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Organic Chemistry · Reaction Library

Alcohol Reactions: Oxidation, Dehydration & Substitution

Use alcohol structure and reaction conditions to predict carbonyls, alkenes, and substitution products.

Step-by-step lessonsCurated examplesInteractive practicePrintable worksheets

1. Understand the concept

An alcohol has an –OH group attached to carbon. The outcome depends on whether the alcohol is primary, secondary, or tertiary and which reagents are present.

Learning goal: Use alcohol structure and reaction conditions to predict carbonyls, alkenes, and substitution products.

2. Use a reliable prediction strategy

  1. Classify the carbon bonded to OH as primary, secondary, or tertiary.
  2. Identify the reagent family: oxidation, dehydration, or activation/substitution.
  3. Identify possible rearrangements under strongly acidic conditions.
  4. Draw the major product and confirm atom connectivity and functional group.

3. Follow the reaction roadmap

Three verified reaction transformations with substrates, reagents and labeled products for Alcohol Reactions
Illustrative pathways; reagent choice and selectivity matter. Structures are shown in condensed notation.

4. Work through examples

Worked example 1

Primary alcohol + PCC

CH₃CH₂OH + PCC → CH₃CHO

Under anhydrous conditions PCC commonly oxidizes a primary alcohol to an aldehyde. Use correct product class before naming.

Worked example 2

Secondary alcohol + oxidant

CH₃CH(OH)CH₃ + Na₂Cr₂O₇/H₂SO₄ → CH₃COCH₃

A secondary alcohol oxidizes to a ketone. Oxidation normally stops there because no hydrogen remains on the carbinol carbon.

5. Common mistakes

  • Assuming every oxidant stops a primary alcohol at the aldehyde; aqueous chromium(VI) conditions generally allow further oxidation to acid.
  • Claiming simple tertiary alcohols undergo ordinary oxidation to ketones; cleavage would be needed under harsh conditions.
  • Predicting only one alkene for unsymmetrical acid-catalyzed dehydrations without checking rearrangement and regioselectivity.

6. Check understanding

Compare the oxidation of 1-propanol under PCC and aqueous Jones conditions.

PCC commonly produces propanal; Jones oxidation generally yields propanoic acid.

Why is 2-methyl-2-propanol resistant to ordinary oxidation?

The carbon bearing OH has no C–H bond; normal oxidation to a carbonyl would require C–C bond cleavage.

7. Practice the reactions

Use the quiz below to apply the rules to new substrates and reagents. A correct answer is explained, not merely marked.

INTERACTIVE PRACTICE

Try the reaction challenge

Answer eight curated questions. Review the explanation after each answer.

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