反应详情

A solution of ethyl 6-ethyl-4-hydroxycinnolin-3-yl carboxylate (5.0 g.) in concentrated sulphuric acid (30 ml.) was stirred at 10° C. as chromium trioxide (6.0 g.) was added. The solution was stirred at room temperature for 5 hours and then was poured onto cracked ice. The resulting aqueous solution was extracted with ethyl acetate (4 × 250 ml.), and the combined extracts were shaken with excess sodium bisulphite solution to extract ketonic material as the bisulphite compound. The aqueous bisulphite solution was washed with ethyl acetate (2 × 250 ml.), and then treated with excess 40% v/v formaldehyde in water and sodium bicarbonate solution. The aqueous solution was extracted with ethyl acetate (3 × 250 ml.) and the combined extracts were dried (MgSO4), and filtered. Evaporation of the filtrate yielded a solid residue which on recrystallisation from a mixture of ethanol and ether gave ethyl 6-acetyl-4-hydroxycinnolin-3-yl carboxylate, m.p. 250°-252° C.

1. additionwas added
2. additionwas poured
3. extractionThe resulting aqueous solution was extracted with ethyl acetate (4 × 250 ml.)
4. stirringthe combined extracts were shaken with excess sodium bisulphite solution
5. extractionto extract ketonic material as the bisulphite compound
6. washThe aqueous bisulphite solution was washed with ethyl acetate (2 × 250 ml.)
7. additiontreated with excess 40% v/v formaldehyde in water and sodium bicarbonate solution
8. extractionThe aqueous solution was extracted with ethyl acetate (3 × 250 ml.)
9. dry with materialthe combined extracts were dried (MgSO4)
10. filtrationfiltered
11. customEvaporation of the filtrate
12. customyielded a solid residue which
13. customon recrystallisation
14. additionfrom a mixture of ethanol and ether