MXPA01002301A - Continuous process for the production of anhydrosugar alcohols - Google Patents

Abstract

A process is described for continuous production of anhydrosugar alcohols by continuous introducing of sugar alcohols and/or monoanhydrosugar alcohols into a reaction vessel and dehydration in the presence of an acid catalyst and solvent, preferably an organic solvent, in which the resultant reaction products are soluble. Water and the organic solvent having the dissolved reaction product are each continuously removed from the reaction chamber. The reaction product is separated from the removed solvent, which is recycled into the reaction vessel. The reaction product is optionally purified by distillation and/or recrystallization. The purified reaction product obtained is particularly suitable as a starting product for producing polymers, and has a purity of at least 99. 0%.

Description

CONTINUOUS PROCESS FOR THE PRODUCTION OF ANCHID SUGAR ALCOHOLS A process for producing alcohols of anhydrous sugars, both monoanhydric sugar alcohols and sugar alcohols dianhydros, is described by means of dehydration of alcohols of associated sugars or alcohols of monoanhydrous sugars, using a catalyst and an organic solvent, wherein the solvent Organic is recycled during the process, and where the resulting anhydrous sugar alcohols are very pure.

Related Requests This solitude vindicates the priority of the German utility application 198 34 778, dated September 9, 1998. In addition, the following application, filed with the attached date, contains the related subject: E'ROCESS AND PRODUCTS OF PURIFICATION OF ANHYDROSUGAR ALCOHOLS, [Atty. Docket No. 032358-018]. The related matter of each of the above applications is incorporated herein by reference. (127379) Background to the Description The alcohols of anhydrous ucares, whether they are alcohols of monoanhydric sugars or alcohols of dianhydrous sugars, are known because they are produced with the aid of several acidic catalysts by means of dehydration. of the alcohols of associated sugars or alcohols of monoanhydric sugars. Examples of these catalysts include sulfonated polystyrenes (form H +) (German Patent DE 3 041 673 C2, description of Canadian Patent CA 1 178 288 Al); and several minera-.es acids, such as HCl (US Pat. No. 4,169,152; German Patent Specification DE 3 233 086 Al), H3P04 (Description of the East German Patent DD 1 32 266; Can. J. Chem., 5_2 (19) 3362-72 (1974)), HF (Description of the International Patent WO 89/00162 A; Carbohydr. Res. 205 (1990) 191-202) and H2P04 (Descriptions of German Patents DE 3 521 809 Al and DE 3 229 412 Al).

These processes are often carried out in the presence of a solvent. As solvents, water (CA 1 178 288 Al; European Patent Description EP 0 052 295 Bl) and organic solvents are known, such as toluene or xylene (Prze.Chem 48 (11) 665-8 (1969).

Batch processes (discontinuous) for the preparation of alcohols of anhydrous sugars by means of acid hydrolysis se. lian described in numerous patents and articles, for example, U.S. Pat. 3,454,603; 4,564,692; and 4,506,086; Canadian Patent 1178288; and articles by J. Am. Chem. Soc., 68 (5) pp. 939-941 (1946); J. Chem. Soc, p. 433-436 (1947); Przern. Chem. 48 (ll) pp. 665-668 (1969); and Pr. Nauk. Inst. Technol. Org. Tworzy Sztucznych Politech. Wroclaw No 3., p 3-14 (1971).

In particular, a batch process for the formation of alcoholic isosorbide of sugar dianhydra has been described in the literature as a two-step process, involving the intramolecular dehydration of sorbitol to sorbitan (1,4 monoanhydrosorb t ol), and the reaction additional sorbitan to isosorbide (1,4: 3,6-dianhydrosorbi tol) in an acid catalyzed reaction, or dehydration, and cyclization. In this process, an aqueous solution of sorbitol is charged to a batch reactor (intermittent). The temperature is increased to 130-135 ° C under vacuum (35 mm Hg) to remove the water. When the sorbitol is melted and is free of water, a catalyst, usually sulfuric acid, is added and the temperature and vacuum levels are maintained. The operable temperature range of the reaction is very small. Higher temperatures lead to the decomposition and carbonization of the final product, while at lower temperatures they inhibit the reaction rate, due to the difficulties in removing the water from the reaction. This reaction produces isosorbide and a high molecular weight byproduct. The byproduct probably occurs through the removal of water between two or more molecules of sorbitol, but its exact nature is not clearly defined. See starch / stárke (1986), 38 (c), 26-30 and Roland Beck, Pharm. Mfg Inc. (1996), 97-100.

As described above, known processes for the production of anhydrous sugar alcohols are intermittent batch processes that produce a high molecular weight product. There is no known teaching to carry out the process in a continuous manner, or to recycle the solvent for use during the process. However, a continuous process for the production of anhydrous sugar alcohols is desirable to facilitate the cheap and large-scale production of both the monoanhydric sugar alcohols and the dianhydrous alcohols.

There is also an absence of teachings in the art regarding the purification of the anhydrous sugar alcohol that is produced, to acquire a level of purity acceptable for use in final products such as polymers. The polymers require a high degree of purity in the initiating materials to achieve clarity in the final product. The impurities in the initiating materials manifest as fading in the polymeric product, usually from yellow to brown. This color interferes with the use of polymeric for the production of certain articles of manufacture, such as optical discs, fibers, films, sheets and containers, which require a high degree of purity.

The contaminants contained in the anhydrous sugar alcohols, for example, the crude isosorbide, contain the degradation products of sorbitol, sorbitan and isosorbide, which cause the crude isosorbide to have a light yellow to brownish color. Therefore additional process steps are necessary for the purification of the product before use.

The commercially available anhydrous sugar alcohols are also of unacceptable purity for the production of polymers. For example, the commercially available isosorbide, although purified and white in its crystalline form, becomes yellow or brown in annealing at temperatures > 250 ° C, which is lower than the temperature required for the formation of polymers, which indicates that a resulting polymer would probably be discolored. Thus, a means is desired to make a purer product that is commercially available or available through means of known manufacturing processes.

Known processes for use in the purification of alcohols of anhydrous sugars include distillation, which can occur with or without the addition of boron compounds, for example in the form of boric acid (US Patent 3,160, 641) or boron borohydride, use of an anion exchange resin (US patent 3,160,641), and recrystallization from organic solvents, such as methyl ethyl ketone or methyl acetate (US Patent 3, 454, 603).

Description of the invention The present disclosure relates to producing alcohols of very pure anhydrous sugars, which are economical and are produced at good yields, in which the formation of by-products and contaminants is minimized, and which can be carried out on a large industrial scale. continuously without interruption for a relatively long time.

A preferred embodiment that is provided for a production process of anhydrous sugar alcohols, wherein the process includes the steps of introducing at least one sugar alcohol or monoanhydric sugar alcohol into a reaction vessel; the dehydration of the sugar alcohol or monoanhydric sugar alcohol in the presence of an acid catalyst and an organic solvent to form a reaction product, which is at least partially soluble in the organic solvent; the removal of water from the reaction vessel; the removal of organic solvent, which comprises the dissolved reaction product from the reaction vessel; the separation of the reaction product from the organic solvent that is removed; and the recycling of the organic solvent inside the reaction vessel.

Another preferred embodiment further includes purifying the separated reaction product by means of distillation, recrystallization, or a combination thereof.

Still another preferred embodiment is provided for a process for producing anhydrous sugar alcohols, wherein the process includes the steps of introducing at least one sugar alcohol or monoanhydric sugar alcohol into a reaction vessel, the dehydration of the alcohol of sugar or monoanhydro sugar alcohol in the presence of an acid catalyst and an organic solvent to form a reaction product, which is at least partially soluble in the organic solvent; the removal of water from the reaction vessel; the removal of organic solvent, which comprises the dissolved reaction product from the reaction vessel; the separation of the reaction product from the organic solvent that is removed; and the recycling of the organic solvent within the reaction vessel, where the steps to introduce the initiating materials, water removal, solvent removal and solvent recycling occur in a simultaneous manner.

In preferred embodiments, it is desired that the solvent be an organic solvent, the acid catalyst be a soluble acid or an anion exchange acid resin, and the reaction product be separated from the solvent by means of extraction. However, as described herein, other materials and methods that may be used are contemplated.

Brief Description of the Drawings Preferred embodiments of the invention are set forth as follows in the accompanying Figures 1-3: Fig. 1 illustrates a preferred embodiment of the continuous process of the invention; Fig. 2 illustrates the solubility of sorbitol, sorbitan and isosorbide in xylene; Y Fig. 3 illustrates a preferred embodiment of the invention, wherein the continuous process for the production of anhydrous sugar alcohol includes purification.

Detailed Description of the Preferred Modalities The present description describes a process for the production of alcohols of monoanhydric sugars and dianhydrides, preferably of extremely high purity.

This process is directed towards the production of anhydrous sugar alcohols, which generally includes the steps of introducing at least one sugar alcohol or monohydric sugar alcohol into a reaction vessel (tank); the dehydration of the sugar alcohol or monoanhydric sugar alcohol in the presence of an acid catalyst and an organic solvent to form a reaction product, which is at least partially soluble in the organic solvent; the removal of water from the reaction vessel; the removal of organic solvent, which comprises the reaction product dissolved from the reaction vessel; the separation of the reaction product from the organic solvent that is removed; and the recycling of the organic solvent inside the reaction vessel. Optionally, the process may additionally include an additional purification step. In addition, the process can be continuous for such steps of introduction of initiating materials, removal of water, removal of solvent comprising the dissolved reaction product and recycling of the solvent after separation of the reaction product occurring in a simultaneous manner. .

Typical sugar alcohols, in particular pentites and hexites, are suitable for use in the process as starting materials. The initiator materials may be sugar alcohols, monoanhydride sugar alcohols, or a mixture thereof. In particular, preferred starter materials include arabinitol, ribitol, D-glucitol (also known as D-sorbitol or sorbitol), D-mannitol (mannitol), galactitol and iditol. The use of sorbitol is desired in a particular form, because sorbitol is readily available and can be obtained on a large industrial scale by means of the reduction of glucose with hydrogen, as known to the person skilled in the art.

The catalysts used to facilitate the dehydration reaction are acid catalysts. Various types of acid catalysts can be used, each one has specific advantages and disadvantages. One kind of acid catalyst that can be used includes soluble acids. Examples of such acidic catalysts include sulfuric acid, phosphoric acid, p-toluensulonic acid, methanesulfonic acid and the like. Sulfuric acid, which is a catalyst of this kind, is preferred. Alternatively, acidic anion exchange resins, such as sulfonated polystyrenes, can also be used. An acid anion exchange resin is AG50W-X12 from BioRad. Inorganic ion exchange materials, such as acidic zeolites, can also be used. In particular, Degussa H-beta zeolite can also be used in the process described herein.

All of the above types of acid catalysts that were described can be used in the process described herein. Each one has specific advantages. For example, soluble acids such as sulfuric acid provide catalytic stability during the long term reaction, which allows the process to continue for long periods of time without recharging the catalyst. However, these catalysts tend to promote the formation of an unwanted by-product, a dark colored oligomeric residue, which can be produced in amounts above about 10%, and sometimes even larger. Alternatively, acidic ion exchange resins produce little or no residue but. n-o provide long-term catalytic stability. Therefore, any type of acid catalyst can be selected with its specific limitations and advantages in mind, which allow the formation of a process with long-term stability or minimum byproduct production. Alternatively, it may be possible to invent a system that incorporates both types of catalysts or a different catalyst that produces long-term stability while minimizing by-product formation.

The solvent useful for the process described herein preferably forms a azotropic mixture with water, or has a boiling point higher than that of water (100 ° C). It is desired that the solvent have a boiling point of 120-150 ° C, preferably at least 130 ° C. Preferred solvents include organic solvents but exclude esters, such as ethyl acetate (EtOAc), because an ester can form undesired ransterification products during the dehydration reaction. The solvents of the invention perform a double function facilitating the removal of water from the reaction mixture, and which act as a solvent for the reaction product. The reaction product must be much more soluble in the solvent than in the initiator material, catalyst or any by-products or intermediates of the reaction. Preferably, the solubility of the initiator material, catalyst and any reaction intermediates or by-products is as low as possible in the organic solvent of the process, to ensure a high degree of purity in the product reaction. Examples of suitable organic solvents include, but are not limited to, xylene, anisole, dichlorobenzene, nonane, n-octane, eumeno, butyl ether, and ethylbenzene. Preferably, the process solvent is selected from xylene, anisole, dichlorobenzene and nonane. More preferably, the solvent is selected from xylene and anisole, with xylene being the most -referred solvent.

It is possible to carry out one or more dehydrations of the initiator sugar alcohol during the reaction, which produces a monoanhydric or dianhydro sugar alcohol. The reaction can be further controlled to produce a combination of sugar alcohols monoanhydrides or dianhydrides by adjusting either the reaction conditions or the initiator materials, which may contain both sugar alcohols and sugar monoanhydride alcohols.

It is desired that the dehydration be carried out at elevated temperatures of between 80 ° C and 180 ° C, preferably at temperatures between 120 ° C and 140 ° C, and more preferably between 130 ° C and 140 ° C. It is advantageous to carry out the dehydration under an atmosphere of protective or non-reactive gas, particularly nitrogen. Dehydration can be carried out at atmospheric pressure, although elevated or reduced pressures can also be used without minor adjustments to process parameters, such as time and temperature, as known to the skilled artisan.

During dehydration, the reaction mixture is preferably maintained under reflux conditions to remove water by azetropic distillation. The water can also be removed by other methods known in the art, such as evaporation.

The dehydration reaction in the reaction vessel can be carried out in various ways. For example, it is possible to maintain the amount of initiator material supplied, compared to the organic solvent present, so that two or more phases are formed in the reaction vessel. These phases comprise at least one lower aqueous phase, which comprises the sugar of molten sugar and / or anhydrous sugar alcohol, and an organic phase before the. aqueous phase, in which the reaction product that is formed dissolves rapidly. The organic phase is removed from the reaction vessel together with the dissolved reaction product by means of pumping, decanting or other methods known in the art. These two phase systems are demonstrated in the Examples, particularly Examples 2-6, which exemplify the use of various solvents, catalysts, initiator material dosages and solvent recirculation rates. The organic solvents useful in the dehydration reaction may have a density lower than that of the aqueous phase, as described above, or higher than that of the aqueous phase. If organic solvents are used with densities greater than that of the aqueous phase, the aqueous phase forms the upper layer and the dissolved product is present in the lower organic layer.

It is possible to use a relatively large amount of organic solvent in the alcohols of sugars or sugar alcohols monoanhydrous, but measuring the catalyst and water. In this case, it is unnecessary to allow the development of two phases in the reaction chamber. Instead, it is preferred that the solvent, in which the reaction product dissolves, be removed continuously, causing the dehydration to be done in a steady state of equilibrium, where the moles of the materials are measured initiators, and the moles of the dissolved reaction product that are removed are equivalent to each other. The continuous removal of the reaction product in the organic solvent from the reaction vessel drives the reaction forward and greatly increases the yield and productivity.

In any case, the dehydration can be carried out in such a way that the catalyst is added only once in the required amount, and only additional catalyst is added when necessary. However, it is possible to add the catalyst in a continuous dosing mode during dehydration.

The high temperature of the dehydration reaction promotes rapid dehydration of the initiator materials. However, it can also promote the formation of by-products and / or the further conversion of monohydric sugar alcohols and dianhydrides to undesirable side products out of time. Therefore, for both one-phase and two-phase reactions, it is desirable to quickly remove the reaction product resulting from the reaction chamber to further protect against decomposition. Preferably, the reaction product is removed from the reaction vessel continuously during the course of the dehydration reaction.

After the dehydration of the initiator material is completed, the acid catalyst can be deactivated and / or removed from the solvent containing the reaction product, which has been preferably removed from the reaction vessel. In the case of soluble acid catalysts, deactivation can be accomplished by any method known in the art, such as the addition of a metal hydroxide base to form an insoluble salt that will precipitate out of the solution. In particular, calcium hydroxide can be used in the process described herein. Inorganic ion exchange or polymeric materials can be recovered by filtration, before being used again, reactivation may be necessary.

To separate the reaction product from the solvent, the reaction product can be recrystallized from the solvent. Alternatively, a liquid-liquid extraction can be carried out instead of recrystallization using water or lower aliphatic alcohols, such as ethanol or methanol, and can be directed as part of the continuous process.

For example, the solvent containing the reaction product can be removed from the reaction vessel, and combined with water or a lower aliphatic alcohol, such as methanol or ethanol. The reaction product is extracted from the solvent in water or aliphatic alcohol, which is then decanted or otherwise separated from the solvent. The reaction product can be recrystallized from the water or lower aliphatic alcohol, while the solvent is recycled for use in the reaction vessel. It is preferable that the solvent and water or lower aliphatic alcohol form a two-phase system to facilitate the separation of the solvent to be reused in the process of the invention.

The extraction of the reaction product by means of the organic solvent from the reaction mixture under reaction conditions is a reactive extraction, which removes the reaction product from the reaction mixture, and furthermore aids in the purification of the reaction product. By means of the reactive extraction, the reaction product is separated from the initiating material that did not react, of the intermediate reaction products and the reaction by-products. The organic solvent comprising the dissolved reaction product is removed from the reaction vessel. The reaction product is subsequently separated from the removed organic solvent by means of crystallization or by means of liquid-liquid extraction with water or lower aliphatic alcohol such as methanol or ethanol. If it is separated by means of crystallization, the reaction product is obtained as a solid. If it is separated by means of liquid-liquid extraction, the reaction product is obtained as a solution in water or lower aliphatic alcohols such as methanol or ethanol. The reaction product that is obtained by means of the reactive extraction that was described above if desired can be further purified. However, the continuous process described herein comprises intrinsic purification steps that result in a purer reaction product that would otherwise result from a batch process as is known in the art thus far. . - Further purification of the crude reaction product may occur by means of distillation, recrystallization, melt recrystallization or a combination thereof, as described in detail in the co-pending application [Atty Docket No. 032358-018], filed with the date attached. A combination of distillation and recrystallization of an aliphatic alcohol such as methanol or ethanol is preferred in order to minimize the number of purification steps, while maximizing the purity of the reaction product. This reaction purification can occur as part of the continuous process or in a separate process. In any case, the purity of the resulting anhydrous sugar alcohol should be at least 99.0%, preferably at least 99.5%, more preferably at least 99.8%, and preferably meeting the purity requirements for use in the production of polymers. , as stated at least in the co-pending application [Atty. Docket No. 032358-018] filed with the attached date.

The most effective way to purify the reaction product is a combination of vacuum distillation and recrystallization of lower aliphatic alcohols, preferably methanol or ethanol. The addition of hydride ions, such as in the form of sodium borohydride, NaBH 4, lithium aluminum hydride, is not necessary to the distillation if further purification of the reaction product has to be done before the use of the reaction product. If only distillation is used as the purification form, then the addition of hydride ions, preferably borohydride ions, more preferably in the form of sodium borohydride, is preferred to acquire a higher purity.

In a preferred embodiment, at least the steps of introduction of the initiating materials, removal of water from the reaction, removal of solvent and recycling of the solvent to the reaction flask are carried out simultaneously, creating a continuous process for the formation of anhydrous sugar alcohols.

The process of the invention described herein has the surprising and unexpected result of providing a large-scale economic method of making anhydrous sugar alcohols. It is a surprising additional result that the anhydrous sugar alcohols made by the process of the invention are exceptionally pure.

A preferred process of the invention will now be described with reference to Figure 1.

As shown in Figure 1, the dehydration takes place in the container (1), which is supplied with supply lines for the initiating materials, such as sugar alcohol or aqueous solution of sugar alcohol, as well as the organic solvent and acid catalyst. In the present case, the sugar alcohol or aqueous solution of sugar alcohol and, if necessary, a catalyst is supplied from the supply container (5) via a pump (6) and a heater (9) to the container (1) by means of a single line (13). The vessel (1) is heated by means of an oil bath (2) at temperatures of about 80-180 ° C, preferably 120-160 ° C, more preferably 130-140 ° C.

In this way, the reaction mixture formed in the vessel (1) is mixed during the dehydration reaction by means of a stirrer (16). A distillation head with. A cooler (14) is used to distill the water that results, in part, from the dehydration process. This water is condensed in the cooler and any distilled solvent that may have bound in the distillation is separated from it. The water and the solvent form two different layers. Which can be easily separated, such as in the water separator (15). The water can be drained, and the solvent, which is lighter than water, flows back continuously into the reaction chamber. A drainage line capable of heating (11) is used to continuously remove solvent from the reaction chamber by means of a pump (8). This solvent, which contains dissolved reaction product, is transported to a recrystallization vessel (3) which is at a lower temperature than that of the reaction chamber, preferably less than 10 ° C. The lower temperature is maintained by means of the ice bath (4). There, the reaction product is recrystallized from the organic solvent. The recrystallization vessel can be provided with an agitator (17) and with other typical measuring instruments, such as temperature sensors and the like. The crystals can be carried in continuous or discontinuous form. The solvent can be withdrawn continuously, reprocessed optionally, and returned to the dehydration mixture via line (12) and pump (7). It is advantageous to heat the solvent to an appropriate temperature before it returns to the dehydration mixture, for example, by passing it through a heat exchanger (10) The process is preferably carried out under conditions in which the resulting reaction product has substantially better solubility in the solvent than in the initiator material or catalyst. It can be seen from Figure 2 that the differences in solubility between the sorbitol and the desired isosorbide end product are considerable at temperatures of 80 ° C and above.

The dehydration temperature of the process is optimum between 60 ° C and 180 ° C, preferably between 120 ° C and 160 ° C, and more preferably between 130 ° C and 140 ° C. however, the dehydration temperature may vary from these ranges when changes in the initiator material, reaction pressure or other process parameters are required, as is known to the skilled artisan.

It is understood that a temperature range favorable for dehydration will be selected on the basis of a few preliminary experiments with appropriate solvents and catalysts using the undesired initiator material, as known to the skilled artisan. If desired, the pressure of the reaction can be changed from atmospheric pressure, with corresponding changes in the temperature of the reaction as is known to the person skilled in the art.

Because of the high purity of the product, the process of the invention is especially suitable for producing monomers used as initiator materials for the production of polymers after purification which was described in the co-pending application [Atty. Docket No. 032358-018], filed with the attached date. For example, the isosorbide produced by this invention is of such high purity that it can be used to make polymers, in particular polyesters, and products made therefrom, such as fibers, packages, sheets, films and optical discs, as described for example in the US Patent Applications co-pending 09 / 064,844; 09 / 064,950; 09 / 064,846; 09 / 064,858; 09 / 064,826; 09 / 064,719; 09 / 064,862; and 09 / 064,720, all filed on April 23, 1998, which are hereby incorporated by reference in their entirety. In particular, the polymers which incorporate the anhydrous sugar alcohols produced by the process described herein can be formed by polycondensation of the anhydrous sugar alcohol with polyfunctional materials containing polycarboxylic monomers, carboxylic acid halides such as acid chloride. , polycarbonate monomers such as diphenylcarbonate or phosgene, isocyanates such as toluene diisocyanate and methylene diphenylisocyanate, and dicarboxylic acids, such as portions of terephthaloyl, or di ethyl esters thereof and, optionally, aliphatic diols, such as ethylene glycol .

All references cited herein are incorporated in their entirety by reference. The following examples will demonstrate the process of the invention. The scope of the invention is not determined by the examples, but is disclosed in the above specification and the following claims, and includes all equivalent materials and methods as those known to the person skilled in the art.

In the following examples, dehydrations using sorbitol as the initiator material are described. . -.

Example 1 In a continuous process of the invention, a reaction flask is charged with xylene as solvent, water, and H2SO4 as a catalyst. The stirring speed is adjusted to 150 rpm. The precipitation flask is charged with xylene, and the stirring speed is adjusted to 300 rpm. Both flasks are purged with inert gas (nitrogen) to prevent the oxidation of the sugar derivatives by air. An oil bath at about 170 ° C, and a cooling bath is cooled to about -15 ° C. The pumps are started, and the pumping rates are adjusted to maintain the amounts of xylene in the reaction flask and flask of precipitation at a rate of at least 2 to 1, respectively. The heaters are started to heat the materials entering the reaction flask. The temperature of the reaction product / xylene mixture is 85 ° C-95 ° C, while the temperature of xylene returning to the reaction flask after separation of the reaction product is about 120 ° C. The internal temperature of the line transporting the reaction product / xylene must be below the melting point of the isosorbide to prevent isosorbide precipitation and blockage of the line, and below a temperature at which the evaporation of the product / xylene mixture occurs due to the reduced pressure in the reaction line, just before the pumping head can cause gas bubbles within the load. pumping, leading to pumping failures. Just after reaching the reflux temperature in the reaction flask, a. pump and heater are started to feed aqueous sorbitol to the reaction flask. The temperature of the aqueous sorbitol that is fed is 95 ° C. then, for a period of 15-30 minutes, the precipitation of isosorbide is observed in the precipitation flask, At the beginning of the reaction, a smaller amount of low density brown flakes, which are degradation products, are located on the surface of the xylene layer, which are formed as agglomerate after 60-90 myrrhtos. Compared to flakes, the agglomerates have higher density and are combined with the aqueous layer. It is therefore advantageous to pump out the product / xylene solution in a region apart from the surfaces of the xylene layer, where the flow velocity is lower to avoid the collection of the agglomerates.

Example 2 The process described in the Example is repeated 1, except that the reaction product dissolved in xylene is added to a methanol solution and subsequently purified, as generally demonstrated in Figure 3.

Figure 3 depicts a process diagram of the reaction, wherein the sugar alcohol, acid catalyst and solvent are fed into a reactor. When the reaction product is generated, it is recovered in the product recovery area. Here, the crude reaction product is separated from the solvent, which is recycled for use in the reactor. The crude reaction product is subsequently purified in the product purification step, resulting in a purified anhydrous sugar alcohol.

In this particular reaction, the solvent xylene and methanol form a two-part solution at room temperature in the product recovery step, wherein the reaction product is extracted into the methanol layer. The methanol layer containing the reaction product is subsequently separated from the xylene by means of decanting. The methanol containing the reaction product is distilled, and the distillation product is recrystallized. The resulting isosorbide has a purity of > 99.8%.

In the examples given in the following tables, dehydrations using various solvents and reaction conditions are described. The solution of initiator material (educt) employed is an aqueous solution of sugar alcohol of the type that is produced as a product in the hydrogenation of glucose. In all cases, the sorbitol used is a commercial product of Aldrich which is approximately 97% pure. 3 This example demonstrates the use of various solvents in the dehydration reaction.

A reaction as described in Example 1 is carried out with 1 ml of concentrated H2SO4 catalyst; 2100 ml of solvent; a recirculation speed of 300 ml / h; .a dosage of sorbitol (in a 45% solution in H20) of 24 g / h (= 132mMol / h); a reaction flask temperature of 130 ° C to 140 ° C; and a precipitation flask temperature < 0 ° C. the duration of the reaction is approximately 4 hours. The amounts of sorbitol, isosorbide, and intermediates are shown in Table 1.

Table 1 As shown in the table, the best results are acquired using the solvent xylene or anisole.

Example 4 This example demonstrates the use of several catalysts: in the dehydration reaction.

A reaction as described in Example 1 is carried out with 2100 ml of xylene; a xylene recirculation rate of 2000 ml / h; a dosage of sorbitol (in a 45% solution in H20) of 24 g / h (= 132mMol / h); a reaction flask temperature of 130 ° C to 140 ° C; and a precipitation flask temperature < 0 ° C. the duration of the reaction is approximately 4 hours. The amounts of sorbitol, isosorbide, and intermediates are shown in Table 2.

Table 2 * interchanger ion (po 1 íes 11 sulfonated reindeer) AG50W-X12 (100-200 mech form H) ** Type H-beta made by Degussa, module 27 As shown in the table, the best results were obtained using the H2S04 or BioRad 50W-X12 catalyst.

Example 5 This example demonstrates the effect of different dosages of the sugar alcohol as the initiator material.

A reaction as described in Example 1 is carried out with 1 ml of concentrated H2SO4 catalyst; 2100 ml of xylene; a recirculation rate of xylene of 3000 ml / h; a reaction flask temperature of 130 ° C to 140 ° C; and a precipitation flask temperature < 0 ° C. the duration of the reaction is approximately 4 hours. The amounts of sorbitol, isosorbide, and intermediates are shown in Table 3.

Table 3 As shown in the table, the yields depend strongly on the feed rates of the starter material.

Example 6 This example demonstrates the effect of varying the speed of recirculation of the solvent.

A reaction as described in Example 1 is carried out with 1 ml of concentrated H2SO4 catalyst; 2100 ml of xylene; a dosage of sorbitol (in a 45% solution in H20, a reaction flask temperature of 130 ° C to 140 ° C, and a flask temperature of <0 ° C.) the duration of the reaction is about 4 hours The amounts of sorbitol, isosorbide, and intermediate products are shown in the Table.

Table 4 As shown in the table, the higher rates of recirculation of the organic solvent led to higher product yields.

Example 7 A reaction as described in Example 1 is carried out with 1400 ml of xylene; a recirculation rate of xylene of 600 ml / h; a dosage of sorbitol (in a 45% solution in H20, containing additionally 0.5% of H2S04) of 24 g / h (= 132 μm / h); a reaction flask temperature of 130 ° C to 140 ° C; and a precipitation flask temperature < 0 ° C. the duration of the reaction is about 4 hours, during the time that the catalyst is added in a continuous dosage.

Starter material (sorbitol): 525 mMol Products: sorbitol: 0 mMol; sorbitan: 37 mMol; isosorbide: 301 mMol; yield of (isosorbide), 57%.

Example 8 The separation of the reaction product from the organic solvent can be done by means of liquid / liquid extraction. For example, at 80 ° C, 200 ml of a 1.1% solution of isosorbide in xylene is extracted with 20 ml of water. The isosorbide is almost completely extracted in the aqueous phase, and the xylene layer retains only about 0.04% isosorbide.

Example 9 The phase behavior of a three component system of mixed xylenes, methanol and isosorbide was studied. For each experiment, a mixture of three components gives isosorbide, methanol and mixed xylenes (20 g total) was prepared by two methods. a) The isosorbide was placed in a small bottle and the bottle was immersed in a preheated oil bath (~ 80 ° C) until the isosorbide is melted. The molten isosorbide is first added to methanol and subsequently to xylene.

The isosorbide and xylene are placed together in a small jar and heated in an oil bath (~ 130 ° C) until the isosorbide is completely dissolved. The bottle is removed from the oil and allowed to cool to approximately 50 ° C while adding methanol.

The bottle is sealed, the solution is mixed well and allowed to cool to room temperature. Then it is allowed to stand for at least.15 minutes, the solutions were examined to show the phase separation. The following Table 5 contains composition information for the samples that remained as a phase as established. Table 6 contains composition information for samples that are separated into two phases as established.

The above examples demonstrate the related matter of the invention, but are not considered to be limiting and do not define the scope of the invention. The invention is intended to include equivalent methods and materials as are known in the art, and are further defined by the following claims.

Table 5- System of a Table 6- System of Phase Two Phases It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following claims is claimed as property:

Claims (33)

1. Claims 1. A process for the production of anhydrous sugar alcohol, characterized in that it comprises: the introduction of at least one sugar alcohol or monoanhydric sugar alcohol into a reaction vessel; - the dehydration of at least one sugar alcohol or monoanhydric sugar alcohol in the presence of an acid catalyst and an organic solvent to form a reaction product, which is at least partially soluble in the organic solvent; - the removal of water from the reaction vessel; - the removal of the organic solvent comprising the dissolved reaction product from the reaction vessel; the separation of the reaction product from the organic solvent that is removed; Y the recycling of the organic solvent in the reaction vessel 2. The process of claim 1, characterized in that the reaction product is separated from the organic solvent which is removed by means of crystallization, evaporation or extraction. 3. The process of claim 2, characterized in that the reaction product is separated from the organic solvent that is removed by means of extraction using a lower aliphatic alcohol or water. 4. The process of claim 3, characterized in that the lower aliphatic alcohol is methanol or ethanol. 5. The process of claim 2, characterized in that it comprises the further distillation of the reaction product that was separated. 6. The process of claim 2, characterized in that the additional recrystallization of the reaction product that was separated. 7. The process of claim 6, characterized in that the recrystallization is melt recrystallization. 8. The process of claim 1, characterized in that it additionally comprises purifying the reaction product that was separated. 9. The process of claim 8, characterized in that the reaction product is purified by distillation. 10. The process of claim 8, characterized in that the reaction product is purified by means of recrystallization. 11. The process of claim 10, characterized in that the recrystallization is melt recrystallization. 12. The process of claim 10, characterized in that the recrystallization is from methanol or ethanol. 13. The process of claim 8, characterized in that the reaction product is purified by means of distillation and recrystallization, forming an anhydrous sugar alcohol of a purity > 99.0%. 14. The process of claim 13, characterized in that the recrystallization is methanol or ethanol. 15. The process of claim 13, characterized in that the recrystallization is melt recrystallization. 16. The process of claim 13, characterized in that the purity is > 99.8%. 17. The process of claim 1, characterized in that the organic solvent forms an azeotropic mixture with the water. 18. The process of claim 1, characterized in that the organic solvent has a boiling point higher than 100 ° C. 19. The process of claim 1, characterized in that the organic solvent is selected from the group consisting of xylene, anisole and nonane 20. The process of. Claim 19, characterized in that the organic solvent is xylene. The process of claim 1, characterized in that the sugar alcohol is pentite, hexadete or a mixture thereof. 22. The process of claim 1, characterized in that the sugar alcohol is sorbitol. 23. The process of claim 1, characterized in that the acid catalyst is a soluble acid, an anionic exchange acid resin or an inorganic ion exchange resin. 24. The process of claim 23, characterized in that the soluble acid is selected from the group consisting of sulfuric acid, phosphoric acid, p-toluensulonic acid and methanesulfonic acid. 25. The process of claim 24, characterized in that the soluble acid is sulfuric acid. 26. An anhydrous sugar alcohol, characterized in that it is produced by means of the process of claim 1. 27. An anhydrous sugar alcohol, characterized in that it is produced by the process of claim 13. 28. An anhydrous sugar alcohol, characterized in that it is produced by the process of claiming. fifteen. 29. A polymer made by means of polycondensation of the anhydrous sugar alcohol of claim 8 with a material containing mu ti ti carboxy lato, mult i-isocyanate containing material, or material containing carbonic acid, characterized in that the polymer is a polyester, polcarbonat o-ester, polycarbonate or polyurethane. 30. A product made, characterized because it is made with the rei indication polymer 29. 31. The product of claim 30, characterized in that it is selected from the group consisting of film, fiber, sheet, package and optical disk. 32. A process for the production of sugar alcohol, characterized in that it comprises: the introduction of at least one sugar alcohol or monoanhydric sugar alcohol into a reaction vessel; the dehydration of at least one sugar alcohol or monoanhydric sugar alcohol in the presence of an acid catalyst and an organic solvent to form a reaction product, which is at least partially soluble in the organic solvent; - the removal of water from the reaction vessel; - the removal of the organic solvent comprising the dissolved reaction product from the reaction vessel; the separation of the reaction product from the organic solvent that is removed; and the recycling of the organic solvent in the reaction vessel. Where the stages of introduction, removal of water, solvent removal and recycling of solvent occur in a simultaneous manner. 33. The process of claim 32, characterized in that it additionally comprises the step of purifying the reaction product.