Preparation method of 2, 3-quinoxaline-1, 4-dioxide
A kind of quinoxaline dimethanol, dioxide technology, applied in the direction of organic chemistry and the like, can solve the problems of expensive raw materials, low yield and the like
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Problems solved by technology
Method used
Image
Examples
Embodiment 1
[0027] The first step: the synthesis of 2,3-dimethylquinoxaline
[0028]
[0029] Put 108.2g (1mol, 1eq) of o-phenylenediamine, 64.9g (0.4mol, 0.4eq) of anhydrous ferric trichloride and 600mL of toluene into a 1L reaction flask, control the temperature at 40-45°C, and add dropwise 2,3- Butanedione 103.3g (1.2mol, 1.2eq), after the dropwise addition, raise the temperature to 65-75°C for 2 hours, and then carry out decompression reflux and water separation for 6-7 hours under a slight vacuum (45 mm water column), and the central control Check that the remaining raw materials are ≤1.0%, cool down to room temperature, filter out insoluble matter with diatomaceous earth, concentrate the filtrate under reduced pressure, raise the temperature to 45-50°C, add 600mL of n-heptane dropwise, and slowly cool down to 15-20°C after the dropwise addition is completed. After filtering and drying, 146.7 g of 2,3-dimethylquinoxaline was obtained, the HPLC purity was 98.6%, and the yield was 9...
Embodiment 2
[0033] The second step: the synthesis of 2,3-dimethylquinoxaline-1,4-dioxide.
[0034]
[0035] Add 126.6g (0.8mol, 1eq) of 2,3-dimethylquinoxaline and 900mL of dichloromethane into a 2L reaction flask, stir and dissolve at 20-25°C, then add 99.5g (0.4mol, 0.5eq) of tungstic acid ), stirred until dissolved and then heated to 35-40°C, slowly added 467.5g (4.4mol, 5.5eq) of 32% hydrogen peroxide dropwise, at this time a large amount of solids were precipitated, and reacted at 35-40°C for 24 hours after the addition was completed. Control sampling single oxide ≤ 2.0%, lower the temperature to 5-10°C, add saturated aqueous sodium sulfite solution to quench, let stand to separate layers, extract the aqueous layer with 300mL of dichloromethane, combine the organic phases, add aqueous sodium bicarbonate solution to adjust the pH = 7.5-8.0, separate layers, concentrate the organic phase, add 800g n-heptane to replace once, then add 800g n-heptane, stir at 20-25°C for 1 hour, filter...
Embodiment 3
[0041] The third step: the synthesis of 2,3-quinoxaline dimethanol.
[0042]
[0043] Add 570mL of trifluoroacetic anhydride into a 1L reaction flask, raise the temperature to 55-65°C, add 95.1g (0.5mol, 1eq) of 2,3-dimethylquinoxaline-1,4-dioxide in batches, After the addition is complete, react at 55-65°C for 10-12 hours. The central control detects that the remaining raw materials are 1 HNMR (400MHz, CDCl3): δ=7.80(m,2H), 7.67(m,2H), 4.79(m,4H), 3.65(s,2H).
[0044]
[0045] Add 570mL of acetic anhydride to a 1L reaction flask, raise the temperature to 55-65°C, add 95.1g (0.5mol, 1eq) of 2,3-dimethylquinoxaline-1,4-dioxide in batches, and the addition is complete Then react at 55-65°C for 4-5 hours, concentrate under reduced pressure and distill off acetic acid and acetic anhydride to the remaining 3 volumes, then add 300mL of acetic anhydride, react at 55-65°C for 4-5 hours, and control raw materials < 0.5%, reduce pressure Concentrate until no liquid, add 800g of i...
PUM
Login to View More Abstract
Description
Claims
Application Information
Login to View More