Disulfides

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General structure of organic (covalent) disulfides with the organyl radicals R 1 and R 2 , which are alkyl radicals, aryl radicals, alkylaryl radicals, etc. The disulfide bridge is marked in blue .

Disulfides are chemical compounds that contain two sulfur atoms bonded together .

Ionic disulfides

Ionic disulfides contain the anion S 2 2− and are formally salts of the unstable disulfane H 2 S 2 . The best-known example is pyrite ( FeS 2 ), also known as fool's gold or fool's gold. Further representatives are cattierite ( CoS 2 ), vaesite ( NiS 2 ) and patrónite ( V [S 2 ] 2 ).

Covalent disulfides

Common stinkhorn ( Phallus impudicus ) secretes the odorous substance dimethyl disulfide.
Structural formula of dimethyl disulfide, the simplest covalent disulfide.

Covalent disulfides, also known as disulfanes out of date, have the general formula R 1 –S – S – R 2 . In the case of symmetrical disulfides, R 1 = R 2 ; in the case of asymmetrical disulfides, the organic radicals R 1 and R 2 are different.

Low molecular weight organic disulfides are non-polar, volatile, malodorous substances. The simplest representative of this class of substances is dimethyl disulfide . Diallyl disulfide, which gives off the characteristic garlic and onion odor, is known . Organic disulfides with a higher molar mass , on the other hand, are odorless.

Occurrence

Disulfide bridges in cystine units of proteins ( insulin , keratin , oxytocin, etc.) play an important role in their tertiary structure. The disulfide structure is also found in heterocyclic natural products such as (+) - lipoic acid and aspartic acid .

Individual evidence

  1. Entry on sulfanes . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.S06092 Version: 2.3.3.
  2. Albert Gossauer: Structure and Reactivity of Biomolecules , Verlag Helvetica Chimica Acta, Zurich, 2006, pp. 229-230, ISBN 978-3-906390-29-1 .
  3. ^ Albert Gossauer: Structure and reactivity of biomolecules , Verlag Helvetica Chimica Acta, Zurich, 2006, pp. 229–232, ISBN 978-3-906390-29-1 .