Organic 2 Review Problem 253

Organic 2 Review Problem 253 - P REPARATIONS 237 Place 20...

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PREPARATIONS 237 Place 20 ml. (21 g.) of benzaldehyde (freshly distilled to ensure absence of benzoic acid), 30 ml. of acetic anhydride, and 10 g. of finely powdered anhydrous sodium acetate* in a ioo ml. round-bottomed flask fitted with a water-condenser closed at the top by means of a calcium chloride tube bent downwards ( c /. Fig. 61, p. 105). Now heat the flask in an oil-bath at 175-180° for 8 hours: the mixture boils vigorously under reflux and white particles separate in the liquid. Pour the mixture whilst still hot into ioo ml. of water contained in a round-bottomed flask (of about i litre capacity) which has previously been fitted for steam- distillation. Now add with vigorous shaking a saturated aqueous solution of sodium carbonate until a drop of the liquid withdrawn on a rod turns red litmus-paper a distinct blue. (Sodium hydrox- ide must not be used for this purpose, as it may generate benzoic acid by the Cannizzaro reaction from any unchanged benzal- dehyde.) Now steam-distil the solution until unchanged benzal-
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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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