Benzyl alcohol (1 mmol), HNO3 (0.5 mmol) and FeCl3
(0.5 mmol) in 5 mL acetone was sonicated at 35 kHz for 10 min.
After complete conversion (monitored on TLC), acetone was evaporated,
diluted with water and extracted with ether (3 10 mL).
The ether extract was washed with saturated NaHCO3, dried over
anhyd. Na2SO4 and concentrated. The crude product was purified
by silica gel column chromatography using EtOAc/ Pet. Ether
(5:95) to get benzaldehyde (94%).