A 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, prolong the reaction time, The effect of reducing the content of N-nitroso compounds
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Embodiment 1
[0036] Preparation of pendimethalin
[0037] 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 .
[0038] 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%.
[0039] De-N-nitroso compounds
[0040] Add 15 g of ammonium chloride, 30% 75g of hydrochloric acid, heat...
Embodiment 2
[0042] 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
[0044] 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...
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