Baeyer's test: cold dil alkaline KMnO4 (unsaturation / vicinal diol) (Cold dil alkaline KMnO4 adds –OH across C=C (syn dihydroxylation); purple MnO4−)
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Cold dil alkaline KMnO4 adds –OH across C=C (syn dihydroxylation); purple MnO4− decolorizes — test for unsaturation.
What each symbol means
| Symbol | What it stands for |
|---|---|
| KMnO4 | Oxidant; cold dilute → diol (Baeyer reagent context) |
| Heat/conc | Further oxidation to acids/cleavage — different outcome |
When to use this
Cold, dilute, alkaline — syn addition of two OH groups. Alkynes also react; aromatic ring stable under mild cold dilute conditions.