Potassium Hydroxide → 2,3,5,6-Tetrabromo-p-xylene-alpha,alpha'-diol

A solution of potassium hydroxide, 20 parts, in water, 50 parts, was added dropwise to a refluxing solution of 20 parts 2,3,5,6-tetrabromo-p-xylene-α,α'-diol diacetate, prepared as in Example III above, in p-dioxane, 200 parts. After 2 hours at reflux the mixture was cooled somewhat and the bulk of the dioxane-water removed by a rotary evaporator. Water was added to the semi-solid residue, the precipitate filtered, washed with water and air dried to give crude diol, 16.7 parts. Recrystalization from dioxane-water gave 12.2 parts 2,3,5,6-tetrabromo-p-xylene-α,α'-diol, melting at 262°-263.5° C. A second crop, 3.95 parts, melted at 260-262° C. A third crop, 0.4 parts, melted at 225°-245° C. Combining the first two crops gives a yield of 96 percent. Analysis showed the following results: Percent bromine calculated -- 70.5; found -- 71.5.