Reaction Summary
Reagents
- Concentrated
or concentrated - or pass vapour over heated
Conditions
- Heat (~170 °C with acid; ~300 °C over
)
Catalyst
- Conc. acid /
act as the dehydrating agent/catalyst
Chemical Equation
Equation
By-Products
Observations
Observations
- No visible change (colourless liquid/solution throughout)
⚠️ 9701 Exam Notes / Pitfalls
Warning
- Dehydration: OH is lost from one carbon and H from an adjacent carbon.
- With a 3-hydroxyketone (aldol product) the C=C forms conjugated with C=O.
- Check for cis/trans (geometric) isomers and for alternative positions of C=C if the OH carbon has two different neighbouring C–H carbons.
- Tertiary OH dehydrates most easily; a tertiary alcohol cannot be oxidised, but it can be dehydrated.