Acetone → 4-(Propan-2-ylidene)cyclohexan-1-one

Participants

Reaction Steps

p-Toluenesulfonic acid (31.16 g, 164 mmol) was added to a solution of ketal (2, 23.0 g, 126 mmol) in acetone (2.3 L) and water (138 mL). The reaction mixture was heated to reflux and maintained at reflux for 3.5 h. The mixture was cooled to room temperature, treated with saturated sodium bicarbonate (60 mL) and concentrated under vacuum. The resulting oily residue was extracted with ethyl acetate (2×130 mL), washed with water (100 mL), then brine (100 mL), and dried over sodium sulfate. The filtered organic layer was concentrated under vacuum to give an oil. Weight: 16 g. Weight yield: 92%. 1H-NMR (400 MHz, CDCl3): δ 1.69 (s, 6H), 2.35 (t, 4H), 2.50 (t, 4H). MS (APCI method): No molecular ion peak was observed (Note: 1H-NMR showed the presence of ˜2% of ketal 2 but used without purification).

Provenance & Evidence