| 摘要 |
Separation of a nitrobenzaldehyde isomer mixt. comprises distilling in the presence of monomeric and/or polymeric aromatic amines, phenols and/or phenothiazines at max. sump temp. of 200 degrees C. Pref. the mixt. is obtained by nitration of benzaldehyde and contains 2 or 3 isomers. It is treated with 0.5-2 wt.% (based on the isomer mixt.) of monomeric or polymeric aromatic amines and/or phenols, (esp. opt. polymerised pyridine, diphenylamine, dihydroquinoline, in naphthyl amine or their derivs. phenyl, 1-4C alkyl or 1-4C acyl gp(s) as amine or cresol, 2,2'-methylene-bis-phenyl or their derivs. contg. opt. cyclic 1-8C alkyl gps.). The sump temp. is 150-190 degrees C, the head temp. is 110-135 degrees C, and the pressure is 1-30 mbar.
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