PREPARATION OF ACETANILIDE FROM ANILINE

Using a medicine dropper, place 0.15 to 0.20 g of aniline (about 10 drops) (d = 1.02 g/ml) in a

large tared test tube and determine the weight to the nearest mg. Add 5 ml of distilled water to

the test tube and then add 20 drops of acetic anhydride again using a medicine dropper .

stir, the mixture using stirring rod for 5 minutes until solid forms.

The product crystallized in the same test tube. Add 5 ml of water and heat the test tube in a hot water bath ( 400 mL beaker)  with occasional stirring until the entire solid dissolved. Set the test tube aside to cool for 3-5 minutes and then chill it in an ice bath. When crystallization is complete, collect the product by vacuum filtration using a small Büchner funnel . Allow the sample to dry completely. Weigh the dry product, calculate the percentage yield and determine its melting point. Collect to product in a paper and write your name and submit it to your instructor. The aqueous filtrate may be flushed down the drain. 

The procedure illustrated in this experiment involve recrystallization, gravity filtration, suction filtration, melting and mixture melting points, as well as calculations of theoretical and percentage yields. Gravity-filtration utilizes a “fluted” filter paper in the decolorizing or recrystallization step. In gravity filtration, generally the filtrate is the desired material, which is used further in the experiment. In suction filtration, a Büchner funnel is employed to collect the desired crystals resulting from a reaction or recrystallization attempt. Be sure to “wet the filter paper” with the solvent/solid mixture to be filtered. When performing a suction filtration, it is usually advisable to install a trap between the aspirator and the suction flask. In any case always break the vacuum before turning the water off. In this operation, the filtrate or “mother liquor” may be concentrated to obtain a second crop, etc. ( or may be disposed- consult with you instructor). This experiment involves four functional groups common in organic chemistry. The substrate (reactants) are both liquids and one of the products is solid. The reaction of aniline with acetic anhydride is a transformation in which products, acetanilide and acetic acid, are obtained. A solid product is often desirable since it may be recrystallized and a melting point determined. Solids prepared in this manner serve a derivative, whose melting point may be correlated with known values and thus is a means of identification and serves as a test for homogeneity or purity.