Organic 2 Review Problem 366

Organic 2 Review Problem 366 - 350 PRACTICAL ORGANIC...

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Unformatted text preview: 350 PRACTICAL ORGANIC CHEMISTRY to give the corresponding esters, which can usually be readily recrystal- lised. The p-bromophenacyl esters usually have higher m.ps. and lower solubilities than the phenacyl esters. Example. Dissolve 0-3 g. of />-chlorobenzoic acid in a small quantity of warm ethanol (about 10 ml.), and carefully add 5% aqueous sodium hydroxide drop- wise until the solution is just pink to phenolphthalein. Evaporate to dryness on a \\ater-bath. Dissolve the sodium p-chlorobenzoate in a minimum of water, add a solution of 0-5 g. of phenacyl bromide in ethanol (about 5 ml.), and boil the mixture under reflux for i hour, and then cool. The phenacyl ester usually crystallises on cooling: if it does not, add water dropuise with stirring to the chilled solution until separation of the ester just begins. Filter the ester, wash on the filter with water, drain and recrystallise from ethanol: m.p. 90. The />-bromophenacyl ester is similarly prepared, and after recrystallisation from...
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