Reaction #1904034

Reaction equation

4-Fluorophenylhydrazine hydrochloride

3-methyl-2-butanone

indole

→

indole

Yield 99.9%

5-fluoro indole

Yield 99.9%

Solvents

acetic acid

Conditions

Workup

1. 1
   Otherto obtain the clear solution
2. 2
   OtherAt the end of 40 min.
3. 3
   workup.ADDITIONthe mixture was poured
4. 4
   ExtractionThe residue was extracted into ethyl acetate (100 ml×2)
5. 5
   Washwashed with water (100 ml×2) and ethyl acetate layer
6. 6
   Dryingwas dried over anhydrous sodium sulfate
7. 7
   FiltrationAfter filtration, ethyl acetate
8. 8
   Otherwas removed
9. 9
   Otherthe residue was dried

Procedure

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%).

Source