| 摘要 |
Bipyridyls are purified by contacting an impure bipyridyl with water and a substantially water-immiscible organic solvent and thereafter separating the organic solvent phase which contains the dipyridyl. Preferably the bipyridyl is dissolved in either the water or the organic solvent before they are contacted with each other. The aqueous phase is preferably maintained at a pH in the range 4 to 8, for example by means of a buffer, e.g. sodium formate/formic acid. Suitable organic solvents are, for example, benzene, toluene, xylenes, trimethyl benzenes, petroleum spirit, chlorinated hydrocarbons and mixtures thereof. The process may be carried out batchwise or continuously preferably at a temperature of 40-80 DEG C. The purified bipyridyls may be separated from the organic solvent by evaporation, distillation or by the formation of bipyridyl salts which may be filtered from the solution. Specification 996,569 is referred to. |
