In organic chemistry, "sulfide" usually refers to the linkage C–S–C, although the term thioether is less ambiguous. For example, the thioether dimethyl sulfide is CH–S–CH. Polyphenylene sulfide (see below) has the empirical formula CHS.  Occasionally, the term sulfide refers to molecules containing the –SH functional group. For example, methyl sulfide can mean CH–SH. The preferred descriptor for such SH-containing compounds is thiol or mercaptan, i.e. methanethiol, or methyl mercaptan.