Methoxy

The structure of a typical methoxy group.

In chemistry (particularly organic chemistry), methoxy refers to the functional group consisting of a methyl group bound to oxygen. This alkoxy group has the formula O–C H₃. The term is used in organic chemistry usually to describe an ether. As quantified by the Hammett equation, methoxy is an electron-donating group.

Occurrence

The simplest methoxy compounds are methanol and dimethyl ether. Other methoxy ethers include anisole and vanillin. Many metal alkoxides contain methoxy groups, e.g. tetramethyl orthosilicate and titanium methoxide. Such compounds are often classified as methoxides.

Biosynthesis

In nature, methoxy compounds are notable by their absence. They do not occur in amino acids, the heterocycles that comprise the genetic code, nor in lipids. They are however common substituents in O-methylated flavonoids. Their biosynthesis entails O-methyltransferases, which act on phenols, e.g., Catechol-O-methyl transferase (COMT). A large number of natural products in plants, e.g. lignins, are generated via catalysis by caffeoyl-CoA O-methyltransferase.^[1]

Methoxylation

Commonly organic methoxides are derived by methylation of alkoxides.^[2]^[3]

Some aryl methoxides are available via metal-catalyzed methylation of phenols, or as well methoxylation of aromatic halogenides.^[4]^[5]

References

↑ Wout Boerjan, John Ralph, Marie Baucher "Lignin Biosynthesis" Annu. Rev. Plant Biol. 2003, vol. 54, pp. 519–46. doi:10.1146/annurev.arplant.54.031902.134938
↑ J. A. Scarrow and C. F. H. Allen "Methoxyacetonitrile" Org. Synth. 1933, 13, 56.doi:10.15227/orgsyn.013.0056
↑ Josep Cornella, Cayetana Zarate, and Ruben Martin "Ni-catalyzed Reductive Cleavage of Methyl 3-Methoxy-2-Naphthoate" Org. Synth. 2014, 91, 260. doi:10.15227/orgsyn.091.0260
↑ Cheung, Chi Wai; Buchwald, Stephen L. (2 August 2013). "Mild and General Palladium-Catalyzed Synthesis of Methyl Aryl Ethers Enabled by the Use of a Palladacycle Precatalyst". Organic Letters 15 (15): 3998–4001. doi:10.1021/ol401796v.
↑ Tolnai, Gergely L.; Pethő, Bálint; Králl, Péter; Novák, Zoltán (13 January 2014). "Palladium-Catalyzed Methoxylation of Aromatic Chlorides with Borate Salts". Advanced Synthesis & Catalysis 356 (1): 125–129. doi:10.1002/adsc.201300687.

Molecules detected in outer space

Molecules

Diatomic	Aluminium monochloride Aluminium monofluoride Aluminium monoxide Argon hydride Carbon monophosphide Carbon monosulfide Carbon monoxide Carborundum Cyanogen radical Diatomic carbon Fluoromethylidynium Hydrogen chloride Hydrogen fluoride Hydrogen (molecular) Hydroxyl radical Iron(II) oxide Magnesium monohydride cation Methylidyne radical Nitric oxide Nitrogen (molecular) Nitrogen monohydride Nitrogen sulfide Oxygen (molecular) Phosphorus monoxide Phosphorus mononitride Potassium chloride Silicon carbide Silicon mononitride Silicon monoxide Silicon monosulfide Sodium chloride Sodium iodide Sulfur monohydride Sulfur monoxide Titanium oxide

Triatomic	Aluminium hydroxide Aluminium isocyanide Amino radical Carbon dioxide Carbonyl sulfide CCP radical Chloronium Diazenylium Dicarbon monoxide Disilicon carbide Ethynyl radical Formyl radical Hydrogen cyanide Hydrogen isocyanide (HCN) Hydrogen isocyanide (HNC) Hydrogen sulfide Hydroperoxyl Iron cyanide Isoformyl Magnesium cyanide Magnesium isocyanide Methylene radical N₂H⁺ Nitrous oxide Nitroxyl Ozone Phosphaethyne Potassium cyanide Protonated molecular hydrogen Sodium cyanide Sodium hydroxide Silicon carbonitride c-Silicon dicarbide Silicon naphthalocyanine Sulfur dioxide Thioformyl Thioxoethenylidene Titanium dioxide Tricarbon Water

Four atoms	Acetylene Ammonia Cyanic acid Cyanoethynyl Cyclopropynylidyne Formaldehyde Fulminic acid HCCN Hydrogen peroxide Hydromagnesium isocyanide Isocyanic acid Isothiocyanic acid Ketenyl Methylene amidogen Methyl radical Propynylidyne Protonated carbon dioxide Protonated hydrogen cyanide Silicon tricarbide Thioformaldehyde Tricarbon monoxide Tricarbon sulfide Thiocyanic acid

Five atoms	Ammonium Ion Butadiynyl Carbodiimide Cyanamide Cyanoacetylene Cyanoformaldehyde Cyanomethyl Cyclopropenylidene Formic acid Isocyanoacetylene Ketene Methane Methoxy radical Methylenimine Propadienylidene Protonated formaldehyde Protonated formaldehyde Silane Silicon-carbide cluster

Six atoms	Acetonitrile Cyanobutadiynyl radical E-Cyanomethanimine Cyclopropenone Diacetylene Ethylene Formamide HC₄N Ketenimine Methanethiol Methanol Methyl isocyanide Pentynylidyne Propynal Protonated cyanoacetylene

Seven atoms	Acetaldehyde Acrylonitrile Cyanodiacetylene Ethylene oxide Hexatriynyl radical Methylacetylene Methylamine Methyl isocyanate Vinyl alcohol

Eight atoms	Acetic acid Aminoacetonitrile Cyanoallene Ethanimine Glycolaldehyde Heptatrienyl radical Hexapentaenylidene Methylcyanoacetylene Methyl formate Propenal

Nine atoms	Acetamide Cyanohexatriyne Cyanotriacetylene Dimethyl ether Ethanol Methyldiacetylene Octatetraynyl radical Propene Propionitrile

Ten atoms or more	Acetone Benzene Buckminsterfullerene (C₆₀ fullerene) ("bucky-ball") C₇₀ fullerene Cyanodecapentayne Cyanopentaacetylene Cyanotetra-acetylene Ethylene glycol Ethyl formate Methyl acetate Methyl-cyano-diacetylene Methyltriacetylene Propanal n-Propyl cyanide Pyrimidine

Deuterated
molecules

Unconfirmed

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Category:Astrochemistry
Category:Molecules
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