Indole → 5-Fluoroindole

Temperature

130 °C

A mixture containing 4-Fluorophenylhydrazine hydrochloride (5.0 g; 30.75 mmol; ALDRICH), 3-methyl-2-butanone (3.7 g; 43 mmol; ALDRICH) and acetic acid (30 ml) was stirred for 30 min. under nitrogen to obtain the clear solution. The mixture was then refluxed at 130° C. The appearance of UV-Vis Abs. Max at 255 nm and the disappearance of the peak at 282 nm confirmed the formation of the indole. At the end of 40 min. the reaction was stopped and the mixture was poured into crushed ice (100 g). The residue was extracted into ethyl acetate (100 ml×2), washed with water (100 ml×2) and ethyl acetate layer was dried over anhydrous sodium sulfate. After filtration, ethyl acetate was removed, and the residue was dried to give 4.15 g of the indole (Yield 76%).

1. customto obtain the clear solution
2. customAt the end of 40 min.
3. additionthe mixture was poured
4. extractionThe residue was extracted into ethyl acetate (100 ml×2)
5. washwashed with water (100 ml×2) and ethyl acetate layer
6. dry with materialwas dried over anhydrous sodium sulfate
7. filtrationAfter filtration, ethyl acetate
8. customwas removed
9. customthe residue was dried

ORD record

ord-8fc42ccc4923492b92e3b384212187a5

Source dataset

uspto-grants-2009_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07504089B2