Reaction #1263

Reaction equation

6-chloro-5-[(4-chlorophenyl)azo]-2,4-pyrimidinediamine

→

desired product

Yield 75.7%

6-Chloro-2,4,5-pyrimidinetriamine

Yield 75.7%

Solvents

ethanol

water

acetic acid

Conditions

Workup

1. 1
   Temperaturewas heated to 70° under nitrogen
2. 2
   Filtrationfiltered under nitrogen
3. 3
   TemperatureThe filtrate was cooled to 0°
4. 4
   Temperaturethe pH was raised to 10 with 10% sodium hydroxide (400 ml)
5. 5
   OtherThe precipitated zinc hydroxide was removed by filtration through Celite
6. 6
   Concentrationconcentrated to 300 ml
7. 7
   workup.ADDITIONWater (50 ml) was added
8. 8
   Temperaturethe reaction was cooled to 0°
9. 9
   Temperaturethe pH raised to 9 with 10% NaOH
10. 10
    OtherThe crystals were collected
11. 11
    Washwashed with water (50 ml)
12. 12
    Dryingether (50 ml), and dried at 35° for 16 hours in vacuo

Procedure

A suspension of 6-chloro-5-[(4-chlorophenyl)azo]-2,4-pyrimidinediamine (24.55 g, 0.0906 mol) in ethanol (640 ml), water (640 ml) and acetic acid (64 ml) was heated to 70° under nitrogen. Zinc dust (75 g) was added slowly over 1 hour, and then the reaction was stirred an additional hour at 70°. Then the reaction was cooled to room temperature and filtered under nitrogen. The filtrate was cooled to 0° and the pH was raised to 10 with 10% sodium hydroxide (400 ml). The precipitated zinc hydroxide was removed by filtration through Celite, and the dark red filtrate was neutralized to pH 7 with glacial acetic acid and concentrated to 300 ml. Water (50 ml) was added, the reaction was cooled to 0°, and the pH raised to 9 with 10% NaOH. The solution was allowed to stand at 5° for 3 days. The crystals were collected, washed with water (50 ml) and then ether (50 ml), and dried at 35° for 16 hours in vacuo to give 10.94 g of desired product.

Source