Organic 2 Review Problem 211

Organic 2 Review Problem 211 - PREPARATIONS!95 nitrile does...

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PREPARATIONS !95 nitrile does not melt under the warmth of the hand. p -Tolunitrile is thus obtained as a pale brown solid: yield, 19 g. Purify the dry material by direct distillation, preferably after mixing it with 1-2 g. of animal charcoal: use a short air-condenser, which will require gentle warming at the beginning of the distillation to prevent premature crystallisation. Collect the fraction having b.p. 214-218°. The distilled nitrile solidifies as colourless crystals, m.p. 29°, b.p. 218°. Hydrolysis of />-Tolunitrile. As in the case of benzonitrile, alkaline hydrolysis is preferable to hydrolysis by 70% sulphuric acid. Boil a mixture of 5 g. of p -tolunitrile, 75 ml. of 10% aqueous sodium hydroxide solution and 15 ml. of ethanol under a reflux water-condenser. The ethanol is added partly to increase the speed of the hydrolysis, but in particular to prevent the nitrile (which volatilises in the steam) from actually crystallising in the condenser. The solution becomes clear after about i hour's heating, but the boiling should be continued for a
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