Chapter 8 · Chemistry
Aldehydes, Ketones and Carboxylic Acids: Chapter Introduction
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Vanilla, cinnamon, vinegar and nail-polish remover share one secret: the carbonyl group, C=O. What sits on the carbonyl carbon makes an aldehyde, a ketone or a carboxylic acid, and what this chapter will cover.
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The Carbonyl Group: Structure and PolarityWhy the carbon of C=O is every nucleophile's target: an sp², planar carbon, a π bond from sideways p–p overlap, and a polar C=O with δ⁺ carbon and δ⁻ oxygen, explained by resonance.Chemistry
Key points
- Aldehydes, ketones and carboxylic acids all contain the carbonyl group, C=O.
- Aldehyde: at least one H on the carbonyl carbon (R–CHO), e.g. vanillin, cinnamaldehyde.
- Ketone: two carbon groups on it (R–CO–R′), e.g. acetone in nail-polish remover.
- Carboxylic acid: an –OH on it (R–COOH), e.g. acetic acid in vinegar.
Three families, one group
| Family | On the carbonyl carbon | Example |
|---|---|---|
| Aldehyde (R–CHO) | at least one H | vanillin, cinnamaldehyde |
| Ketone (R–CO–R′) | two carbon groups | acetone (propanone) |
| Carboxylic acid (R–COOH) | an –OH group | acetic acid (vinegar) |
What this chapter covers
How these compounds are made; why the polar C=O undergoes nucleophilic addition; tests that tell an aldehyde from a ketone; and why carboxylic acids are acidic.
Quick quiz
5 questions. Choose an answer for each, then submit to see your score and the explanations.
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Aldehydes, Ketones and Carboxylic Acids: The Whole Chapter in One MinuteThe chapter in one place: the polar, planar C=O group; how aldehydes and ketones are made; nucleophilic addition; aldol and Cannizzaro; Tollens' and Fehling's tests; and why carboxylic acids are acidic.Chemistry