Acetic Acid → 4,4-Dimethyl-3,4-dihydro-2H-naphthalen-1-one

Participants

Reaction Conditions

Reaction Steps

A solution of 350 ml of glacial acetic acid and 170 ml of acetic anhydride was cooled to 0° C. and CrO3, 25.0 g (0.25 mol) carefully added in small portions. The resulting mixture was stirred for 30 minutes before 120 ml of benzene was added. 1,2,3,4-tetrahydro-1,1-dimethylnaphthalene was added slowly as a solution in 30 ml of benzene. Upon completing the addition the reaction was stirred for 4 hours at 0° C. The solution was diluted with H2O (200 ml) and extracted with Et2O (5×50 ml). The combined organic layers were washed with water, saturated aqueous NaCO3, and saturated aqueous NaCl, before being dried over MgSO4. Removal of the solvents under reduced pressure, and distillation afforded 16.0 g (74%) of the product as a pale-yellow oil, bp 93-96° C./0.3 mm Hg 1H NMR (CDCl13): δ 8.02 (1H, dd, J=1.3, 7.8 Hz), 7.53 (1H, m), 7.42 (1H, d, J=7.9 Hz), 7.29 (1H, m), 2.74 (2H, t, J=6.8 Hz), 2.02 (2H, t, J=6.8 Hz), 1.40 (6H, s).

Provenance & Evidence