Acetone

Ball-and-stick Stick Space-filling

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10 atoms, 9 bonds.

IUPAC name: propan-2-one
Molar mass: 58.0800(82) g/mol
Atoms: 10
SMILES: CC(=O)C
InChIKey: CSCPPACGZOOCGX-UHFFFAOYSA-N
PubChem CID: 180

Made of

Structural formula of acetone. Each unlabelled corner is a carbon atom. It shows which atoms are joined to which, not the shape. The model above shows the shape.

Nail polish remover and many paint strippers depend on the same small solvent. OpenStax calls it dimethyl ketone and ranks it as the simplest ketone. A ketone is a compound whose carbonyl group, a carbon atom double-bonded to an oxygen atom, is joined to two further carbon atoms. The IUPAC name, propan-2-one, spells out that layout: a chain of three carbons with the oxygen on the middle one.

The molecule is built from carbon, hydrogen and oxygen, with a molar mass of 58.08 g/mol. At room temperature it is a clear liquid that NIOSH, the US National Institute for Occupational Safety and Health, describes as having a fragrant, mint-like odour. It boils at 56 °C, far below water, yet it mixes with water in any proportion. Alcohol, ether, chloroform and most fixed oils mix with it just as freely, according to PubChem’s property data.

Structure and bonding

The viewer draws ten atoms and nine bonds. At the centre, the carbonyl carbon holds the oxygen by a double bond and two methyl carbons by single bonds. With Labels on, each outer carbon shows three H symbols, matching OpenStax’s condensed formula CH₃COCH₃.

In the ball-and-stick view, the model’s computed angles are 121.6° for each O=C–C and 116.7° for C–C–C, which add to almost exactly 360°. Turned edge-on, the oxygen, the middle carbon and both methyl carbons lie in one plane. OpenStax calls this geometry trigonal planar. The methyl carbons are different: their bonds spread at 109 to 110° in the model. Two of each methyl’s three hydrogens sit above and below that plane, and the third lies in it.

The Stick view thins the atoms down to their bonds, all nine of them, with the doubled C=O line at one end. Space-filling shows the whole outline, the oxygen bulging from a body wrapped in hydrogens. The C=O bond is polar: oxygen has much the higher electronegativity, the pull an atom exerts on shared electrons, so those electrons sit nearer the oxygen. The model draws no charges, so this uneven sharing shows in none of the views.

Where it turns up

Acetone is not only a factory product. ATSDR (Agency for Toxic Substances and Disease Registry), a US federal body, lists plants, trees, volcanic gases and forest fires among its natural sources. Vehicle exhaust, tobacco smoke and landfill sites release it too. Your own body makes some when it breaks down stored fat. Even so, the same agency judges that industry puts more acetone into the environment than nature does.

Indoors, the obvious place is the bathroom shelf, in nail polish remover. Some 1,176 products contain it, according to the Consumer Product Information Database quoted on PubChem. California’s Safe Cosmetics Program counts 105 cosmetics. It reaches the kitchen in small ways as well. Food-additive listings on PubChem name it both as a flavouring agent and as an extraction solvent. An extraction solvent is a liquid used to pull other substances out of a food material.

Why it matters

Only a fraction of the acetone made reaches a bottle of remover. The Toxin and Toxin Target Database, quoted on PubChem, says most of it becomes other chemicals, which go on to make plastics, fibres and drugs. According to the Hazardous Substances Data Bank (HSDB), methyl methacrylate, methacrylic acid and higher methacrylates take 34 per cent, coatings solvents 15, bisphenol-A 12 and methyl isobutyl ketone 10.

OpenStax notes that many reactions of ketones begin at the carbonyl carbon, the slightly positive partner in the polar C=O bond. In the model, that carbon is the one at the centre of the flat corner. The scale is large: HSDB put global demand at 5 million tonnes in 2005. The US Environmental Protection Agency’s 2023 reporting places national output between 1 and 2.5 billion pounds. As a solvent it also serves drug and chemical manufacture, and it strips paint and varnish.

Properties

Properties of acetone Molar mass summed from IUPAC/CIAAW 2024 standard atomic weights; formula, atom and bond counts and PubChem's molecular weight from PubChem CID 180.
Property	Value	Unit	Source
Molecular formula (Hill order)	C₃H₆O
Molar mass	58.0800(82) g/mol	g/mol	IUPAC/CIAAW 2024
Carbon atoms	3
Hydrogen atoms	6
Oxygen atoms	1
Bonds	9
Single bonds	8
Double bonds	1
PubChem molecular weight	58.08 g/mol	g/mol	PubChem

Safety

Acetone is a highly flammable liquid, and its vapour is heavier than air, so it can creep along the ground to a flame some distance away. The European Chemicals Agency’s classification also warns that it causes serious eye irritation and may cause drowsiness or dizziness. Repeated contact removes the natural oils from skin, which may leave it dry or cracked. The PubChem Laboratory Chemical Safety Summary, and for workplace exposure the NIOSH Pocket Guide card for acetone give the authoritative detail.

Questions

Why does acetone remove nail polish?

Nail polish is a lacquer, and acetone dissolves lacquers. PubChem's property data list the liquid as the working solvent in removers for paint and for nail polish, and the same ability puts it to work on varnishes, plastics and cellulose acetate. It also strips the natural oils from skin, so repeated contact can leave the skin around the nails dry or cracked.

What shape is an acetone molecule?

No single shape word fits the whole molecule, since each of its three carbons has its own surroundings. OpenStax calls the middle carbon trigonal planar: the oxygen and both end carbons lie flat around it. In OpenStax's account that carbon forms its three single (σ) bonds with sp² hybrid orbitals, mixed orbitals aimed at the corners of a flat triangle. A leftover p orbital overlaps one on oxygen to form the C=O's second, π, bond.

Why can someone's breath smell of acetone?

When fat breakdown overloads the Krebs cycle, the pathway that turns acetyl CoA into usable energy, the surplus is diverted into ketone bodies, a fuel in prolonged starvation or uncontrolled diabetes. They can be oxidised for energy, but when they are made faster than they are used, some split into carbon dioxide and acetone, and the acetone is breathed out. OpenStax notes the sweet smell as one sign that diabetes is poorly controlled.

How is acetone made?

According to the Hazardous Substances Data Bank, the main source of acetone worldwide is now the oxidation of cumene, a route that makes phenol at the same time: about 0.6 kg of acetone for every kilogram of phenol. OpenStax gives two other routes, fermenting corn or molasses and oxidising 2-propanol. Before the First World War, industry heated calcium acetate made from lime and wood distillate.

Made of the same elements

CH₃OCH₃ Dimethyl ether 9 atoms, 8 single bonds.
C₂H₅OH Ethanol 9 atoms, 8 single bonds.
C₂H₅COOH Propionic acid 11 atoms, 10 bonds.
C₃H₇OH 1-Propanol 12 atoms, 11 single bonds.
C₂H₆O₂ Ethylene glycol 10 atoms, 9 single bonds.
C₃H₈O Isopropyl alcohol 12 atoms, 11 single bonds.
C₃H₆O₃ Lactic acid 12 atoms, 11 bonds.
CH₃CHO Acetaldehyde 7 atoms, 6 bonds.

All 51 compounds made of carbon, hydrogen and oxygen

C₄H₈O Butanone 13 atoms, 12 bonds.
C₂H₄O Ethylene oxide 7 atoms, 7 single bonds.
C₆H₅OH Phenol 13 atoms, 13 bonds.
C₃H₈O₂ Propylene glycol 13 atoms, 12 single bonds.
CH₃COOH Acetic acid 8 atoms, 7 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.
CH₃OH Methanol 6 atoms, 5 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.
C₂H₄O₃ Glycolic acid 9 atoms, 8 bonds.
C₄H₆O₅ Malic acid 15 atoms, 14 bonds.
CH₂O Formaldehyde 4 atoms, 3 bonds.
C₇H₆O₃ Salicylic acid 16 atoms, 16 bonds.
C₄H₆O₆ Tartaric acid 16 atoms, 15 bonds.
HCOOH Formic acid 5 atoms, 4 bonds.
H₂CO₃ Carbonic acid 6 atoms, 5 bonds.
H₂C₂O₄ Oxalic acid 8 atoms, 7 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.