Method for reducing sucralose-6-acetate residue in sucralose alcoholysis process

Abstract

The invention discloses a method for reducing the residue of sucralose-6-acetate in the sucralose alcoholysis process, the alcoholysis reaction can be more thorough through three evaporators and a multi-stage alkali supplement mode, so that the residue level of sucralose-6-acetate in the alcoholysis reaction process is effectively reduced; and the methanol solvent is recycled, so that the total consumption of methanol is reduced, the production cost is reduced, the evaporation capacity of each evaporator is increased, and the alcoholysis reaction is further promoted. The method is simple, the material temperature in the whole process ranges from 20 DEG C to 50 DEG C, reaction conditions are mild, the requirement for equipment is low, safety is high, and the method has the advantages of being low in energy consumption and beneficial to improving the product purity and the conversion rate and is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of sucralose production, and particularly to a method for reducing the residue of sucralose-6-acetate during the alcoholysis of sucralose. Background Art

[0002] Sucralose (TGS), with the chemical name 4,1’,6’-trichloro-4,1’,6’-trideoxygalactosucrose, is currently the only sweetener made from sucrose. It has a sweetness 400 - 800 times that of sucrose, with a taste basically the same as sucrose and no bitter aftertaste. Due to its high safety and the characteristic of not being absorbed and utilized by the human body, it is regarded as the optimal sweetener.

[0003] During the production of sucralose, sucralose-6-acetate is a key intermediate in the production of sucralose. This intermediate product is regarded as an impurity in the finished product, which has a certain impact on the taste and safety of sucralose. The residual level of this intermediate product in the material after the alcoholysis reaction directly affects the quality of the final product.

[0004] Currently, there are various methods for synthesizing sucralose from sucralose-6-acetate in industrial production, but most of them directly carry out an alcoholysis reaction in a methanol system to generate sucralose in one step. How to reduce the residue of sucralose-6-acetate on the basis of the existing methanol system and reduce the production cost plays an important role in improving the quality and conversion rate of sucralose products and the economic benefits of industrial production. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for reducing the residue of sucralose-6-acetate during the alcoholysis of sucralose. Through three sets of evaporators and multi-stage alkali supplementation, the alcoholysis reaction can be made more complete, thereby effectively reducing the residual level of sucralose-6-acetate in the alcoholysis reaction process, facilitating the improvement of the quality and conversion rate of sucralose products, and reducing the production cost.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for reducing the residue of sucralose-6-acetate during the alcoholysis of sucralose provided by the present invention includes the following steps:

[0008] (1) Mix and stir sucralose-6-acetate with methanol according to a mass ratio of sucralose-6-acetate:methanol = 1:2 - 5, and dissolve all of the sucralose-6-acetate with a content of 90 - 100%, preferably 92 - 99%, to obtain a sucralose-6-acetate solution;

[0009] (2) Dissolve sodium methoxide and methanol by mixing them according to a mass ratio of sodium methoxide∶methanol = 1∶18 - 30 to obtain a sodium methoxide solution;

[0010] (3) Add the sucralose-6-acetate solution and the sodium methoxide solution to a reaction tank and mix them to make the pH value of the solution system 10.0 - 12.0, obtaining a sucralose-6-acetate alcoholysis solution;

[0011] (4) Transfer the sucralose-6-acetate alcoholysis solution to an Evaporator I and evaporate it at a temperature of 20 - 50°C. When the bottom density of the distillate is 1.05 - 1.30 kg / m 3 , discharge it to the feed tank of Evaporator II;

[0012] (5) In the Evaporator II, supplement the sodium methoxide solution to control the pH value of the material to 10.0 - 12.0, and evaporate the material at a temperature of 20 - 50°C. When the bottom density of the distillate is 1.05 - 1.30 kg / m 3 , discharge it to the feed tank of Evaporator III; The methanol distilled out from Evaporator II is recycled and supplemented to step (1) for dissolving sucralose-6-acetate;

[0013] (6) In the Evaporator III, supplement the sodium methoxide solution to control the pH value of the material to 10.0 - 12.0, and evaporate the material at a temperature of 20 - 50°C. When the bottom density of the distillate is 1.05 - 1.30 kg / m 3 , discharge it to a neutralization tank; The methanol distilled out from Evaporator III is recycled and supplemented to the feed tank of Evaporator II and mixed with the material;

[0014] (7) Adjust the pH value of the reaction solution in the neutralization tank to neutral to obtain a reaction solution with a sucralose-6-acetate content ≤ 0.015%.

[0015] The present invention has the following beneficial effects:

[0016] (1) By recycling the methanol distilled out by three sets of evaporators in the present invention, not only the total amount of methanol used is reduced, the cost of methanol recovery is saved, but also the evaporation amount of each evaporator is increased, which can effectively promote the progress of the alcoholysis reaction.

[0017] (2) In the evaporation process of the present invention, a multi-stage alkali supplementation method is adopted to maintain the alkalinity of the reaction solution, so that the alcoholysis reaction can proceed more thoroughly. After neutralization to stop the reaction, the sucralose-6-acetate reacts sufficiently, and there are few impurities decomposed from sucralose, thereby effectively reducing the residue of sucralose-6-acetate in the alcoholysis reaction process.

[0018] (3) The process method of the present invention is simple. During the whole process, the material temperature is between 20°C and 50°C, the reaction conditions are mild, the requirements for equipment are low, the safety is high, and it has the characteristics of low energy consumption, being conducive to improving the product purity and conversion rate, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described in detail below in conjunction with embodiments and drawings:

[0020] Figure 1 It is a schematic process flow diagram of an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] Example 1:

[0022] In this example, a method for reducing the residue of sucralose-6-acetate during the alcoholysis of sucralose is as Figure 1 shown, and the steps are as follows:

[0023] (1) Add 2000 kg of sucralose-6-acetate with a content of 93% and 3200 kg of methanol (including the methanol evaporated from the No. II evaporator) into the batching tank for mixing and stirring until all the sucralose-6-acetate is dissolved, obtaining a sucralose-6-acetate solution;

[0024] (2) Mix and dissolve sodium methoxide and methanol in the sodium methoxide dissolution tank to obtain a sodium methoxide solution with a mass fraction of 5%;

[0025] (3) Add the above-mentioned sucralose-6-acetate solution and sodium methoxide solution into the reaction tank for mixing, so that the pH value of the solution system is 11.0, obtaining a sucralose-6-acetate alcoholysis solution;

[0026] (4) Transfer the above-mentioned sucralose-6-acetate alcoholysis solution into the No. I evaporator and evaporate it at a temperature of 40°C. When the bottom density of the distillate is 1.10 kg / m 3 , discharge it to the feed tank of the No. II evaporator;

[0027] (5) In the above-mentioned No. II evaporator, supplement the sodium methoxide solution to control the pH value of the material (including the methanol evaporated from the No. III evaporator) to 11.0, and evaporate the material at a temperature of 40°C. When the bottom density of the distillate is 1.10 kg / m 3 , discharge it to the feed tank of the No. III evaporator; the methanol evaporated from the No. II evaporator is temporarily stored in the first temporary storage tank for reuse and supplemented to step (1) for dissolving sucralose-6-acetate;

[0028] (6) In the above-mentioned No. III evaporator, supplement the sodium methoxide solution to control the pH value of the material to 11.0, and evaporate the material at a temperature of 40°C. When the bottom density of the distillate is 1.10 kg / m3 When the time comes, discharge the material to the neutralization tank; the methanol distilled out by the No. III evaporator is temporarily stored in the second temporary storage tank for reuse and supplementation to the feed tank of the No. II evaporator for mixing with the material;

[0029] (7) Adjust the pH value of the reaction solution in the above-mentioned neutralization tank to neutral to obtain a reaction solution with a sucralose-6-acetate content of 0.015%.

[0030] Example Two:

[0031] A method for reducing the residue of sucralose-6-acetate during the alcoholysis of sucralose in this example is as Figure 1 shown, and the steps are as follows:

[0032] (1) Add 2000 kg of sucralose-6-acetate with a content of 93% and 3200 kg of methanol (including the methanol distilled out by the No. II evaporator) to the batching tank for mixing and stirring to completely dissolve the sucralose-6-acetate, obtaining a sucralose-6-acetate solution;

[0033] (2) Mix and dissolve sodium methoxide and methanol in the sodium methoxide dissolution tank to obtain a sodium methoxide solution with a mass fraction of 5%;

[0034] (3) Add the above-mentioned sucralose-6-acetate solution and sodium methoxide solution to the reaction tank for mixing, so that the pH value of the solution system is 11.5, obtaining a sucralose-6-acetate alcoholysis solution;

[0035] (4) Transfer the above-mentioned sucralose-6-acetate alcoholysis solution to the No. I evaporator and evaporate it at a temperature of 40 °C. When the bottom density of the distillate is 1.10 kg / m 3 discharge the material to the feed tank of the No. II evaporator;

[0036] (5) In the above-mentioned No. II evaporator, supplement the sodium methoxide solution to control the pH value of the material (including the methanol distilled out by the No. III evaporator) to 11.5, and the material is evaporated at a temperature of 40 °C. When the bottom density of the distillate is 1.10 kg / m 3 discharge the material to the feed tank of the No. III evaporator; the methanol distilled out by the No. II evaporator is temporarily stored in the first temporary storage tank for reuse and supplementation to step (1) for dissolving sucralose-6-acetate;

[0037] (6) In the above-mentioned No. III evaporator, supplement the sodium methoxide solution to control the pH value of the material to 11.5, and the material is evaporated at a temperature of 40 °C. When the bottom density of the distillate is 1.10 kg / m 3 discharge the material to the neutralization tank; the methanol distilled out by the No. III evaporator is temporarily stored in the second temporary storage tank for reuse and supplementation to the feed tank of the No. II evaporator for mixing with the material;

[0038] (7) Adjust the pH value of the reaction solution in the above neutralization tank to neutral to obtain a reaction solution with a sucralose-6-acetate content of 0.011%.

[0039] Example 3:

[0040] A method for reducing the residue of sucralose-6-acetate during the alcoholysis of sucralose in this example is as follows Figure 1 shown, and its steps are as follows:

[0041] (1) Add 2000 kg of sucralose-6-acetate with a content of 93% and 3200 kg of methanol (including the methanol distilled out from the No. II evaporator) to the batching tank for mixing and stirring to completely dissolve the sucralose-6-acetate, obtaining a sucralose-6-acetate solution;

[0042] (2) Mix and dissolve sodium methoxide with methanol in the sodium methoxide dissolution tank to obtain a sodium methoxide solution with a mass fraction of 5%;

[0043] (3) Add the above sucralose-6-acetate solution and sodium methoxide solution to the reaction tank for mixing to make the pH value of the solution system 11.5, obtaining a sucralose-6-acetate alcoholysis solution;

[0044] (4) Transfer the above sucralose-6-acetate alcoholysis solution to the No. I evaporator and evaporate it at a temperature of 40 °C. When the bottom density of the distillate is 1.15 kg / m 3 , discharge it to the feed tank of the No. II evaporator;

[0045] (5) In the above No. II evaporator, supplement the sodium methoxide solution to control the pH value of the material (including the methanol distilled out from the No. III evaporator) to 11.5, and evaporate the material at a temperature of 40 °C. When the bottom density of the distillate is 1.15 kg / m 3 , discharge it to the feed tank of the No. III evaporator; the methanol distilled out from the No. II evaporator is temporarily stored in the first temporary storage tank for reuse and supplemented to step (1) for dissolving sucralose-6-acetate;

[0046] (6) In the above No. III evaporator, supplement the sodium methoxide solution to control the pH value of the material to 11.5, and evaporate the material at a temperature of 40 °C. When the bottom density of the distillate is 1.15 kg / m 3 , discharge it to the neutralization tank; the methanol distilled out from the No. III evaporator is temporarily stored in the second temporary storage tank for reuse and supplemented to the feed tank of the No. II evaporator for mixing with the material;

[0047] (7) Adjust the pH value of the reaction solution in the above neutralization tank to neutral to obtain a reaction solution with a sucralose-6-acetate content of 0.008%.

[0048] Comparative example:

[0049] Taking only one evaporation as a comparative example, the steps are as follows:

[0050] (1) Add 2000 kg of sucralose-6-acetate with a content of 93% and 3200 kg of methanol into a batching tank and mix and stir to completely dissolve the sucralose-6-acetate to obtain a sucralose-6-acetate solution;

[0051] (2) Mix and dissolve sodium methoxide and methanol in a sodium methoxide dissolution tank to obtain a sodium methoxide solution with a mass fraction of 5%;

[0052] (3) Add the above-mentioned sucralose-6-acetate solution and sodium methoxide solution into a reaction tank and mix to make the pH value of the solution system 11.5 to obtain a sucralose-6-acetate alcoholysis solution;

[0053] (4) Transfer the above-mentioned sucralose-6-acetate alcoholysis solution into an evaporator and evaporate at a temperature of 40 °C. When the bottom density is 1.10 kg / m 3 , discharge to a neutralization tank;

[0054] (5) Adjust the pH value of the reaction solution in the above-mentioned neutralization tank to neutral to obtain a reaction solution with a sucralose-6-acetate content of 0.055%.

Claims

1. A method for reducing the residual sucralose-6-acetate during the alcoholysis of sucralose, characterized in that The following steps are involved: (1) mixing 90-100% sucralose-6-acetate and methanol in a mass ratio of sucralose-6-acetate to methanol = 1:2-5, stirring to dissolve all the sucralose-6-acetate, thereby obtaining a sucralose-6-acetate solution; (2) mixing and dissolving sodium methoxide and methanol in a mass ratio of sodium methoxide to methanol = 1:18-30 to obtain a sodium methoxide solution; (3) adding the sucralose-6-acetate solution and the sodium methoxide solution into a reaction tank and mixing them so that the pH value of the solution system is 10.0 to 12.0, thereby obtaining a sucralose-6-acetate alcoholysis solution; (4) The sucralose-6-acetate alcoholysis liquid is transferred to evaporator No. 1 and evaporated at a temperature of 20 to 50° C. When the bottom density is 1.05 to 1.30 kg / m 3 When the material is discharged to the feed tank of evaporator No. II; (5) In the evaporator II, sodium methoxide solution is added to control the pH value of the material to 10.0-12.0, and the material is evaporated at a temperature of 20-50° C. When the bottom density is 1.05-1.30 kg / m 3 When the evaporator is heated to 100 ℃, the material is discharged to the feed tank of evaporator No. III; the methanol evaporated from evaporator No. II is used to replenish step (1) for dissolving sucralose-6-acetate; (6) In the evaporator No. III, sodium methoxide solution is added to control the pH value of the material to 10.0-12.0, and the material is evaporated at a temperature of 20-50° C. When the bottom density is 1.05-1.30 kg / m 3 When the material is discharged to the neutralization tank, the methanol evaporated from the evaporator No. III is used to supplement the feed tank of the evaporator No. II and mix with the material; (7) adjusting the pH value of the reaction solution in the neutralization tank to neutral to obtain a reaction solution with a sucralose-6-acetate content of ≤0.015%.

2. The method for reducing the residual sucralose-6-acetate during the alcoholysis of sucralose according to claim 1, characterized in that: The content of sucralose-6-acetate in the step (1) is 92-99%.

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