Reaction #2467965

Reaction equation

ammonium hydroxide

Methyl 3-[(dimethylamino)diazenyl]thiophene-2-carboxylate

sulfuric acid

nitric acid

→

solid

Yield 26.0%

Methyl 3-[(dimethylamino)diazenyl]-5-nitrothiophene-2-carboxylate

Yield 26.0%

Solvents

water

Conditions

Workup

1. 1
   workup.ADDITIONThe mixture was poured into ice
2. 2
   ExtractionThe solution was extracted with chloroform (3×100 mL)
3. 3
   Washthe combined organic layer was washed with water, brine
4. 4
   Dryingdried over sodium sulfate
5. 5
   FiltrationThe solution was filtered
6. 6
   Otherevaporated the solvent
7. 7
   OtherThe residue was chromatographed over silica gel column

Procedure

Methyl 3-[(dimethylamino)diazenyl]thiophene-2-carboxylate (2 g, 9.38 mmol) was added slowly for 15 min at 0 to −5° C. to concentrated sulfuric acid (20 mL). Then concentrated nitric acid (0.54 mL, 70%, 10.7 mmol) was added to the above reaction mixture for 10 min and stirred at the same temperature for 1 h and rt for 16 h. The mixture was poured into ice cooled water and basified with ammonium hydroxide. The solution was extracted with chloroform (3×100 mL) and the combined organic layer was washed with water, brine and dried over sodium sulfate. The solution was filtered and evaporated the solvent. The residue was chromatographed over silica gel column using hexane-ethyl acetate (80:20) as eluents to give the product as a yellow color solid (450 mg, 26%), mp 128-130° C.

Source