Preparation of Fenebute
1. Prepare the first intermediate
Benzaldehyde and ethyl acetoacetate into ethanol, stir at room temperature under the catalysis of organic alkali reaction with filter cake filtration after 45 ~ 50 h, after the completion of the filter with ethanol elution filter cake, dry cake solids, then ethanol filtrate concentrated to a quarter of the original volume, to cold, concentrate filtering alcohol washing, solid, merging two solid is the first intermediate; The mole ratio of benzaldehyde, ethyl acetoacetate and ethanol is 1:2.5 -3:12-15.
2. Prepare the second intermediate
The first intermediate is added to the mass concentration of 20% sodium hydroxide solution, and the reaction is stirred at 85-90°C for 2-5 hours. After filtration, the filter cake is used for filtration. After filtration, the filter cake is washed, the filtrate is combined and cooled, and the filtrate is cooled by stirring for 3h. Solid second intermediate; The mass ratio of the first intermediate to the sodium hydroxide solution is I: 1.8-2.0;
3. Prepare the third intermediate
The second intermediate was dissolved in pure acetic anhydride solution for reflux 3 ~ 5h. After the reflux, the acetic anhydride was concentrated and dissolved with toluene. After the dissolution, ammonia water was added, and the reaction took place at 60_65°C for 1 ~ 1.5 h. Filtrate, wash and dry the precipitated solid to get the solid third intermediate; The mass ratio of the second intermediate, pure acetic anhydride solution, toluene and ammonia water is 5:1-1.2:0.5-0.8:0.5-0.8;
4. Prepare Finebute
The third intermediate was dissolved in 25% sodium hydroxide solution and cooled to _5°C ~ 10°C. After cooling, sodium hypochlorite was added slowly within 15-20min for 1h reaction, followed by ice bath reaction of 0.5 ~ 1.5 h and water bath reaction of 0.5 ~ 1.5 h. Finally, the temperature was gradually increased to 60 ~ 80°C for 1-5 h, and the reaction was cooled again after completion. After cooling, hydrochloric acid was added in the ice water bath to adjust the PH to 2, and the decolorization was stirred at room temperature. After filtration, sodium hydroxide was added in the ice water bath to adjust the PH to 6-7, and the cooling was stirred for 2 hours. The mass ratio of the third intermediate, sodium hydroxide solution and sodium hypochlorite is 1.0:0.8-1.0:1.0-1.1.
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Phosphorus and potassium application of phosphorus can promote the development of rapeseed roots and enhance the resistance of plants; potassium can improve the ability of rape cold resistance, disease resistance, lodging resistance. When fertilizing the rapeseed field, the amount of nitrogen fertilizer should be controlled appropriately, and phosphorus and potassium fertilizers should be added to prevent the plants from being tender and juicy, and their ability to resist cold should be deteriorated.
Increase the cover covering rapeseeds with soil fertilizer, grass ash, and crop stalks before winter, so as to maintain the ground temperature relatively stable, reduce the transpiration of the leaves, avoid the direct damage of the cold air to the leaves, and also can bridge the earth seams to prevent air leakage. Such as covering rice straw, 200-300 kilograms per acre, not only protect the antifreeze, but also increase the soil organic matter. The straw that covers the surface of the crop can be naturally implemented in the event of rainfall, and generally does not affect the photosynthesis of rapeseed.
Spraying paclobutrazol on rapeseed fields with early, long-growing, and tendon-seeding trends, spraying paclobutrazol solution at the seedling stage can make the plants dull and prevent or reduce freezing damage. In general, 15% paclobutrazol wettable powder per acre 50 ~ 60 grams, add 60 kg of water spray, pay attention not to spray, not heavy spray.
Foliar spraying rapeseed before winter spraying foliar spray, the key is to spray phosphorus and potassium fertilizers, can increase the cell liquid concentration, reduce the freezing point, and enhance the ability of plants to resist cold. The spraying of 0.2% borax solution on boron-deficient rapeseeds is also beneficial to freeze-proof seedlings.
Controlling early emergence of early rapeseed rape not only consumes more nutrients, but also has weaker cold resistance. For deep-middle-cultivation plots with signs of early onset and early flowering, damage to part of the root system can delay the occurrence of early infestation and early flowering; rapeseed with early inflorescence and early flowering can be picked, and sunny days can be picked at high temperatures. And timely application of available nitrogen fertilizer, promote plant regeneration.
"Applying spray" to prevent rape damage
Rape is a winter crop, and improper cultivation and management are prone to frost damage. In addition to the selection of hardy-tolerant varieties, timely sowing, and cultivation of strong seedlings for transplanting, the following technical measures should be taken seriously.