Pyrimethanil

420-04-2

62-53-3

123-54-6

53112-28-0

First, aniline and 50% aqueous cyanamide were added sequentially in an inert atmosphere reactor protected by nitrogen. Subsequently, 32% hydrochloric acid solution was added dropwise to adjust the pH of the reaction system to 2.5, after which the reaction mixture was gradually heated up from 45°C to 95°C within 2 hours, and the pH was maintained at 2.5 by adding hydrochloric acid during the heating process. 80°C was reached, acetylacetone was added dropwise to the reaction system, and at the same time, 50% sodium hydroxide solution was added dropwise to adjust the pH of the reaction system to 7.9, and the reaction was stirred and stirred for 1 hour to keep the temperature at this level. The reaction was maintained at this temperature and stirred for 1 h. At the end of the reaction, the reaction was allowed to stand and stratified, and the lower aqueous phase was separated and discarded. The upper organic phase was distilled at 750-35 mbar under reduced pressure, controlling the temperature at the bottom of the tower not to exceed 125°C, and recovering the excess acetylacetone for subsequent use. At the end of the distillation, the residue was cooled to 80 °C and diluted with the addition of isopropanol. The mixture was then slowly cooled to 0°C to precipitate a solid product, which was collected by filtration through a glass sand core funnel. The reactor was washed with a small amount of water and the washings were combined into the filtrate. The product was washed twice with isopropanol and placed in a vacuum drying oven and dried at 70 °C and 10 mbar. Finally, 324 g (1.626 mol) of 4,6-dimethyl-N-phenylpyrimidin-2-amine was obtained in 81.3% yield of the theoretical value, with 97.6% purity by HPLC (internal standard method) or 99.9% purity by GC (area normalization method). GC analysis conditions: 30 m DB-1701 capillary column (0.32 mm I.D., 0.25 μm film thickness), inlet temperature of 250 ℃, detector (FID) temperature of 300 ℃, injection volume of 0.2 μl (0.1 g/l methanol solution), programmed heating: 50 ℃ was held for 2 min, and then increased to 250 ℃ at 10 ℃/min for 8 min. HPLC analysis conditions: Agilent 1100 series high performance liquid chromatograph; Nucleosil 120-5 C18 column (250×4 mm); injection volume 5 μl, flow rate 1 ml/min, room temperature detection, column pressure 90 bar, detection wavelength 268 nm, running time 8 min; mobile phase: 250 mL Millipore water+ 750 mL acetonitrile+ 1 g of methanol solution. 750 mL acetonitrile + 1 g ammonium acetate; sample solvent: 250 mL Millipore water + 750 mL acetonitrile; quantitative analysis was carried out using pyrimethamine standards of known concentration.