Process for the preparation of derivatives of benzodioxole
A technology for carbon dioxide and compounds, which is applied in the field of preparing compounds of formula V and compound of formula III, and can solve problems such as unfavorable industry and difficult operation
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Embodiment 1
[0061] Embodiment 1: the preparation of 2,2-dichloro-1,3-benzodioxole
[0062]Pentafluorobenzene (718g, 4.92mol) was placed in a 2000ml round bottom flask equipped with a magnetic stirrer, reflux condenser, pressure equalizing addition funnel and drying tube. At 85°C, azobisisobutyronitrile (1.5g, 0.009mol), 1,3-benzodioxole (300g, 2.46mol) and chlorine (358g, 5.04mol) were simultaneously added to the in the flask. The temperature of the mass was maintained at 85°C for 1 hour to complete the reaction. The progress of the reaction was monitored by gas chromatography. The temperature of the batch was then lowered to 25°C and nitrogen was bubbled through for 2 hours to remove excess chlorine and dissolved hydrogen chloride. The title compound was purified under vacuum.
[0063] Yield (%): 90
[0064] Purity (%): 98 (by gas chromatography)
Embodiment 2
[0065] Example 2: Preparation of 5-bromo-2,2-difluorobenzo-1,3-dioxole
[0066] 2,2-difluoro-1,3-benzodioxole (200g, 1.27mol) and water (456g, 25.3mol) were placed in a mixture equipped with a mechanical stirrer, a reflux condenser and a pressure equalizing feed funnel into a 1000mL round bottom flask. Bromine (284 g, 1.77 mol) was added dropwise over 1 hour at 25°C. During the addition, the temperature of the batch increased from 25°C to 85°C. The temperature of the reaction mass was maintained at 85°C for 8 hours. The progress of the reaction was monitored by liquid chromatography. The temperature of the reaction mass was lowered to 25 °C. The layers were separated and the organic layer was washed with sodium bisulfite solution followed by sodium bicarbonate solution to obtain the title compound. The crude material was purified by vacuum distillation.
[0067] Yield (%): 80
[0068] Purity (%): 99.8 (by liquid chromatography)
Embodiment 3
[0069] Example 3: Preparation of 2,2-difluorobenzo-1,3-dioxol-5-carboxylic acid
[0070] Magnesium turnings (11.12 g, 0.464 mol) and anhydrous tetrahydrofuran (600 ml) were placed in a round bottom flask equipped with a mechanical stirrer, reflux condenser, pressure equalizing addition funnel and drying tube. 5-Bromo-2,2-difluoro-1,3-benzodioxole (100 g) was added to the flask under nitrogen atmosphere. The temperature of the reaction mass was raised to 40°C during initiation. Once initiated, the remaining 5-bromo-2,2-difluoro-1,3-benzodioxole (100 g) was added dropwise to the reaction mass. The temperature of the reaction mass was maintained below 40°C. The progress of the reaction was monitored by gas chromatography. The reaction mass was then cooled to 0°C and carbon dioxide gas was bubbled at 0°C for 2 hours. The reaction was monitored for completion by liquid chromatography. The reaction mass was quenched with 10% HCl (230 g). The organic layer was separated and c...
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