Acetic Acid → Cyclopentadiene

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%.

1. temperatureThe mixture was cooled with an ice bath
2. customto rise to room temperature
3. customThe organic layer was separated
4. extractionthe aqueous layer was extracted with four 100-mL portions of ether
5. washThe combined organic liquids were washed with two portions of 250 mL of water and two portions of 150 mL of NaCl solution
6. dry with materialfinally dried over magnesium sulfate
7. concentrationThe solution was concentrated
8. customto afford
9. additiona mixture of red crystals
10. customwas stored in the freezer overnight
11. customThe crystals were separated through suction filtration
12. washwere washed with small portions of cold methanol in order
13. customto remove adhering oil residues
14. customThe product was dried under oil-pump vacuum for 4 hours

ORD record

ord-0dae486b06114f4db8f2bd327477a5f8

Source dataset

uspto-grants-2001_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06175026B1