Ketone
A ketone is an organic compound containing a carbonyl group (C=O) flanked on both sides by carbon atoms, represented by the general formula R–CO–R'. Unlike aldehydes, the carbonyl carbon in a ketone carries no hydrogen atom, making ketones less susceptible to oxidation and generally less reactive towards nucleophiles. Ketones are widely found in nature (fructose, steroid hormones) and in industry (acetone as a solvent, cyclohexanone in nylon synthesis).
Key Formula
R-CO-R' (where R and R' are organic groups)
LaTeX: R\text{-}C(=O)\text{-}R'
| Symbol | Meaning | Unit |
|---|---|---|
| R | First organic substituent | none |
| R' | Second organic substituent (may equal R) | none |
| C=O | Carbonyl group | none |
Worked Example
Problem
Propanone (acetone, CH₃COCH₃, M = 58.08 g/mol) is used as a solvent. How many molecules of acetone are present in 5.00 g of acetone?
Solution
Step 1: Calculate moles of acetone. n = mass / molar mass = 5.00 g / 58.08 g mol⁻¹ = 0.08609 mol Step 2: Convert moles to molecules using Avogadro's number. N = n × Nₐ = 0.08609 mol × 6.022 × 10²³ mol⁻¹ N = 5.184 × 10²² molecules
Answer
5.18 × 10²² molecules of acetone in 5.00 g
Comparison of Common Ketones
| IUPAC Name | Common Name | Formula | Boiling Point (°C) | Application |
|---|---|---|---|---|
| Propanone | Acetone | CH₃COCH₃ | 56 | Solvent, nail polish remover |
| Butanone | Methyl ethyl ketone | CH₃COC₂H₅ | 80 | Lacquer solvent |
| Cyclohexanone | Cyclohexanone | C₆H₁₀O | 155 | Nylon precursor |
| Acetophenone | Acetophenone | C₆H₅COCH₃ | 202 | Fragrance, pharmaceuticals |
| Benzophenone | Diphenyl ketone | (C₆H₅)₂CO | 305 | UV stabiliser in plastics |
Interactive Tools
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Related Terms
Aldehyde
An aldehyde is an organic compound containing a carbonyl group (C=O) in which the carbon atom is bonded to at least one hydrogen atom, giving the characteristic –CHO functional group at the end of a carbon chain. Aldehydes are more reactive than ketones because the carbonyl carbon is less sterically hindered and more electrophilic. They are important industrial chemicals — formaldehyde is used in resins, acetaldehyde in vinegar production, and benzaldehyde gives almonds their characteristic scent.
Addition Reaction
An addition reaction is a chemical reaction in which two or more molecules combine to form a single, larger product with no atoms lost as a by-product. Addition reactions occur most commonly at carbon–carbon multiple bonds (alkenes, alkynes) and at polar carbonyl groups, where a reagent adds across the unsaturation. They are fundamental to industrial synthesis — the hydrogenation of vegetable oils, the production of polymers like polyethylene, and the manufacture of alcohols from alkenes all proceed via addition reactions.
Nucleophile
A nucleophile is a chemical species that donates an electron pair to an electrophile to form a new covalent bond, acting as a Lewis base. Nucleophiles are characterised by the presence of a lone pair of electrons, a negative charge, or a region of high electron density that attacks electron-deficient centres (electrophilic carbons). Strong nucleophiles drive SN2 reactions and nucleophilic addition; weaker nucleophiles favour SN1 pathways — making nucleophilicity a key parameter in predicting organic reaction outcomes.
From German "Keton", introduced by Leopold Gmelin in 1848, derived from "Aketon" (acetone) — itself from French "acétone", from Latin "acetum" (vinegar). The IUPAC suffix "-one" is used for all ketones in systematic nomenclature.