Aluminium sulfide

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Aluminium sulfide
Names
IUPAC name
Aluminium sulfide
Systematic IUPAC name
Aluminium sulfide
Other names
Aluminium sulphide
Identifiers
Jmol-3D images Image
Properties
Al2S3
Molar mass 150.158 g/mol
Appearance Gray solid
Density 2.02 g/cm3
Melting point 1,100 °C (2,010 °F; 1,370 K)
Boiling point 1,500 °C (2,730 °F; 1,770 K)
Hydrolyses to release H2S
Solubility Insoluble in organic solvents
Thermochemistry
116.9 J/mol K
-724 kJ/mol
Hazards
Safety data sheet LTS Research Laboratories, Inc.
Related compounds
Related compounds
Aluminium sulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Aluminium sulfide or aluminium sulphide is a gray chemical compound, that readily hydrolyzes in air to release hydrogen sulfide gas. It has the chemical formula Al2S3.

Properties

Chemical

Aluminium sulfide reacts with water to release hydrogen sulfide:

Al2S3 + 6 H2O → 2 Al(OH)3 + 3 H2S

This reaction is a cheap and accessible way to obtain hydrogen sulfide.

Aluminium sulfide will react with alcohols at high temperature to give their respective thiols. such as: With methanol, it forms methanethiol and dimethyl sulfide, the yield being 40-45 % and 15% for each product, at 300 °C; reaction with ethanol gives ethanethiol at temperatures between 310-360 °C, with a 39% yield. At 310 °C it reacts with propanol to give propanethiol, with a 32.5 % yield. Reaction with ethers gives thioethers.[1]

Aluminium sulfide will not react with aromatic hydrocarbons. It also tends to decompose slightly under vacuum.

Physical

Aluminium sulfide is a greyish solid, with a bad sulfide smell, especially in moist air. It reacts with water to release hydrogen sulfide, and is insoluble in most solvents. It melts at 1100 °C and sublimes at 1,500 °C. Aluminium sulfide has at least six crystalline forms, the more important ones being α, β, γ and δ.

Availability

Aluminium sulfide is sold by various chemical suppliers.

Preparation

Aluminium sulfide can be prepared through a thermite-like reaction between aluminium and sulfur powders.

2 Al + 3 S → Al2S3

The mixture is somewhat difficult to ignite and burns much slower than the classical thermite. The resulting sulfide results in a fused form and is very hard, requiring grinding. If it reaches temperatures greater than 1100 °C, it may melt its way through steel.

Another route involves the reaction of potassium thiocyanate with aluminium powder at temperatures over 600°C, in a 1:1 wight ratio. If the KSCN is present in excess, it will lower the yield.[2]

4 Al + 5 KSCN = 2 AlN + Al2S3 + 2 K2S + KCN + 4 C + N2

Burning aluminium powder in carbon disulfide also produces aluminium sulfide. However the yield is not very good.[3][4]

Projects

  • Make hydrogen sulfide
  • Make ethanethiol (ethyl mercaptane)
  • Make aluminium metal, by reacting aluminium sulfide with alumina at high temperatures[5][6]

Handling

Safety

Aluminium sulfide releases hydrogen sulfide vapors in moist air, which has an extremely unpleasant smell and is very toxic. Given that the latter is detectable in minute quantities, sealing the container is mandatory, otherwise you will stink your lab.

Storage

Aluminium sulfide must be stored in air tight sealed containers or ampoules, as it will hydrolyze in the presence of moisture to release hydrogen sulfide, an extremely toxic and unpleasant gas.

Disposal

Aluminium sulfide can be neutralized with hydrogen peroxide or bleach.

References

  1. Levi, G. R.; Natta, G.; Atti della Accademia Nazionale dei Lincei, Classe di Scienze Fisiche, Matematiche e Naturali, Rendiconti; vol. 33; (1924); p. 350
  2. "Z. Anorg. Chem.; vol. 156; (1926); p. 228". 
  3. Cavazzi, A.; Mem. Accad. Bologna (4); vol. 7; (1887); p. 27 - 27; C.; (1887); p. 888
  4. Matignon, C.; Comptes Rendus Hebdomadaires des Seances de l'Academie des Sciences; vol. 130; (1900); p. 1392
  5. DE407927
  6. CA251381

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