Reaktion #592831

Reaktionsgleichung

6-amino-2,2-dimethyl-7-nitro-1-benzopyran

sodium nitrite

→

2,2-dimethyl-7-nitro-1-benzopyran

Ausbeute 61.0%

Lösungsmittel

methanol

hypophosphorous acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigeuntil bubbling
2. 2
   workup.ADDITIONThe reaction solution was diluted with ethyl acetate
3. 3
   Waschenwashed with water and saturated sodium chloride solution
4. 4
   TrocknenThe organic phase was dried over magnesium sulfate
5. 5
   Einengenconcentrated under a reduced pressure
6. 6
   SonstigeThe resulting solid was recrystallized in methanol

Vorschrift

To a mixed solution of 6-amino-2,2-dimethyl-7-nitro-1-benzopyran (19.5 g, 88.7 mmol) in methanol-concentrated hydrochloric acid (1:1 v/v, 280 mL) and hypophosphorous acid aqueous solution (100 mL), an aqueous solution of sodium nitrite (12.2 g, 178 mmol) was added dropwise over 30 minutes at −3° C., and the resulting solution was stirred at room temperature until bubbling ceased. The reaction solution was diluted with ethyl acetate, washed with water and saturated sodium chloride solution. The organic phase was dried over magnesium sulfate and then concentrated under a reduced pressure. The resulting solid was recrystallized in methanol to obtain 2,2-dimethyl-7-nitro-1-benzopyran (yield: 61%).

Quelle