Reaktion #7064

Reaktionsgleichung

2-amino-4-chlorobenzoic acid

hydrobromic acid

sodium nitrate

→

title compound

Ausbeute 59.0%

2-Bromo-4-chlorobenzoic acid

Ausbeute 59.0%

Lösungsmittel

water

water

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturcooled
2. 2
   workup.ADDITIONUpon the completion of the addition
3. 3
   ExtraktionAfter extraction with ethyl acetate/hexanes (3:1; 2×400 mL)
4. 4
   Waschenthe combined organic layers are washed with brine (200 mL)
5. 5
   Sonstigedried
6. 6
   Einengenconcentrated
7. 7
   Sonstigechromatographed on silica (1% methyl alcohol and 0.5% acetic acid in chloroform)

Vorschrift

An aqueous solution of sodium nitrate (2.21 g) in water (15 mL) is added dropwise to a stirred, ice-cooled mixture of 2-amino-4-chlorobenzoic acid (5.00 g, 29.1 mmol) and 48% hydrobromic acid (150 mL) in water (150 mL). The resultant mixture is stirred for 2 hr at 0° C. Then it is treated dropwise with an aqueous solution of copper bromide (7.81 g) in water (20 mL). Upon the completion of the addition, the reaction mixture is allowed to warm to ambient temperature where it is stirred overnight. After extraction with ethyl acetate/hexanes (3:1; 2×400 mL), the combined organic layers are washed with brine (200 mL), dried, concentrated, and chromatographed on silica (1% methyl alcohol and 0.5% acetic acid in chloroform) to give the title compound (4.04 g, 59% yield). mp 154–155° C.; ES(−)MS m/z 233, (M−H)− consistent with 1 Br an 1 Cl.

Quelle