反应详情

A solution of 4.55 g of sodium nitrite in 12 ml of water was added dropwise to a stirred mixture of 15.1 g of 8-amino-3-methyl-4-oxo-2-phenyl-4H-1-benzopyran (prepared as described in Da Re, P. et al., Il. Farmac (Ed. Sci.) 11: 670, 1956) in 150 ml of hydrochloric acid (d=1.18) at -5° C. Stirring was continued at 0° C. for 30 minutes. The solution was poured, over a period of 10 minutes and at -5° to 0° C., into 120 ml of a 30% by weight solution of sulfur dioxide in acetic acid containing 1.53 g of cupric chloride dihydrate and 13 ml of water. After 1 hour at 0° C. and 1 hour at 20°-25° C., 300 ml of iced water was added to the mixture. A precipitate formed and was collected by suction filtration, washed with water and dried in a desiccator over sodium hydroxide until of constant weight to give 18 g of crude title product, m.p. 165°-170° C., for use without further purification.

1. waitAfter 1 hour at 0° C.
2. customA precipitate formed
3. filtrationwas collected by suction filtration
4. washwashed with water
5. dry with materialdried in a desiccator over sodium hydroxide until of constant weight