Reaction of alcohols with Dehydrating agents Dehydration Reaction: removal of a water molecule from a molecule Reaction: Alcohol Alkene Reagents: Concentrated Sulphuric or Phosphoric acids Conditions: warm (under reflux) Role of reagent: dehydrating agent/catalyst Type of reaction: acid catalysed elimination C C + H2O H H H C H H H C O H H H C H H C H H H propan-1-ol Propene Some 2o and 3o alcohols can give more than one product, when the double bond forms between different carbon atoms C H C H C H H H C H H H O H H C C C C H H H H H H H H C H H C C C H H H H H H Butan-2-ol can form both alkenes although more but-2-ene would be formed Butan-2-ol But-1-ene But-2-ene But-2-ene could also exist as E and Z isomers
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4.2.1 Alcohols
(d) elimination of H2O from alcohols in the presence of an acid catalyst (e.g. H3PO4 or H2SO4) and heat to form alkenes Mechanism not required.
4.2.1 alcohols Page 4
Oxford Textbook Pages : 228
CGP Revision Guide Pages : 101