KR101323631B1 - A method to dehydrate polyols - Google Patents

Abstract

The present invention relates to a dehydration method of polyols such as sorbitol, mannitol, xyitol, and arabinitol, and more particularly, to a dehydration process that can effectively promote the dehydration reaction using microwave as a heat source without decompression or pressurization.

Description

Description of the Related Art A method for dehydration polyols

The present invention relates to a method for dehydrating a polyol, and more particularly, to a technique for easily dehydrating the reaction proceeds without maintaining the reactor at low or high pressure in the dehydration reaction to obtain the desired object.

The polyol may be defined as sorbitol, mannitol, xylitol, arabinitol, and mixtures thereof, and may be defined primarily as a polyol of hexanediol and pentanediol, and mixtures thereof are also possible .

Polyols are obtained from renewable biomass, and dehydration reactions can provide useful chemical intermediates such as isobarbide. This dehydration reaction can proceed in the presence of various catalysts and is a very important reaction commercially. The catalyst may be a liquid acid such as sulfuric acid, as well as heteropoly acids, cation exchange resins, zeolites, metal-organic frameworks, acidic clays, sulfated zirconia, molecular sieves such as aluminophosphate and mesoporous materials. During the reaction, if water is obtained as a by-product and not removed, it is difficult to increase the conversion of the reaction due to the nature of the dehydration reaction, which is an equilibrium reaction.

Therefore, in many cases, the pressure of the reactor is lowered to remove the water formed (USP 7728156, 7649099, 7615652), thereby increasing the conversion rate of the equilibrium reaction. Hydrogen was injected at high pressure counter-current to the reactants to remove water and inhibit the production of colored material (USP No. 772412). Nitrogen was also used to dehydrate the zeolite catalyst at a high pressure of 65-85 bar (USP 2008 / 0249323A1).

However, maintaining the reactor at vacuum or high pressure is not only economical in terms of reactor configuration, but also has high operating costs.

The results of increasing the reaction rate by applying microwaves in organic and inorganic reactions are known (A. de la Hoz, A. Diaz-Ortiz and A. Moreno, Chem. Soc. Rev., 2005, 34, 164? 178; GA Tompsett, WC Conner, KS Yngvesson, Chem. Phys. Chem., 2006, 7, 296-319.)

Products such as isobarbide obtained by dehydration of a polyol such as sorbitol are used as an additive in the production of polymers such as polyethylene terephthalate, and are used as a copolymer for polymers and for medicines (such as hydrocephalus, urination and glaucoma treatment) It is a useful compound. Especially, polyol such as sorbitol is a material derived from biomass that can be regenerated in nature. Therefore, it is considered that the necessity and importance of technology development is very high.

Products such as isosorbide, which are useful in many respects, do not have high pressure or reduced pressure, and there is no process for removing byproduct water, which requires a simple process for dehydration of polyols.

The present invention provides a method for easily dehydrating polyols without vacuum or pressurization.

More specifically, the present invention provides a simple process for preparing dehydrated polyols that can be used for a variety of applications.

The present invention provides a method capable of selectively and effectively performing dehydration reaction of various polyols by applying various acid catalysts under a solvent using microwave as a heat source without pressure or reduced pressure.

The present invention relates to a dehydration method of a renewable polyol, characterized in that the dehydration reaction is effectively carried out by removing the water at a low pressure or applying a high pressure such as hydrogen or nitrogen by applying microwave to the dehydration reaction.

In addition, the present invention is to provide a method for surprisingly increasing the dehydration conversion of the polyol and obtain the desired dehydrated material in a higher yield by applying the microwave as a heat source in the dehydration reaction of the polyol.

The present invention provides a method for dehydrating a polyol comprising the following steps and a method for producing anhydrous sugars or sugar alcohols such as isosorbide using the same.

More specifically, the present invention relates to a dehydration reaction of a polyol, which is one or a mixture of two or more selected from sorbitol, mannitol, ziitol, and arabinitol,

1) mixing a catalyst with a polyol, which is one or more mixtures selected from sorbitol, mannitol, ziitol, and arabinitol, in the absence of solvent;

 2) reacting the mixture of the above step by heating the microwave with a heat source;

 3) cooling the reactants of the step;

 4) separating and drying the cooled reactant to obtain a product; And

 5) separating and drying the product of said step.

The polyol applied by the dehydration method according to the present invention is a polyol of pentose or hexose sugar and specifically, may be defined as sorbitol, mannitol, xylitol, arabinitol and mixtures thereof. have. However, any polyol is applicable.

In addition, the target of the present invention is a material that can be any dehydration product, but one water molecule or two water molecules per polyol molecule is the main target product. For example, sorbitol dehydration may be sorbitan and isosorbide in which one or two water molecules are removed, respectively.

Next, the catalyst of a dehydration reaction is demonstrated.

The dehydration reaction proceeds easily in the presence of an acid catalyst, in particular solid acids being useful in terms of separation and environment compared to liquid acids. That is, the present invention includes not only liquid acids such as sulfuric acid but also heteropoly acids, cation exchange resins, zeolites, porous metal-organic frameworks, acidic clays, sulfonated zirconia, aluminophosphates and mesoporous materials. The same molecular sieve may be used, but cation exchange resins are preferred because they are inexpensive and have a high catalyst concentration. Since porous materials such as metal-organic frameworks and zeolites have small pores, they are particularly useful because they prevent secondary side reactions after dehydration. Do. Zeolites, molecular sieves, ion exchange resins, metal-organic frameworks and mesoporous materials need to be converted or introduced into the proton (H ⁺ ) form to have acidity.

The porous metal-organic framework material in the present invention may be defined as a porous organic-inorganic polymer compound formed by combining a central metal ion with an organic ligand, and include both organic and inorganic materials in a skeleton structure and have a molecular or nano-sized pore structure. It means a crystalline compound having a.

In addition, the ion exchange resin in the present invention refers to a material having ion exchange ability, consisting of an organic polymer containing a sulfonic acid group, and mainly refers to Amberlyst-15, Amberlyst-35 and Nafion resin, but is not limited thereto.

In addition, the zeolite in the present invention refers to a substance composed of Si, Al, O skeleton and additionally cations such as Na ⁺ , H ⁺ for the neutral charge. Any zeolite can be applied to the present invention if it has an acid and is H-ZSM-5 (MH-MFI), HY (H-FAU), H-mordenite (H-MOR), H-beta (H-BEA), H- MCM-22 (H-MWW) may be usefully applied, but is not limited thereto.

The catalyst in the present invention may be the above-described liquid acid, heteropoly acid, cation exchange resin, zeolite, metal-organic framework, acid clay, sulfonate zirconia and aluminophosphate.

Among the various catalysts possible, Amberlyst-15 or Amberlyst-35 having macropores and large ion exchange capacity is preferable when the catalyst is a catalyst, and when the catalyst is a metal-organic framework, it has excellent stability and large porosity. MIL-101, MIL-53 and MIL-100 are preferred. In addition, the zeolite catalyst is H-ZSM-5 (MH-MFI), HY (H-FAU), H-mordenite (H-MOR), H-beta (H-BEA), H-MCM-22 (H-MWW) Is particularly useful because these zeolites have high acid strength and excellent stability.

The present invention proceeds at a high temperature and uses microwave heating as a heat source of the reaction, the microwave is any electromagnetic wave of the frequency range of 1 ~ 30 GHz, but it is easy to use a microwave of 2.45 GHz frequency that is widely used industrially Efficient Microwaves can be irradiated continuously or intermittently and it is useful to set the desired reaction temperature to control the irradiation time and intensity.

The dehydration reaction temperature is not practically limited, but a temperature higher than room temperature and lower than the boiling point of the polyol is preferred. The reaction temperature may be any temperature above room temperature, but a temperature of 100 ^° C. or more at which the reaction proceeds rapidly is preferable, preferably 120-220 ^° C. is more suitable, and a temperature of 150-200 ^° C. is most suitable. If the reaction temperature is too low, the reaction rate is too slow to be unrealistic, if too high a side reaction occurs to lower the reaction efficiency.

Dehydration can proceed at any pressure, but atmospheric or autogeneous pressure is most appropriate. The reaction rate and efficiency are improved by removing water as a by-product when it is maintained at a low pressure, but it is costly and requires another gas when it is maintained at a high pressure, which also increases operating costs. In addition, the flow of hydrogen can increase the reaction rate by removing the water, as well as to suppress the generation of impurities that induce color, which is useful and can further increase the efficiency by applying in the present invention.

The dehydration reaction can be carried out without a solvent, and the presence of a solvent facilitates mixing and temperature control of the reactants. The solvent may be any inorganic solvent, but may be any solvent that can dissolve any part of the polyol, such as ethanol, methanol, ethyl ether, and chloroform, especially at a low price that is easy to obtain.

The dehydration reaction can be carried out continuously as well as batchwise. The batch type dehydration reactor is suitable for dehydration of a small amount of polyol because the production rate is low per hour. The dehydration reaction time is suitably about 1 minute to 100 hours in the case of the batch type, and if the dehydration reaction time is too long, impurities are easily incorporated and energy efficiency is low. If the dehydration reaction time is too short, the dehydration efficiency is low. The dehydration reaction time is more preferably from 1 minute to 24 hours. The residence time of the continuous dehydration reactor is suitably about 1 minute to 1 hour. If the residence time is too long, the productivity is low and the side reaction is likely to occur. If the residence time is too short, the conversion rate of the dehydration reaction is low. A residence time of 1 to 20 minutes is more suitable. During the batch reaction, the reactants may be stirred, and the stirring speed may be 100-1000 rpm, but it may be carried out without stirring.

The dehydration method of the polyol according to the present invention can effectively proceed the dehydration reaction without using vacuum or high pressure by using microwave as a heat source, and this dehydration method is a simple and economical dehydration method.

In more detail, the present invention provides a simple and effective dehydration reaction in the dehydration reaction of polyols such as sorbitol, mannitol, ziitol, and arabinitol as a heat source, and also has a high dehydration conversion rate and high product selectivity. have.

In addition, the polyol dehydrated according to the dehydration method of the polyol of the present invention may be utilized as additives for medical synthesis and medical compounds.

Hereinafter, the present invention is described in more detail in the following non-limiting examples.

Example 1

15.0 g of sorbitol and 0.3 g of an ion exchange resin catalyst (Amberlyst-15) were placed in a Teflon reactor, blocked well, and dehydrated by heating at 150 ^° C. for 1 hour using a microwave oven (MARS-5, CEM). After the reaction, the reaction mixture was cooled to open a reactor, filtered at a high temperature to separate a solid catalyst, and the obtained product was dried at 110 ^° C. to remove water. RI detector and Asahipak NH2P-50 4E (No. N712004) columns. The reaction conditions and results are summarized in Table 1.

 The dehydration reaction proceeded with a short reaction time of 1 hour using microwave as a heat source without vacuum and high pressure treatment, resulting in 100% dehydration conversion and 40% yield of isosorbide.

[Example 2]

The dehydration reaction was carried out in the same manner as in Example 1 except that the heating time was 2 hours. The results are summarized in Table 1.

The dehydration conversion of the dehydration reaction was 100% without vacuum and high pressure treatment, and the yield of isosorbide was 60%.

[Example 3]

The dehydration reaction was performed in the same manner as in Example 1 except that the heating time was 4 hours. The results are summarized in Table 1.

Dehydration reaction proceeded easily using microwave as a heat source without vacuum and high pressure treatment with hydrogen or nitrogen. The dehydration conversion rate reached 100% and the yield of isosorbide reached 70%.

Example 4

The dehydration reaction was carried out in the same manner as in Example 1 except that it was heated for 4 hours at 130 ^° C. The results are summarized in Table 1.

The conversion rate of the dehydration reaction was 100%, and the yield of isosorbide was obtained at 35%.

[Example 5]

MIL-101 (Cr) -AS was synthesized (Crystal Growth Design, 10, 1860, 2010). 0.3 g of the synthesized MIL-101 (Cr) -AS was added to a glass test tube, and 20 mL of DMF was added to make a suspension. After heating to 70 ^° C., ultrasonic waves were irradiated to the suspension in the test tube for 60 minutes using an ultrasonic generator (VC × 750, Sonic & materials). After cooling, the solid was collected by filtration and dried at 100 ^° C. for 5 hours to obtain 0.25 g of purified MIL-101 (Cr). 0.3 g of MIL-101 (Cr), which was collected and purified twice, was dried at 150 ° C. under a vacuum of 0.8 atm, cooled, and 0.096 g (1.25 mmol) of cysteamine was added to 30 mL of ethanol for 8 hours at 80 ^° C. Heated to reflux. Then filtered and after drying 0.3 g of MIL-101 (Cr) (called MIL-101 (Cr) -SH) was obtained. 0.4 g of MIL-101 (Cr) -SH synthesized in this manner was oxidized with 20 mL (15%) of H ₂ O ₂ at 45 ^° C. for 2 hours. After 15 minutes of oxidation, 10 mL of 0.2 M sulfuric acid was finally added to complete acidification, and about 0.4 g of the final functionalized material (named MIL-101 (Cr) -SO ₃ H) obtained after drying was obtained.

10 g of sorbitol and 0.2 g of MIL-101 (Cr) -SO ₃ H were added to a Teflon reactor and well sealed, followed by heating at 180 ^o C for 3 hours using a microwave oven (MARS-5, CEM) to proceed with dehydration. I was. After the reaction, the reaction mixture was cooled to open a reactor, filtered at a high temperature to separate a solid catalyst, and the obtained product was dried at 110 ^° C. to remove water. RI detector and Asahipak NH2P-50 4E (No. N712004) columns. The reaction conditions and results are summarized in Table 1.

The dehydration conversion was 100% and isosorbide was obtained at a yield of 49.6%.

Comparative Example 1

The dehydration reaction was conducted in the same manner as in Example 1 except that the electric heating method was used as the heat source, and the results are summarized in Table 1.

The dehydration conversion was 80% and isosorbide was obtained only in 10% yield.

When the dehydration reaction was conducted by electric heating without microwave irradiation, the dehydration reaction did not proceed to a satisfactory level, and the yield of isosorbide was also low.

Comparative Example 2

The dehydration reaction was conducted in the same manner as in Example 1 except that the heating was performed for 5 hours using the electric heating method. The results are summarized in Table 1.

As the dehydration conversion rate increased, the dehydration conversion rate was high as 100%, but the yield of dehydrated compound isosorbide was low as 30%. As described above, when the dehydration reaction was carried out by electric heating without microwave irradiation, the dehydration reaction did not proceed to a satisfactory level even with a long heating time of 5 hours.

[Comparative Example 3]

The dehydration reaction was carried out in the same manner as in Example 1 except that the heating was performed at 130 ° C. for 6 hours using an electric heating method. The results are summarized in Table 1 below.

Even with long heating times, the dehydration conversion was as low as 60% and the yield of isosorbide was very low at only 10%.

In other words, if the dehydration reaction proceeds by electric heating without microwave irradiation, it can be seen that the dehydration reaction did not proceed to a satisfactory level even at a long heating time of 6 hours at 130 ^° C.

Dehydration Conditions and Results of Polyols Example
And
Comparative Example
number reaction
Temperature
( ^o C) reaction
time
(h) catalyst
(g) Heating method Polyol
(g) Conversion Rate
(%) Isoboride yield (%) Example 1 150 One Amberlyst-15
(0.3) microwave Sorbitol
(15) 100 40 Example 2 150 2 Amberlyst-15
(0.3) microwave Sorbitol
(15) 100 60 Example 3 150 4 Amberlyst-15
(0.3) microwave Sorbitol
(15) 100 70 Example 4 130 4 Amberlyst-15
(0.3) microwave Sorbitol
(15) 100 35 Example 5 180 3 MIL-101 (Cr) -SO3H
(0.2) microwave Sorbitol
(15) 100 49.6 Comparative Example 1 150 One Amberlyst-15
(0.3) Electric heating Sorbitol
(15) 80 10 Comparative Example 2 150 5 Amberlyst-15
(0.3) Electric heating Sorbitol
(15) 100 30 Comparative Example 3 130 6 Amberlyst-15
(0.3) Electric heating Sorbitol
(15) 60 10

According to the present invention from the results of Examples and Comparative Examples, a method for dehydrating a polyol using a microwave as a heat source is obtained by dehydrating a polyol quickly and easily without the removal of water as a reaction by-product or a high-pressure treatment process. The id can optionally be obtained in high yield. On the other hand, from the results of the comparative example, the dehydration reaction proceeded without microwave irradiation is low in the dehydration conversion rate and low isosorbide even with a long heating time, it can be seen that the reaction activity is very low.

Polyols such as sorbitol, mannitol, xylitol and arabinitol are derived from biomass and dehydrated products are important for comonomers and medicines, so their simple, easy and successful dehydration reaction is very important.

Claims (4)

1) mixing a solvent-free, polyol, which is one or more mixtures selected from sorbitol, mannitol, ziitol, and arabinitol, with a cationic exchange resin as a catalyst;
2) reacting the mixture of the above step by heating the microwave to a heat source at 150 to 220 ℃;
3) cooling the reactants of the step;
4) separating and drying the cooled reactant to obtain a product; And
5) Dehydration method of a polyol comprising the step of separating and drying the product of the step. delete The method of claim 1,
The cation exchange resin is a polyol dehydration method having a sulfonic acid group. The method of claim 1,
The reaction is carried out for 1 minute to 100 hours in the case of a batch reactor, the dehydration method of the polyol is carried out for 1 minute to 1 hour in the case of a continuous reactor.