the Gallic acid (or Benzene-1,2,3-triol) and Phthalic anhydride in 190 ~ 200 ℃, then reactions and concentrated sulfuric acid heated to 200 ℃ or so,Then transformed insoluble mordanting Gallic acid green ?a water-soluble bisulfite compound.
Properties and Applications
deep green. Slightly soluble in water for deep green light brown, soluble in hot ethanol for Copenhagen blue. In concentrated sulfuric acid to dark brown, dilution after green black.
