Trimethylsulfonium

Trimethylsulfonium

Names
IUPAC name Trimethylsulfonium
Systematic IUPAC name Trimethylsulfanium
Other names Trimesium Trimethylsulfur(1+)
Identifiers
CAS Number	676-84-6  Y
3D model (JSmol)	Interactive image
ChemSpider	1115
PubChem CID	1147
UNII	8U5M0SJV65  Y
CompTox Dashboard (EPA)	DTXSID50862857
InChI InChI=1S/C3H9S/c1-4(2)3/h1-3H3/q+1 Key: NRZWQKGABZFFKE-UHFFFAOYSA-N
SMILES C[S+](C)C
Properties
Chemical formula	(CH3)3S+
Molar mass	77.17 g·mol−1
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) is an organic cation with the chemical formula (C H ₃)₃ S ⁺ (also written as C₃H₉S⁺).

Compounds

Structure of (CH₃)₃S in its tetraphenylborate salt.

Several salts of trimethylsulfonium are known. X-ray crystallography reveals that the ion has trigonal pyramidal molecular geometry at sulfur atom, with C-S-C angles near 102° and C-S bond distance of 177 picometers. Unless the counteranion 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. Decomposes at 172 °C, melts in a sealed tube at 201-201 °C, reacts in neutral aqueous solution.[ clarification needed ] [4]
Trimethylsulfonium iodide	[(CH3)3S]+I−	204	Colorless crystals, decomposes at 203-207 °C. [4] [5] crystal structure monoclinic, with these parameters: a = 5.94  μm, b = 8.00 μm, c = 8.92 μm, β = 126°32′ 2 formulas per unit cell,[ clarification needed ] density = 1.958 g/cm3 [6]
Trimethylsulfonium tetrafluoroborate	[(CH3)3S]+[BF4]−	163.97	melting point = 205-210 °C [7]
Trimethylsulfonium methylsulfate	[(CH3)3S]+CH3OSO−3	188.27	melting point = 92-94 °C [8] Crystal structure orthorhombic with these parameters: a = 12.6157 μm, b = 8.2419 μm, c = 7.540 μm cell volume 784.0 2 formulas per unit cell[ clarification needed ]

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)₂S + CH₃I → [(CH₃)₃S]⁺I⁻

Related

An extra oxygen atom can bond to the sulfur atom to yield the trimethylsulfoxonium ion [(CH₃)₃S=O]⁺, where the sulfur atom is tetravalent and tetracoordinated.

Use

Glyphosate herbicide is often supplied as a trimethylsulfonium salt, referred to as trimesium. ^[9]

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. ^[10]

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): 401–408. 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. "Glyphosate-trimesium". PubChem.
10. 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

• Onium compounds