Organic Chemistry-Acetylation Procedure

ACETYLATION

Apparatus A 250-ml Erlenmeyer flask, thermometer, ice-water bath, apparatus for magnetic stirring, vacuum filtration, and hotplate.

Setting Up

1. Add 100 ml 0.4 M HCl and a stirbar to 250 mL Erlenmeyer flask.

2. Add 3.7g (3.6mL) aniline to the same 250 mL Erlenmeyer flask

3. Stir the mixture magnetically to dissolve

4. Warm, to about 50 °C on hotplate while swirling w/ hand.

5. Put reaction flask/Erlenmeyer to stir plate…...”anilinium hydrochloride”

6. Prepare a solution containing 6.0 g sodium acetate trihydrate dissolved in 20 ml water

7. In a separate container/ graduated cylinder, measure out 4.4 ml acetic anhydride.

Reaction and Isolation

1. Add the acetic anhydride in one portion to the warm anilinium hydrochloride solution.

2. Stir the above solution vigorously and then add the solution of sodium acetate immediately and in one portion.

3. Cool the reaction mixture to 5 °C in an ice-water bath, and continue to stir the mixture until crystalline product completely precipitates

* ???So we stir while in ice bath or after cooling????

4. Collect the acetanilide by vacuum filtration…..wash it with a small portion of ice-cold water

* In order to assure that all of your aniline has been acetylated:

a. Add an additional 2-mL acetic anhydride to the filtrate obtained from collection of your acetanilide

b. Swirl to dissolve the anhydride in the solution

c. Cool the flask in ice.

d. Additional acetanilide may precipitate from the solution.

e. If a precipitate does form, collect the solid on a Buchner, wash it with a small amount of cold water, and combine it with the first crop.

5. Consult your TA to make sure that your product is of sufficient quantity and quality for subsequent use.

* If impure or slightly colored acetanilide is obtained, recrystallize it from a minimum volume of hot water, using decolorizing carbon to give a colorless...