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Method for preparing mesotrione with stable crystal form

A technology of stable mesotrione and mesotrione, which is applied in the field of preparation of stable crystalline mesotrione, can solve the problems of increasing the pressure and investment of three wastes treatment, the thermal decomposition of mesotrione crystallization, and the increase of unknown impurity content. Significant significance, reduced energy consumption, and strong practicability

Active Publication Date: 2015-04-29
SHENYANG SINOCHEM AGROCHEMICALS R&D CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But this method has great defects: when acetonitrile is used as a solvent to control the generation of crystal form I, the amount of acetonitrile is large and the recovery is difficult, which not only brings about the improvement of raw material consumption, but also increases the pressure and investment of three wastes treatment; when not used In the case of a solvent, a large amount of crystal form I needs to be added as a seed crystal, and the seed crystal accounts for about 25% of the weight of the crystalline material, resulting in a reduction in equipment utilization
At the same time, a large amount of mesotrione in crystal form I is repeatedly used as seed crystals, which will cause some crystals of mesotrione to decompose under heat for a long time, and the content of unknown impurities in the product will increase
Up to now, there is no method for preparing stable crystalline mesotrione suitable for industrial production

Method used

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  • Method for preparing mesotrione with stable crystal form

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Example 1 Add denaturant without adding defoamer

[0016] Take 300g of mesotrione potassium salt solution, add 1.5g of dichloromethane, control the temperature at 35-45°C, slowly add hydrochloric acid dropwise until pH=2-2.5, and add dropwise for about 0.5 hours. After the acidification is finished, adjust the vacuum degree of the system to 0.09Mpa, and carry out vacuum distillation at a temperature of 35-45°C. A large amount of foam is produced during the distillation process, the distillation speed is controlled to avoid flushing, and the vacuum distillation is stopped after 15 g of fractions are evaporated, and the distillation time is 8 hours. Cool down to 10-15°C, filter and wash to obtain mesotrione crystals with a yield of 97.2%, and the content of unknown impurities in the product is 1.2%. Analysis showed that the solid crystallized as Mesotrione Form I.

Embodiment 2

[0017] Embodiment 2 Add denaturing agent and defoamer

[0018] Take 300g of mesotrione potassium salt solution, add 0.3g of 1,1-dichloroethane, control the temperature at 35-45°C, slowly add hydrochloric acid dropwise until pH=2-2.5, and add dropwise for about 0.5 hours. After acidification, add 0.05g of soybean oil, adjust the vacuum degree of the system to 0.09Mpa, and carry out vacuum distillation at a temperature of 35-45°C. During the distillation process, the foam height is 6 mm, and the defoaming time is less than 5 seconds. After 15 g of distillate is evaporated, the vacuum distillation is stopped, and the distillation time is 45 to 55 minutes. Cool down to 10-15°C, filter and wash to obtain mesotrione crystals with a yield of 98.5%, and the content of unknown impurities in the product is 0.07%. Analysis showed the crystals to be Mesotrione Form I.

Embodiment 3

[0019] Embodiment 3 Add denaturing agent and defoamer

[0020] Take 300g of mesotrione potassium salt solution, add 0.03g of dichloroethane, control the temperature at 35-45°C, slowly add hydrochloric acid dropwise until pH=2-2.5, and add dropwise for about 0.5 hours. After acidification, add 0.015g of soybean oil, adjust the vacuum degree of the system to 0.09Mpa, and carry out vacuum distillation at a temperature of 35-45°C. The foam height is 10 mm, the defoaming time is less than 7 seconds, and the vacuum distillation is stopped after 15 g of distillate is evaporated, and the distillation time is 45 to 55 minutes. The temperature was lowered to 10-15°C, filtered and washed to obtain mesotrione crystals with a yield of 98.3%, and the content of unknown impurities in the product was 0.09%. Analysis showed that the resulting crystalline solid was Form I of mesotrione.

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Abstract

The invention discloses a method for preparing mesotrione with a stable crystal form. The method comprises the following steps of: using chloroalkane as a denaturant which forms mesotrione with a thermodynamically stable crystal form (crystal form I), and selectively obtaining mesotrione with the stable crystal form from aqueous liquor of mesotrione; and when the thermodynamically stable crystal form I is completely formed, decompressing and distilling to remove chloroalkane in the liquor. The invention simultaneously provides a method for eliminating distillation foam. The method provided by the invention not only ensures generation of stable crystal form of products and guarantees the product quality, but also improves the distillation safety. Meanwhile, in the crystallization process, a lot of seed crystals are not added in advance, and the product obtained is easy to filter, so that the utilization ratio of the equipment is greatly improved, and therefore, the production capacity is improved and the energy consumption is reduced.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and relates to a preparation method of the herbicide mesotrione, in particular to a method for preparing a stable crystal form of mesotrione. Background technique [0002] Mesotrione can effectively control dry field weeds, chemical name (2-(4-methylsulfonyl-2-nitrobenzoyl)-cyclohexane-1,3-dione), structural formula is as follows: [0003] [0004] The last step of the mesotrione production process is as follows: the alkaline solution of mesotrione (sodium salt or potassium salt solution) is acidified and crystallized, cooled and filtered to obtain the mesotrione product. It is known that mesotrione can form two different forms of crystals, the two crystals are different in appearance size, infrared spectrum analysis, X-ray diffraction analysis and 13 There were significant differences in C NMR analysis. Two different crystals of mesotrione are thermodynamically stable forms (refer...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C317/24C07C315/06A01N41/10A01P13/00
Inventor 程春生李子亮李涛
Owner SHENYANG SINOCHEM AGROCHEMICALS R&D CO LTD
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