Oxidation of alcohols

• What can primary alcohols be oxidized to?

  Aldehydes or carboxylic acids
• How are alcohols categorized?

  Into primary, secondary, and tertiary alcohols
• What is a primary alcohol?

  Alcohol bonded to a carbon with one other carbon
• What happens when a primary alcohol is oxidized?

  It is converted to an aldehyde
• What is produced alongside an aldehyde during oxidation?

  One molecule of water
• What is a common oxidizing agent for alcohols?


  Potassium dichromate AND dilute sulfuric acid
• What color change occurs with potassium dichromate during oxidation?

  From orange to green
• What does the capital O in square brackets represent?

  One molecule of oxidizing agent
• Why must aldehydes be removed quickly during oxidation?

  They easily oxidize further to carboxylic acids
• How can aldehydes be removed during the reaction?

  By distillation
• What is required to oxidize an aldehyde to a carboxylic acid?

  Two molecules of oxidizing agent
• What is used to ensure complete oxidation of aldehyde?

  An excess of oxidizing agent
• What is the role of concentrated sulfuric acid in oxidation?

  It can replace dilute sulfuric acid
• What does heating under reflux do?

  Condenses volatile products back to the reaction
• What is produced at the end of the oxidation of a primary alcohol?

  A carboxylic acid
• Why do carboxylic acids have higher boiling points than aldehydes?

  They can form hydrogen bonds
• How can carboxylic acids be separated from the reaction mix?

  By distillation
• What are the steps for oxidizing a primary alcohol to an aldehyde?

  • Use an oxidizing agent (e.g., potassium dichromate)
  • Heat the primary alcohol with the oxidizing agent
  • Remove the aldehyde by distillation as it forms
• What are the steps for oxidizing an aldehyde to a carboxylic acid?

  • Use an excess of oxidizing agent
  • Heat the reaction under reflux
  • Ensure all aldehyde is oxidized to carboxylic acid
• What are the differences in boiling points between ethanol, aldehydes, and carboxylic acids?

  • Ethanol: ~78°C
  • Aldehydes: lower boiling points, cannot form hydrogen bonds
  • Carboxylic acids: higher boiling points, can form hydrogen bonds
• What is the significance of using reflux in oxidation reactions?

  • Allows for continuous heating
  • Prevents loss of volatile products
  • Ensures complete reaction
• What can secondary and tertiary alcohols be oxidized to?

  Secondary alcohols to ketones; tertiary alcohols cannot oxidize
• What happens to primary alcohols during oxidation?

  They oxidize to aldehydes, then carboxylic acids
• What is a common oxidizing agent for alcohol oxidation?

  Potassium dichromate and dilute sulfuric acid
• What color change indicates the reduction of dichromate ion?

  From orange to green
• What is produced when a secondary alcohol is oxidized?

  A ketone and water
• Why can't ketones be oxidized further?

  They lack hydrogen atoms bonded to carbon
• What does the notation [O] represent in oxidation reactions?

  One molecule of oxidizing agent
• What is the purpose of heating under reflux during oxidation?

  To maximize ketone formation
• What happens at the end of the oxidation reaction of a secondary alcohol?

  A mixture of ketone, water, unreacted alcohol, and oxidizing agent
• How are ketones separated from the reaction mixture?

  By distillation
• Why are ketones considered volatile chemicals?

  They cannot form hydrogen bonds
• What is the structure of a tertiary alcohol?

  Carbon bonded to the alcohol group has no hydrogen
• What occurs when a tertiary alcohol is heated with acidified potassium dichromate?

  No reaction occurs; the solution remains orange
• What are the key differences in the oxidation of primary, secondary, and tertiary alcohols?

  • Primary alcohols oxidize to aldehydes, then carboxylic acids.
  • Secondary alcohols oxidize to ketones and water.
  • Tertiary alcohols do not oxidize under normal conditions.
• What are the steps involved in the oxidation of a secondary alcohol using potassium dichromate?

  1. Heat the secondary alcohol with acidified potassium dichromate.
  2. Observe the color change from orange to green.
  3. Form a ketone and water.
  4. Use distillation to separate the ketone from the mixture.
• What is the significance of the carbon atom bonded to the alcohol group in tertiary alcohols?

  • It is not bonded to any hydrogen atoms.
  • This structure prevents oxidation under normal conditions.