| 摘要 |
PURPOSE:To efficiently obtain a compound useful as an intermediate for dye and pigment and a heat-resistant polymer raw material, by adding an aromatic diamine as a separating agent to a solution containing 2,6-naphthalenedisulfonic acid, crystallizing and separating. CONSTITUTION:A solution containing 2,6-naphthalenedisulfonic acid is reacted with a compound to form an aromatic diamine shown by formula (R<1>-R<4> are H, Cl, F, Br, I or 1-3C alkyl) at 60-90 deg.C for several hours to give the aimed substance, 2,6-naphthalenedisulfonic acid, as crystal. The amount of the diamine used is preferably 0.9-1.3mol. based on 1mol. 2,6-naphthalenedifulsonic acid content. By this method, the aimed substance can be approximately completely separated and 2,6-naphthalenedisulfonic acid can be recovered from a solution having low 2,6-naphthalenedisulfonic acid content in sufficiently yield. Loss of the diamine used in mother liquor is small and complicated recovery operation is not required.
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