Synthesis method of pyroxasulfone pesticide intermediate
A technology of pyraclofenazole and its synthesis method, which is applied in the field of chemical synthesis, can solve the problems of low total yield, and achieve the effects of simple raw materials, reduction of three wastes, and simple process operation
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[0039] The present invention provides a kind of synthetic method of metazazol pesticide intermediate, described metazazole sulfone pesticide intermediate is 3-halogenated-5,5-dimethylisoxazole compound, and chemical structure is general formula ( 4) shown, this synthetic method glyoxylic acid is starting raw material, comprises the following steps:
[0040] (1) Glyoxylic acid obtains glyoxylic acid through oxime-forming reaction;
[0041] (2) the acetaldoxime formic acid obtains the compound shown in the general formula (1) through a halogenation reaction;
[0042] (3) performing a [3+2] cyclization reaction between the compound represented by the general formula (1) and the compound represented by the general formula (2) to obtain an isoxazole ring;
[0043] (4) The isoxazole ring is subjected to Huang Minglong reaction to obtain a compound represented by general formula (4), that is, 3-halo-5,5-dimethylisoxazole;
[0044] Wherein, (1) to (4) general reaction formula is as ...
Embodiment 1
[0057] (1) Synthesis of dibromoformaldoxime
[0058] Add 200g of 50% glyoxylic acid aqueous solution to a 1000mL four-neck flask, then add 100g of hydroxylamine hydrochloride and 200g of water, and stir at 25°C for 3h; then add 200g of dichloromethane to the reaction, and lower the reaction temperature to 0 ℃, then add 250g liquid bromine dropwise to the reaction, after the drop, the reaction temperature is raised to 25°C, and kept for 3h; The phase was distilled under reduced pressure to obtain 200 g of dibromoformaldoxime light yellow solid, yield: 74%.
[0059] (2) Synthesis of 3-bromo-5-methyl-5-formyl-4,5-dihydroisoxazole
[0060] in N 2 Under the condition, add 200g dibromoformaldoxime and 300g methanol and 50g water in the 1000mL four-necked bottle, then add the KHCO of 148g 3 (1.5eq), control the reaction temperature at 0°C; then add 66g of acrolein (1.2eq) dropwise to the reaction, after the dropwise addition, raise the reaction temperature to 30°C and keep it warm...
Embodiment 2
[0064] (1) Synthesis of dibromoformaldoxime
[0065] Add 200g of 50% glyoxylic acid aqueous solution to a 1000mL four-neck flask, then add 100g of hydroxylamine hydrochloride and 200g of water, and stir at 25°C for 3h; then add 200g of dichloromethane to the reaction, and lower the reaction temperature to 0 ℃, then feed 400g chlorine gas into the reaction, then raise the reaction temperature to 25 ℃, and keep it warm for 3h; Pressure distillation, to obtain 132g dichloroformaldoxime light yellow solid, yield: 86%.
[0066] (2) Synthesis of 3-bromo-5-methyl-5-formyl-4,5-dihydroisoxazole
[0067] in N 2 Under the condition, add 132g dichloroformaldoxime and 200g methanol and 50g water in the 1000mL four-necked bottle, then add the KHCO of 174g 3 , control the reaction temperature at 0°C; then add 62g of acrolein (1.3eq) dropwise to the reaction, after the dropwise addition, raise the reaction temperature to 30°C, and keep the temperature for 2h; after the reaction, add 400g o...
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