Sulfuric Acid → 4-Bromo-2-thiophenecarboxylic Acid

Temperature

0 °C

Chromium(VI) oxide (20 g), and concentrated sulfuric acid (32 g) were dissolved in water (50 mL) and when dissolution was complete, the volume was made up to 100 mL with water. 55 mL of the resulting solution was added dropwise to a solution of 4-bromothiophene-2-carboxaldehyde (19.1 g) in acetone (200 mL) stirred at 0° C. After 2 h, the solution was diluted with water and extracted with chloroform. The organic extracts were washed with water, then extracted with aqueous sodium hydroxide. The alkaline mixture was acidified by cautious addition of concentrated hydrochloric acid then extracted with chloroform. The organic layer was then dried(Mg2SO4), filtered, and evaporated. The resulting solid was recrystallised from diethyl ether/hexane to give a colourless solid; MS (ES+) 207, 209 (MH+).

1. dissolutionwhen dissolution
2. extractionextracted with chloroform
3. washThe organic extracts were washed with water
4. extractionextracted with aqueous sodium hydroxide
5. additionThe alkaline mixture was acidified by cautious addition of concentrated hydrochloric acid
6. extractionthen extracted with chloroform
7. filtrationdried(Mg2SO4), filtered
8. customevaporated
9. customThe resulting solid was recrystallised from diethyl ether/hexane
10. customto give a colourless solid

ORD record

ord-ec0dc283c3d244f7b243d209f975ed3c

Source dataset

uspto-grants-2009_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07491734B2