S. Krishnamurthy, T h o m a s W. Nvlund. M. ~ a v i n d r a n a t h a n ; and I e r r y L Thompson1 Richard B. Wetlierill Laboratory Purdue University West Lafayette, Indiana 47907
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Aqueous Chromic Acid Oxidation of Secondarv. Alcohols in Diethvl . Ether A convenient undergraduate organic chemistry experiment
T h e conversion of a secondarv alcohol t o a ketone bv chromium (VI) oxidation is a frequently encountered procedure in oreanic svnthesis. T o t h a t end, manv different urocedures using different reagents and solvents have beendeveloped t o overcome frequently encountered problems such as solubility, protection of acid-sensitive groups on other parts of t h e molecule, possible epimerization of t h e ketone and unusual sluggishness of t h e alcohol t o oxidatiun.' W e a r e describing a simple two-phase procedure for the oxidation of secondary alcohols t o ketones which is applicable t o a wide variety of substrates and is also ideally suited for t h e undergraduate laboratory. This is a n exceptionally simple, highly general procedure developed by Brown and coworkers,:' using aqueous chromic acid and diethyl ether. T w o were developed: (A) a stoichiometric amount of chromic acid a t 25'C for 2 hr and (B) a 100% excess of chromic acid a t 0°C for 30 min. Both are applicable t o t h e preparation of a wide variety of ketones (table). T h e relatively easy workup procedure (separation and washing of t h e ethereal layer) is a particularly attractive feature a s well. Must undrrxratluate organic chemistry lnlr~ratirytexts d o dar.~ not include the chrwnic acid
