Nitrous Acid → 7-Chloro-8-fluoroisoquinoline

Participants

Reaction Steps

8-Amino-7-chloroisoquinoline (0.005 mole), prepared as in Example 12, in 40% fluoboric acid (30 ml.) is cooled to -10° C. and diazotized with finely powdered sodium nitrite (3.5 g.). After 30 minutes, the reaction mixture is tested for nitrous acid with starch/iodide paper as described in Example 15. When a positive reaction is obtained, the reaction mixture is washed with small portions of ether and then agitated with a mixture of ethanol and ether (20 ml. each). The diazonium tetrafluoroborate is filtered, washed with ether, dried in vacuo and decomposed on an oil bath at approximately 150° C. The residue is partitioned between ether and 5% aqueous sodium hydroxide solution. The ether phase and extracts are combined, washed with water, dried over sodium sulfate and evaporated to yield 7-chloro-8-fluoroisoquinoline.

Provenance & Evidence