Hydrogen Bromide → 4-Bromo-2-ethyl-1-nitrobenzene

Temperature

60 °C

1.66 g (10 mmol) of 5-amino-1-ethyl-2-nitrobenzene (2) are added to a mixture of 12.5 ml of 48% hydrobromic acid and 7.5 ml of H2O heated to 60° C. and cooled rapidly in an ice bath. At a temperature below 5° C., the mixture is subjected to diazotisation with 760 mg (11 mmol) of sodium nitrite in 10 ml of H2O. After 10 minutes, a pinch of urea from a spatula is added and the mixture stirred for another 5 minutes in the ice bath. This reaction mixture is fed into a suspension of 1.5 g (6 mmol) of copper sulfate pentahydrate and 600 mg (9.4 mmol) of copper powder in 12.5 ml of 48% hydrobromic acid and 7.5 ml of H2O and heated to 80° C. for 30 min. After cooling, the reaction solution is extracted 3 times with 50 ml each of EE and the combined organic phases washed once with 50 ml each of 1 n NaOH and H2O. After drying over Na2SO4, concentration by means of a rotary evaporator is carried out. The crude product is placed on silica gel and purified by flash chromatography (40 g of silica gel, 3.5×13 cm, LM: PE/EE, cond. PE, gradient: 150 ml PE, 600 ml 150: 1, 150 ml 150:2). 1.55 g (6.7 mmol, 67%) of (7) are obtained as a yellow oil.

1. temperaturecooled rapidly in an ice bath
2. customAt a temperature below 5° C.
3. temperatureheated to 80° C. for 30 min
4. temperatureAfter cooling
5. extractionthe reaction solution is extracted 3 times with 50 ml each of EE
6. washthe combined organic phases washed once with 50 ml each of 1 n NaOH and H2O
7. dry with materialAfter drying over Na2SO4, concentration by means of a rotary evaporator
8. custompurified by flash chromatography (40 g of silica gel, 3.5×13 cm, LM: PE/EE, cond. PE, gradient: 150 ml PE, 600 ml 150: 1, 150 ml 150:2)

ORD record

ord-39fab8841b7d47029ce5537b283a7255

Source dataset

uspto-grants-2004_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06750335B2