Réaction #52992

Équation de réaction

4-Amino-2,6-dichlorobenzoic acid methyl ester

NaNO2

HBF4

→

2,6-dichloro-4-fluorobenzoic acid methyl ester

Solvants

HCl

Conditions de réaction

Traitement

1. 1
   workup.STIRRINGthe mixture was stirred for 30 min at that temperature
2. 2
   workup.STIRRINGthe mixture was stirred for 30 min
3. 3
   AutreThe resulting precipitate was collected
4. 4
   Lavagewashed successively with cold water, MeOH and ether
5. 5
   SéchageThe solid was then dried over conc. H2SO4 in a vacuum dessicator for a few days
6. 6
   TempératureThe solid was heated with a bunsen burner until all the solid
7. 7
   workup.DISTILLATIONThe resulting fumes were collected over water (distilling apparatus)
8. 8
   AutreThe product was then recovered with Et2O
9. 9
   AutreThe solvent was evaporated
10. 10
    Autrethe crude product was purified by preparative TLC (silica gel; eluent: hexane/AcOEt 50:1 to 20:1)

Mode opératoire

4-Amino-2,6-dichlorobenzoic acid methyl ester (0.5 g) was suspended in 15% HCl (10 mL) and stirred for 30 min then cooled to 0-5° C. After addition of NaNO2 (188 mg) in small portions, the mixture was stirred for 30 min at that temperature. Precooled HBF4 (0.46 mL) was added and the mixture was stirred for 30 min. The resulting precipitate was collected and washed successively with cold water, MeOH and ether. The solid was then dried over conc. H2SO4 in a vacuum dessicator for a few days. The solid was heated with a bunsen burner until all the solid has melted. The resulting fumes were collected over water (distilling apparatus). The product was then recovered with Et2O. The solvent was evaporated and the crude product was purified by preparative TLC (silica gel; eluent: hexane/AcOEt 50:1 to 20:1) to give 2,6-dichloro-4-fluorobenzoic acid methyl ester (241 mg).

Source