KR20150089684A - Method for preparing diesters of anhydrosugar alcohol with improved color - Google Patents

Abstract

The present invention relates to a method for preparing diesters of anhydrosugar alcohol with improved color and, more specifically, to a method for simply and economically preparing diesters of anhydrosugar alcohol with excellently improved color without an extra post-processing in order to improve color by getting rid of a solvent, activated carbon and the unreacted material in a simple way after esterifying of anhydrosugar alcohol in the presence of activated carbon in inert gas atmosphere.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method for preparing an alcohol-free alcohol diester having improved color,

More particularly, the present invention relates to a process for producing an alcohol-free alcohol diester having improved color, and more particularly, to a process for producing an alcohol-free alcohol diester having improved color, In a simple and economical manner, without the necessity of a separate post-treatment step for color improvement, with an improved colorless alcoholic diester.

Anhydrous alcohol has a diol form with two hydroxyl groups in the molecule and can be prepared using hexitol derived from starch. Since alcohol-free alcohol is an eco-friendly substance derived from renewable natural resources, there has been much interest for a long time and studies on the manufacturing method have been carried out. Among these alcohol-free alcohols, isosorbide prepared from sorbitol has the widest industrial application currently.

The use of anhydrous alcohol is widely used in the treatment of cardiovascular diseases, patches, adhesives, oral cleansers and the like, solvents for compositions in the cosmetics industry, and emulsifiers in the food industry. In addition, it is possible to increase the glass transition temperature of a polymer substance such as polyester, PET, polycarbonate, polyurethane, and epoxy resin, to improve the strength of these materials, and to be an environmentally friendly material derived from natural materials. useful. It is also known to be used as an environmentally friendly solvent for adhesives, environmentally friendly plasticizers, biodegradable polymers, and water-soluble lacquers.

A variety of anhydrosugar alcohol derivatives have been developed and used, and examples thereof include diesters of anhydrosugar alcohol obtained by esterification of two hydroxy groups present in anhydrous alcohol with an alkylcarboxylic acid. Diesters of alcohol-free alcohols have many advantages as plasticizers for polyvinylchloride (PVC). Therefore, it is now attracting much attention as an eco-friendly plasticizer that can replace petroleum-derived plasticizer of PVC. Such anhydrosugar alcohol diester has a problem in that the color characteristics are deteriorated (that is, the yellowness index (YI) is increased) during the esterification reaction for the preparation thereof.

International Patent Publication No. WO01 / 83488 discloses a technique for improving the color of an article by synthesizing an anhydrous glycitol ester using a macroporous acid ion exchange resin catalyst. However, this technique uses a costly macroporous acid ion exchange resin catalyst, which causes a problem in that the manufacturing cost is increased, and the color improvement effect is also unsatisfactory.

U.S. Patent No. 8,129,549 discloses a process for the production of anhydrous hexitol diesters by mixing hypophosphorous acid with an acid catalyst as a reaction catalyst and then distilling the unreacted fatty acid, Or less. However, when using hypophosphorous acid as such, a specific odor is generated in the reaction liquid, so the workability is poor and the reaction time is also delayed. Further, addition of an additional acid in addition to the acid catalyst increases the amount of NaOH added for neutralization after the completion of the reaction, and as a result, the yield decreases. Further, by using 3 equivalents or more of an expensive carboxylic acid, not only the production cost is increased but also unreacted carboxylic acid is removed through distillation. Moreover, even with this technique, the color improvement effect is not satisfactory.

Therefore, there is a demand for development of a technique capable of satisfactorily improving the color of alcohol-free alcohol diester by a simple and economical method which does not require a separate post-treatment step for improving color.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to overcome the problems of the prior art described above, and it is an object of the present invention to provide a colorless alcohol diester which is remarkably inexpensive, simple, environment- The present invention also provides a process for producing an alcohol-free alcohol diester which does not require an alcohol.

In order to solve the above technical problems, the present invention provides a process for producing an anhydrous alcohol diester, which comprises esterifying an anhydrosugar alcohol and a carboxylic acid in the presence of an activated carbon and an acid catalyst in an inert gas atmosphere.

According to one preferred embodiment of the present invention, there is provided a process for producing a polyisocyanate compound, which comprises: (1) introducing a solvent, anhydrosugar alcohol, a carboxylic acid, an activated carbon and an acid catalyst into a reactor; (2) making the interior of the reactor an inert gas atmosphere; And (3) performing an esterification reaction between an anhydrosugar alcohol and a carboxylic acid, thereby producing a dihydric alcohol diester.

According to the present invention, it is possible to prepare an alcohol-free alcohol diester in which a color is remarkably improved (for example, a yellowness index (YI) of 10 or less, more preferably 5 or less, and even more preferably 3 or less) in a simple and economical manner . The process for producing the alcohol-free alcohol diester of the present invention is remarkably inexpensive and simple compared with the conventional process and does not require a separate post-treatment process for color improvement, so it is very suitable for commercial mass production of alcohol-free alcohol diester, to be.

Hereinafter, the present invention will be described in detail.

The method for producing an anhydropoly alcohol diester of the present invention is characterized in that an esterification reaction of anhydrosugar alcohol and a carboxylic acid is carried out in the presence of an activated carbon and an acid catalyst in an inert gas atmosphere.

The alcohol-free alcohol is a substance obtained by removing one or more water molecules (dehydration reaction) from the original internal structure of the hydrogenated sugar (or sugar alcohol). The hydrogenated sugar is classified into tetritol, pentitol, hexitol and heptitol (the number of carbon atoms is 4, 5, 6 and 7, respectively) according to the number of carbon atoms, and is obtained by adding hydrogen to the reducing end group of the saccharide. Hexitol having 6 carbon atoms includes sorbitol, mannitol, iditol, galactitol and the like. In the present invention, isosorbide obtained by dehydration reaction of hexitol is preferably used as the anhydrosugar alcohol, but the present invention is not limited thereto.

The inert gas atmosphere may be formed by replacing the interior of the reactor with an inert gas. The inert gas may be, for example, nitrogen or argon, but is not limited thereto. In the present invention, this inert gas is used to prevent the discoloration during the reaction by preventing the flow of oxygen into the reactor before the esterification reaction and during the reaction.

As the activated carbon, there may be used one or more selected from the group consisting of plant raw materials such as wood and coconut, activated carbon obtained by activating mineral raw materials such as lignite, bituminous coal, bituminous coal and anthracite. The shape of the activated carbon particles is not particularly limited.

In the method for producing an anhydrous alcohol diester of the present invention, the amount of the activated carbon to be used is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 3 parts by weight, based on 100 parts by weight of the anhydrous alcohol. If the amount of activated carbon used is less than 0.1 part by weight based on 100 parts by weight of alcohol free alcohol, the color improving effect may be insufficient. If the amount is more than 5 parts by weight, process efficiency may be inferior.

The present invention relates to the use of activated carbon in a relatively low amount of activated carbon, compared to conventional techniques (in the range of 7 to 10 parts by weight per 100 parts by weight of an alcohol-free alcohol diester) Effect can be obtained.

As the acid catalyst, an acid substance usable for the esterification of anhydrosugar alcohol can be used without particular limitation. Preferably at least one member selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, p-toluenesulfonic acid (PTSA), phosphoric acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, And more preferably p-toluenesulfonic acid can be used. The amount of the acid catalyst to be used is preferably 0.5 to 10 parts by weight based on 100 parts by weight of an alcohol without sugar (for example, isosorbide). If the amount of the acid catalyst is less than 0.5 part by weight per 100 parts by weight of alcohol free alcohol, the conversion time to the diester may be too long, and if it exceeds 10 parts by weight, the amount of NaOH added for coloring or neutralization may increase, , Increase in waste, and the like.

The carboxylic acid can be used without particular limitation as long as it can react with two hydroxyl groups of anhydrosugar alcohol to form a diester. Such carboxylic acids may specifically be a C3-C20 saturated or unsaturated aliphatic or aromatic carboxylic acid on a straight or branched chain, and more specifically may be selected from the group consisting of propionic acid, hexanoic acid, 2-ethylhexanoic acid, octanoic acid, But is not limited to, at least one selected from the group consisting of lauric acid, stearic acid, cyclohexanecarboxylic acid, benzoic acid, phenylacetic acid and naphthalenecarboxylic acid.

According to one embodiment of the present invention, the amount of carboxylic acid remaining unreacted after the completion of the reaction can be minimized by using the carboxylic acid in an amount of 2 equivalents or less (for example, 1.8 to 2 equivalents) based on 1 equivalent of anhydrous alcohol, It is preferable to carry out the distillation step additionally for the removal.

The esterification reaction between anhydrosugar alcohol and carboxylic acid is carried out at a temperature of, for example, 100 to 180 ° C, more preferably 100 to 150 ° C, even more preferably 110 to 125 ° C, and 50 to 700 torr, (For example, 5 to 30 hours), more preferably 15 hours or more (for example, 15 to 20 hours) at a pressure of 300 to 300 torr, more preferably 100 to 200 torr, It is not.

According to a preferred embodiment of the present invention, there is provided a process for preparing an alcohol-free alcohol diester, comprising the steps of: (1) introducing a solvent, anhydrosugar alcohol, carboxylic acid, activated carbon and an acid catalyst into a reactor; (2) making the interior of the reactor an inert gas atmosphere; And (3) performing an esterification reaction of an anhydrosugar alcohol and a carboxylic acid.

The anhydrosugar alcohol, carboxylic acid, activated carbon and acid catalyst are as described above, and the reactor may be a batch reactor. As the solvent, an organic solvent capable of effectively removing azeotropically generated water during the reaction is suitable. Preferably, at least one organic solvent selected from the group consisting of xylene, toluene and benzene may be used, but is not limited thereto.

A solvent, an alcohol without anhydride, a carboxylic acid, an activated carbon and an acid catalyst are introduced into the reactor, and then the inside of the reactor is replaced with an inert gas such as nitrogen to obtain an inert gas atmosphere. After the inert gas replacement is complete and during the reaction, the oxygen flow into the reactor is shut off.

After the inside of the reactor is put into an inert gas atmosphere, the esterification reaction of an alcohol with no alcohol and a carboxylic acid is carried out. Specific reaction conditions are as described above. The water generated during the reaction can be removed with a Dean-Stark Trap apparatus by azeotropically with the solvent.

The method for producing the anhydrosugar alcohol diester of the present invention may further comprise the step of removing the solvent from the mixture as a result of the esterification reaction. Removal of the solvent may be carried out by a conventional method, for example, the solvent may be removed under reduced pressure to concentrate the resultant.

The method for producing the anhydropoly alcohol diester of the present invention may further comprise the step of removing the activated carbon from the mixture as a result of the esterification reaction. The removal of the activated carbon can be carried out by a conventional method, for example, filtration.

The process for preparing the anhydropoly alcohol diester of the present invention may further comprise the step of removing the acid catalyst and the unreacted kerubic acid from the mixture as a result of the esterification reaction. The removal of the acid catalyst and the unreacted kerubic acid is carried out by introducing an appropriate amount of a base material (for example, NaOH) into the esterification reaction product, neutralizing these acid materials and precipitating the salt materials, and then filtering the precipitated salt material . In the present invention, since unreacted residual amount of carboxylic acid can be minimized, unreacted carboxylic acid can be removed only by the above neutralization and filtration step without further distillation step for its removal.

The removal of the solvent, the removal of the activated carbon, and the removal of the acid catalyst and the unreacted kerosene acid are preferably performed in this order, but the order may be changed if necessary. For example, the solvent may be removed after removal of activated carbon in the apparatus configuration. Also, the removal of the activated carbon and the removal of the acid catalyst and unreacted kerosene acid may be carried out in one step. For example, a base may be added to the resultant from which the solvent has been removed to precipitate a salt, which may then be removed by filtration with activated carbon.

According to the above-described method of the present invention, it is possible to provide a color filter having a significantly improved hue, for example, a yellow color (YI) 4 (yellow color), without performing an additional post- Or less, more preferably 3 or less, can be produced in an excellent yield.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the following examples are intended to assist the understanding of the present invention, and the scope of the present invention is not limited thereto.

[ Example ]

Example

73 g of isosorbide, 140.5 g (1.95 eq) of 1-octanoic acid, 86.4 g of xylene, 1.46 g of activated carbon (2 parts by weight relative to 100 parts by weight of isosorbide) 1.5 g of p-toluenesulfonic acid (PTSA) was added to a batch reactor equipped with a Dean-Stark trap apparatus. The inside of the reactor was replaced with nitrogen and the flow of oxygen into the reactor was blocked. Subsequently, the reaction was carried out for 15 hours or more under the conditions of an internal temperature of 110 to 125 ° C and an internal pressure of 100 to 200 torr, thereby completing the reaction. After completing the reaction, the xylene solvent was removed at a jacket temperature of about 100 to 150 ° C and a pressure of 20 torr or less, and the reaction product was concentrated as much as possible. The concentrate was then filtered through a vacuum filter to remove the activated carbon. After the acid catalyst and the unreacted 1-octanoic acid were neutralized and precipitated by adding about 1 to 4 g of 50% NaOH to the filtrate, the precipitated salt material was removed with a filter to remove isosorbide dicaprylate . The final product, isosorbide dicaprylate purity, was 91%, and the purity of isosorbide monocaprylate, the reaction by-product, was 7%. The yellowness index (measured according to YI, ASTM D1925) of the final product was 2.66 and the yield of isosorbide dicaprylate was 92%.

Comparative Example  One

140 g (1.95 eq) of 1-octanoic acid, 86.4 g of xylene, and 1.5 g of p-toluenesulfonic acid (PTSA) were fed into a batch reactor equipped with a Dean-Stark trap apparatus. The inside of the reactor was replaced with nitrogen and the flow of oxygen into the reactor was blocked. Subsequently, the reaction was carried out for 15 hours or more under the conditions of an internal temperature of 110 to 125 ° C and an internal pressure of 100 to 200 torr, thereby completing the reaction. After completing the reaction, the xylene solvent was removed at a jacket temperature of about 100 to 150 ° C and a pressure of 20 torr or less, and the reaction product was concentrated as much as possible. To the concentrate was added about 1 to 4 g of 50% NaOH to neutralize and precipitate the acid catalyst and unreacted 1-octanoic acid, and the precipitated salt material was removed by a filter. 1.46 g of activated carbon (2 parts by weight relative to 100 parts by weight of iso-sorbide) was added to the filtrate, and the mixture was stirred at 80 to 100 ° C for about 2 hours to perform post-treatment for decolorization. Thereafter, the resultant of the post-treatment was filtered with a vacuum filter to remove activated carbon to finally obtain isosorbide dicaprylate. The final yield of isosorbide dicaprylate purity was 91% and isosorbide monocaprylate purity was 7%. The yellowness index (YI) of the final product was 33.91, and the yield of isosorbide dicaprylate was 92%.

Comparative Example  2

140 g (1.95 eq) of 1-octanoic acid, 86.4 g of xylene, and 1.5 g of p-toluenesulfonic acid (PTSA) were fed into a batch reactor equipped with a Dean-Stark trap apparatus. The inside of the reactor was replaced with nitrogen and the flow of oxygen into the reactor was blocked. Subsequently, the reaction was carried out for 15 hours or more under the conditions of an internal temperature of 110 to 125 ° C and an internal pressure of 100 to 200 torr, thereby completing the reaction. After completing the reaction, the xylene solvent was removed at a jacket temperature of about 100 to 150 ° C and a pressure of 20 torr or less, and the reaction product was concentrated as much as possible. To the concentrate was added about 1 to 4 g of 50% NaOH to neutralize and precipitate the acid catalyst and the unreacted 1-octanoic acid, and the precipitated salt material was removed with a filter to finally obtain isosorbide dicaprylate. The final yield of isosorbide dicaprylate purity was 91% and isosorbide monocaprylate purity was 7%. The yellowness index (YI) of the final product was 41.15, and the yield of isosorbide dicaprylate was 92%.

Comparative Example  3

(1.95 eq) of 1-octanoic acid, 86.4 g of xylene, 1.46 g of activated carbon (2 parts by weight based on 100 parts by weight of isosorbide) and 1.5 g of p-toluenesulfonic acid (PTSA) Were introduced into a batch reactor equipped with a Stark Trap device. The nitrogen substitution work inside the reactor was omitted. The reaction was carried out for 15 hours or more under the conditions of an internal temperature of the reactor of 110 to 125 ° C and an internal pressure of 100 to 200 torr. After completing the reaction, the xylene solvent was removed at a jacket temperature of about 100 to 150 ° C and a pressure of 20 torr or less, and the reaction product was concentrated as much as possible. The concentrate was then filtered through a vacuum filter to remove the activated carbon. To the filtrate was added about 1 to 4 g of 50% NaOH to neutralize and precipitate the acid catalyst and the unreacted 1-octanoic acid, and the precipitated salt material was removed with a filter to finally obtain isosorbide dicaprylate. The final yield of isosorbide dicaprylate purity was 91% and isosorbide monocaprylate purity was 7%. The yellowness index (YI) of the final product was 56.85, and the yield of isosorbide dicaprylate was 92%.

Comparative Example  4

140 g (1.95 eq) of 1-octanoic acid, 86.4 g of xylene, and 1.5 g of p-toluenesulfonic acid (PTSA) were fed into a batch reactor equipped with a Dean-Stark trap apparatus. The nitrogen substitution work inside the reactor was omitted. The reaction was carried out for 15 hours or more under the conditions of an internal temperature of the reactor of 110 to 125 ° C and an internal pressure of 100 to 200 torr. After completing the reaction, the xylene solvent was removed at a jacket temperature of about 100 to 150 ° C and a pressure of 20 torr or less, and the reaction product was concentrated as much as possible. To the concentrate was added about 1 to 4 g of 50% NaOH to neutralize and precipitate the acid catalyst and the unreacted 1-octanoic acid, and the precipitated salt material was removed with a filter to finally obtain isosorbide dicaprylate. The final yield of isosorbide dicaprylate purity was 91% and isosorbide monocaprylate purity was 7%. The yellowness index (YI) of the final product was 109.05, and the yield of isosorbide dicaprylate was 92%.

The results of the above Examples and Comparative Examples are summarized in Table 1 below.

As shown in Table 1, when the inside of the reactor was not replaced with an inert gas (Comparative Examples 3 and 4), and when no activated carbon was used (Comparative Examples 2 and 4), the color of the final product was poor. Also, even though the reaction was carried out in an inert gas atmosphere and the activated carbon was used, the color of the final product was improved as compared with Comparative Examples 2 to 4 in the case of Comparative Example 1 in which activated carbon was used in a post- Still poor. On the other hand, in the case of the example of the present invention in which the reaction was carried out in the presence of activated carbon in an inert gas atmosphere, the final product having a significantly improved yellowness index (YI) of 2.66 was obtained using only a small amount of activated carbon.

Claims (14)

Wherein an esterification reaction between an anhydrosugar alcohol and a carboxylic acid is carried out in an inert gas atmosphere in the presence of an activated carbon and an acid catalyst. The process for producing an alcohol-free alcohol diester according to claim 1, wherein the alcohol free alcohol is isosorbide. The method of producing an alcohol-free alcohol diester according to claim 1, wherein the inert gas is nitrogen. The method for producing an alcohol-free alcohol diester according to claim 1, wherein 0.1 to 5 parts by weight of activated carbon is used based on 100 parts by weight of an alcohol-free alcohol. The process of claim 1 wherein the acid catalyst is selected from the group consisting of sulfuric acid, nitric acid, hydrochloric acid, p-toluenesulfonic acid, phosphoric acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, By weight based on the weight of the alcohol-free alcohol diester. The process according to claim 1, wherein the carboxylic acid is a C3-C20 saturated or unsaturated aliphatic or aromatic carboxylic acid on a straight or branched chain. The process according to claim 1, wherein not more than 2 equivalents of carboxylic acid is used per 1 equivalent of anhydrous alcohol. The method of claim 1, further comprising the steps of: (1) introducing a solvent, an alcohol without anhydride, a carboxylic acid, an activated carbon and an acid catalyst into a reactor; (2) making the interior of the reactor an inert gas atmosphere; And (3) performing an esterification reaction between an anhydrosugar alcohol and a carboxylic acid. 9. The process for producing an alcohol-free alcohol diester according to claim 8, wherein the solvent is at least one selected from the group consisting of xylene, toluene and benzene. 9. The process according to claim 8, further comprising the step of removing the solvent from the mixture as a result of the esterification reaction. 9. The process according to claim 8, further comprising the step of removing the activated carbon from the mixture as a result of the esterification reaction. 9. The method of claim 8, further comprising removing acid catalyst and unreacted kerubic acid from the mixture as a result of the esterification reaction. 13. A process according to any one of claims 1 to 12, characterized in that there is no additional post-treatment step for color improvement. An alcohol-free alcohol diester produced by the process according to claim 13 and having a yellowness index (YI) of 10 or less.