Process for the preparation of naphthalene-1,4,5,8-tetracarboxylic acid and its 1,8-monoanhydride in a high degree of purity

Process for the preparation of naphthalene-1,4,5,8-tetracarboxylic acid and its 1,8-monoanhydride in a high degree of purity

Process for the preparation of naphthalene-1,4,5,8-tetracarboxylic acid (called "NTC" below) and its 1,8-monoanhydride in a high degree of purity, which comprises dissolving impure NTC or impure NTC-1,8-monoanhydride as the tetra-alkali metal salt of NTC in water in known manner, removing...

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Bibliographische Detailangaben
Hauptverfasser: SPIETSCHKA, ERNST, SCHIESSLER, SIEGFRIED
Format: Patent
Sprache:eng
Schlagworte:
ACYCLIC OR CARBOCYCLIC COMPOUNDS
CHEMISTRY
HETEROCYCLIC COMPOUNDS
METALLURGY
ORGANIC CHEMISTRY
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Beschreibung
Zusammenfassung:Process for the preparation of naphthalene-1,4,5,8-tetracarboxylic acid (called "NTC" below) and its 1,8-monoanhydride in a high degree of purity, which comprises dissolving impure NTC or impure NTC-1,8-monoanhydride as the tetra-alkali metal salt of NTC in water in known manner, removing any insoluble impurities present, bringing the clarified solution to a pH value of 4-5 below 45 DEG C., separating off the di-alkali metal salt of NTC which thereby crystallizes out and converting the latter into free NTC or into free NTC-1,8-monoanhydride by treatment with a strong acid at 20 DEG to 100 DEG C.