(
A)
Preparation of Ethyl Benzoylacetoacetate.—In a
5-l. three-necked flask, fitted with a
liquid-sealed mechanical stirrer and a
reflux condenser, are placed
3.4 l. of dry benzene (Note
1),
195 g. (1.5 moles) of ethyl acetoacetate (Org. Syn. Coll. Vol. I, 1941, 235), and
34.5 g. (1.5 gram atoms) of clean sodium. The mixture is heated on a
steam cone with stirring and allowed to reflux gently for twenty-four hours. After the suspension of the
sodioacetoacetic ester has been cooled slightly,
263 g. (218 cc., 1.9 moles) of benzoyl chloride is added over a period of three hours. The mixture is refluxed with stirring for an additional eight hours. It is then cooled to room temperature, and 375 g. of cracked ice is added. After thorough shaking, the
benzene layer, which contains the
ethyl benzoylacetoacetate, is separated, washed with
75 cc. of 5 per cent sodium bicarbonate solution, dried with
sodium sulfate, and the
benzene distilled (Note
2). The residue is distilled
in vacuo from a
500-cc. Claisen flask with a 50-cm. fractionating side arm. After a small fore-run of
benzoyl chloride, the fraction boiling at
142–148°/6 mm., or
177–181°/20 mm., is collected. The yield is
223–263 g. (
63–75 per cent of the theoretical amount).
(
B)
Hydrolysis of Ethyl Benzoylacetoacetate.—
Thirty-two grams (0.6 mole) of ammonium chloride is dissolved in 150 cc. (8.3 moles) of water in a
500-cc. Erlenmeyer flask, and
10 cc. (0.15 mole) of ammonia (sp. gr. 0.9) is added. The solution is warmed to 42°,
58.5 g. (0.25 mole) of ethyl benzoylacetoacetate at 20° is added quickly, and the mixture is shaken (Note
3). The flask is placed in a
water bath at 42° for exactly ten minutes and then cooled rapidly by placing it in an
ice bath. The solution is extracted twice with
100-cc. portions of ether, and the
ether solution is dried with anhydrous
magnesium sulfate. The
ether is distilled, and the residue distilled
in vacuo; the yield is
37.0–37.5 g. (
77–78 per cent of the theoretical amount) of
ethyl benzoylacetate boiling at
132–137°/4 mm., or
165–169°/20 mm.