Acetic Acid → Cyclopentadiene

Participants

Reaction Steps

A solution of 20.4 mL (0.16 mol) of trans-cinnamaldehyde and 33 mL (0.40 mol) of freshly-distilled cyclopentadiene in 200 mL of reagent-grade methanol was prepared. The mixture was cooled with an ice bath, and 20 mL (0.24 mol) of pyrrolidine were slowly added. The temperature was allowed to rise to room temperature and the reaction mixture was stirred overnight. A 15 mL portion of acetic acid (0.26 mol) were added to the dark red slurry, followed by 0.4 L of ether and 0.4 L of water. The organic layer was separated and the aqueous layer was extracted with four 100-mL portions of ether. The combined organic liquids were washed with two portions of 250 mL of water and two portions of 150 mL of NaCl solution and finally dried over magnesium sulfate. The solution was concentrated to afford a mixture of red crystals and a red oil which was stored in the freezer overnight. The crystals were separated through suction filtration and were washed with small portions of cold methanol in order to remove adhering oil residues. The product was dried under oil-pump vacuum for 4 hours and stored under argon in the freezer. Yield: 15.4 g (85.5 mmol) 54%.

Provenance & Evidence