MXPA00002197A - Method of purifying and recovering sweetener - Google Patents

Abstract

A method of purifying and recovering a sweetener efficiently in a high yield without conducting complicated steps, which comprises contacting crude methyl N-(3,3-dimethylbutyl)-a-L-aspartyl-L-phenylalaninate containing at least methyl a-L-aspartyl-L-phenylalaninate as an impurity with a mixed solvent having two layers respectively consisting of water and an organic solvent immiscible with water to extract the methyl N-(3,3-dimethylbutyl)-a-L-aspartyl-L-phenylalaninate with the organic solvent layer.

Description

PROCESS FOR PURIFICATION OR RECOVERY OF SWEETENER DESCRIPTION OF THE INVENTION The present invention relates to a novel process for the purification or recovery of a sweetener having a high degree of sweetness, and more particularly, relates to a process for the purification or recovery of N- (3, 3-dim.ethylbutyl) ) -uL-aspartyl-L- in ± lalan ± na methyl ester represented by the following general formula (1) described in Patent Publication Kohyou, Tokuhyouhéi-JP-A-8-503206 (503206/1996) of PCT.

H a C C H 2 - C H 2 - N H «- C- H C H 2 COOH Since the compound in the present invention is synthesized by reacting α-L-aspartyl-L-phenylalanine methyl ester with 3, 3-dimethylbutyl aldehyde as described in the publication, eg, Tokuhyouhei-JP-A-8-503206, Publication of EP Patent O95 / 30689, or etc., it is difficult to avoid mixing unreacted a-L-aspartyl-L-phenylalanine methyl ester in N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester. Accordingly, it is more important to remove α-L-aspartyl-L-phenylalanine methyl ester for the purification of N- (3,3-dimethylbutyl) -a-L-aspartyl-L-phenylalanine methyl ester. It is described in the publication of Tokuhyouhei-JP-A-503206 that the compound of the present invention can be purified by a standard technique such as recrystallization and chromatography. Chromatography is not an appropriate technique for an industrial purification method. And, recrystallization has a more common use for an industrial purification method, and yet since the desired compound is dissolved in the mother liquor, and the dissolved compound is very low, it is difficult to say that this is an efficient technique in view of performance. Therefore, a method of recovery of the mother liquor is used industrially for the need to improve the yield. Meanwhile, there is little difference between the solubility of aL-aspartyl-L-phenylalanine methyl ester and the solubility of N- (3,3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester at a temperature of 5 to 25 ° C in the water that is usually used by the solvent in the recrystallization of peptides and in this way an amount of N- (3,3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester almost equal to that of aL-aspartil -L-phenylalanine methyl ester is lost in the mother liquor through the recrystallization step. In addition, a method of recovering the mother liquor is not described in any of the specifications of the two prior patent publications mentioned above. Typically, the target compound (desired) can be recovered by concentrating and cooling the mother liquor for recrystallization, and yet this recovery method requires heavy steps or operations in concentration, crystallization and separation, and is also not efficient from the ratio of recovery of the same (yield), since the compound object is lost in the mother liquor. The problem to be solved by the present invention, which is the object of the present invention, is to provide an effective process for the purification or recovery of N- (3, 3-dimethylbutyl) -a-L-aspartyl-L-phenylalanine methyl ester. In order to solve the problem, a process for purifying N- (3,3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester represented by the aforementioned general formula containing at least aL has been studied. -aspartyl-L-phenylalanine methyl ester as an impurity, and also a process for recovering the subject compound from an aqueous solution of N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester containing at least α-aspartyl-L-phenylalanine methyl ester as a dissolved substance, and consequently it has unexpectedly been found that N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester of high purity not containing a- Aspartyl-L-phenylalanine methyl ester can be obtained by contacting N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester containing at least a-L-aspartyl-L-phenylalanine methyl ester as an impurity, with mixed solvents having two layers of a given layer starting at less an organic solvent (one or more organic solvents) that does not mix (is immiscible) with water homogeneously and a layer of water to extract N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester in the side of the organic solvent layer in the separated layers, and on the other hand, to extract α-L-aspartyl-L-phenylalanine methyl ester on the side of the water layer therein for selectivity. In addition, it has been found in the present that N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester of N- (3,3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl can be recovered. ester containing aL-aspartyl-L-phenylalanine methyl ester by contacting an aqueous solution of such N- (3-3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester containing a-L-aspartyl-L-phenylalanine methyl ester as a substance dissolved with at least one organic solvent that does not mix with water homogeneously to extract such desired compound on the side of the organic layer. The present invention has been completed based on the above findings. That is, the present invention is directed to a process for the purification of N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester represented by the general formula mentioned above comprising the step of: contacting N- (3, 3-dimethylbutyl) -aL- aspartyl-L-phenylalanine impure methyl ester containing at least a-L-aspartyl-L-phenylalanine methyl ester as an impurity, with mixed solvents having two layers of a given layer of at least one organic solvent (one or more solvents) that does not mix (is immiscible) with water homogeneously and a layer of water to extract N- (3,3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester in the organic layer. The present invention includes the following contents: [1] The above purification process, wherein the at least organic solvent (one or more solvents) is used that does not mix with water homogeneously, at least one organic solvent selected from the group which consists of toluene, ethyl acetate and butyl acetate. [2] A process for the recovery of N- (3,3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester represented by the general formula mentioned above (1), which comprises the step of: contacting a solution aqueous N- (3,3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester by dissolving at least α-aspartyl-L-phenylalanine as an impurity, with at least one organic solvent (one or more solvents) it is not mixed with water homogeneously to dissolve and extract N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester in the organic solvent layer. [3] N- (3, 3-dimethylbutyl) -a-L-aspartyl-L-phenylalanine methyl ester as obtained in any prior processes for the purification or recovery thereof. For examples of organic solvents that do not mix (are immiscible) with water homogeneously usable for the present invention, aromatic hydrocarbons such as toluene and xylene, esters of fatty acids such as ethyl acetate and butyl acetate, and halogenated hydrocarbons such as Methylene chloride and chloroform are cited. Among them, toluene, ethyl acetate and butyl acetate are preferably used in view of an industrial application. As the organic solvent, any organic solvents that do not mix with water homogenously in the present invention can be employed, and a mixture of plural organic solvents that can form a separate layer against the water layer in the solution can also be employed. For mixed solvents having 2 layers, mixed solvents forming 2 layers are typically used where a layer is separated from the water layer in the solution. The mixed solvents forming 3 separate layers therein can also be used in such circumstances. For the amount used of the organic solvent (one or more solvents), there are no special limitations in it. The superior yield is improved as the proportion of the amount of organic solvent used increases compared to the amount of water used. In the event that such extraction operations are repeated, the performance of the masses approaches 100% of them without limit. There are no problems, of course that the solvent does not have reactivities for the starting materials and the desired product, for example, acetic acid, methanol, dioxane, dimethylformamide, etc. they can be mixed in the solution having two layers consisting of such an organic solvent and water with the condition that two separate layers are maintained without decomposition. With respect to the temperature for treatment in the process of the present invention, there are no problems that temperatures higher than the boiling point of the organic solvent can be used. And yet, the decomposition of the desired product in the treatment step in the very high temperature range can be brought about, and therefore preferably a temperature range of from 0 to 100 ° C is preferably selected. About the period of time for the treatment in the process of the present invention there are no special limitations therein. And yet, the decomposition of the product in the treatment can be caused under the very long period of time, and therefore the treatment typically operates for 60 minutes or less if it is sufficient. For the steps of the purification method, the following aspects may be employed. The crystals containing aL-aspartyl-L-phenylalanine methyl ester are placed in the 2 separate layers of the solution from a layer of water and an organic layer obtained from one or more organic solvents immiscible with water homogeneously, and Stir the mixture to dissolve the crystals. After confirmation of the fact that the crystals dissolve perfectly in the solution, it is further stirred for a given period of time. After this, stirring is stopped, and after confirmation of the fact that the two separate layers are formed in the solution, one layer of the other layer can be separated. On the other hand, for the steps of the recovery method in the present invention, the following aspects may be employed. To an aqueous solution (eg, crystallization mother liquor) that dissolves both α-L-aspartyl-L-phenylalanine methyl ester and N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester, it is added at less an organic solvent (one or more solvents) and the mixture is stirred for a given period of time. After this, agitation is stopped, and after confirmation of the fact that the two separate layers are formed in the solution, one layer of the other layer can be separated. In both previous methods, in order to improve the performance more, the organic solvent can also be added to the water layer and the extraction operations in the same can be repeated. In both methods, the organic layer extracted and obtained from the two layers separated in the solution can be concentrated under reduced pressure to the solid material to obtain N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester which does not contains aL-aspartyl-L-phenylalanine methyl ester. On the other hand, in order to improve its purity by removing a very small amount of impurities, the crystals obtained in this way can be subjected to recrystallization. In the crystallization mother liquor, the a-L-aspartyl-L-phenylalanine methyl ester is not contained, and therefore can easily be recycled, of course. The present invention is illustrated specifically with reference to the following examples. [EXAMPLE 1] Crystals consisting of 4.5 g of a-L-aspartyl-L-phenylalanine methyl ester and 10 g of N- (3, 3-dimethylbutyl) -a-L-aspartyl-L-phenylalanine methyl ester are added to the solvents. mixed consisting of 1000 ml of ethyl acetate and 500 ml of water, and the mixture is stirred at room temperature. The crystals are completely dissolved in the solution, and then the mixture is further stirred for 25 minutes. The mixture is allowed to stand for 5 minutes to make two separate layers in solution. The organic layer obtained is washed in this way with 100 ml of water and concentrated under reduced pressure to give 9.1 g of white crystals. In the crystals, the a-L-aspartyl-L-phenylalanine methyl ester is not contained. The recovery yield of N- (3, 3-dimethylbutyl) -a-L-aspartyl-L-phenylalanine methyl ester is 91%. [EXAMPLE 2] The crystals consisting of 4.5 g of aL-aspartyl-L-phenylalanine methyl ester and 10 g of N- (3, 3-dimethylbutyl) are added to the mixed solvents of 500 ml of toluene and 100 ml of water. ) -L-aspartyl-L-phenylalanine methyl ester, and the mixture obtained in this way is stirred at 50 ° C. After confirming the fact that the crystals have been completely dissolved in the solution, the mixture is further stirred for 10 minutes. The mixture is allowed to stand for 5 minutes to make two separate layers in solution. The organic layer obtained in this way is washed with 20 ml of water, and concentrated under reduced pressure to obtain 9.3 g of white crystals. In the crystals, a-L-aspartyl-L-phenylalanine methyl ester is not contained. The recovery yield of N- (3, 3-dimethylbutyl) -a-L-aspartyl-L-phenylalanine methyl ester is 93%. [EXAMPLE 3] To the mixed solvents of 1000 ml of toluene and 100 ml of water are added, the crystals consisting of 4.5 g of aL-aspartyl-L-phenylalanine methyl ester and 10 g of N- (3, 3-dimethylbutyl) ) -L-aspartyl-L-phenylalanine methyl ester, and the mixture obtained in this way is stirred at 50 ° C. The crystals are completely dissolved in the solution, and then the mixture is further stirred for 10 minutes. The mixture is allowed to stand for 5 minutes to make 2 separate layers in the solution. The organic layer obtained in this way is concentrated under reduced pressure to obtain 9.5 g of white crystals. The crystals thus obtained are recrystallized from water to obtain 8.8 g of N- (3, 3-dimethylbutyl) -a-L-aspartyl-L-phenylalanine methyl ester. A-L-aspartyl-L-phenylalanine methyl ester is not contained in the crystals. The recovery yield of the same is 88%. [EXAMPLE 4] It is added to 500 ml of an aqueous solution in the concentrations of 0.9 g / dl of aL-aspartyl-L-phenylalanine methyl ester and 0.9 g / dl of N- (3,3-dimethylbutyl) -aL-aspartil -L-phenylalanine methyl ester, 500 ml of ethyl acetate, and the mixture is stirred at room temperature for 10 minutes. It is allowed to stand the mixture for 2 minutes to give 2 separate layers in the solution. To the water layer obtained in this way, 500 ml of ethyl acetate are added, and the operations are repeated in the same previous manner. The organic layers obtained in this way are combined, and concentrated under reduced pressure to obtain 4.3 g of N- (3,3-dimethylbutyl) -a-L-aspartyl-L-phenylalanine methyl ester in the crystalline form. In crystals, a-L-aspartyl-L-phenylalanine methyl ester is not contained. The recovery performance of the same is 95%. [EXAMPLE 5] The mixed solvents of 1000 ml of butyl acetate and 500 ml of water are added to the solvents, the crystals consisting of 4.5 g of aL-aspartyl-L-phenylalanine methyl ester and 10 g of N- (3, 3) -dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester, and the mixture obtained in this manner is stirred at room temperature. After confirming the fact that the crystals have been completely dissolved in the solution, the mixture is further stirred for 25 minutes. The mixture is allowed to stand for 5 minutes to make two separate layers in the solution. The organic layer obtained in this way is washed with 100 ml of water and concentrated under reduced pressure to obtain 9.0 g of white crystals. In crystals, a-L-aspartyl-L-phenylalanine methyl ester is not contained. The recovery performance of N- (3, 3-dimethylbutyl) -a-L-aspartyl-L-phenylalanine is 90%. [EXAMPLE 6] An aqueous solution (500 ml) is concentrated in the concentrations of 0.9 g / dl of a-L-aspartyl-L-phenylalanine <; methyl ester and 0.9 g / dl of N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester under reduced pressure to 100 ml of aqueous solution in the volume 500 ml of toluene is added to the solution , and the mixture is stirred at 60 ° C for 10 minutes.The mixture is allowed to stand for 2 minutes to give 2 separate layers in the solution.The organic layer obtained in this way is washed with 100 ml of water. under reduced pressure to obtain 4.0 g of N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester in the crystalline form In the crystals, the aL-aspartyl-L-phenylalanine methyl ester is not contained The recovery yield thereof is 89% Effect of the invention Under the present invention, it can be purified N- (3, 3-dimet; ilbutyl) -aL-aspartyl-L-phenylalanine methyl ester having a high degree of purity or efficiently recovered in a high yield without using heavy steps or operations The process in the present invention It is preferably used for the purification or recovery thereof, particularly from N- (3,3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester which includes at least a-L-aspartyl-L-phenylalanine methyl ester as an impurity

Claims (4)

1. CLAIMS 1. A process for "purification of N- (3,3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester comprising the step of: contacting N- (3, 3-dimethylbutyl) -aL-aspartil -L-phenylalanine methyl ester containing at least aL-aspartyl-L-phenylalanine methyl ester as an impurity with mixed solvents having two layers of a given layer from at least one organic solvent that does not mix with water homogeneously and a water layer to extract N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester in the organic layer
2. 2. The process according to claim 1, characterized in that the at least organic solvent that is not mixed with water homogeneously is toluene
3. 3. The process according to claim 1, characterized in that the at least organic solvent that is not mixed with water homogeneously is at least one of ethyl acetate and butyl acetate. 4. A process for the recovery of N- (3,3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester comprising the step of: contacting an aqueous solution of N- (3,3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester by dissolving at least α-L-aspartyl-L-phenylalanine methyl ester as an impurity, with at least one organic solvent that does not mix with water homogeneously to extract N- (3, 3-dimethylbutyl) -aL-aspartyl-L-phenylalanine methyl ester in the organic layer. 5. N- (3, 3-dimethylbutyl) -a-L-aspartyl-L-phenylalanine methyl ester obtained in the process according to claim 1 or
4. 4.