In a small flask, place 0.5 mL of ethanol, 1 mL of water, and 0.2 mL or 0.20 g of the unknown compound. To this solution add in portions, with vigorous shaking, 2 mL of 20% sodium hydroxide solution. Stopper the flask and shake the mixture for several minutes and then test the solution with litmus paper to make sure that it is still alkaline. The anhydrides and acyl halides will undergo a reaction with alcohols under basic conditions to form esters. Esters are both insoluble in water and less dense than water and thus will form a layer on top of the water.
Formation of an oily layer on top of the water is a positive test.
None.
A mixture of 0.20 g of the compound, 0.40 mL of absolute ethanol, and 0.20 mL of concentrated sulfuric acid is warmed over a steam bath for 2 min. The mixture is poured slowly into an evaporating dish containing 2 mL of saturated sodium bicarbonate solution. A second layer should be formed. Carefully smell the mixture. The presence of a sweet, fruity smell in the product, where no such smell existed in the original unknown, indicates that the original compound was a carboxylic acid and the acid was esterified. Large molecular weight carboxylic acids produce esters that are odorless.
Formation of an oily layer on top of the water is a positive test.
None.
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