Pentabromonitrobenzene, pentabromobenzoic acid, pentabromobenzamide, pentabromoacetanilide, barium pentabromobenzenesulphonate, 1, 2, 4, 5 - tetrabromo-3-chloro-6-(trifluoromethyl)benzene, 2, 3, 5, 6-tetrabromo-4-methoxytoluene 2, 3, 5, 6-tetrabromo-4-methoxybenzamide, methyl 2, 3, 5, 6-tetra-bromo-4-methoxybenzoate, and 1, 2, 5-tribromo-3, 4-dichloro-6-fluorobenzene have been synthesized in good yield by bromodemercuration of the corresponding fully mercurated (permercurated) arenes, e.g. C6(HgO2CCF3)5NO2, which were prepared by reaction of an excess of molten mercuric trifluoroacetate with suitable arenes at c. 180-245°. Permercuration of p-methoxybenzoic acid was accompanied by complete decarboxylation giving, after bromodemercuration, pentabromo(methoxy)-benzene, which was also obtained in low yield from preparations of methyl 2, 3, 5, 6-tetrabromo-4-methoxybenzoate and 2, 3, 5, 6-tetrabromo-4-methoxybenzamide. Conditions have been devised for conversion of phenylmercuric chloride into either a pentamercurated or a hexamercurated benzene derivative, and hence into pentabromo-or hexabromobenzene. The results establish permercuration/bromodemercuration as a simple and versatile route to polybromobenzene.