Reaction #1543036

Reaction equation

sulfuric acid

cyclohexane-1,4-dione bisphenylhydrazone

→

5,11-dihydroindolo[3,2-b]carbazole

Yield 71.1%

Solvents

acetic acid

Conditions

Workup

1. 1
   OtherIn a 1.5 liter flask equipped with a mechanical stirrer and a condenser
2. 2
   workup.ADDITIONAfter the aforementioned addition
3. 3
   Otherthe ice bath was removed
4. 4
   Temperatureto warm to 23° C.
5. 5
   workup.STIRRINGstirred for a further 10 minutes
6. 6
   TemperatureSubsequently, the mixture was heated to about 65° C. (Centigrade throughout)
7. 7
   Otheruntil an exothermic reaction
8. 8
   TemperatureThe reaction mixture was cooled with an ice bath
9. 9
   Otherwithin 5 minutes a light brown solid was formed
10. 10
    Filtrationfiltered
11. 11
    WashThe filtered cake was then washed with acetic acid, water
12. 12
    workup.STIRRINGstirred
13. 13
    Otherfor 30 minutes
14. 14
    Filtrationbefore filtering
15. 15
    Otherdrying in vacuo for about 2 to 5 hours

Procedure

In a 1.5 liter flask equipped with a mechanical stirrer and a condenser were added glacial acetic acid (100 milliliters) and concentrated sulfuric acid (20 milliliters). Into this mixture, which was maintained at 10° C. with an ice bath, was added powdered cyclohexane-1,4-dione bisphenylhydrazone (22.0 grams) in small portions with stirring. After the aforementioned addition, the ice bath was removed and the mixture was allowed to warm to 23° C., and stirred for a further 10 minutes. Subsequently, the mixture was heated to about 65° C. (Centigrade throughout) until an exothermic reaction occurred. The reaction mixture was cooled with an ice bath, and within 5 minutes a light brown solid was formed. The reaction mixture was allowed to remain at room temperature, about 25° C., for about 18 hours, and filtered. The filtered cake was then washed with acetic acid, water, and then stirred in boiling methanol for 30 minutes before filtering and drying in vacuo for about 2 to 5 hours to provide 7.2 grams of pure 5,11-dihydroindolo[3,2-b]carbazole as pale yellow crystals.

Source