Methanol

Ball-and-stick Stick Space-filling

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6 atoms, 5 single bonds.

IUPAC name: methanol
Molar mass: 32.0420(38) g/mol
Atoms: 6
Polarity: polar
SMILES: CO
InChIKey: OKKJLVBELUTLKV-UHFFFAOYSA-N
PubChem CID: 887

Made of

Structural formula of methanol. Every atom in the molecule is drawn. It shows which atoms are joined to which, not the shape. The model above shows the shape.

The old name, wood alcohol, records where methanol once came from: the destructive distillation of wood, which breaks wood down by heating it. It is the alcohol with a single carbon atom, CH₃OH, where an −OH group has replaced one hydrogen of methane. The IUPAC name is simply methanol, and the molar mass is 32.042 g/mol.

The carbon in methane has an oxidation number of −4; in methanol it is −2. That number is bookkeeping, not a real charge: one C–H bond has been traded for a C–O bond. Further oxidation climbs on through CH₂O and HCO₂H to carbon dioxide.

At room temperature methanol is a mobile liquid that boils at 64.7 °C and freezes at −97.8 °C. It mixes with water in any proportion. Pure, it smells faintly of alcohol; the crude product smells repulsive and pungent.

Structure and bonding

The model holds six atoms and five single bonds. At one end the carbon carries three hydrogen atoms and the oxygen; the oxygen carries the carbon and one last hydrogen. With Labels on, the C, the O and four H symbols make that split plain: three hydrogens crowd the carbon, one sits alone on the oxygen.

In Ball-and-stick, the angles at carbon measure 109.0° to 109.5° in this computed model. At oxygen the C–O–H angle closes to 107.1°. OpenStax gives the general rule that lone pairs fill more space than bonding pairs and bend angles away from the ideal; the viewer draws no lone pairs. Stick view strips the atoms to lines and shows the O–H bond set off at an angle from the C–O axis. Space-filling merges everything into a compact lump with the lone hydrogen jutting from the oxygen side.

Every bond is drawn single, matching the real bonding of an alcohol’s oxygen. The Hazardous Substances Data Bank (HSDB) calls the liquid highly polar and gives the molecule a dipole moment of 1.69 debyes. OpenStax defines that as the net charge separation across a whole molecule, the sum of its bond moments in three dimensions.

Where it turns up

Methanol occurs naturally in humans, animals and plants, and it is present in blood and urine. The main sources in the human body are foods: fresh fruit and vegetables, fruit juices, fermented drinks and diet soft drinks sweetened with aspartame. Volcanic gases, vegetation and microbes release it into the environment as well.

In a garage it is an ingredient of windscreen washer fluid, and it also goes into paint removers and duplicating fluids. Campers meet it as fuel for picnic stoves. The California Safe Cosmetics Program reports that formulators add it to alcohol-based cosmetics to discourage people from drinking them. EU rules cap it at 11 per cent by weight in tattoo ink. Out in the oil field, it holds back corrosion and scale in water-based fracking fluids, liquids pumped into wells under pressure to crack rock and free oil and gas.

Why it matters

Industry makes methanol exclusively by catalytic conversion of synthesis gas, hydrogen mixed with oxides of carbon, in the low-pressure process at 5 to 10 MPa. OpenStax prints one such reaction: a molecule of carbon monoxide joins two of hydrogen to give methanol gas, releasing 90.5 kJ per mole. That is only the carbon monoxide route. HSDB explains why a recycling loop pays: methanol and water condense out, so unreacted gas can go round again for high conversion.

The low-pressure route offers lower investment and running costs, better reliability and freer plant sizing. US output was reported at 20 to 25 billion pounds in 2023.

Much of it becomes other chemicals. In 2013, HSDB records, formaldehyde took 31 per cent of all methanol use, MTBE (methyl tert-butyl ether) 11 per cent and acetic acid 10 per cent. Methanol also serves as a solvent for inks, resins, adhesives and dyes, and in medicine-making for vitamins, hormones and streptomycin. Blended into petrol it acts as an antifreeze and octane booster, and HSDB lists it as a hydrogen source for fuel cells.

Properties

Properties of methanol Molar mass summed from IUPAC/CIAAW 2024 standard atomic weights; formula, atom and bond counts and PubChem's molecular weight from PubChem CID 887.
Property	Value	Unit	Source
Molecular formula (Hill order)	CH₄O
Molar mass	32.0420(38) g/mol	g/mol	IUPAC/CIAAW 2024
Carbon atoms	1
Hydrogen atoms	4
Oxygen atoms	1
Bonds	5
PubChem molecular weight	32.042 g/mol	g/mol	PubChem

Safety

Methanol is toxic and highly flammable. The EU classification carries the signal word Danger: toxic if swallowed, in contact with skin or if inhaled, and damaging to organs. The NIOSH card lists optic nerve damage, which can mean blindness, among the symptoms of poisoning. The Emergency Response Guidebook says its flame is invisible, and HSDB describes it as a bluish flame that gives off little light. The PubChem Laboratory Chemical Safety Summary and the NIOSH card for methyl alcohol are the authoritative sheets.

Questions

What shape is a methanol molecule?

No single shape word fits, since methanol has two central atoms. The carbon holds three hydrogens and the oxygen, and in PubChem's computed model the angles around it are 109.0° to 109.5°. The oxygen holds the carbon and one hydrogen, with a C−O−H angle of 107.1° in the same model. These are model values, not measurements, and the viewer leaves out the oxygen's lone pairs.

Is methanol the same as the alcohol in drinks?

No. The alcohol in wine, beer and spirits is ethanol, CH₃CH₂OH, which has one more carbon. Methanol is classed as toxic if swallowed, and NIOSH, the US federal institute for workplace safety research, says most poisonings come from drinking beverages contaminated with it or products that contain it. The California Safe Cosmetics Program reports that makers of alcohol-based cosmetics add methanol to discourage people from drinking the product.

Is methanol a good fuel?

OpenStax calls it a possible excellent alternative fuel, and the US Environmental Protection Agency reports its use as an alternative motor fuel and as a fuel for picnic stoves. Burning one mole of liquid methanol releases 726.1 kJ, against 1366.8 kJ for a mole of ethanol, per OpenStax's table of combustion enthalpies. Its flame is a hazard of its own: the Emergency Response Guidebook calls it invisible.

Does methanol mix with water?

Yes. The Hazardous Substances Data Bank (HSDB) lists methanol as miscible with water at 25 °C, meaning the two mix in any proportion. It is also miscible with ethanol, ether, benzene, ketones and most organic solvents. HSDB adds that water is the usual impurity in commercial methanol, alongside acetone and ethanol, and describes the pure liquid as mobile and highly polar.

Made of the same elements

CH₃CHO Acetaldehyde 7 atoms, 6 bonds.
C₂H₄O Ethylene oxide 7 atoms, 7 single bonds.
CH₃COOH Acetic acid 8 atoms, 7 bonds.
CH₂O Formaldehyde 4 atoms, 3 bonds.
CH₃OCH₃ Dimethyl ether 9 atoms, 8 single bonds.
C₂H₅OH Ethanol 9 atoms, 8 single bonds.
HCOOH Formic acid 5 atoms, 4 bonds.
C₂H₄O₃ Glycolic acid 9 atoms, 8 bonds.

All 51 compounds made of carbon, hydrogen and oxygen

C₃H₆O Acetone 10 atoms, 9 bonds.
H₂CO₃ Carbonic acid 6 atoms, 5 bonds.
C₂H₆O₂ Ethylene glycol 10 atoms, 9 single bonds.
C₂H₅COOH Propionic acid 11 atoms, 10 bonds.
C₃H₇OH 1-Propanol 12 atoms, 11 single bonds.
C₃H₈O Isopropyl alcohol 12 atoms, 11 single bonds.
C₃H₆O₃ Lactic acid 12 atoms, 11 bonds.
H₂C₂O₄ Oxalic acid 8 atoms, 7 bonds.
C₄H₈O Butanone 13 atoms, 12 bonds.
C₆H₅OH Phenol 13 atoms, 13 bonds.
C₃H₈O₂ Propylene glycol 13 atoms, 12 single bonds.
C₆H₅CHO Benzaldehyde 14 atoms, 14 bonds.
C₃H₇COOH Butyric acid 14 atoms, 13 bonds.
CH₃COOC₂H₅ Ethyl acetate 14 atoms, 13 bonds.
C₃H₈O₃ Glycerol 14 atoms, 13 single bonds.
C₄H₉OH 1-Butanol 15 atoms, 14 single bonds.
C₆H₅COOH Benzoic acid 15 atoms, 15 bonds.
C₂H₅OC₂H₅ Diethyl ether 15 atoms, 14 single bonds.
C₄H₆O₅ Malic acid 15 atoms, 14 bonds.
C₇H₆O₃ Salicylic acid 16 atoms, 16 bonds.
C₄H₆O₆ Tartaric acid 16 atoms, 15 bonds.
C₈H₈O₃ Methyl salicylate 19 atoms, 19 bonds.
C₈H₈O₃ Vanillin 19 atoms, 19 bonds.
C₆H₈O₆ Ascorbic acid 20 atoms, 20 bonds.
C₉H₈O₄ Aspirin 21 atoms, 21 bonds.
C₆H₈O₇ Citric acid 21 atoms, 20 bonds.
C₆H₁₂O₆ Fructose 24 atoms, 24 single bonds.
C₆H₁₂O₆ Glucose 24 atoms, 24 single bonds.
C₁₀H₂₀O Menthol 31 atoms, 31 single bonds.
C₁₄H₁₄O₃ Naproxen 31 atoms, 32 bonds.
C₁₅H₁₆O₂ Bisphenol A 33 atoms, 34 bonds.
C₁₃H₁₈O₂ Ibuprofen 33 atoms, 33 bonds.
C₂₀H₁₄O₄ Phenolphthalein 38 atoms, 41 bonds.
C₁₈H₂₄O₂ Estradiol 44 atoms, 47 bonds.
C₁₂H₂₂O₁₁ Lactose 45 atoms, 46 single bonds.
C₁₂H₂₂O₁₁ Sucrose 45 atoms, 46 single bonds.
C₁₉H₂₈O₂ Testosterone 49 atoms, 52 bonds.
C₁₆H₃₂O₂ Palmitic acid 50 atoms, 49 bonds.
C₂₁H₃₀O₂ Progesterone 53 atoms, 56 bonds.
C₁₈H₃₄O₂ Oleic acid 54 atoms, 53 bonds.
C₂₁H₃₀O₅ Cortisol 56 atoms, 59 bonds.
C₂₇H₄₄O Cholecalciferol 72 atoms, 74 bonds.
C₂₇H₄₆O Cholesterol 74 atoms, 77 bonds.