A
2-L, three-necked, round-bottomed flask equipped with a nitrogen inlet, a mechanical stirrer, and a
Dean–Stark trap and condenser (Note
1) is placed in a
Glas-Col heating mantle. To the flask are added
100 g (0.665 mol) of p-tert-butylphenol,
135 mL of 37% formalin solution
(1.8 mol of HCHO), and
15 g (0.227 mol) of potassium hydroxide pellets (corresponding to 0.34 equiv of the
phenol) (Note
2) and (Note
3). Heating and stirring are begun, and after 15 min
nitrogen is blown across the reaction mixture at a brisk rate and out through the condenser on top of the Dean–Stark trap (Note
4); the reaction mixture is heated and stirred for 2 hr (Note
5). As the reaction progresses, the originally clear solution turns bright lemon yellow and, as water is removed, the reaction mixture eventually changes to a thick, golden-yellow mass of taffylike consistency (Note
6). During this period some frothing occurs, and the reaction mixture expands somewhat before shrinking to the original volume.
Xylene (1 L) is now added to the flask to dissolve the semisolid mass and give a yellow solution that is brought quickly to reflux by increasing the temperature of the heating mantle (Note
7). After 30 min a precipitate begins to form, and the color of the reaction mixture changes from yellow to orange. Refluxing is continued for 3 hr, the heating mantle is removed, and the mixture is allowed to cool to room temperature. The mixture is filtered, and the precipitate is washed with
xylene and dried on a
Büchner funnel to yield
105–110 g of crude, almost colorless product. This material is powdered, placed in an
Erlenmeyer flask, dissolved in
2.5 L of chloroform (not completely soluble), and treated with
800 mL of 1 N hydrochloric acid. After 10–15 min the stirred solution turns yellow to light orange; stirring is continued for an additional 10 min, and the mixture is transferred to a
separatory funnel. The
chloroform layer is drawn off, the aqueous layer is extracted with an additional
250 mL of chloroform, and the combined
chloroform extracts are washed once with water and dried over
magnesium sulfate.
Magnesium sulfate is removed by filtration, the
chloroform solution is concentrated to ca. 1 L by boiling, and
1 L of hot acetone is added to the boiling
chloroform solution. The mixture is allowed to cool and is then filtered to give
90–95 g (
83–88%) of product as a white powder: mp
372–374°C (Note
8),(Note
9),(Note
10).