Organic 2 Review Problem 250

Organic 2 Review Problem 250 - 234 PRACTICAL O RGANIC C...

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234 PRACTICAL ORGANIC CHEMISTRY Filter at the pump, and wash well with water. (Yield, about 20 g.) Recrystallise a portion from hot methylated spirit, reserving the remainder for the following preparation. Benzoin is a very pale yellow (almost colourless) crystalline substance, m.p. 137°. Benzil. C 6 H 6 CO-COC 6 H 5 . The secondary alcohol group, - CH(OH) -, in benzoin is readily oxidised to a ketone group, and thus benzil, a diketone, is obtained. C 6 H 6 CH(OH)COC 6 H 6 + O = C 6 H 5 CO-COC 6 H 5 + H 2 O For this purpose, the usual oxidising agent is nitric acid, which in these circum- stances (i.e., in the absence of sulphuric acid) does not nitrate the benzene ring. Owing to the nitrous fumes formed by the reduction of the nitric acid, the experiment should be performed in a fume-cupboard. Required: Benzoin, io g.; nitric acid, 25 ml. Place io g. of powdered benzoin and 25 ml. of concentrated nitric acid in a 150 ml. flask fitted with a reflux water-condenser, and heat the flask on a boiling water-bath. A flask having a
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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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