Organic 2 Review Problem 284

Organic 2 Review Problem 284 - 268 PRACTICAL ORGANIC...

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268 PRACTICAL ORGANIC CHEMISTRY If a vacuum-distillation apparatus is not available for the above preparation, the crude product may be distilled at atmospheric pressure and the acetoacetate collected as the fraction boiling at 175-185°. A pure preparation cannot be obtained in this way, however, because the ester decomposes slightly when distilled at atmospheric pressure. Ethyl acetoacetate is a colourless liquid, d , 1-03, slightly soluble in water, but almost insoluble in brine. It has a faint but pleasant odour. It is widely used in chemical syntheses. Demonstrate both the presence and the interconversion of the keto and enol forms in the ester thus: (1) Dissolve about i ml. of the ester in about 3 ml. of ethanol and then add 2-3 drops of aqueous ferric chloride solution. A deep violet- red coloration at once appears. This is strong evidence for the presence of the enol form, since similar colorations with ferric chloride are given by most phenols (p. 338) and many higher aliphatic hydroxy-com-
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