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US 4,376,216 AGranted
Process for the purification of photographic developer substances
AssigneeAgfa-Gevaert
InventorHelmut Haseler
Life of this patent
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Abstract
A new process for the purification of photographic developer compounds using an anionic surfactant wherein unwanted impurities are removed either by being precipitated or dissolved. In this process the developer substance is freed from difficult to remove impurities.
Claims8
A process for the purification of a compound of the p-phenylene diamine series to free it from organic impurities, wherein said compound is treated in an aqueous solution with an anionic surfactant of a pH at which the the surfactant precipitates.
Dependencies are inferred from the claim text.