Enol and Keto Forms

• What is an alpha carbon in organic chemistry?

  The carbon adjacent to a carbonyl carbon
• Why is the position of the alpha carbon important?

  It is key for reactions involving protons
• What are alpha hydrogens?

  Hydrogens attached to alpha carbons
• Why are alpha hydrogens important in keto-enol tautomerism?

  They can be removed to form the enol
• What defines an alpha carbon in ketones and aldehydes?

  • Ketone: Carbon bonded to two alkyl groups
  • Aldehyde: Carbon bonded to one alkyl group and one hydrogen
• What happens when you protonate the carbonyl oxygen?

  It enhances the carbonyl's electrophilic character
• What are the steps to protonate the carbonyl oxygen?

  1. Identify the carbonyl oxygen
  2. Add a proton to the oxygen
• What is the result of protonating the carbonyl oxygen in propanone?

  It creates a positively charged oxygen
• How do alpha hydrogens differ in ketones and aldehydes?

  • Ketone: Hydrogen atoms bonded to alpha carbons
  • Aldehyde: Hydrogen atoms bonded to alpha carbons
• What is the process to deprotonate an alpha carbon to form an enol?

  Remove a proton from the alpha carbon
• What are the steps to form an enol from an alpha carbon?

  1. Identify alpha carbons and hydrogens
  2. Remove alpha hydrogen using a base
  3. Form a double bond
  4. Attach hydrogen to oxygen
• What is the structure of an enol?

  Carbon-carbon double bond and hydroxyl group
• How do enols and ketones differ in structure?

  • Ketone: Carbonyl group ($C =$$O$)
  • Enol: Carbon-carbon double bond and hydroxyl group ($- OH$)
• What is the process to redraw the enol structure?

  Shift the double bond and attach hydroxyl
• What defines hydroxyl groups in enediols?

  • Hydroxyl groups: $- OH$
  • Found on carbon atoms with single bonds to hydrogen and oxygen
• How many hydroxyl groups are in enediols?

  Two hydroxyl groups
• What is the process to reprotonate a hydroxyl group to form a keto?

  Attach a proton to the hydroxyl oxygen
• How do enol and keto forms differ in structure?

  • Enol: Double bond between carbons, one -OH group
  • Keto: Double bond between carbon and oxygen, no -OH group
• What happens when converting the enol $CH_{3} - C(OH) =$$CH_{2}$ back to propanone?


  A double bond forms between carbon and oxygen
• What is the final structure of propanone after reprotonation?

  $CH_{3} - C( = O) - CH_{3}$
• What are the steps to redraw the keto form from an enol?

  1. Identify the enol double bond and hydroxyl group
  2. Shift the double bond to form a carbonyl group
  3. Remove the hydroxyl group