Sulfuric Acid → Indolo(3,2-b)carbazole

Participants

Reaction Steps

In a 2,000-ml three-necked flask that had been deaerated and filled with nitrogen were placed 50.69 g (205.8 millimoles) of 3,3′-methylenediindole and 30.55 g (206.1 millimoles) of triethyl orthoformate, then 640 g of methanol was added, and the mixture was stirred. To this mixture was added dropwise 5.0 g (51.5 millimoles) of concentrated sulfuric acid over 3 minutes and the mixture was heated under reflux for 1 hour. The mixture was cooled to room temperature and the reddish-brown crystals formed were collected by filtration and washed twice by reslurrying in 500 ml of methanol. The solvent was stripped off under reduced pressure and 36.8 g (143.8 millimoles, 69.9% yield) of indolo[3,2-b]carbazole was obtained as a reddish-brown powder.

Provenance & Evidence