polysulfiden

Polysulfiden, or polysulfides, are chemical species that contain chains of sulfur atoms, typically linking two organic or inorganic groups. They occur as both covalently bonded organic or inorganic compounds and as polysulfide anions in solution. The term encompasses short sulfur chains and longer, more complex sequences.

Inorganic polysulfides are best known as S_n^2− anions, formed in alkaline sulfide solutions when elemental sulfur is present. Commonly, n ranges from about 2 to 8, giving species such as S2^2−, S3^2−, S4^2−, and so on. These species exhibit characteristic colors in solution and can undergo redox transformations, hydrolyze under certain conditions, and react with electrophiles. They are often studied in the context of corrosion chemistry, mining, and analytical chemistry.

Organic polysulfides consist of two organic fragments connected by a chain of sulfur atoms, with a general form R−S−(S)_n−R′ where n ≥ 1. When n = 1, the compound is a disulfide (R−S−S−R′); higher values of n give longer polysulfide linkages. Organic polysulfides are commonly prepared by reactions that assemble sulfur into S−S bonds between suitable organic units, such as thiols or bromides, and they form the backbone of several commercially important materials, including polysulfide rubbers and sealants.

Applications and significance include use of polysulfide polymers in sealants, coatings, and vulcanized rubber formulations due to chemical resistance and weatherability. In energy storage, polysulfide species are intermediates in lithium‑sulfur battery chemistry, where their mobility can influence performance. Safety considerations include the irritant and toxic potential of sulfur compounds; many polysulfides can release hydrogen sulfide under acidic conditions and require appropriate handling.