1966 Volume 4 Issue 1-2 Pages 30-35
Phthalic anhydride reacts with hydroquinone in sulphuric acid, and changes into quinizarin. Phthalodinitrile can be determined as the yellow benzene solution of quinizarin using this reaction. Though this method is very simple, the temperature of reaction and the amount of sulphuric acid or hydroquinone affect the yield of quinizarin delicately. So the conditions of reaction should be controlled severely.