Organic 2 Review Problem 274

Organic 2 Review Problem 274 - 258 PRACTICAL O RGANIC...

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258 PRACTICAL ORGANIC CHEMISTRY i .4 g. The phenylhydrazone, after standing for a few days, develops a brown colour and ultimately decomposes. Acetophenone similarly gives an oxime, CH 3 (C 6 H 5 )CiNOH, of m.p. 59°: owing to its lower m.p. and its greater solubility in most liquids, it is not as suitable as the phenylhydrazone for characterising the ketone. Its chief use is for the preparation of i-phenyl-ethylamine, CH 3 (C 6 H 5 )CHNH 2 , which can be readily obtained by the reduction of the oxime or by the Leuckart reaction (p. 223), and which can then be resolved by ^-tartaric acid and /-malic acid into optically active forms. The optically active amine is frequently used in turn for the resolution of racemic acids. Acetophenone Semicarbazone. CH 3 (C 6 H 5 )C :N NHCONH 2 . (Semi-micro Scale.) Aldehydes and ketones may frequently be identified by their semicarbazones, obtained by direct condensation with semicarbazide (or ammo-urea), NH a NHCONH a> a compound which is a monacidic base and usually available as
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