Process for the preparation of 2,5-diarylaminoterephthalic acids
AssigneeBayer Aktiengesellschaft
InventorsDetlef-Ingo Schutze, Reinold Schmitz
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Abstract
A process for the preparation of 2,5-diarylaminoterephthalic acids by oxidation of 2,5-diarylamino-3,6-dihydroterephthalic acid esters using oxygen or oxygen-containing gases, preferably air, in alcoholic-alkaline or alcoholic-aqueous-alkaline solution or suspension in the presence of an oxygen-transferring agent and working up to give the 2,5-diarylaminoterephthalic acids, characterized in that the oxidation is carried out in the presence of quaternary ammonium compound.
Claims20
A process for the preparation of a 2,5-diarylaminoterephthalic acid by oxidation of a 2,5-diarylamino-3,6-dihydroterephthalic acid dialkyl ester with oxygen or an oxygen-containing gas in an alcoholic-alkaline or alcoholic-aqueous-alkaline solution or suspension in the presence of an oxygen-transferring agent and liberating the 2,5-diarylaminoterephthalic acid by conducting acidification and filtering, the improvement wherein the oxidation is carried out in the presence of a quaternary ammonium compound.
Dependencies are inferred from the claim text.