| 摘要 |
Alkylidene bis-dibromophenols are prepared by direct bromination of alkylidene diphenols in a solvent non-solvent system. The preferred solvents are aliphatic alcohols of 1-4 carbon atoms, and the preferred non-solvent is water. The entire process may be effected in a solvent non-solvent system, or the bromination may be effected in a solvent only and a non-solvent then added to precipitate the product. The latter procedure is particularly useful when methanol or ethanol is used as the solvent and it is desired to recover, as a distillate, methyl or ethylbromide formed as a by-product from the alcohol and hydrogen bromide liberated in the bromination. The bromination may be effected at 15-45 DEG C. over a period of at least one hour, and the reaction mixture may then be heated under reflux, suitably for half an hour; the mixture may then be cooled and the product filtered. Examples are given of the bromination of 4, 41-isopropylidene diphenol to yield 4, 41-isopropylidene-bis (2, 6-dibromophenol). The bromination of 4, 41-sec.-butylidene diphenol and of 4, 41-cyclohexylidene diphenol is also mentioned.
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