Bromination of 3-phenanthrol(1)was investigated inconnectiotion with of its chlorin-ation reaction which is known to effect stepwise substitution at the 4- and 9-positions. Thus, upon treatment of (1) with an equimolar amount of elementary bromine dissolved in carbon tetrachloride or glacial acetic acid at room temperature, 9-br-omo-3-phenanthrol (2) was readily obtained as a sole product. Further bromination of (2) in carbon tetrachloride gave practically pure unstable 4, 9-dibromo-3-phen-anthrol (3), whereas that in glacial acetic acid, predominantly the stable 2, 9-dibromo isomer (4). Bromination of 4-chloro-3-phenanthrol or chlorination of (2) with sulfuryl chloride gave a common proruct, 4-chloro-9-bromo-3-phenanthrol (7). An attempt to obtain a tribromo compound from (4) was unsuccessful, while chlorination of (4) with sulfuryl chloride readily gave the corresponding 4-chloro compound, the structure of which was confirmed based on its alternative formation by bromination of (7). Bromination of the methyl ether and the acetate of (1) resulted in 9-substitution in the following order of readiness: OH>OCH
3>OCOCH
3. In order to establish the structures of the newly obtained phenanthrols, some compounds including 3-methoxyphenanthrene-4, 9- and -2, 9-dicarboxylic acids were synthesized.
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