Methyloxonium
| Identifiers | |
|---|---|
3D model (JSmol)
|
|
| ChemSpider | |
PubChem CID
|
|
| |
| |
| Properties | |
| CH5O+ | |
| Molar mass | 33.049 g·mol−1 |
| Related compounds | |
Related compounds
|
Dimethyloxonium, Trimethyloxonium, Ethyloxonium, Methylammonium |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
| |
The methyloxonium ion is a protonated methanol molecule. It is a kind of oxonium ion and is the conjugate acid of methanol.
Formation
Methyloxonium is formed when methanol is treated with a superacid which add a proton.[1]
When methanol undergoes autoprotolysis, if forms methyloxonium along with an equal amount of methoxide.[2]
- 2 CH3OH → CH3OH+2 + CH3O−
Dissolving trifluoromethanesulfonic acid in methanol, produces methyloxonium triflate.[3]
Heat of formation ΔHf° at standard conditions is 574.9 kJ/mol.[4]
Reactions
Methyloxonium is unstable in the presence of water as it reacts:
- CH3OH+2 + H2O → H3O+ + CH3OH[5]
Methyloxonium methylates nucleophiles by displacing a hydrogen ion and releasing a water molecule:[1]
- CH3OH+2 + ArH → CH3Ar + H2O + H+
Between 100 and 300 °C, methanol in superacids forms methyloxonium ions which then methylate themselves and polymerise to yield alkanes, toluene and other aromatic hydrocarbons.[1]
Methyloxonium forms in the interstellar medium, where it can be broken by UV light to form singlet methylene, or it can react with ethylene to form propylene.[6]
References
- ^ a b c Olah, George A. (June 1993). "Superelectrophiles". Angewandte Chemie International Edition in English. 32 (6): 767–788. doi:10.1002/anie.199307673. ISSN 0570-0833.
- ^ Cassone, Giuseppe; Pietrucci, Fabio; Saija, Franz; Guyot, François; Saitta, A. Marco (2017). "One-step electric-field driven methane and formaldehyde synthesis from liquid methanol". Chemical Science. 8 (3): 2329–2336. doi:10.1039/c6sc04269d. hdl:11104/0280705. PMID 28451337.
- ^ Devi Yadav, Geeta; Mishra, Manish; Singh, Surendra (August 2015). "Methyloxonium Triflate: an Efficient Catalyst for ring Opening of Epoxides with Alcohols under Ambient Conditions". Current Catalysis. 4 (2): 133–144. doi:10.2174/2211544704666150727220138.
- ^ "Methyloxonium Enthalpy of Formation". Retrieved 1 November 2025.
- ^ Grunwald, Ernest.; Jumper, Charles F. (July 1963). "Kinetics and Mechanism of the Proton Transfer between Methyloxonium Ion and Benzoic Acid in Methanol Solution". Journal of the American Chemical Society. 85 (14): 2051–2052. Bibcode:1963JAChS..85.2051G. doi:10.1021/ja00897a004.
- ^ Mathew, Thomas; Esteves, Pierre Mothé; Prakash, G. K. Surya (10 August 2022). "Methanol in the RNA world: An astrochemical perspective". Frontiers in Astronomy and Space Sciences. 9 809928. Bibcode:2022FrASS...9.9928M. doi:10.3389/fspas.2022.809928.