Reaktion #1256702

Reaktionsgleichung

5-amino-4-cyano-3-methylisothiazole

sodium nitrite

water

→

4-cyano-3-methyl-5-nitrosoaminoisothiazole

Lösungsmittel

formic acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONAfter completion of dropwise addition
2. 2
   workup.STIRRINGthe mixture was continuously stirred at 0° C. further for one hour
3. 3
   Sonstigeto precipitate crystals, which
4. 4
   Filtrationwere collected by filtration
5. 5
   Waschenwashed with ice cold water
6. 6
   SonstigeThe crystals were dried in the air at room temperature overnight

Vorschrift

First, 4 g (0.028 mol) of 5-amino-4-cyano-3-methylisothiazole was dissolved in 40 mL of 98% formic acid. While the mixture was stirred, an aqueous sodium nitrite solution (containing 2.1 g (0.03 mmol) of sodium nitrite in 6 mL of water) was added dropwise at 0° C. or less. After completion of dropwise addition, the mixture was continuously stirred at 0° C. further for one hour. To the solution, 100 mL of water was added to precipitate crystals, which were collected by filtration and washed with ice cold water. The crystals were dried in the air at room temperature overnight to obtain 2.6 g (56% in yield) of 4-cyano-3-methyl-5-nitrosoaminoisothiazole. To 2 g (0.012 mol) of the obtained nitrosoaminoisothiazole, 20 mL of methanol was added, stirred while heating to an inner temperature of 55 to 60° C. for one hour and cooled to room temperature to precipitate crystals, which were collected by filtration. The crystals were recrystallized from methanol to obtain 0.66 g (41% in yield) of triazene dissociative direct dye D-34.

Quelle