2-Furanacrylic Acid

Abstract

A mixture of 192 g (2 moles) of freshly distilled 2-furaldehyde, 208 g (2 moles) of malonic acid, dried at 100°, and 96 ml (1.2 moles) of pyridine, dried over potassium hydroxide, was prepared in a one-liter round-bottomed flask fitted with reflux condenser. The mixture was heated for two hours in a boiling water bath; it was then cooled to room temperature, and 200 ml of water was added. Concentrated aqueous ammonia was then added to the stirred mixture until the acid had almost dissolved; the solution was filtered, and the filter was washed with a little water. The solution was acidified to Congo red with dilute hydrochloric acid and left for 1.5–2 hours in an ice bath. The precipitated 2-furanacrylic acid was filtered off, washed with three 80-ml portions of water, and dried in a desiccator over calcium chloride. The product, which amounted to 252–254 g (91–92%), consisted of colorless needles, m.p. 141° (see Notes).