JOC 40(11), 1664-1665, 1975
Selective Oxidation of Allylic Alcohols
with Chromic Acid
Jones Oxidation of Cinnamyl Alcohol. A solution of 500 mg
(3.72 mmol) of cinnamyl alcohol and 10 ml of reagent-grade acetone
was placed in a 50-ml round-bottom flask under nitrogen and
cooled to 0' (ice-water bath). To the magnetically stirred solution
was added dropwise a solution consisting of 2 ml of 8 N Jones reagent
and 18 ml of reagent acetone. The Jones solution was added
over a period of ca. 20 min until an orange tint persisted in the
reaction mixture. Isopropyl alcohol was then added dropwise to
destroy excess Jones reagent, as indicated by the reappearance of a
deep green color. The reaction mixture was then extracted twice
with ether, and the combined ether extracts were washed (water,
sodium bicarbonate, and brine), dried over anhydrous magnesium
sulfate, and concentrated. Evaporative distillation (0.1 mm, 100')
yielded 420 mg (2.96 mmol, 84%) of a cinnamon-smelling, pale yellow
oil (>92% pure by GLC) identified as cinnamaldehyde by comparison
of the ir and NMR spectra with literature spectra.
Jones Oxidation of Benzyl Alcohol. A solutipn of 500 mg (4.63
mmol) of benzyl alcohol and 10 ml of reagent-grade acetone was
placed in a 50-ml round-bottom flask and cooled to 0' (ice-water
bath). Oxidation in the same manner gave material which upon
evaporative distillation (water aspirator pressure, looo) yielded
380 mg (3.52 mmol, 76%) of a clear oil (>99% pure by GLC) identified
by ir and NMR as benzaldehyde. |
