Pentanal → (2E)-2-Pentylidenecyclopentanone

Participants

Reaction Steps

A stirred solution of 42.0 grams (g) (0.5 mole) of cyclopentanone in 80 milliliters (ml) of 1 percent (%) NaOH was treated with 21.5 g (0.25 mole) of n-pentanal at about 30 degrees Celsius (°C.). After stirring for about 2 hours, the solution was neutralized with 36% acetic acid, then extracted with three 30 ml portions of benzene. Then 1.0 ml of phosphoric acid was added to the combined extracts. After the resulting mixture was refluxed through a condenser equipped with a Dean-Stark trap for about 2 hours, the solvent was removed on a rotary evaporator to give an oil residue, which was subjected to distillation to give 28.5 g of 2-(E)-pentylidene cyclopentanone as a yellowish liquid. The boiling point of this intermediate compound was determined to be 98°-102° C. at a pressure of 6 millimeters (mm) mercury (Hg).

Provenance & Evidence