2,5-Dianilinoterephthalic acid → Quinacridone

Participants

Reaction Conditions

Reaction Steps

A stirred vessel is charged with 450 parts of polyphosphoric acid containing 83.0% P2O5. Then 37.5 parts of 2,5-dianilinoterephthalic acid and 112.5 parts of 2,5-di-(4-toluidino)terephthalic acid are introduced at 125° C. with stirring and the mixture is heated at 125° C. for 1 hour during which ring closure takes place to form the quinacridone. The reaction is then metered over the course of 5 minutes into a second stirred vessel containing 1431 parts of 70% strength phosphoric acid and is hydrolyzed at 30° C. with stirring. During hydrolysis, the temperature rises to 60° C.

Provenance & Evidence