A. Preparation of "precursor." A mixture of 100 g (0.666 mol) of p-tert-butylphenol, 62 mL of 37% formaldehyde solution (0.83 mol of HCHO), and 1.2 g (0.03 mol) of sodium hydroxide (corresponding to 0.045 equiv with respect to phenol) (Note 1) in 3 mL of water is placed in a 3-L, three-necked, round-bottomed flask equipped with a mechanical stirrer. The contents of the open flask are allowed to stir for 15 min at room temperature, and then heated for 2 hr at 100–120°C by means of a heating mantle (Note 2). The reaction mixture, which is clear and colorless at the beginning, becomes light yellow after 30 min, a somewhat deeper yellow after 2 hr, and eventually changing to a thick slurry as the water evaporates and finally turning to a deep yellow or brown-yellow very viscous mass. During this period there is considerable frothing, and the reaction mixture fills most of the flask before shrinking back to the original volume. Stirring is discontinued, the reaction vessel is removed from the heating mantle, and the reaction mixture is allowed to cool to room temperature. To dissolve the residue 800–1000 mL of warm diphenyl ether (Note 3) is added to the flask and the contents are stirred, the process generally requiring at least 1 hr.

B. Pyrolysis of the precursor. The 3-L, three-necked flask is fitted with a nitrogen inlet. The contents of the flask are stirred and heated (110–120°C) with a heating mantle while a stream of nitrogen is blown rapidly over the reaction mixture to facilitate the removal of the water as it is evolved. During this period the color of the solution changes from yellow to a gray or a light brown. When the evolution of water subsides and a solid starts to form (prior to attaining the reflux temperature) (Note 4), the flask is fitted with a condenser, and the contents of the flask are stirred and heated to ca. 150–160°C (Note 5) for a few minutes and then at reflux for 3–4 hr under a gentle flow of nitrogen (Note 6). During this phase of the reaction the solid dissolves, and a clear dark-brown to grayish-black solution is formed. The reaction mixture is cooled to room temperature (some solid separates), and the product is precipitated by the addition of 1.5 L of ethyl acetate. The resulting mixture is stirred for 15–30 min and allowed to stand for at least 30 min (Note 7). Filtration yields material that is washed twice with 100-mL portions of ethyl acetate, once with 200 mL of acetic acid, twice with 100-mL portions of water, and twice with 50-mL portions of acetone to yield ca. 66 g (61%) of crude product (Note 8). The white-to-beige-colored crude product is dissolved in ca. 1600–1800 mL of boiling toluene that is concentrated to ca. 700–900 mL. On cooling, 61 g (49%) of product is obtained as glistening white rhombic crystals, mp 342–344°C (Note 9) and (Note 10).