Preparation method of clomazone

Abstract

The invention discloses a preparation method of clomazone, which comprises the following steps: dissolving a clomazone crude product used as a raw material in a nitrile-alkane mixed solvent, cooling the mixture, and crystallizing the mixture to obtain the clomazone. According to the preparation method, a mixed solvent of a nitrile solvent and alkanes is selected as a re-dissolving solvent of a crude clomazone product, wherein the crude clomazone product is directly dissolved in a nitrile-containing solvent, and the clomazone is separated from impurities by utilizing the characteristic that the clomazone and the impurities have different solubility in nitrile, so that the clomazone is separated from the impurities. The clomazone is separated out from the mixed solvent through cooling, and all or most of impurities are still left in the solution, so that the purification purpose is finally achieved. The purity of the prepared clomazone reaches 99% or above. The process omits the pretreatment step of hydrogen chloride gas and other substances on the clomazone crude product, and is lower in preparation cost, less in secondary pollution, and more environment-friendly. The method has the advantages of simple process, simple operation, low cost, good crystallization effect, environmental protection and the like, and is suitable for industrial popularization.

Description

technical field [0001] The invention relates to a preparation method of high-quality clomazone. Background technique [0002] Command is an organic heterocyclic selective pre-emergence herbicide developed and produced by FMC Corporation in 1984. The Chinese common name is clomazone and clomazone, and its chemical name is 2- (2-Chlorobenzyl)-4,4-dimethylisoxazolin-3-one. [0003] Clomazone is absorbed by the roots and young shoots of plants, transported upwards, diffuses to leaves through xylem, inhibits the synthesis of chlorophyll and carotene in sensitive plants, forms white seedlings, and dies in a short time. It is suitable for controlling annual grass weeds and broad-leaved weeds in crop fields such as soybeans and peanuts. It has the advantages of wide herbicidal spectrum, good weeding effect, long application period, and environmental safety. [0004] The existing methods for preparing clomazone mainly include the o-chlorobenzaldehyde method and the chloropivaloyl ...

AI Technical Summary

Problems solved by technology

[0006] 1. Adopt hydrogen chloride refining process: anhydrous HCl is passed into the crude clomazone, and while the yield is increased, the content is increased, but high-quality clomazone cannot be obtained;

[0007] 2. Distillation purification process: clomazone is easy to decompose under high temperature, and the yield is low, so high-quality clomazone cannot be obtained;

[0008] 3. Adopt continuous crystallization process: multiple crystallizers in series are required, relatively large equipment investment, long crystallization time, high energy consumption, and high cost; at the same time, clomazone products still contain more impurities

However, there are still following defects in this method: (1) the purification steps are complicated, and it is necessary to use hydrogen chloride gas, sodium hydroxide and sodium carbonate to process the crude product of clomazone before the recrystallization of isopropanol / petroleum ether can improve the clomazone (2) the use of hydrogen chloride gas, sodium hydroxide and sodium carbonate will increase the preparation cost, and waste water and waste gas will be easily produced in the preparation and use of hydrogen chloride gas, sodium hydroxide and sodium carbonate, while the new The waste water and waste gas produced will inevitably increase the difficulty and cost of treatment, making it difficult to achieve green purification; (3) clomiral products still contain more impurities