Synthesis of Fluoresceine

Chemicals

GHS Pictograms

Phthalic anhydride - DANGER

H302, H315, H317, H318, H334, H335
P280, P302+P352, P304+P340, P305+P351+P338

Resorcinol - DANGER

H302, H315, H319, H317, H370, H410
P260, P273, P280, P308, P311, P333+P313, P337+P313

Sulfuric acid, conc. - DANGER

H290, H314
P280, P301+P330+P331, P305+P351+P338, P308+P310

Sodium hydroxide solution, w = 10% - DANGER

H290, H314
P280, P301+P330+P331, P305+P351+P338, P308+P310

One spatula tip each of phthalic anhydride and resorcinol is placed in a test tube and mixed. A few drops of concentrated sulphuric acid are added and the mixture is then heated for approx. 2 minutes on a low flame. After cooling to room temperature, the reaction mixture is dissolved in approx. 20 mL sodium hydroxide solution, w = 10%, and the solution is poured into a standing cylinder with approx. 50 mL water.

• The solution fluoresces in violet or UV light of an LED flashlight yellowish green.