Chapter 8 · Chemistry
The Haloform Reaction: Iodoform Test
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Yellow crystals with a hospital smell reveal the CH₃CO group. How the iodoform test works and which compounds pass it.
Download the short notesPDF, 177 KB · solved examples, practice set and answer key Download the workbook
PDF, 184 KB · fill in the blanks, true/false, assertion-reason, MCQ, numericals, short answer, match the columns; detailed solutions at the end Up next in this chapter
Aldol Condensation: The Alpha Hydrogen KeyTwo small ethanal molecules join into one bigger molecule. How the alpha hydrogen makes it happen, and which compounds cannot do it.Chemistry · simulation
Key points
- Iodine and NaOH act on compounds with a CH₃CO group.
- The 3 H atoms of the methyl group are replaced by iodine, giving CI₃.
- The C–C bond breaks: yellow iodoform, CHI₃, and a carboxylate with 1 carbon fewer.
- Positive: ethanal, methyl ketones, and ethanol or propan-2-ol, which oxidise to them.
- Negative: methanol, propanal, pentan-3-one.
Who passes
| Compound | Iodoform test | Why |
|---|---|---|
| Ethanal | Positive | CH₃CO group |
| Propanone | Positive | Methyl ketone |
| Ethanol | Positive | Oxidises to ethanal |
| Propan-2-ol | Positive | Oxidises to propanone |
| Methanol | Negative | Cannot form CH₃CO |
| Propanal | Negative | No CH₃CO |
| Pentan-3-one | Negative | No methyl next to C=O |
Try it yourself
Goal: Test which compounds give iodoform, and use it to identify a mystery compound.
- Choose a compound and predict.
- Press Iodoform and read the result and the reason.
- Try methanol and ethanol, then propanal and ethanal.
- Use Mystery compound and Reveal.
Quick quiz
3 questions. Choose an answer for each, then submit to see your score and the explanations.
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