The main use of phthalimide is as a precursor for anthranilic acid which can be used to make azo dyes, and saccharin – an artificial sweetener. For this experiment I use 2 grams of urea, 10 grams of phthalic anhydride and 300 millilitres of methanol. I’ve shown in a previous video where you can get the phthalic anhydride, and the urea can be found in instant cold packs. Two grams of urea is added to a round-bottom flask. This is followed by an addition of 10 grams of phthalic anhydride. The flask is then shaken to mix up the chemicals as much as possible. The mixture is then placed on an oil bath and heated until 135 °C. The overall reaction that’s occurring is shown above. In the solid state not much reacting occurs, but once we reach the melting point of urea, which is around 135 °C, that’s when the reaction starts taking place. First the urea reacts with the phthalic anhydride to form phthalimide, CO2, and ammonia. The ammonia that’s produced is able to react with another molecule of phthalic anhydride, and form another molecule of phthalimide. Several minutes after reaching 135 °C, the mixture will froth up and this will signify the end of the reaction. The flask is removed from the oil bath and allowed to cool until room temperature. 10 milliliters of cold distilled water is then added. Using a glass stir rod, the solids are broken up, and it is mixed with the water as much as possible. What we’re doing here is trying to dissolve any unreacted urea, as phthalimide is almost completely insoluble in water. It is then vacuum filtered and dried under vacuum, and we’re left with our crude phthalimide. The phthalimide was transferred to a beaker, and it was recrystallized from about 300 milliliters of methanol. It was cooled in a freezer and afterwards the cold methanol was decanted off. At the bottom we’re left with our nearly pure phthalimide crystals, which were vacuum filtered to dry them and then transferred to a dram vial. The final yield of the phthalimide was 7.4 grams.