Reaction #2467975

Reaction equation

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

sodium hydroxide

→

solid

Yield 86.5%

3-[(dimethylamino)diazenyl]-5-nitrothiophene-2-carboxylic acid

Yield 86.5%

Solvents

methanol

Conditions

Workup

1. 1
   OtherExcess of methanol was evaporated under reduced pressure
2. 2
   workup.ADDITIONthe residue was diluted with ice cold water
3. 3
   Otherthe solid separated
4. 4
   Filtrationwas filtered
5. 5
   Washwashed with water
6. 6
   Otherdried

Procedure

To a solution of methyl 3-[(dimethylamino)diazenyl]-5-nitrothiophene-2-carboxylate (550 mg) in methanol (10 mL) was added an aqueous solution of sodium hydroxide (0.25 g in 5 mL of water) at rt and stirred the mixture for 14 h. Excess of methanol was evaporated under reduced pressure and the residue was diluted with ice cold water. The solution was acidified with dil. HCl and the solid separated was filtered, washed with water and dried to give the product as a yellow color solid (450 mg, 86%). The crude product was recrystallized from chloroform-methanol (290 mg), mp 184-186° C. 1H NMR (400 MHz, DMSO-d6): δ 13.26 (1H, br s), 8.00 (1H, s), 3.59 (3H, s), 3.25 (3H, s); LC-MS (positive ion mode): m/z 245 (M+H)+.

Source