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Flashcards · 9701 · A Level Topic 32
Hydroxy compounds (A Level) flashcards
11 cards on A Level Topic 32, subtopics 32.1 to 32.2. Pick a subtopic or study them all.
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32.1 Alcohols
- Alcohol + acyl chloride: conditions and products
- Room temperature, no catalyst: ester + HCl. CH₃COCl + CH₃CH₂OH → CH₃COOCH₂CH₃ + HCl
- Compare making an ester from an acyl chloride with using a carboxylic acid
- Acyl chloride: room temperature, vigorous, not reversible, high yield, HCl by-product. Carboxylic acid: heat with conc. H₂SO₄, slow, reversible, yield limited by equilibrium, H₂O by-product.
- Mechanism type for alcohol + acyl chloride
- Nucleophilic addition–elimination: the O lone pair of the alcohol attacks the δ+ carbonyl carbon, then Cl⁻ is lost (as HCl).
32.2 Phenol
- How is phenol made from phenylamine?
- 1 NaNO₂ + dilute HCl (giving HNO₂), below 10 °C → benzenediazonium chloride. 2 Warm the solution with water: C₆H₅N₂⁺Cl⁻ + H₂O → C₆H₅OH + N₂ + HCl.
- Phenol with NaOH(aq) and with sodium
- NaOH: C₆H₅OH + NaOH → C₆H₅ONa + H₂O (dissolves). Na: 2C₆H₅OH + 2Na → 2C₆H₅ONa + H₂ (effervescence). No CO₂ with carbonates.
- Phenol with bromine water
- Room temperature, no catalyst: orange colour removed, white precipitate of 2,4,6-tribromophenol. C₆H₅OH + 3Br₂ → C₆H₂Br₃OH + 3HBr
- Nitration of phenol
- Dilute HNO₃ at room temperature (no H₂SO₄) gives a mixture of 2-nitrophenol and 4-nitrophenol.
- Order of acidity of phenol, water and ethanol, and why
- Phenol > water > ethanol. In phenoxide the negative charge is delocalised into the ring, stabilising it. In ethoxide the electron-donating ethyl group intensifies the charge on O, destabilising it.
- Why does phenol react with electrophiles more readily than benzene?
- An O lone pair is partly delocalised into the ring, increasing its electron density, so it attracts electrophiles more strongly and can polarise Br₂ without a halogen carrier.
- Coupling a diazonium salt with phenol
- Diazonium salt + phenol in NaOH(aq), below 10 °C: substitution at the 4-position gives a yellow/orange azo compound (–N=N– link), used as a dye.
- How many moles of Br₂ react with 4-methylphenol, and why?
- Two: the 4-position is occupied, so only the 2- and 6-positions are brominated, giving 2,6-dibromo-4-methylphenol + 2HBr.