High-temperature continuous reaction method in chlorination step of sucralose production

Abstract

The invention provides a high-temperature continuous reaction method in a chlorination step of sucralose production, and belongs to the technical field of organic synthesis. The method comprises the following steps: (1) placing trichloroethane, thionyl chloride and esterification liquid in a low-temperature material collecting tank to obtain a low-temperature material; (2) pumping the low-temperature material into a high-temperature kettle to obtain a high-temperature material; in the step (2), the low-temperature materials are pumped into the high-temperature kettle in a continuous stage feeding mode. In order to balance the liquid level in the high-temperature kettle, the low-temperature material is pumped into the high-temperature kettle while the high-temperature material is conveyed to the high-temperature material collecting tank, the device is simple, the process is not complicated, excessive participation of personnel in device production is avoided, manpower is saved, the labor cost is reduced, and meanwhile, the safety of the device is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a method for high-temperature continuous reaction in a chlorination step of sucralose production. Background Art

[0002] Sucralose is a high-intensity sweetener made from sucrose through a chlorination reaction. It was jointly developed and patented by Tate & Lyle and the University of London in 1976 and was put on the market in 1988. The chemical name of sucralose is 4,1′,6′-trichloro-4,1′,6′-trideoxygalactosucrose, and its molecular formula is C 12 H 19 O8Cl3, molecular weight is 397.64.

[0003] Sucralose has the following advantages: (1) High sweetness: The sweetness of sucralose is about 400 to 800 times that of sucrose; (2) High stability: It has high stability at room temperature and different pH values, and does not undergo chemical changes when stored for more than one year; (3) Good solubility: It is very soluble in water and can also be dissolved in organic solvents such as ethanol and methanol; (4) High safety: It does not participate in metabolism in the human body, has a zero calorie value, and is suitable for use by diabetic patients. It does not cause tooth decay: It is not used by tooth decay bacteria and helps to prevent tooth decay. In addition, sucralose is not absorbed in the human body and does not participate in metabolism. It was approved by the US FDA in 1998 and can be used as a universal sweetener for all foods.

[0004] The synthesis process of sucralose mainly includes: chemical synthesis method: using sucrose as raw material, it is synthesized through steps such as tritylation, acetylation, deacetylation and chlorination. The chemical synthesis method has more steps and the process is relatively complicated; chemical-enzymatic synthesis method: combining chemical methods and enzyme-catalyzed reactions, it is synthesized through protective groups and chlorination steps. The enzyme synthesis method also has the problem of more steps, high cost and great difficulty in purification; monoester method: using sucrose as raw material, generating monoester and then selectively chlorinating, and finally deesterifying to obtain sucralose. The monoester method has fewer steps, lower cost and is suitable for industrial production.

[0005] Sucralose has become one of the important sweeteners in the food industry due to its high sweetness, stability and safety, and has been widely used and recognized around the world. At present, sucralose has been widely used in a variety of foods, such as carbonated beverages, still beverages, alcoholic beverages, sweets, canned fruits and vegetables, pickled foods, sauces, jams, baked goods, ice cream, dairy products, etc.

[0006] The prior art generally uses sucrose as raw material, and sequentially undergoes tinization, esterification, and chlorination to obtain sucralose-6-acetate, which is then deacylated to obtain sucralose. In the chlorination reaction of sucralose, the material needs to absorb heat so that the material undergoes a chlorination reaction. During the entire heating process, the material rises from a low temperature of less than 10°C to 110°C, which takes about 10 hours and is a single-pot intermittent operation. The overall process time is long, the operation is frequent, and the heating rate requirements are high. If the rate is slow, it will affect the overall production progress. If the rate is too fast, the amount of tail gas released in the chlorination reaction will be too large, which will have a certain impact on safe production. Therefore, it is necessary to develop a sucralose processing technology with a simple overall process, short reaction time, high production efficiency, and low production cost. Summary of the invention

[0007] Based on the deficiencies in the prior art, the present invention aims to provide a method for high-temperature continuous reaction in the chlorination step of sucralose production, which has a simple overall process, short reaction time, high production efficiency and low production cost.

[0008] In order to achieve the above object, the present invention adopts the following scheme:

[0009] A method for high temperature continuous reaction in the chlorination step of sucralose production, comprising the following steps:

[0010] (1) placing trichloroethane, thionyl chloride and esterification liquid in a low-temperature material collecting tank to obtain a low-temperature material;

[0011] (2) Pump the low-temperature material into the high-temperature kettle to obtain the high-temperature material.

[0012] in:

[0013] The esterification liquid described in step (1) is a DMF solution of sucrose-6-acetate.

[0014] The volume ratio of trichloroethane, thionyl chloride and esterification liquid in step (1) is 4-6:1-2:1.5-2.2; preferably, the volume ratio of trichloroethane, thionyl chloride and esterification liquid is 5.4:1.2:1.9.

[0015] Specifically, the low-temperature material described in the above step (1) is prepared according to the method disclosed in patent CN111644118A.

[0016] In the above step (2), the low-temperature material is pumped into the high-temperature kettle in a continuous staged feeding manner.

[0017] The continuous staged feeding is divided into three stages, specifically:

[0018] The first stage of feeding: the low-temperature material in the low-temperature material collection tank is pumped into the high-temperature kettle by a centrifugal pump. The temperature in the high-temperature kettle continues to rise. After reaching the ideal temperature, the second stage of feeding is carried out;

[0019] The second stage of feeding: after the low-temperature materials in the first stage of feeding are heated to the ideal temperature and the liquid level in the kettle reaches 6000L, a centrifugal pump is used to transport them into the high-temperature material collection tank. At the same time, the low-temperature materials in the low-temperature material collection tank are pumped into the high-temperature kettle to ensure the liquid level balance in the high-temperature kettle;

[0020] The third feeding stage: Same as the second feeding stage, on the basis of ensuring the liquid level balance, the low-temperature material is continuously transported from the low-temperature material collection tank into the high-temperature kettle to achieve continuous heating of the low-temperature material.

[0021] The power of the centrifugal pump in the above steps is 5.5kw.

[0022] The pumping flow rate of the centrifugal pump in the first stage of the above feed is 1.0-1.5m 3 / h; the pumping flow rate of the centrifugal pumps in the second and third stages of the above-mentioned feeding is 1.5-3m 3 / h.

[0023] The ideal temperature as described in the above steps is 109-111°C.

[0024] The pressure of the high temperature autoclave in the above steps is -5Kpa-2Kpa.

[0025] In the above steps, in order to balance the liquid level in the high-temperature kettle, the high-temperature material is transported to the high-temperature material collection tank while the low-temperature material is pumped into the high-temperature kettle. The purpose is to ensure that the temperature in the high-temperature kettle is maintained at 109-111°C.

[0026] As some preferred embodiments, the above method further comprises a tail gas collection step.

[0027] The tail gas collection is as follows: in step (2), tail gas is generated during the heating of the low-temperature material, and the tail gas is sent to a condenser for condensation. The condensed trichloroethane is reprocessed and then re-enters the low-temperature kettle for use as a solvent, thereby achieving the purpose of recycling.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The method for high-temperature continuous reaction in the chlorination step of sucralose production provided by the present invention realizes the continuous high-temperature reaction, thereby improving production efficiency and reducing unnecessary depreciation losses of the device.

[0030] (2) The method of the present invention is simple and the process is not complicated, which avoids too many people from participating in the production of the device, saves manpower, reduces labor costs, and improves the safety of the device;

[0031] (3) This process improves the efficiency of high-temperature production reactions. The process disclosed in the present invention can save 2-3 hours for each batch of high-temperature material output, saving production time and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a flow chart of the method for high temperature continuous reaction in the chlorination step of sucralose production. DETAILED DESCRIPTION

[0033] The present invention is further described below by way of examples and drawings, but the present invention is not limited thereto.

[0034] Example 1 A method for high temperature continuous reaction in the chlorination step of sucralose production

[0035] The steps include:

[0036] (1) placing trichloroethane, thionyl chloride and esterification liquid in a low-temperature material collecting tank to obtain a low-temperature material;

[0037] Specifically, trichloroethane cooled to -1-5 degrees Celsius is mixed at a flow rate of 1800L / H and thionyl chloride at a flow rate of 400L / h, and the flow rates are adjusted by a pump and pumped into the two inlet ends of the first-level Y-type tubular reactor for mixing. The mixed liquid at the outlet end of the first-level Y-type tubular reactor is rapidly cooled to 0-5 degrees with -20 degrees Celsius frozen brine and then pumped into a buffer tank.

[0038] The mixed liquid in the buffer tank is pumped into the two inlet ends of the secondary Y-type tube separator at a flow rate of 1300L / H and the esterification constant volume liquid (300g / L) is pumped into the two inlet ends of the secondary Y-type tube separator at a flow rate of 400L / H. The secondary mixed liquid flowing out of the outlet end of the secondary Y-type tube separator is again rapidly cooled to 0-5 degrees with -20 degrees Celsius frozen brine, and then pumped into a glass-lined reactor with stirring, and continued to cool with frozen brine and maintained at -5 to 15 degrees Celsius. Keep it cold for one hour, and finally the secondary mixed liquid with uniform ingredients is continuously sampled from the outlet of the circulation pump.

[0039] (2) pumping the low-temperature material into a high-temperature kettle, wherein the final temperature of the high-temperature kettle is 109-111° C. and the pressure in the kettle is -5Kpa-2Kpa, to obtain a high-temperature material;

[0040] Specifically:

[0041] The first stage of feeding: the low-temperature material in the low-temperature material collection tank is pumped with a 5.5kw centrifugal pump at 1.0m 3 / h flow rate is pumped into the high-temperature kettle, and the temperature in the high-temperature kettle continues to rise to the ideal temperature of 109℃. After the pressure reaches -5Kpa, the second stage of feeding is carried out;

[0042] Feeding the second stage: After the low-temperature materials in the first stage of feeding are heated to the ideal temperature of 109°C and the liquid level in the kettle reaches 6000L, use a 5.5kw centrifugal pump at 1.5m 3 / h flow rate to transport it into the high temperature material collection tank, and at the same time, the low temperature material in the low temperature material collection tank is transported at a rate of 1.5m 3 / h flow rate is pumped into the high-temperature kettle to ensure the liquid level balance in the high-temperature kettle;

[0043] The third feeding stage: Same as the second feeding stage, on the basis of ensuring the liquid level balance, the low-temperature material is continuously transported from the low-temperature material collection tank into the high-temperature kettle to achieve continuous heating of the low-temperature material.

[0044] Example 2 A method for high temperature continuous reaction in the chlorination step of sucralose production

[0045] The steps include:

[0046] (1) placing trichloroethane, thionyl chloride and esterification liquid in a low-temperature material collecting tank to obtain a low-temperature material;

[0047] Specifically, trichloroethane cooled to -1-5 degrees Celsius is mixed at a flow rate of 1800L / H and thionyl chloride at a flow rate of 400L / h, and the flow rates are adjusted by a pump and pumped into the two inlet ends of the first-level Y-type tubular reactor for mixing. The mixed liquid at the outlet end of the first-level Y-type tubular reactor is rapidly cooled to 0-5 degrees with -20 degrees Celsius frozen brine and then pumped into a buffer tank.

[0048] The mixed liquid in the buffer tank is pumped into the two inlet ends of the secondary Y-type tube separator at a flow rate of 1300L / H and the esterification constant volume liquid (300g / L) is pumped into the two inlet ends of the secondary Y-type tube separator at a flow rate of 400L / H. The secondary mixed liquid flowing out of the outlet end of the secondary Y-type tube separator is again rapidly cooled to 0-5 degrees with -20 degrees Celsius frozen brine, and then pumped into a glass-lined reactor with stirring, and continued to cool with frozen brine and maintained at -5 to 15 degrees Celsius. Keep it cold for one hour, and finally the secondary mixed liquid with uniform ingredients is continuously sampled from the outlet of the circulation pump.

[0049] (2) pumping the low-temperature material into the high-temperature kettle to obtain the high-temperature material;

[0050] Specifically:

[0051] The first stage of feeding: the low-temperature material in the low-temperature material collection tank is pumped into the low-temperature material collection tank with a 5.5kw centrifugal pump at a speed of 1.5m 3 / h flow rate is pumped into the high-temperature kettle, and the temperature in the high-temperature kettle continues to rise to the ideal temperature of 111°C. After the pressure reaches 2Kpa, the second stage of feeding is carried out;

[0052] Feeding the second stage: After the low-temperature material in the first stage of feeding is heated to the ideal temperature of 111°C and the liquid level in the kettle reaches 6000L, use a 5.5kw centrifugal pump at 3m 3 / h flow rate to transport it into the high temperature material collection tank, and at the same time, the low temperature material in the low temperature material collection tank is transported at a rate of 3m 3 / h flow rate is pumped into the high-temperature kettle to ensure the liquid level balance in the high-temperature kettle;

[0053] The third feeding stage: Same as the second feeding stage, on the basis of ensuring the liquid level balance, the low-temperature material is continuously transported from the low-temperature material collection tank into the high-temperature kettle to achieve continuous heating of the low-temperature material.

[0054] Example 3 A method for high temperature continuous reaction in the chlorination step of sucralose production

[0055] The steps include:

[0056] (1) placing trichloroethane, thionyl chloride and esterification liquid in a low-temperature material collecting tank to obtain a low-temperature material;

[0057] Specifically, trichloroethane cooled to -1-5 degrees Celsius is mixed at a flow rate of 1800L / H and thionyl chloride at a flow rate of 400L / h, and the flow rates are adjusted by a pump and pumped into the two inlet ends of the first-level Y-type tubular reactor for mixing. The mixed liquid at the outlet end of the first-level Y-type tubular reactor is rapidly cooled to 0-5 degrees with -20 degrees Celsius frozen brine and then pumped into a buffer tank.

[0058] The mixed liquid in the buffer tank is pumped into the two inlet ends of the secondary Y-type tube separator at a flow rate of 1300L / H and the esterification constant volume liquid (300g / L) is pumped into the two inlet ends of the secondary Y-type tube separator at a flow rate of 400L / H. The secondary mixed liquid flowing out of the outlet end of the secondary Y-type tube separator is again rapidly cooled to 0-5 degrees with -20 degrees Celsius frozen brine, and then pumped into a glass-lined reactor with stirring, and continued to cool with frozen brine and maintained at -5 to 15 degrees Celsius. Keep it cold for one hour, and finally the secondary mixed liquid with uniform ingredients is continuously sampled from the outlet of the circulation pump.

[0059] (2) pumping the low-temperature material into the high-temperature kettle to obtain the high-temperature material;

[0060] Specifically:

[0061] The first stage of feeding: the low-temperature material in the low-temperature material collection tank is pumped into the low-temperature material collection tank with a 5.5kw centrifugal pump at a speed of 1.2m 3 / h flow rate is pumped into the high temperature kettle, and the temperature in the high temperature kettle continues to rise to the ideal temperature of 110℃. After the pressure reaches 2Kpa, the second stage of feeding is carried out;

[0062] Feeding the second stage: After the low-temperature materials in the first stage of feeding are heated to the ideal temperature of 110°C and the liquid level in the kettle reaches 6000L, use a 5.5kw centrifugal pump at 2m 3 / h flow rate to transport it into the high temperature material collection tank, and at the same time, the low temperature material in the low temperature material collection tank is transported at a rate of 2m 3 / h flow rate is pumped into the high-temperature kettle to ensure the liquid level balance in the high-temperature kettle;

[0063] The third feeding stage: Same as the second feeding stage, on the basis of ensuring the liquid level balance, the low-temperature material is continuously transported from the low-temperature material collection tank into the high-temperature kettle to achieve continuous heating of the low-temperature material.

[0064] It should be noted that, although the above embodiments have been described in this article, this does not limit the scope of patent protection of the present invention. Therefore, based on the innovative concept of the present invention, changes and modifications made to the embodiments described herein, or equivalent structure or equivalent process transformations made using the contents of the present specification and drawings, directly or indirectly applying the above technical solutions to other related technical fields, are all included in the scope of patent protection of the present invention.

Claims

1. A method for high temperature continuous reaction in the chlorination step of sucralose production, characterized in that: The steps include: (1) placing trichloroethane, thionyl chloride and esterification liquid in a low-temperature material collecting tank to obtain a low-temperature material; (2) pumping the low-temperature material into the high-temperature kettle to obtain the high-temperature material; In step (2), the low-temperature material is pumped into the high-temperature kettle in a continuous staged feeding manner.

2. The method according to claim 1, characterized in that: The volume ratio of trichloroethane, thionyl chloride and esterification liquid in step (1) is 4-6:1-2:1.5-2.

2.

3. The method according to claim 1, characterized in that: The continuous staged feeding is divided into three stages, specifically: The first stage of feeding: the low-temperature material in the low-temperature material collection tank is pumped into the high-temperature kettle by a centrifugal pump. The temperature in the high-temperature kettle continues to rise. After reaching the ideal temperature, the second stage of feeding is carried out; The second stage of feeding: after the low-temperature materials in the first stage of feeding are heated to the ideal temperature and the liquid level in the kettle reaches 6000L, a centrifugal pump is used to transport them into the high-temperature material collection tank. At the same time, the low-temperature materials in the low-temperature material collection tank are pumped into the high-temperature kettle to ensure the liquid level balance in the high-temperature kettle; The third feeding stage: Same as the second feeding stage, on the basis of ensuring the liquid level balance, the low-temperature material is continuously transported from the low-temperature material collection tank into the high-temperature kettle to achieve continuous heating of the low-temperature material.

4. The method according to claim 3, characterized in that: The pumping flow rate of the centrifugal pump in the first stage of feeding is 1.0-1.5m 3 / h.

5. The method according to claim 4, characterized in that: The pumping flow rate of the centrifugal pump in the first stage of feeding is 1.2m 3 / h.

6. The method according to claim 1, characterized in that: The pumping flow rate of the centrifugal pump in the second and third stages of feeding is 1.5-3m 3 / h.

7. The method according to claim 6, characterized in that: The pumping flow rate of the centrifugal pump in the second and third stages of feeding is 2m 3 / h.

8. The method according to claim 1, characterized in that: The ideal temperature as stated in the steps is 109-111°C.

9. The method according to claim 1, characterized in that: The pressure of the high temperature autoclave in the step is -5Kpa-2Kpa.

10. The method according to claim 1, characterized in that: The method further comprises a tail gas collection step.

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