Water → 6-Bromochromone-3-carboxylic acid

Reaction equation

[C:1]([C:3]1[C:12](=[O:13])[C:11]2[C:6](=[CH:7][CH:8]=[C:9]([Br:14])[CH:10]=2)[O:5][CH:4]=1)#N.N([O-])=[O:16].[Na+].[OH2:19]>S(=O)(=O)(O)O>[Br:14][C:9]1[CH:10]=[C:11]2[C:6](=[CH:7][CH:8]=1)[O:19][CH:1]=[C:3]([C:4]([OH:16])=[O:5])[C:12]2=[O:13]

Participants

Procedure

26 g of the product of step (b) are stirred overnight in 150 ml of conc. sulphuric acid at room temperature. The mixture is then diluted with 10 ml of water and cooled to 0°. Under stirring, a solution of 15 g of sodium nitrite in 30 ml of water is introduced slowly under the liquid surface, the temperature being maintained by cooling at 15°. After addition, the mixture is warmed at 70° for 1 hour and poured over ice and the precipitate is suction filtered off, suspended in 600 ml of acetone, refluxed, hot-filtered and the filtrate then evaporated on a rotary evaporator. The residue is recrystallised from chloroform, to obtain the heading compound, m.p. 260°-264°.