| 摘要 |
Aromatic compounds, containing more than three bromine atoms in the molecule, are prepared by bromination of aromatic compounds, which contain non-condensed benzene nuclei, in an inert reaction medium in the presence of a halogenation catalyst and with vigorous stirring at a temperature of 10 DEG to 160 DEG C., using a mixture of bromine and chlorine (the quantities being 1.0-1.5 atom per qm. atom of hydrogen to be substituted in the organic compound), an excess of at least 0.2 gm. atom of bromine, relative to chlorine per molecule of aromatic compound present, being maintained until the reaction is complete, followed by the addition of a quantity of chlorine at the end of the reaction at least equivalent to the excess of bromine present. Halogenation catalysts specified are iodine, iron, aluminium. ferric bromide or mixtures thereof. Inert solvents mentioned are carbon tetrachloride, tetrachloroethane and acetic acid. The mother liquor remaining after separation of the bromine derivative may be used again to prepare a fresh batch of the bromine derivative. Examples illustrate the preparation of hexabromobenzene and tetrabromobenzene from benzene; tetra- and pentabromodiphenyl from diphenyl, polybromo derivatives of diphenyl ether containing small proportions of chlorine from diphenyl ether, and b ,b 1-bis (3,5-dibromo-4-hydroxyphenyl)-propane from b ,b 1 - bis (4 - hydroxyphenyl)-propane.
|
