| 摘要 |
PURPOSE:To efficiently obtain a compound useful as an intermediate for dye and pigment such as H-acid, polymer raw material and raw material for dye intermediate, by adding an aromatic diamine as a separating agent to a solution containing an isomer mixture of naphthalenedisulfonic acid, crystallizing and separating. CONSTITUTION:A solution containing an isomer mixture of naphthalenedisulfonic acid is reacted with a compound (e.g. methylenedianiline) to form an aromatic diamine shown by the formula (R<1>-R<8> are H, Cl, F, Br, I or alkyl) at 60-90 deg.C for several hours, 2,7-naphthalenedisulfonic acid diamine salt is crystallized and separated to give the aimed substance. The amount of the diamine used is preferably 0.9-1.3mol. based on 1mol. 2,7-naphthalenedisulfonic acid content. In this method, 2,7-naphthalenedisulfonic acid can be directly separated from the reaction product without previously separating 2,6-naphthalenedisulfonic acid.
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