Organic Syntheses, Coll. Vol. 5, p.866 (1973); Vol. 45, p.77 (1965).
The oxidation reagent is prepared by dissolving 70 g. (0.70 mole) of chromium trioxide
in 100 ml. of water in a 500-ml. beaker
. The beaker
is immersed in an ice bath
, and 112 g. (61 ml., 1.10 moles) of concentrated (18M) sulfuric acid
followed by 200 ml. of water is added cautiously with manual stirring. The solution is cooled to 0–5°.
A solution of 110 g. (1.00 mole) of nortricyclanol (Note 1)
in 600 ml. of acetone (analytical reagent grade)
is cooled to 0–5° in a 2-l. three-necked flask
immersed in an ice bath and equipped with an efficient mechanical stirrer
, a thermometer
, and a dropping funnel with a pressure-equalizing arm
. The cooled oxidation reagent prepared above is poured into the dropping funnel, and the reagent is added with vigorous stirring, at a rate to maintain the temperature of the reaction mixture at about 20°. The stirring is continued for 3 hours after the addition is completed.
is added in small portions until the brown color of chromic acid
is gone from the upper layer of the two-phase mixture. The top layer is decanted, and the dense, green, lower layer is extracted with 200 ml. of 30–60° petroleum ether
. Combination of this extract with the original upper layer causes a separation into two phases. The lower phase is drawn off and added to the original lower phase, which is then extracted with there 200-ml. portions of 30–60° petroleum ether (Note 2)
. The extracts are combined, washed successively with two 50-ml. portions of saturated sodium chloride
, two 50-ml. portions of saturated sodium bicarbonate
solution, and 50 ml. of saturated sodium chloride
solution, and dried over magnesium sulfate
. The solvent is removed by distillation through a short column containing glass helices
, and the residue is distilled under reduced pressure to give 85–95 g.
) of nortricyclanone
, b.p. 103–105° (77 mm.)
1.4873 (Note 3)
and (Note 4)
The preparation of nortricyclanol
is described in this volume, p. 863
. The crude, unsublimed nortricyclanol
is a satisfactory starting material.
Sufficient time between extraction and separation of layers must be allowed, for the organic layer separates slowly from the thick aqueous phase.
The product was shown to contain <1% of the starting material and no other detectable impurity by vapor-phase chromatographic analysis.
properties of this material are b.p. 78–79° (24 mm.)
has been prepared by oxidation of nortricyclanol
using chromic acid
in acetic acid2,3
and using a modified Oppenauer reaction.4
The present procedure is based on the Jones modification5
of chromic acid
4. Merits of the Preparation
This preparation illustrates a general and convenient way of oxidizing secondary alcohols to ketones. The novel feature of the reaction is represented by acetone
solvent which affects markedly the properties of the oxidizing agent. The reaction is very rapid (if not instantaneous), and the yields are high, the reagent rarely attacking unsaturated centers. The procedure is applicable to acetylenic carbinols, allyl and other unsaturated alcohols, and saturated carbinols. The main limitation is the low solvent power of acetone
. Another example of the Jones oxidation is given on p. 310
of this volume.
An attractive alternative to the Jones oxidation is oxidation with chromic acid
in the two-phase system, water-ether
, the details of which were reported recently;6
however, this method has not been applied to the preparation of nortricyclanone
The preparation illustrates the utility of the reaction in preparing the highly strained and reactive nortricyclanone, a compound of current interest in studies of strained ring systems.
This preparation is referenced from:
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