its structure by ¹³ C-NMR. As a result, almost 100% of the —CH 2 OH group at the 6-position of the pyranose unit constituting the starting starch, and 2,3-
It was confirmed that almost 40% of the -CHOH- groups were tricarboxystarch oxidatively cleaved into carboxyl groups. GPC
The weight average molecular weight measured was 1,300.

Example 2 Tapioca starch was used as a polysaccharide raw material, and the reaction temperature was adjusted to
The reaction was carried out in the same manner as in Example 1 except that the temperature was 70 ° C. and 23.08 g of equilibrated peracetic acid (10-fold mol of pyranose units) was added. Six hours after the start of peracetic acid addition, a portion was collected and subjected to iodine titration analysis. As a result, the conversion of peracetic acid was 100%.

The reaction mixture is a purple almost homogeneous liquid.
The same treatment as in Example 1 was carried out to obtain 0.50 g of tricarboxystarch having a carboxyl group content of 7.3 meq / g and a weight average molecular weight of 1,400. ¹³ C-NM
According to the structural analysis by R, almost 100% of the 6-CH2OH group of the pyranose unit constituting the raw starch and 2, 3
Almost 30% of the -CHOH- groups at the position were tricarboxy starch oxidatively cleaved to carboxyl groups.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1 except that no ruthenium compound was used. Six hours after the start of addition of 34.62 g of equilibrated peracetic acid (15-fold mol of pyranose units), a part was sampled and subjected to iodine titration analysis. The conversion of peracetic acid was 37%.
was.

The reaction mixture was a colorless homogeneous liquid having a weight-average molecular weight of less than 1,000. The same treatment as in Example 1 was carried out, and no precipitate was formed even when 120 ml of methanol was added. That is, when the ruthenium compound was not used, only the reduction of the molecular weight of starch proceeded.

Comparative Example 2 Example 1 was repeated except that the reaction was carried out at a reaction temperature of 50 ° C.
The reaction was carried out in the same manner as described above. Six hours after the start of the addition of 34.620 g of peracetic acid (15 times the mol of pyranose units), a portion was collected and subjected to iodine titration analysis. The conversion of peracetic acid was 90%.
was.

The reaction mixture was a purple-gray suspension, which was cooled to room temperature and then filtered with a precision filter. As a result, a large amount of gray solid was filtered off in addition to the insolubilized ruthenium compound. Structural analysis of the residue by ¹³ C-NMR revealed that the chart was almost the same as the raw corn starch, indicating that the starch remained unreacted. Thereafter, the filtrate was treated in the same manner as in Example 1, and the content of carboxyl groups was 7.
A product having 0 meq / g and a weight average molecular weight of 1,800 was obtained, but the yield of the product was reduced to 0.10 g. That is,
When the reaction temperature was low, the conversion decreased.

[0034]

According to the present invention, there is provided a method for industrially producing a tricarboxy polysaccharide having a high carboxyl group content from a polysaccharide. The tricarboxypolysaccharide produced according to the present invention is particularly suitable as a detergent builder giving excellent detergency.

Claims (4)

[Claims] 1. A process for producing a tricarboxypolysaccharide, comprising oxidizing a polysaccharide with a percarboxylic acid at a reaction temperature of 60 ° C. or higher in the presence of a ruthenium compound. 2. The method for producing a water-soluble tricarboxypolysaccharide according to claim 1, wherein the reaction solvent is a carboxylic acid. 3. The method for producing a tricarboxypolysaccharide according to claim 1, wherein the reaction solvent is formic acid, peracetic acid or perpropionic acid. 4. The method according to claim 1, wherein the ruthenium compound is water-soluble.
A method for producing the tricarboxypolysaccharide according to the above.