反应详情

17.1 g of 4-hydroxy-3-methoxy-5-nitrobenzaldehyde are treated with 170 ml of constant-boiling hydrobromic acid and heated under reflux for 3.5 hours. After cooling the separated precipitate is filtered under suction, washed twice with ice-water and taken up in ethyl acetate. The organic phase is washed twice with 50 ml of sodium chloride solution each time, dried over magnesium sulfate and evaporated in a water-jet vacuum. The crystals obtained are taken up in methylene chloride, whereupon the solution is filtered over a ten-fold amount of silica gel. The material obtained is crystallized from ethyl acetate/isopropyl ether. There is obtained 3,4-dihydroxy-5-nitrobenzaldehyde in the form of yellow crystals of m.p. 142°-143°.

1. temperatureheated
2. temperatureunder reflux for 3.5 hours
3. temperatureAfter cooling the separated precipitate
4. filtrationis filtered under suction
5. washwashed twice with ice-water
6. washThe organic phase is washed twice with 50 ml of sodium chloride solution each time
7. dry with materialdried over magnesium sulfate
8. customevaporated in a water-jet vacuum
9. customThe crystals obtained
10. filtrationis filtered over a ten-fold amount of silica gel
11. customThe material obtained
12. customis crystallized from ethyl acetate/isopropyl ether