Octasulfur
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Names | |||
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Systematic IUPAC name | |||
Other names
Octasulfur
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Identifiers | |||
3D model (
JSmol ) |
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ChEBI | |||
ChEMBL | |||
ChemSpider | |||
2973 | |||
MeSH | Cyclooctasulfur | ||
PubChem CID
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UNII | |||
CompTox Dashboard (EPA)
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Properties | |||
S8 | |||
Molar mass | 256.48 g·mol−1 | ||
Appearance | Vivid, yellow, translucent crystals | ||
Density | 2.07 g/cm3 | ||
Melting point | 119 °C; 246 °F; 392 K | ||
Boiling point | 444.6 °C; 832.4 °F; 717.8 K | ||
log P | 6.117 | ||
Thermochemistry | |||
Std molar
entropy (S⦵298) |
32 J·mol−1·K−1[3] | ||
Std enthalpy of (ΔfH⦵298)formation |
0 kJ/mol[3] | ||
Related compounds | |||
Related compounds
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Hexathiane
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Octasulfur is an
Nomenclature
The name octasulfur is the most commonly used for this chemical. It is systematically named cyclo-octasulfur (which is the preferred IUPAC name) and cyclooctasulfane. It is also the final member of the thiocane heterocylic series, where every carbon atom is substituted with a sulfur atom, thus this sulfur allotrope is systematically named octathiocane as well.
Structure
The chemical consists of rings of 8 sulfur atoms. It adopts a crown conformation with D4d
λ-Sulfur is the liquid form of octasulfur, from which γ-sulfur can be crystallised by quenching. If λ-sulfur is crystallised slowly, it will revert to β-sulfur. Since it must have been heated over 115 °C, neither crystallised β-sulfur or γ-sulfur will be pure. The only known method of obtaining pure γ-sulfur is by crystallising from solution.
Octasulfur easily forms large crystals, which are typically yellow and are somewhat translucent.
Production and reactions
Octasulfur is not typically produced as S8 per se. It is the main (99%) component of elemental sulfur, which is recovered from volcanic sources and is a major product of the Claus process, associated with petroleum refineries.
See also
- Sulfur (pharmacy)
References
- ISBN 0-85404-438-8. p. 49. Electronic version.
- ^ "cyclooctasulfur (CHEBI:29385)". Chemical Entities of Biological Interest. UK: European Bioinformatics Institute. Main.
- ^ ISBN 978-0-618-94690-7.
- ^ Steudel, R., "Homocyclic Sulfur Molecules", Topics Curr. Chem. 1982, 102, 149.
External links
- Media related to Octasulfur at Wikimedia Commons