Reaction of Phenol with Zinc Dust

Heating phenol with zinc dust reduces it to benzene, eliminating the aromatic -OH group entirely: C6H5-OH + Zn (heat) gives C6H6 + ZnO. This reaction is diagnostic -- it shows that the -OH is directly attached to the ring (an aliphatic alcohol shows no comparable reaction with zinc dust) -- and it is used elsewhere in this chapter (see the Evaluation short-answer set) as a first step to strip the -OH from phenol before running a Friedel-Crafts alkylation or acylation on the result …