Trimethylsulfonium

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

Trimethylsulfonium
Names
Other names
Trimesium
Identifiers
3D model (JSmol)
ChemSpider
UNII
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

Compounds
Structure of (CH3)3S+ as its tetraphenylborate salt.[1]

Several salts of trimethylsulfonium are known. X-ray crystallography reveals that the sulfur is pyramidal, with C-S-C angles near 102° and C-S bond distance of 177 picometers. Unless the anion is colored, all trimethylsulfonium salts are white or colorless.

Salt Formula Molecular weight (g/mol) Properties[2]
Trimethylsulfonium chloride [(CH3)3S]Cl 112.5 Colorless crystals, decompose at 100 °C, very soluble in ethanol, very hygroscopic.[3]
Trimethylsulfonium bromide [(CH3)3S]Br 157 Colorless crystals from H2O. Decomposes at 172 °C, melts in a sealed tube at 201-201 °C, reacts in neutral aqueous solution.[4]
Trimethylsulfonium iodide [(CH3)3S]I 204 Colorless crystals from ethanol, decomposes at 203-207 °C.[4][5] crystal structure monoclinic a=5.94 b=8.00 c=8.92 μm β=126°32′ 2 formulas per unit cell density=1.958[6]
Trimethylsulfonium tetrafluoroborate [(CH3)3S]BF4 163.97 mp 205-210°[7]
Trimethylsulfonium methylsulfate [(CH3)3S]CH3OSO3 188.27 mp 92-94°[8] 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.[9]

References
  1. Knop, Osvald; Cameron, T. Stanley; Bakshi, Pradip K.; Linden, Antony; Roe, Stephen P. (1994). "Crystal chemistry of tetraradial species. Part 5. Interaction Between Cation Lone Pairs and Phenyl Groups in Tetraphenylborates: Crystal Structures of Me3S+,Et3S+, Me3SO+, Ph2I+, and 1-Azoniapropellane Tetraphenylborates". Canadian Journal of Chemistry. 72 (8): 1870–1881. doi:10.1139/v94-238.
  2. Heilbron's Dictionary of Organic Compounds, volume 4, revised edition published in 1953. Published in Great Britain
  3. Blättler, H. (1919). "Über Trimethylsulfoniumverbindungen". Monatshefte für Chemie und verwandte Teile anderer Wissenschaften. 40 (8): 417–429. doi:10.1007/BF01559085. S2CID 197766904.
  4. Steinkopf, W.; Müller, S. (1923). "Über die Einwirkung von Jodmethyl auf Disulfide". Chem. Ber. 56 (8): 1926–1930. doi:10.1002/cber.19230560834.
  5. Mussgnug, F. (1941). "Trimethylammoniumjodid und Trimethylsulfoniumjodid". Naturwissenschaften. 29 (17): 256. Bibcode:1941NW.....29..256M. doi:10.1007/BF01479158. S2CID 33842580.
  6. 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. S2CID 98338161.
  7. "Trimethylsulfonium tetrafluoroborate". Sigma-Aldrich. Retrieved 23 September 2016.
  8. "Trimethylsulfonium methyl sulfate". Sigma-Aldrich. Retrieved 23 September 2016.
  9. 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
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.