| 摘要 |
The purification of a mixture of aromatic polyamines, obtained by hydrogenation of the corresponding polynitrated aromatics comprises distilling isomers of the amines such that a primary flux is separated, corresponding to flux recovered from the base of the column, which is chemically reacted, and a secondary flux is obtained which corresponds to specified conditions. A process for the purification of a mixture of aromatic polyamines, obtained by hydrogenation of the corresponding polynitrated aromatics, is claimed. The mixture comprises isomers of the amines and is subjected to distillation under the following conditions: a primary flux is separated, corresponding to a fraction or totality of the flux recovered from the base of the column, which is subjected to a chemical reaction; a secondary flux is obtained which corresponds to: (i) a gaseous flux withdrawn laterally from the lower third of the column representing no more than 20% or more than 80% of the total vol (primary + secondary flux); or (ii) a fraction of the primary flux (2 - 50% vol) for subsequent treatment. Figure 1 represents, schematically, a form of the process in which the secondary flux (i) is withdrawn, then condensed, to recover the desired metaisomers free of heavy by-products. At the base of the column a primary flux is recovered containing some metaisomers and heavy residues. This is submitted to a chemical reaction, e.g. phosgenation, to recover remaining meta isomers. |
