any of several organic compounds that contain a mercapto group (—SH) at the carbon atom of the aromatic ring; thiophenols are colorless, high-boiling liquids with an unpleasant odor. Thiophenols are insoluble in water but soluble in most organic solvents. The simplest thiophenol is thiophenol (phenyl mercaptan), C₆H₅SH, which boils at 169°C. Thiophenols are obtained by the reduction of diaryl disulfides, ArS—SAr, as well as by other methods. They are used in the synthesis of dyes and polymers, as inhibitors of radical reactions, and as stabilizers and other additives to synthetic rubbers.