Trimethylsulfonium

Trimethylsulfonium
Names
Other names
Trimesium
Identifiers
676-84-6
3D model (Jmol) Interactive image
ChemSpider 1115
Properties
C3H9S+
Molar mass 77.17 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Trimethylsulfonium (systematically named trimethylsulfanium and trimethylsulfur(1+)) is an organic cation with the chemical formula (CH3)3S+ (also written as C
3
H
9
S+
). It is the simplest sulfonium cation.

Compounds

Several salts of trimethylsulfonium are known:

Salt Molecular formula Chemical formula Molecular weight (g/mol) Properties[1]
Trimethylsulfonium chloride (CH3)3SCl C3H9ClS 112.5 Colorless crystals, decompose at 100 °C, very soluble in ethanol, very hygroscopic.[2]
Trimethylsulfonium bromide (CH3)3SBr C3H9BrS 157 Colorless crystals from H2O. Decomposes at 172 °C, melts in a sealed tube at 201-201 °C, reacts in neutral aqueous solution.[3]
Trimethylsulfonium iodide (CH3)3SI C3H9IS 204 Colorless crystals from ethanol, decomposes at 203-207 °C.[3][4] crystal structure monoclinic a=5.94 b=8.00 c=8.92 μm β=126°32′ 2 formulas per unit cell density=1.958[5]
Trimethylsulfonium tetrafluoroborate (CH3)3SBF4 C3H9BF4S 163.97 mp 205-210°[6]
Trimethylsulfonium methylsulfate (CH3)3SSO4CH2 C4H12O4S2 188.27 mp 92-94°[7] Crystal structure orthorhombic a=12.6157 b=8.2419 μm c=7.540 cell volume 784.0 2 formulas per unit cell

Preparation

Sulfonium compounds can be synthesised by treating a suitable alkyl halide with a thioether. For example, the reaction of dimethyl sulfide with iodomethane yields trimethylsulfonium iodide:

CH3–S–CH3 + CH3–I → (CH3)3SI

An extra oxygen atom can bond to the sulfur atom to yield the trimethylsulfoxonium ion.

Use

Glyphosate herbicide is often supplied as a trimethylsulfonium salt. When mixed with aluminium bromide, or aluminium chloride or even hydrogen bromide, trimethylsulfonium bromide forms an ionic liquid, which melts at temperatures below standard conditions.[8]

References

  1. Heilbron's Dictionary of Organic Compounds, volume 4, revised edition published in 1953. Published in Great Britain
  2. Blättler, H. (1919). "Über Trimethylsulfoniumverbindungen". Monatshefte für Chemie und verwandte Teile anderer Wissenschaften. 40 (8): 417–429. doi:10.1007/BF01559085.
  3. 1 2 Steinkopf, W.; Müller, S. (1923). "Über die Einwirkung von Jodmethyl auf Disulfide". Chem. Ber. 56 (8): 1926–1930. doi:10.1002/cber.19230560834.
  4. Mussgnug, F. (1941). "Trimethylammoniumjodid und Trimethylsulfoniumjodid". Naturwissenschaften. 29 (17): 256. doi:10.1007/BF01479158.
  5. Zuccaro, D. Ε.; McCullough, J. D. (1 January 1959). "The crystal structure of trimethylsulfonium iodide". Zeitschrift für Kristallographie - Crystalline Materials. 112 (1-6). doi:10.1524/zkri.1959.112.jg.401.
  6. "Trimethylsulfonium tetrafluoroborate". Sigma-Aldrich. Retrieved 23 September 2016.
  7. "Trimethylsulfonium methyl sulfate". Sigma-Aldrich. Retrieved 23 September 2016.
  8. Ma, M.; Johnson, K.E. (April 1995). "Some physicochemical characteristics of molten salts derived from trimethylsulfonium bromide". Canadian Journal of Chemistry. 73 (4): 593–598. doi:10.1139/v95-076.

See also

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