Methyloxonium
Topic: Chemistry
From HandWiki - Reading time: 2 min
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 CH
3OH → CH
3OH+
2 + CH
3O−
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:
- CH
3OH+
2 + H
2O → H
3O+
+ CH
3OH[5]
Methyloxonium methylates nucleophiles by displacing a hydrogen ion and releasing a water molecule:[1]
- CH
3OH+
2 + ArH → CH
3Ar + H
2O + 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
- ↑ 1.0 1.1 1.2 Olah, George A. (June 1993). "Superelectrophiles" (in en). 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. 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". https://atct.anl.gov/Thermochemical%20Data/version%201.124/species/?species_number=433.
- ↑ 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. doi:10.1021/ja00897a004. Bibcode: 1963JAChS..85.2051G.
- ↑ 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. doi:10.3389/fspas.2022.809928. Bibcode: 2022FrASS...9.9928M.
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