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💏intro to chemistry review

Tertiary (3°) alcohols

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Tertiary (3°) alcohols are a class of alcohols in which the hydroxyl (-OH) group is attached to a carbon atom that is connected to three other carbon atoms. This structure influences their chemical properties, including their reactivity and the types of reactions they can undergo, such as dehydration and oxidation. Tertiary alcohols are often less stable than primary or secondary alcohols but have unique characteristics that make them important in organic synthesis.

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5 Must Know Facts For Your Next Test

  1. Tertiary alcohols do not undergo oxidation reactions as readily as primary and secondary alcohols because they lack hydrogen atoms on the carbon bearing the -OH group.
  2. The presence of three alkyl groups on the carbon atom bonded to the hydroxyl group enhances the steric hindrance, making tertiary alcohols less nucleophilic.
  3. Tertiary alcohols can be converted into alkenes through dehydration, usually by heating with an acid catalyst, leading to the elimination of water.
  4. Common examples of tertiary alcohols include tert-butanol and isopropanol, both of which are used widely in industrial applications.
  5. Tertiary alcohols can react with strong acids, leading to the formation of carbocations, which can be intermediates in various organic reactions.

Review Questions

  • Compare and contrast tertiary alcohols with primary and secondary alcohols in terms of their structural features and reactivity.
    • Tertiary alcohols are characterized by having the hydroxyl (-OH) group attached to a carbon that is bonded to three other carbons, while primary alcohols have it on a carbon connected to one other carbon, and secondary alcohols have it on a carbon connected to two others. This difference in structure affects their reactivity; for example, tertiary alcohols are resistant to oxidation because they lack hydrogens on the -OH bearing carbon. Additionally, tertiary alcohols are more likely to undergo dehydration reactions compared to primary and secondary ones due to their ability to form stable carbocations.
  • Discuss the significance of dehydration reactions for tertiary alcohols and the conditions under which these reactions typically occur.
    • Dehydration reactions for tertiary alcohols are significant as they lead to the formation of alkenes, which are important in organic synthesis. These reactions typically require heating the tertiary alcohol in the presence of a strong acid catalyst, such as sulfuric acid or phosphoric acid. The heat and acid facilitate the elimination of water from the alcohol, resulting in the formation of an alkene. This transformation is crucial in processes such as petrochemical refining and the production of various organic compounds.
  • Evaluate the role of carbocations in the reactions of tertiary alcohols, including their stability compared to other types of carbocations.
    • Carbocations play a crucial role in the reactivity of tertiary alcohols as they are formed during reactions with strong acids or when undergoing dehydration. Tertiary carbocations are more stable than primary or secondary carbocations due to hyperconjugation and inductive effects from surrounding alkyl groups that help stabilize the positive charge. This increased stability allows tertiary carbocations to act as intermediates in various reactions, making tertiary alcohols more reactive under certain conditions despite their overall resistance to oxidation.