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Method for removing n-nitroso compounds from pendimethalin

A technology of nitroso compounds and pendimethalin, which is applied in the purification/separation of amino compounds, organic chemistry, etc., can solve the problem that hydrochloric acid is not well utilized, so as to reduce the formation of waste salt, reduce emissions, and ensure effect of effect

Active Publication Date: 2021-10-15
JIANGSU YONGAN CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0012] Moreover, the hydrochloric acid used in the above conversion scheme has not been well utilized, and is usually treated as wastewater, and a large amount of waste salt is generated during the treatment process

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] Preparation of pendimethalin

[0036] Add pentylamine to 1,2-dichloroethane to dissolve, heat to 50-60°C, add 35-45% nitric acid dropwise, control the reaction temperature at 50-60°C, and layer to obtain dilute nitric acid with a concentration of 1-4% into the wastewater treatment system .

[0037] The organic phase obtained by stratification is added dropwise with 68-70% nitric acid, and the dropping temperature is controlled at 50-60°C. After the addition is completed, the reaction is kept for 30 minutes, and the nitric acid (concentration 30-40%) layer is separated, and the organic phase is washed with water and separated. Aqueous phase influent treatment system. The organic phase obtained by stratification is dichloroethane solution of pendimethalin crude product, and analyzed by HPLC, wherein the content of N-nitroso compounds is less than or equal to 30%.

[0038] De-N-nitroso compounds

[0039] Add 15 g of ammonium chloride, 30% 75g of hydrochloric acid, heat...

Embodiment 2

[0041] Add 6 g of ammonium chloride, 25% 30g of hydrochloric acid, heated up to 82°C and reacted for 6 hours, sampled, analyzed by HPLC, the content of N-nitroso compounds in the reaction solution was less than 0.05%, and the reaction was stopped. Add 60g water in reaction system, leave standstill layering after stirring, separate organic phase, organic phase washes with 100g 5% NaOH solution successively, 100g water washes, 100g 2% hydrochloric acid washes, after 100g water washes, normal pressure concentration reclaims solvent to After the internal temperature reached 130°C, vacuum precipitation was carried out to obtain 90 g of pendimethalin product. The content is 97.8%. The content of N-nitroso compounds is 1200 ppm.

Embodiment 3

[0043] Add 6 g of ammonium chloride, 25% 90g of hydrochloric acid, heated up to 78°C and reacted for 6 hours, sampled, analyzed by HPLC, the content of N-nitroso compounds in the reaction solution was less than 0.05%, and the reaction was stopped. The reaction device is connected to the water separator, and distilled at atmospheric pressure until the internal temperature rises to 100°C, and no more water is produced in the water separator, and the distillation is completed (during the solvent distillation process, the water is continuously separated through the water separator, and the organic solvent Return to the distillation device), the distillation time is about 6h, the organic phase after distillation is washed successively with 100g 5% NaOH solution, 100g water wash, 100g 2% hydrochloric acid wash, after 100g water wash, normal pressure concentration recovery solvent recovery solvent to the internal temperature to After 135°C, 132 g of pendimethalin product was obtained b...

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Abstract

The invention discloses a method for removing N-nitroso compounds from pendimethalin, comprising the following steps: adding pendimethalin to a dichloroethane solution containing N-nitroso compounds after the nitration reaction is completed Add hydrochloric acid, ammonium chloride and auxiliary catalyst, heat up to 78~82°C, stir and react for 6~10 h, stop the reaction when the content of N-nitroso compounds in the detection reaction system is less than 0.05%; after the reaction solution is post-treated, Concentration and desolventization give pendimethalin products. The method uses ammonium chloride as an additive for denitration under concentrated hydrochloric acid. Ammonium chloride reacts with nitrosyl chloride formed in the denitration process to form ammonium nitrite and hydrogen chloride. Ammonium nitrite is unstable and easily decomposed. Nitrogen and water, the formed hydrogen chloride dissolves in water to form hydrochloric acid, does not introduce organic impurities, and does not produce saline wastewater.

Description

technical field [0001] The invention belongs to the field of herbicide preparation and relates to the preparation of pendimethalin, in particular to a method for removing N-nitroso compounds from pendimethalin. Background technique [0002] Pendimethalin is an aniline herbicide developed by American Cyanamid Corporation (now owned by BASF). The original drug is orange-yellow crystal with a melting point of 56-58°C. It has little solubility in water, is easily soluble in chlorinated hydrocarbons and aromatic hydrocarbon solvents, and is stable to acid and alkali. [0003] At present, pendimethalin production technology mainly uses N-(3-pentyl)-2,3-xylaniline as raw material and concentrated nitric acid as nitrating agent. During the nitration process, the N atom of the amino group is easy to form N-NO products (US4136117), so there is a process of removing nitroso groups after nitration in the production process, and the obtained product is post-processed and concentrated to...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C209/86C07C211/52
CPCC07C209/86C07C211/52
Inventor 耿敬坤方浙能陈夕鹏厉大双
Owner JIANGSU YONGAN CHEM CO LTD
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