Aldehydes and Ketones

• What are carbonyl compounds?

  Compounds with a C=O bond
• How can carbonyls be classified?

  As aldehydes or ketones
• What defines an aldehyde?

  C=O at the end of the chain
• What is the suffix for aldehyde names?

  -al
• What is the name of CH3CHO?

  Ethanal
• What defines a ketone?

  C=O in the middle of the chain
• What is the suffix for ketone names?

  -one
• What is the name of CH3COCH3?

  Propanone
• Why are smaller carbonyls soluble in water?

  They can form hydrogen bonds with water
• What type of intermolecular forces do pure carbonyls exhibit?

  Permanent dipole forces
• How does the C=O bond compare to the C=C bond in alkenes?

  C=O is stronger and less reactive
• Why is the C=O bond polarized?

  O is more electronegative than carbon
• What attracts nucleophiles to the C=O bond?

  The positive carbon atom
• What happens to primary alcohols during oxidation?

  They form aldehydes
• What happens to secondary alcohols during oxidation?

  They form ketones
• What happens to tertiary alcohols during oxidation?

  They do not oxidize
• What is the oxidizing agent that causes alcohols and aldehydes to oxidize?

  Potassium dichromate K2Cr2O7
• What is a key point about aldehydes and ketones regarding oxidation?

  Aldehydes can oxidize, ketones cannot
• What are the reagents for oxidizing aldehydes to carboxylic acids?

  Potassium dichromate (VI) and dilute sulfuric acid
• What are the conditions for oxidizing aldehydes?

  Heat under reflux
• What is the full equation for the oxidation of aldehydes?

  3CH3CHO + Cr2O7^2- + 8H+ → 3CH3CO2H + 4H2O + 2Cr3+
• What color change occurs during the oxidation of aldehydes with potassium dichromate?

  Orange to green
• What reagents can oxidize aldehydes besides potassium dichromate?

  Fehling’s solution or Tollen’s reagent
• What is the observation when aldehydes are oxidized with Fehling’s solution?

  Blue Cu2+ ions change to red precipitate
• What happens to ketones when treated with Fehling’s solution?

  They do not react
• What is the reaction of aldehydes with Tollen’s reagent?

  Aldehydes are oxidized to carboxylic acids
• What is the observation when aldehydes react with Tollen’s reagent?

  A silver mirror forms in the test tube
• What is the reaction of carbonyls with hydrogen cyanide?

  Carbonyls form hydroxynitriles
• What reagents are used to add hydrogen cyanide to carbonyls?

  Potassium cyanide and dilute sulfuric acid
• What are the conditions for the reaction of carbonyls with hydrogen cyanide?

  Room temperature and pressure
• What is the mechanism for the addition of hydrogen cyanide to carbonyls?

  Nucleophilic addition
• How does the CN group behave when naming hydroxy nitriles?

  It becomes part of the main chain
• What is the optical activity of the product formed from the addition of HCN to carbonyls?

  No optical activity is seen
• What type of mixture is formed when HCN adds to unsymmetrical carbonyls?

  A racemic mixture forms
• What is the advantage of using KCN over HCN in reactions?

  KCN completely ionizes for higher CN- concentration
• Why is HCN considered difficult to contain?

  It is a toxic gas
• What is the role of H+ ions in the nucleophilic addition mechanism?

  They are needed in the second step
• What is the source of nucleophilic hydride ions in the reduction of carbonyls?

  NaBH4 or LiAlH4
• What type of alcohol do aldehydes reduce to?

  Primary alcohols
• What type of alcohol do ketones reduce to?

  Secondary alcohols