KR101079518B1 - A method for preparation of anhydrosugar alcohols - Google Patents

Abstract

Disclosed is a method for producing anhydrosugar alcohols using hexitols such as sorbitol and mannitol derived from starch. Anhydrous sugar alcohols are of great value as physical modifiers that can be used mainly in the plastics industry in the form of diols having two hydroxyl groups in the molecule. Representative anhydrosugar alcohols include isosorbide, isomannide, and the like. These anhydrosugar alcohols can raise the glass transition temperature of PET, polyester, polycarbonate and the like, and can improve the strength. It is a major material and has high utilization value.

Starch, anhydrosugar alcohol, isosorbide

Description

Method for preparing anhydrosugar alcohol {A METHOD FOR PREPARATION OF ANHYDROSUGAR ALCOHOLS}

The present invention relates to a process for the preparation of anhydrosugar alcohols in diol form from hexitol. More specifically, the present invention relates to a method for producing anhydrosugar alcohols, which comprises dehydrating hexitol with a mixed acid of a first acid and a second acid.

Sugar alcohol is a general term for a compound obtained by adding hydrogen to a reducing end group of a saccharide, and generally has a chemical formula of HOCH ₂ (CHOH) nCH ₂ OH (where n is an integer of 2 to 5), and has carbon number (4, 5, 6 and 7), it is classified as tetritol, pentitol, hexitol and heptitol. Among them, hexitol having 6 carbon atoms belongs to sorbitol, mannitol, inititol and the like, and sorbitol and mannitol are particularly useful substances.

It is known that a method of preparing anhydrosugar alcohols using hexitol is carried out by dehydration with an inorganic acid such as sulfuric acid or hydrochloric acid (Starch / Starke vol. 38. pp26-30). In addition, the dehydration reaction of hexitol may be performed by a cationic resin, zeolite, or the like. Inorganic acids such as hydrochloric acid and sulfuric acid may be relatively inexpensive and easy to prepare anhydrosugar alcohols, but there is a problem in that the yield of purification is lowered because a large amount of polymer is produced as a by-product. Cationic resins and zeolites are expensive, costly to recover, and have low conversion to anhydrosugar alcohols.

Anhydrosugar alcohols are known to have the property of raising the glass transition temperature of a polymer such as polyester. In addition, anhydrosugar alcohol derivatives are useful for diseases of the heart and blood vessels, and can be used for adhesives of patches, oral cleansing agents, cosmetic compositions, etc. In the chemical industry, polyester, polyurethane, epoxy resins as well as eco-friendly plasticizers and eco-friendly solvents It is known that it can also be used as a raw material. In particular, industrial use such as polyester, plasticizer, etc. using anhydrosugar alcohols is of interest, but the use is still insufficient industrially. This is because the conventional method for producing anhydrosugar alcohol has limitations such as high catalyst cost used for dehydration reaction, low conversion rate and low purification yield.

Therefore, there is an urgent need for a method for preparing anhydrosugar alcohol with high conversion rate and high purification yield while reducing cost.

In order to overcome the problems of the prior art, the present inventors have continuously studied to develop a method for producing anhydrosugar alcohol which can be industrially utilized, and thus, a first acid (sulfuric acid) and a sulfur-containing diacid (sulfur-containing acid salt) In the case of using a mixed acid, it was confirmed that the anhydrosugar alcohol can be prepared in a high conversion rate and a purification yield when the dehydration of hexitol is inexpensive, but the present invention has been completed.

It is therefore an object of the present invention to provide an economical method for producing anhydrosugar alcohols with high conversion and purification yields.

In order to achieve the above object, the present invention is a method for producing anhydrosugar alcohol, wherein the dehydration reaction of hexitol with a mixed acid of the first acid and the second acid, the first acid is sulfuric acid and the second acid is p Toluene sulfonic acid, methane sulfonic acid, ethane sulfonic acid, benzene sulfonic acid, naphthalene sulfonic acid, and at least one sulfur-containing acid (sulfur-containing acid salt) selected from the group consisting of aluminum sulfate. do.

Hexitols that can be used in the preparation method of the present invention include sorbitol, mannitol, iditol and the like. Of these, sorbitol, which can be easily prepared through the hydrogenation reaction of glucose derived from starch, is most preferred for use.

Sulfuric acid is used as the first acid of the mixed acid used in the dehydration reaction, and as the second acid, 1 is selected from p-toluene sulfonic acid, methane sulfonic acid, ethane sulfonic acid, benzene sulfonic acid, naphthalene sulfonic acid, and aluminum sulfate. More than one species are selected and used.

The lower the amount of mixed acid catalyst added in view of the efficiency of the process, the higher the conversion and economic efficiency. In the present invention, the amount of mixed acid may be used in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of hexitol, and preferably 0.5 to 5 parts by weight, more preferably 0.5 to 3 parts by weight. When the amount of the mixed acid is less than 0.5 parts by weight, the dehydration reaction takes too long, and when the amount of the mixed acid is more than 10 parts by weight, there is a problem in that the production of saccharide polymer as a by-product increases and the conversion rate decreases.

The first acid and the second acid may be used in the concentrations generally used, and those skilled in the art may be appropriately selected and used in accordance with the purpose and disclosure of the present invention. Some acid concentrations are illustrated in the examples below.

The ratio of the first acid and the second acid in the mixed acid may be used in a weight ratio of 1: 9 to 7: 3. If the ratio is less than 1: 9, there is a phenomenon that the production rate of anhydrosugar alcohol is lowered, and if the ratio exceeds 7: 3, there is a disadvantage in that the production of saccharide polymer is increased because there is too much sulfuric acid.

The dehydration reaction is performed by adding a mixed acid to hexitol, and it is preferable to proceed under vacuum conditions of 5 mmHg or less for 1 to 10 hours at a temperature of 105 to 190 ° C.

Anhydrosugar alcohols produced by the production method of the present invention include isosorbide, isomannide, isoidide and the like.

In addition, according to the object of the present invention, the present invention is a method for producing anhydrosugar alcohol, dehydration reaction of hexitol with a mixed acid of the first acid and the second acid to produce anhydrosugar alcohol and purify the resulting anhydrosugar alcohol Wherein the first acid is sulfuric acid and the second acid is at least one selected from the group consisting of p-toluene sulfonic acid, methane sulfonic acid, ethane sulfonic acid, benzene sulfonic acid, naphthalene sulfonic acid and aluminum sulfate Provided is a sulfur-containing acid (sulfur-containing acid salt).

Hexitol, mixed acid and dehydration reaction and anhydrosugar alcohol are as described above.

The purification may be carried out by distillation and the like, preferably by distillation under vacuum conditions of 5 mmHg or less at 150 to 250 ° C. If the distillation temperature is less than 150 ℃ distillation of the anhydrosugar alcohol is not well done, the color of the anhydrosugar alcohol becomes dark at 250 ℃ or more, it is difficult to discolor. Distillation may utilize a common condenser type or thin film distillation unit.

If necessary, the distillate obtained by distillation may be further treated with activated carbon / activated clay for decolorization. In addition, if necessary, prior to distillation, the temperature of the reactant after the dehydration reaction is completed to 60 to 120 ℃ can be subjected to the step of neutralizing by adding an alkali such as sodium hydroxide, calcium hydroxide, ammonium hydroxide and the like.

According to the preparation method of the present invention, the conversion rate of the anhydrosugar alcohol may be increased to 80% or more while improving the purification yield to 65% or more.

The method for producing anhydrosugar alcohols according to the present invention makes it possible to obtain anhydrosugar alcohols with high conversion and purification yields in a short time by utilizing an inexpensive acid catalyst (mixed acid) with simple equipment.

In particular, the method of producing anhydrosugar alcohols according to the present invention extends the range of utilization of starch by using hexitol derived from starch, which is a main raw material of eco-friendly green industry, as biomass.

The anhydrosugar alcohol prepared by the production method of the present invention is useful as an industrial raw material that can be utilized in heat resistant PET, polyester fiber, high strength sheet, film, polyurethane and the like.

The present invention will be described in more detail by the following examples, which are merely illustrative of the present invention and do not limit the scope of the invention.

Example

<Efficiency measurement>

Conversion rate and purity analysis of the prepared anhydrosugar alcohols were carried out using a gas chromatography (GC, gas chromatography, HP5890).

Conversion rate: produced anhydrosugar alcohol mole / charged hexitol mole x 100

Yield: anhydrous alcoholic mole / charged hexitol mole x 100 after purification / bleaching

Example  One

1,000 g of sorbitol powder (D-Sorbitol, Samyang Genex) was placed in a three-necked glass reactor equipped with a stirrer, and dissolved in a vacuum of 3 mmHg by raising the temperature to 110 ° C. And a mixed acid of 10 g of methanesulfonic acid (70%, Sigma) were added, and the reaction temperature was raised to 145 ° C. The dehydration reaction was performed under vacuum for 3 hours to convert to anhydrosugar alcohol isosorbide. After lowering the temperature of the reactor to 110 ° C, the dehydration reaction solution was neutralized by adding 20 g of 50% sodium hydroxide solution (Samjeon Pure Chemical Co., Ltd.). At this time, the conversion rate of anhydrosugar alcohol was 85.4%, and the content of the produced polymer was 6.3%.

The neutralized anhydrous sugar-alcohol liquid was distilled under vacuum of 3 mmHg while raising the temperature to 190 ° C. Distilled water was added to the distilled liquid thus obtained to make a 40% solution, activated carbon was added to decolorize and concentrated to give anhydrous sugar alcohol (isosorbide) having a solid content of 85%. The purity of the anhydrosugar alcohol (analysis of the conversion solution by GC to calculate the amount of isosorbide in total solids) was 99.2%, the total yield was 67.3%.

Example  2

The same procedure was followed as in Example 1 except that 10 g of sulfuric acid and 10 g of methane sulfonic acid were used as mixed acids and 30 g of calcium hydroxide was used for neutralization. The conversion was 91.2% and the amount of polymer produced was 4.8%. The yield and purity after purification were 72.1% and 99.7%, respectively.

Example  3

15 g of sulfuric acid and 15 g of methane sulfonic acid were used as the mixed acid, and the dehydration temperature was 130 ° C., except that 50 g of calcium hydroxide was used for neutralization. The conversion was 94.5% and the amount of polymer produced was 3.6%. The yield and purity after purification were 76.1% and 99.7%, respectively.

Example  4

10 g of sulfuric acid and 10 g of aluminum sulfate (99%, Daejung Co., Ltd.) were used as mixed acids, and the amount of calcium hydroxide used for neutralization was the same as that of Example 1 except that the amount was 30 g. The conversion was 90.2% and the amount of polymer produced was 5.7%. The yield and purity after purification were 66.9% and 99.3%, respectively.

Example  5

10 g of sulfuric acid and 15 g of aluminum sulfate were used as mixed acids, and the amount of calcium hydroxide used for neutralization was performed in the same manner as in Example 1. The conversion was 91.2% and the amount of polymer produced was 4.9%. The yield and purity after purification were 68.4% and 99.3%, respectively.

Example  6

10 g of sulfuric acid and 15 g of p-toluene sulfonic acid (99%) were used as the mixed acid, and the dehydration reaction temperature was 150 ° C., and the amount of calcium hydroxide used for neutralization was 35 g. The conversion was 88.1% and the amount of polymer produced was 5.3%. The yield and purity after purification were 70.6% and 99.3%, respectively.

Comparative example  One

The same procedure as in Example 1 was carried out except that 20 g of sulfuric acid was used as a catalyst for the dehydration reaction. The conversion was 87.7% and the amount of polymer produced was 9.6%. The yield and purity after purification were 48.2% and 98.5%, respectively.

Comparative example  2

The same procedure as in Example 1 was conducted except that 30 g of methane sulfonic acid was used as a catalyst for the dehydration reaction. The conversion was 79.3% and the amount of polymer produced was 8.2%. The yield and purity after purification were 56.2% and 99.1%, respectively.

Comparative example  3

The same procedure as in Example 1 was carried out except that 20 g of aluminum sulfate was used as a catalyst for the dehydration reaction. The conversion was 66.5% and the amount of polymer produced was 6.9%. The yield and purity after purification were 51.2% and 99.0%, respectively.

Comparative example  4

The same procedure as in Example 1 was carried out except that 10 g of sulfuric acid and 10 g of phosphoric acid (99%) were used as catalysts for the dehydration reaction. The conversion was 64.0% and the amount of polymer produced was 7.7%. The yield and purity after purification were 48.5% and 98.2%, respectively.

Table 1. Conversion, Polymer Production and Yield]

Catalyst (to 100 parts by weight of hexitol
About weight parts) Conversion rate
(%) Polymer
(weight%) yield(%) Example 1 Sulfuric acid 0.5
Methane Sulfonic Acid 1.0 85.4 6.3 67.3 Example 2 Sulfuric acid 1.0
Methane Sulfonic Acid 1.0 91.2 4.8 72.1 Example 3 Sulfuric acid 1.5
Methane sulfonic acid 1.5 94.5 3.6 76.1 Example 4 Sulfuric acid 1.0
Aluminum Sulfate 1.0 90.2 5.7 66.9 Example 5 Sulfuric acid 1.0
Aluminum Sulfate 1.5 91.2 4.9 68.4 Example 6 Sulfuric acid 1.0
p-toluene sulfonic acid 1.5 88.1 5.3 70.6 Comparative Example 1 Sulfuric acid 2.0 87.7 9.6 48.2 Comparative Example 2 Methane Sulfonic Acid 3.0 79.3 8.2 56.2 Comparative Example 3 Aluminum sulfate 2.0 66.5 6.9 51.2 Comparative Example 4 Sulfuric acid 1.0
Phosphoric Acid 1.0 64.0 7.7 48.5

As can be seen from Table 1, according to the production method according to the present invention using a mixed acid as a catalyst for dehydration of hexitol (Examples 1 to 6), it was confirmed that the conversion and yield are high, and the production rate of polymer as a byproduct is low.

Claims (10)

A process for preparing anhydrosugar alcohols, wherein the hexitol is dehydrated with a mixed acid of a first acid and a second acid, wherein the first acid is sulfuric acid and the second acid is p-toluene sulfonic acid, methane sulfonic acid, ethane And at least one sulfur-containing acid or sulfur-containing acid salt selected from the group consisting of sulfonic acid, benzene sulfonic acid, naphthalene sulfonic acid and aluminum sulfate. A process for preparing anhydrosugar alcohols, which comprises dehydrating hexitol with a mixed acid of a first acid and a second acid to produce anhydrosugar alcohol and purifying the resulting anhydrosugar alcohol, wherein the first acid is sulfuric acid. And the second acid is at least one sulfur-containing acid or sulfur-containing acid salt selected from the group consisting of p-toluene sulfonic acid, methane sulfonic acid, ethane sulfonic acid, benzene sulfonic acid, naphthalene sulfonic acid and aluminum sulfate. Phosphorus manufacturing method. The method according to claim 1 or 2, wherein the mixed acid is added in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of hexitol. The method according to claim 1 or 2, wherein the ratio of the first acid and the second acid in the mixed acid is 1: 9 to 7: 3 by weight. The method according to claim 1 or 2, wherein the hexitol is at least one member selected from the group consisting of sorbitol, mannitol and iditol. The method of claim 1, wherein the dehydration reaction is performed under vacuum at a temperature of 105 to 190 ° C. for 1 to 10 hours. The method of claim 2, wherein the purification is performed by distillation under vacuum at 150 to 250 ° C. 8. A process according to claim 7, further comprising an activated carbon / activated clay treatment step for bleaching. 8. The method of claim 7, further comprising the step of neutralizing by adding alkali to the reactant having completed the dehydration reaction prior to performing distillation. The production method according to claim 1 or 2, wherein the anhydrosugar alcohol is at least one member selected from the group consisting of isosorbide, isomannide, and isoidide.