Citric Acid → Anhydromethylenecitric acid

Participants

Reaction Steps

Anhydrous citric acid (1), (120 g, 0.625 mole) and paraformaldehyde (21 g, 0.70 mole) were mixed in a beaker which was then immersed in an oil bath preheated to 145° C. The mixture, with intermittent stirring, was held at this temperature for 2 hours. The mixture melted, then resolidified during this time. The cooled mixture was dissolved in a minimal amount of boiling water on the hot plate (total volume ≈225 ml). On cooling, crystals formed. The mixture was kept overnight in the refrigerator, then, the crystals were collected, washed with cold water and dried on the filter using a heat lamp to give 2 (69 g, 53%) as white crystals, mp 205°-207° C.

Provenance & Evidence