Why is acetone called a ketone?

Acetone's carbonyl group (C=O) is attached to two carbon atoms on both sides. This makes it different from aldehydes, where the carbonyl group sits at the end of the carbon chain.

Does acetone dissolve in water?

Yes, acetone dissolves completely in water because it is polar and can accept hydrogen bonds, making it a highly versatile solvent in chemistry.

Why does acetone evaporate fast?

Acetone evaporates quickly because of its low boiling point of approximately 56 °C and high volatility, which also gives it a strong characteristic smell.

Exposure to large amounts of acetone can cause dizziness, headaches, and skin or eye irritation. In small quantities, such as in nail polish remover, it is generally safe when handled carefully.

Why does acetone not give the Tollens test?

Acetone is a ketone and is not easily oxidised under Tollens' test conditions. Only aldehydes, which have the carbonyl carbon at the terminal position, get oxidised in this test.

Can acetone act as a solvent?

Yes, acetone is an excellent solvent. It dissolves a wide range of organic compounds and some inorganic substances, making it very useful in laboratories and industries.

Why does acetone smell strong?

Acetone has a strong, sharp smell because it evaporates quickly at room temperature. Its high volatility allows vapours to reach the nose easily.

Is acetone flammable?

Yes, acetone is highly flammable and its vapours can catch fire easily. It should always be kept away from open flames and sparks.

Acetone (Propanone) – Structure, Properties, Uses & Reactions | Aakash

Organic Chemistry

Acetone (Propanone)

The simplest and most studied ketone. Understand its IUPAC name, structure, properties, reactions, and uses — essential for NEET and JEE chemistry.

Formula: C₃H₆O IUPAC: Propanone Class: Ketone BP: ~56 °C

Chemical Formula

C₃H₆O

IUPAC Name

Propanone

Molar Mass

58.08 g/mol

Boiling Point

56.05 °C

Density

0.79 g/cm³

Functional Group

C=O

What is Acetone?

Acetone is an organic compound belonging to the ketone family. Its IUPAC name is propanone, and its chemical formula is C₃H₆O. It contains a carbonyl group (C=O), where the central carbon atom is bonded to two other carbon atoms on either side — this arrangement is what classifies it as a ketone rather than an aldehyde.

Acetone is a colourless, highly volatile liquid with a sharp, characteristic smell. It is miscible with water in all proportions because of its polar nature and ability to accept hydrogen bonds. It is commonly found in nail polish removers, laboratory solvents, and many industrial cleaning applications.

Structure of Acetone

Acetone has a simple, symmetrical structure with three carbon atoms. The middle carbon is double-bonded to an oxygen atom, and the two outer carbons are methyl groups (–CH₃).

CH₃ – C(=O) – CH₃

Structural representation of Propanone (Acetone)

Key Structural Features

Feature	Detail
Total carbon atoms	3
Functional group	Carbonyl group (C=O) — ketone
Position of C=O	Central carbon (C-2)
Side groups	Two methyl groups (–CH₃)
Symmetry	Symmetrical molecule
Bond angle at C=O	~120° (sp² hybridised)

The symmetry of acetone makes it a very predictable compound for reaction mechanism studies, and is one reason it is widely used as a model ketone in organic chemistry courses.

Physical Properties of Acetone

Property	Value / Description
Appearance	Colourless liquid
Smell	Sharp, fruity odour
Boiling Point	56.05 °C
Melting Point	−94.7 °C
Density	0.79 g/cm³ (lighter than water)
Solubility in water	Completely miscible
Volatility	Very high — evaporates rapidly at room temperature
Flammability	Highly flammable
Hydrogen bonding	Accepts H-bonds (cannot donate — no O–H)

Although acetone mixes completely with water, it differs from alcohols in one important way: it cannot donate hydrogen bonds because it has no O–H group. It can only accept them via the carbonyl oxygen. This subtle difference significantly affects its physical behaviour compared to alcohols like ethanol.

Chemical Behaviour of Acetone

Acetone displays the typical reactions of ketones. The slightly electron-deficient (δ+) carbonyl carbon makes it susceptible to nucleophilic attack. Below are its key chemical behaviours:

Nucleophilic Addition Reactions

1
With HCN (Hydrogen Cyanide): Acetone reacts with HCN to form a cyanohydrin (acetone cyanohydrin). The CN⁻ ion acts as the nucleophile attacking the carbonyl carbon.
2
With NaHSO₃ (Sodium Bisulphite): Acetone forms a bisulphite addition product. This reaction is reversible and used in the purification of ketones.
3
With Grignard Reagents: Reaction with RMgX (Grignard reagent) followed by hydrolysis gives a tertiary alcohol. This is an important synthetic route in organic chemistry.

Identification Tests — What Acetone Does NOT Give

Test	Acetone Result	Why
Tollens' Test (Silver Mirror)	Negative	Ketones are not easily oxidised; only aldehydes respond.
Fehling's Test	Negative	Same reason — ketones do not reduce Fehling's solution.
2,4-DNP Test	Positive	Acetone gives an orange/yellow precipitate — confirms carbonyl group.
Iodoform Test	Positive	Acetone gives a yellow precipitate of CHI₃ with I₂/NaOH.

Oxidation

Acetone is relatively resistant to oxidation under mild conditions. Under strong oxidising agents, it can be cleaved to form acetic acid and other products. This resistance to easy oxidation is a distinguishing feature of ketones compared to aldehydes.

Preparation of Acetone

1. Oxidation of Isopropyl Alcohol (Lab Method)

The most common lab method involves oxidising isopropyl alcohol (propan-2-ol) using an oxidising agent such as acidified K₂Cr₂O₇ or KMnO₄. A secondary alcohol gives a ketone on oxidation.

CH₃–CH(OH)–CH₃ → [O] → CH₃–CO–CH₃

Isopropyl alcohol → Acetone (oxidation)

2. Dry Distillation of Calcium Acetate (Classical Method)

Heating calcium acetate (CH₃COO)₂Ca produces acetone along with calcium carbonate. This is an older method, but important for understanding pyrolysis-based reactions.

3. Cumene Process (Industrial Method)

Industrially, acetone is produced as a co-product of phenol via the cumene process. Cumene (isopropylbenzene) is oxidised and then cleaved with an acid to simultaneously yield both phenol and acetone. This is the most economically important industrial source of acetone.

Uses of Acetone

🧪 Laboratory Solvent Dissolves a wide range of organic compounds; used for rinsing glassware before drying.

💅 Nail Polish Remover The most recognised consumer application — dissolves lacquers and resins quickly.

🏭 Paint Thinner Used to thin paints, varnishes, and lacquers in industrial and domestic use.

🧴 Pharmaceutical Production Acts as a reaction solvent and intermediate in the synthesis of medicines.

♻️ Plastics & Fibres Raw material in production of polycarbonates, acrylic glass (Plexiglas), and synthetic fibres.

🧼 Cleaning Agent Removes grease, oil, adhesives, and resins from surfaces and equipment.

Safety and Health Effects

⚠️ Important Safety Information

Flammability: Acetone is highly flammable. Its vapour has a low flash point and can ignite easily near open flames or sparks. Always keep acetone containers closed and away from ignition sources.

Health hazards: Inhaling large concentrations of acetone vapour causes dizziness, headaches, and irritation of the eyes and nose. Prolonged skin contact leads to dryness and irritation. Ingestion is harmful. Despite being common, acetone must always be handled with care.

Lab precautions: Store in a closed container (high volatility causes rapid vapour spread), use in a well-ventilated area or fume hood, and keep away from all ignition sources.

Why Acetone is Important in Chemistry

Acetone is a model compound for ketones. Because it is simple, symmetrical, and readily available, most reaction mechanisms involving the carbonyl group are first explained using acetone. Its predictable behaviour makes it the starting point for understanding nucleophilic addition, oxidation resistance of ketones, and hydrogen bond behaviour in polar aprotic solvents.

Beyond the classroom, acetone serves as a bridge between basic organic chemistry and industrial applications — students encounter it in textbooks, labs, and everyday life, giving it a unique practical relevance.

Frequently Asked Questions (FAQs)

Why is acetone called a ketone?

Acetone's carbonyl group (C=O) is attached to two carbon atoms on either side. In ketones, the carbonyl carbon is bonded to two other carbon atoms — unlike aldehydes, where it sits at the end of the chain with at least one hydrogen attached.
Does acetone dissolve in water?

Yes, acetone is completely miscible with water in all proportions. It is a polar molecule and the carbonyl oxygen can accept hydrogen bonds from water molecules, enabling this full solubility.
Why does acetone evaporate so quickly?

Acetone has a very low boiling point (~56 °C) and high vapour pressure at room temperature. Weak intermolecular forces (no H-bond donation) mean molecules escape the liquid phase easily, causing rapid evaporation.
Is acetone harmful to health?

In large amounts, acetone vapour causes dizziness, headaches, nausea, and irritation to the eyes and respiratory tract. Prolonged skin exposure leads to dryness. Small amounts (like in nail polish remover) are generally safe with proper ventilation.
Why does acetone not give the Tollens' test?

Acetone is a ketone, and ketones are not easily oxidised under mild conditions. The Tollens' test works by oxidising aldehydes (which have a C–H bond on the carbonyl carbon). Since acetone lacks this feature, it gives a negative result.
What is the iodoform test result for acetone?

Acetone gives a positive iodoform test, producing a yellow precipitate of iodoform (CHI₃) when treated with iodine in sodium hydroxide solution. This is because acetone has a CH₃–CO– group, which is required for this reaction.
Is acetone flammable?

Yes, acetone is highly flammable. Its flash point is approximately −20 °C, meaning its vapours can ignite at room temperature. It must always be stored away from open flames, sparks, and any ignition source.
How is acetone produced industrially?

Acetone is primarily produced via the cumene process, where cumene (isopropylbenzene) is oxidised and then acid-cleaved to simultaneously produce phenol and acetone. This is the dominant industrial route globally.