JPS6159311B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing sorbitan by heating and stirring D-sorbitol with H-type strongly acidic cation exchange fibers under reduced pressure. Sorbitan is obtained by removing one molecule of water from two hydroxyl groups of D-sorbitol, and therefore sorbitan can be divided into 1-4 sorbitan, 3-6 sorbitan, and 2-5 sorbitan depending on the position of the hydroxyl group to be dehydrated. It is a mixture (hereinafter, sorbitan refers to this isomer mixture). The sorbitan obtained by dehydrating D-sorbitol can be esterified with fatty acids such as lauric acid, palmitic acid, stearic acid, and oleic acid to form a highly lipophilic nonionic product known as "span". of surfactant is obtained. These fatty acid esters are widely used as food additives such as emulsifiers for ice cream and the like. An object of the present invention is that sorbitan can be produced in a much simpler process than D-sorbitol. Conventionally, to obtain sorbitan, D-sorbitol is heated under reduced pressure in the presence of a dehydrating agent such as a mineral acid, and after the dehydration is completed, the reaction solution is diluted with water and dissolved, and then neutralized with calcium hydroxide. By desalting and purifying the filtered solution using an ion exchange resin and concentrating it, a concentrated liquid or powder can be obtained. Dehydrating agents used include sulfuric acid, toluenesulfonic acid,
Inorganic and organic acids such as oxalic acid are used. However, the disadvantages of this conventional production method are that after the dehydration reaction, the reaction solution must be diluted with water to remove the added dehydrating agent, and calcium hydroxide is added to reduce the load on the ion exchange resin. These problems include the need to precipitate it as a calcium salt, and the complicated process of desalting using an ion exchange resin and then concentrating it. Furthermore, a drawback of the conventional method is that because a strong acid such as sulfuric acid is added as a dehydrating agent, side reactions such as polymerization other than dehydration occur, which causes coloring due to impurities. Therefore, a large amount of activated carbon is required to decolorize this, resulting in extremely expensive sorbitan. In order to improve the drawbacks of these conventional methods, the present inventors have succeeded in producing sorbitan with extremely little coloring by using H-type strongly acidic cation exchange fibers as a dehydrating agent, and also simplifying the production process. I was able to do it. To explain the method of the present invention in detail, for example, an aqueous solution of D-sorbitol or anhydrous sorbitol is concentrated or melted to an anhydrous state, and a strongly acidic cation exchange fiber made into an H-type is added to the solution at 1% for D-sorbitol.
Add ~15% (as anhydrous) and stir while stirring.
Heat to 100-150°C for 1-10 hours under 100 mmHg vacuum. After the dehydration reaction is completed, a slightly yellow liquid is obtained by heating, and the liquid contains 60 to 85% sorbitan (based on the anhydrous raw material). By treating this reaction solution with activated carbon, a colorless sorbitan solution can be obtained. The strongly acidic cation exchange fibers used in the present invention are prepared by impregnating and absorbing a mixture of a vinyl polymer such as styrene, a crosslinking agent such as divinylbenzene, and a polymerization initiator into, for example, polyolefin fibers or polyacrylic fibers. It can be obtained by introducing a sulfon group after polymerization. This exchange fiber has a diameter of 200 μm or less and an aspect ratio of 3 to 5,000, preferably 10 to 2,000. If the aspect ratio is too small or too large, handling becomes difficult.
This replacement fiber also has the advantage that it can withstand repeated use in the process of the invention. The temperature of the dehydration reaction in the method of the present invention is 100°C or higher and 150°C or higher, preferably 110°C or higher and 140°C or lower. At a temperature below 100°C, the dehydration reaction will not be carried out well, and at a temperature above 150°C, the coloring of the reaction solution will become strong and the fibers will decompose, which is undesirable. The reaction product of the present invention obtained above is a slightly yellow liquid and contains almost no ionic substances, so it has the advantage that it can be used as a raw material for fatty acid ester as it is. It goes without saying that powdered sorbitan can also be obtained from this reaction product. Next, the present invention will be explained in more detail with reference to Examples. Example 1 A stirrer is inserted into the center of a three-necked flask, and a vacuum-resistant seal is placed between the flask and the three-necked flask. The other port is connected to a thermometer, and one port is connected to a vacuum pump via a condenser. The three-necked flask is heated in an oil bath. 500 g of D-sorbitol powder is placed in this flask and melted by heating to bring the temperature of the melt to 120°C. H to this
25g of molded sulfonic acid type cation exchange fiber
(As anhydride; manufactured by Mitsubishi Rayon Co., Ltd., QCS-
110), and while stirring at a speed of 300 rpm per minute, keep the temperature at 120°C under a reduced pressure of 50 mmHg to allow a dehydration reaction for 3 hours. Water produced by dehydration of D-sorbitol is collected by the above-mentioned condenser. After the dehydration reaction is completed, the contents are taken out and filtered under suction while hot (while heating if necessary). 5 g of powdered activated carbon (manufactured by Hokuetsu Tanso Kogyo Co., Ltd., SD) is added to the liquid, and the mixture is heated to approximately 120°C. The colorless liquid was removed by suction. When this liquid was analyzed by gas chromatography, the following results (solid content composition; the same applies hereinafter) were obtained. Sorbitan 77.9% D-sorbitol 16.9% Isosorbide 3.8% Others 1.4% Example 2 Using the same equipment as in Example 1, 500 g of D-sorbitol powder was heated and melted at 110°C, and then subjected to cation exchange in the same manner as in Example 1. 50 g of fiber (as anhydrous) was added and heated at a temperature of 105° C. for 8 hours under a vacuum of 30 mmHg and stirring at a speed of 300 rpm. After the reaction was completed, the contents were taken out from the flask and filtered under suction while hot to obtain a slightly yellow liquid. When this liquid was analyzed by gas chromatography, the following results were obtained. Sorbitan 63.5% D-sorbitol 34.9% Isosorbide 1.2% Others 1.4% Example 3 Using the same equipment as in Example 1, 500 g of D-sorbitol powder was heated and dissolved at 130°C, and then subjected to cation exchange in the same manner as in Example 1. 15 g of fiber (as anhydrous) was added and heated for 2 hours under a reduced pressure of 5 mmHg with stirring at a speed of 300 rpm. After the reaction was completed, the contents were taken out from the flask, filtered through a hot cloth, 10 g of activated carbon was added to the solution, and the solution was filtered with suction while heating to about 120° C. to obtain a slightly yellow liquid. When this liquid was analyzed by gas chromatography, the following results were obtained. Sorbitan 77.5% D-sorbitol 17.0% Isosorbide 4.5% Others 1.0% Example 4 Using the same equipment as in Example 1, 500 g of D-sorbitol powder was heated and dissolved at 140°C, and then subjected to cation exchange in the same manner as in Example 1. Add 10g of fiber (as anhydrous) and 300rpm/min under vacuum of 80mmHg.
The mixture was heated at 145°C for 2 hours while stirring at a speed of . After the reaction was completed, the contents were taken out from the flask, filtered under suction while hot, 20 g of activated carbon was added to the liquid, and heated to about 120°C and filtered under suction to obtain a slightly yellow liquid. When this liquid was analyzed by gas chromatography, the following results were obtained. Sorbitan 79.1% D-sorbitol 13.9% Isosorbide 5.2% Others 1.8% Example 5 Using the same equipment as in Example 1, 500 g of D-sorbitol powder was heated and melted at 120°C, and to this was added the reaction-completed liquid of Example 1. The separately collected cation exchange fibers were added and heated at a temperature of 120° C. for 3 hours under reduced pressure of 50 mmHg and stirring at a rotation speed of 300 rpm. After the reaction was completed, the contents were taken out and filtered under hot suction. Add 5g of activated carbon to this and make about 120
A colorless liquid was obtained by suction while heating to ℃. When this liquid was analyzed by gas chromatography, the following results were obtained. Sorbitan 76.4% D-sorbitol 18.8% Isosorbide 3.6% Others 1.2% Next, the sorbitan-containing aqueous solution obtained by heating and dehydrating D-sorbitol with strongly acidic cation exchange fibers as described above is treated with an alkaline earth metal. High purity sorbitan could be produced by passing it through a column of adsorbed cation exchanger. As mentioned above, conventionally, sorbitan obtained by dehydration of D-sorbitol has been esterified with higher fatty acids to obtain a highly lipophilic nonionic surfactant. Furthermore, if a surfactant is produced from highly pure sorbitan with impurities removed, the resulting surfactant will have different properties, and it is thought that this will have applications in the medical field as well. Conventionally, highly pure sorbitan can be obtained by crystallization or distillation from a dehydrated solution of D-sorbitol. However, when obtaining sorbitan by crystallization, the yield is low due to the high solubility of sorbitan in water; if a solvent is used, the yield increases but the production cost increases; and when obtained by distillation, the boiling point is low. Due to its high temperature, further dehydration is required to produce isosorbide, making it impractical (JACS 68 , 919; US
P.3484459). However, as mentioned above, a column is packed with a cation exchanger adsorbed with an alkaline earth metal, and a dehydrated aqueous solution of D-sorbitol is passed through the column.
Next, by elution with water, extremely high purity sorbitan can be obtained at low cost. As the cation exchanger, cation exchange resins, cation exchange fibers, cation exchange Cephadex, etc. can be used, but sulfonic acid type strongly acidic cation exchange resins are most effective. This cation exchanger is packed in a column, and H
After forming a mold, it is loaded with a salt of an alkaline earth metal (calcium, barium, magnesium, strontium, etc.) to form an alkaline earth metal type cation exchanger. A fixed amount of a dehydrated aqueous solution (concentration: 50 to 70%) of D-sorbitol according to the method of the present invention is passed through this, and then eluted with water.
Next, isosorbide and D-sorbitol are eluted (the elution temperature is preferably 30 to 90°C). The first eluting portion of sorbitan is highly purified sorbitan containing no D-sorbitol or isosorbide. Furthermore, the D-sorbitol portion that comes out later can be reused as a raw material for sorbitan by concentrating it. The particle size of the cation exchange resin used as the cation exchanger is preferably 30 to 200 mesh. Further, as the cation exchange fiber, for example, the same fiber as that used in the dehydration reaction of D-sorbitol described above can be used. To describe the above production example of high-purity sorbitan,
Calcium type polyvinylbenzenesulfonic acid type cation exchange resin SK-IBS (Mitsubishi Kasei Corporation)
50-10 mesh) was packed into a jacketed column (diameter 2.4 cm/length 80 cm) and maintained at 60°C. A sorbitan aqueous solution produced by the method of the present invention (solid composition: sorbitan 78.2%, isosorbide 4.8%, D-sorbitol 17.0%) was placed in this packed column.
25 ml of a 60% aqueous solution was supplied and then fractionated using a fraction collector that was continuously eluted with water. The flow rate of the eluate was 100 ml/hour;
The volume of each fraction was 12 ml. Each fraction was analyzed by gas chromatography and the results are shown in Table 1 and Figure 1. Fraction No.12 to 24
By collecting the above, a 100% pure sorbitan aqueous solution was obtained.

[Table] The same procedure as above was performed except that the strontium type filler was used, and the analysis results were as shown in Table 2 and Figure 2.

【table】 [Brief explanation of the drawing]

Both Figures 1 and 2 are D by the method of the present invention.
- This is an example of a chromatogram obtained when a sorbitan aqueous solution produced by dehydrating sorbitol is subjected to ion exchange column chromatography.

Claims (1)

[Claims] 1. Strongly acidic cation exchange fibers made into H type are added to D-sorbitol, and this is heated at 100°C or higher at 150°C under reduced pressure.
A method for producing sorbitan characterized by heating and stirring at a temperature below ℃. 2 Strongly acidic cation exchange fibers with a diameter of 200μ or less,
The method according to claim 1, wherein the shape has an aspect ratio of 3 to 500.