Organic Syntheses, Coll. Vol. 4, p.594 (1963); Vol. 39, p.37 (1959).
A dry 1-l. three-necked, round-bottomed flask is equipped with an efficient stirrer (Note 1)
, a spiral reflux condenser
, and a dropping funnel
, and all openings are protected by calcium chloride drying tubes
. A suspension of 58 g. (1.07 moles) of sodium methoxide (Note 2)
and (Note 3)
in 330 ml. of anhydrous ether (Note 4)
is added, and stirring is begun. To the stirred suspension is added dropwise a solution of 133 g. (1 mole) of 2-chlorocyclohexanone2 (Note 5)
and (Note 6)
diluted with 30 ml. of dry ether
. The exothermic reaction is regulated by the rate of addition of the chloroketone; about 40 minutes is required for the addition. After the addition of the chloroketone is complete, the mixture is stirred and heated under reflux for 2 hours (Note 7)
and is then cooled. Water is added until the salts are dissolved (Note 8)
. The ether
layer is separated, and the aqueous layer is saturated with sodium chloride
. After extraction of the aqueous layer two 50-ml. portions of ether
, the ethereal solutions are combined and washed successively with 100-ml. portions of 5% hydrochloric acid
, 5% aqueous sodium bicarbonate
solution, and saturated sodium chloride
solution. The ether
solution is dried over magnesium sulfate
, and the magnesium sulfate
is removed by filtration and washed with ether
. Removal of the ether
by distillation at atmospheric pressure leaves the crude ester, which is distilled, with fractionation (Note 9)
, at 70–73°/48 mm., n25D
1.4341. The yield of methyl cyclopentanecarboxylate
is 72–78 g.
) (Note 10)
A mercury seal and a Hershberg stirrer made from tantalum wire
A slight excess of sodium methoxide
should always be used. When an equivalent amount is employed, slightly lower yields are obtained.
Commercial anhydrous analytical reagent ether
, from sealed cans, was employed by the checkers without further drying.
is added to the sodium methoxide
, since the reverse mode of addition results in lower yields through increased formation of high-boiling condensation products.
The submitters report that equivalent yields are obtained when the mixture is allowed to stand overnight after the addition of the chloroketone is complete.
The checkers found that approximately 175 ml. of water is required.
The checkers employed a Podbielniak column
, 0.8 × 125 cm., with tantalum wire spiral and partial reflux head
The residue of higher-boiling material arises from the condensation of both the starting material and the product under the influence of sodium methoxide
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