2,5-Dianilinoterephthalic acid → Quinacridone

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A mixture of 85 parts of 2,5-di(4'-methylphenylamino)terephthalic acid and 15 parts of 2,5-diphenylaminoterephthalic acid is cyclized at 125° C. in 300 parts of monomethyl polyphosphate (P2O5 concentration: 81%). After hydrolysis of the ring closure melt in 1,200 parts of water at 20° C. in which 5 parts of (3'-dimethylaminopropyl) quinacridonebissulfonamide had been suspended, the crude quinacridone isolated was subjected to a solvent finish at 125° C.

Provenance & Evidence