2,5-Dianilinoterephthalic acid → Quinacridone

Participants

Reaction Conditions

Reaction Steps

A mixture (one part) of 2,5-dianilino-terephthalic acid (96%) and 2,5-dianisidino-terephthalic acid (4%) was dissolved in polyphosphoric acid (4 parts at 117.5%). The solution was heated and drowned into methanol as described in Example 3. The mixture was then heated for 4 hours at 112° C. to produce a transparent, beta-phase quinacridone pigment, which exhibited an X-ray diffraction spectrum identical to that of Examples 5 thus confirming the product to be a pure beta-phase quinacridone.

Provenance & Evidence