Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Polysulfides are a class of chemical compounds containing chains of sulfur atoms. The two main classes of polysulfides are anions with the general formula Sn2 . These anions are the conjugate bases of the hydrogen polysulfides H2Sn. Organic polysulfides are also known, the main representatives have the formulae RSnR, where R = alkyl or aryl. In commerce, the term "polysulfide" usually refers to a class of polymers with alternating chains of several sulfur atoms and hydrocarbons. The general formula for the repeat unit is [(CH2)m Sx]n , where x indicates the number of sulfur atoms (or rank), and n indicates the number of repeating units. Polymers containing sulfur atoms separated by hydrocarbon sequences are usually not classified polysulfides, e.g. polyphenylene sulfide (C6H4S)n.