2-Bromobiphenyl → 9-(2-Biphenylyl)-2,7-dibromo-9-fluorenol

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Reaction Steps

The Grignard reagent prepared from 0.72 g (30 mmol) of magnesium turnings and 5.1 ml (30 mmol) of 2-bromobiphenyl in 15 ml of diethyl ether is added dropwise over a period of 2 hours, while stirring (in an ultrasonic bath), to a boiling suspension of 10.0 g (29.6 mmol) of 2,7-dibromo-9-fluorenone in 100 ml of dry diethyl ether. After the addition is complete, the mixture is boiled for a further 3 hours. After cooling overnight, the precipitated solid is filtered off with suction and washed with cold ether. The magnesium complex filtered off is hydrolyzed in a solution of 15 g of ammonium chloride in 250 ml of ice water. After 1 hour, the 9-(2-biphenylyl)-2,7-dibromo-9-fluorenol formed is filtered off with suction, washed with water and sucked dry. For the ring-closure reaction, the dried fluorenol is boiled in 100 ml of glacial acetic acid for 6 hours, after addition of 3 drops of concentrated HCl. The mixture is allowed to crystallize overnight, the product formed is filtered off with suction and is washed with glacial acetic acid and water.

Provenance & Evidence