Organic 2 Review Problem 275

Organic 2 Review Problem 275 - PREPARATIONS 259 containing...

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PREPARATIONS 259 containing acetonitrile and zinc chloride is saturated with hydrogen chloride, the acetonitrile forms the unstable but reactive imine, CH,-C(Cl) :NH, which OH CH 3 -CrNH (II) CH 3 -CO (III) under the influence of the zinc chloride reacts with the resorcinol to give the keto-imine (II). Keto-imines are basic and form salts, which are readily hydro- lysed by aqueous acids to the corresponding ketone. The keto-imine (II) will therefore separate initially as the chlorozincate, which on hydrolysis gives 2,4- dihydroxy-acetophenone. Required: Resorcinol, 5 g.; acetonitrile, 3*5 ml.; zinc chloride, 2 g.; anhydrous ether, 25 ml. The Hoesch Reaction requires anhydrous conditions : therefore the ether and the acetonitrile should each be dried and distilled before use, and the resorcinol should be dried in a desiccator. Fit a 50 ml. conical flask with a rubber stopper carrying a long inlet and a short outlet tube, the latter being joined to a calcium chloride guard-tube. Add in turn 25 ml. of ether, 5 g. of resorcinol and
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.

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