Thiamethoxam and its uses
A technology of thiamethoxam and thiazole, which is applied in application, pesticides, organic chemistry, etc., can solve the problems of unsatisfactory yield and purity
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Embodiment 1
[0072] Embodiment 1: the synthesis of thiamethoxam
[0073] 1.1 Preparation of 3,6-dihydro-3-methyl-N-nitro-2H-1,3,5,oxadiazin-4-amine
[0074] The reaction formula for the preparation of 3,6-dihydro-3-methyl-N-nitro-2H-1,3,5,oxadiazin-4-amine:
[0075]
[0076] 100 kg of N-methyl-nitroguanidine and 64 kg of paraformaldehyde were added to the 1000 L reactor. 350 kg of acetic acid were added, the resulting mixture was heated to 70° C. and kept at this temperature for 6 hours, then the solvent (acetic acid) was removed by vacuum distillation. 175 kg of 10% NaOH in water were added, stirring continued, and the resulting mixture was cooled and stirred for 30 minutes. The resulting mixture was separated in a centrifuge. The obtained cake was dried with a double-cone drier to obtain 98 kilograms of 3-methyl-N-nitro-1,3,5, the white powder of oxadiazine-4-imine (purity 97%, productive rate 71.5 %).
[0077] 1.2 2-chloro- Allylthioisonitrile preparation of
[0078] The ...
Embodiment 2
[0089] Embodiment 2: Preparation of thiamethoxam crystal form A
[0090] In 10 grams of methanol, 2 grams of thiamethoxam prepared in Example 1 was heated until completely dissolved. The resulting solution was heated to reflux for 30 to 60 minutes and then cooled to room temperature. The resulting mixture was filtered to separate solids. The solid was washed several times with methanol, and dried under high vacuum to obtain pure thiamethoxam technical crystals (purity: 98%).
[0091] Infrared (IR) spectrometer and X-ray diffractometer were used to confirm that the crystal was Form A of thiamethoxam.
[0092] The X-ray powder diffraction pattern of crystal form A thiamethoxam is shown in figure 1 , and the reflection values are listed in Table 1 below.
[0093] Table I
[0094]
[0095] figure 2 Infrared spectrum of thiamethoxam in form A is shown. The infrared spectrum is displayed at positions 2933.62, 2161.78 and 1593.88cm -1 characteristic peaks appear.
Embodiment 3
[0096] Embodiment 3: Preparation of thiamethoxam crystal form A
[0097] 2 grams of thiamethoxam prepared according to Example 1 were dissolved in 10 grams of xylene while heating at a low temperature on a heating plate. The resulting mixture was heated to reflux for 30 to 60 minutes and cooled to room temperature. The resulting mixture was filtered to separate a solid. After filtration, the solid was washed several times with xylene, and then dried under high vacuum to obtain pure thiamethoxam technical crystals (purity: 97%).
[0098] As described in Example 2, it was determined that the crystal was Form A of thiamethoxam with an infrared spectrometer and an X-ray diffractometer.
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