Synthesis of Fluorescein
(a) Reaction Setup
Set an oil bath to a temperature between 180° and 200°C. To a large test tube (15 X 150 mm) or
small Erlenmeyer flask add 0.3 g of resorcinol and 0.2 g of ground powdered phthalic anhydride. To this
mixture of powders add 6 drops of 2M H2SO4 (DO NOT ADD MORE THAN 6 DROPS). Stir the mixture
briefly with a spatula. Place the test tube in the preheated oil bath. The reaction should be run at a
temperature between 180° and 200°C. (Note: It is extremely important to monitor the temperature and
keep it within this range. Overheating will cause the product to decompose.) The reaction should run for
30 minutes within this temperature range. Once the reaction time is up, remove the test tube from the
oil bath and allow it to cool for about 5 min.