Reaction Condensation of Phthalic Anhydride with a Phenol to an Anthraquinone Derivative

REACTION CONDENSATION OF PHTHALIC ANHYDRIDE WITH A PHENOL TO AN ANTHRAQUINONE DERIVATIVE 

Example Quinizarin from Phthalic Anhydride and Hydroquinone1 

A mixture of 5 grammes of pure hydroquinone and 20 grammes of phthalic anhydride is heated in an open flask with a mixture of 100 grammes of pure concentrated sulphuric acid and 10 

Under the preparation of fluorescein, it has already been mentioned that phthalic anhydride condenses with phenols in certain proportions, to form derivatives of anthraquinone. The reaction just effected takes place in accordance with the following equation  

In an analogous way, mono-add- as well as poly-add phenols, combine with phthalic anhydride. It is of theoretical importance that from pyrocatecbol (o-dioxybenzene), besides a second isomer, alizarin is 

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