Organic 2 Review Problem 306

Organic 2 Review Problem 306 - 2 90 P RACTICAL ORGANIC...

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290 PRACTICAL ORGANIC CHEMISTRY fractionate the crude ethyl-benzene, collecting the fraction of b.p. 130-135°. Yield, 16 g. Ethyl-benzene is a colourless liquid of b.p. 134°, and d , 0-876: it has only a faint odour. /7-Ethyltoluene. C 2 H 5 -C 6 H 1 -CH 3 . (Clemmensen Reduc- tion.) Many aldehydes and ketones can be reduced directly by Clemmensen's method, in which the aldehyde or ketone is boiled with dilute hydrochloric acid and amalgamated zinc. p-Methylacetophenone (or methyl />-tolyl ketone) is reduced under these conditions to />-ethyltoluene. An excess of the reducing agent is employed in order to prevent the formation of unsaturated hydrocarbons. The />-methylacetophenone is readily prepared by the Friedel-Crafts' reaction (cf. p. 254), toluene being treated with acetyl chloride in the presence of aluminium chloride. The toluene is employed in considerable excess so that it 8 \? CH 3 \T > + ClCOCH 3 > CH 8 \_> COCH 3 + HCl may act both as a reagent and a solvent. Note that in this reaction
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