Aldehydes & ketones

Cards (29)

  • What are carbonyl compounds?
    Compounds with a C=O bond
  • What defines an aldehyde in terms of structure?
    C=O at the end of the chain
  • What suffix do aldehydes end with?
    -al
  • What defines a ketone in terms of structure?
    C=O in the middle of the chain
  • What suffix do ketones end with?
    -one
  • What type of species are attracted to the positive carbon atom in carbonyls?
    Nucleophiles
  • What happens when primary alcohols are oxidised?
    aldehydes are formed
  • What happens when secondary alcohols are oxidised?
    ketones are formed
  • What happens when tertiary alcohols are oxidised?
    They do not oxidize
  • What is the oxidizing agent that causes alcohols and aldehydes to oxidize?
    Potassium dichromate (K2Cr2O7)
  • What is the key difference in the oxidation of aldehydes and ketones?
    Aldehydes can oxidize, ketones cannot
  • What is formed when an aldehyde oxidises?
    a carboxylic acid is formed
  • What reagents are used for the oxidation of aldehydes?
    Potassium dichromate (VI) and dilute sulfuric acid
  • What conditions are required for the oxidation of aldehydes?
    Heat under reflux
  • What is the full equation for the oxidation of ethanal?
    3CH3CHO + Cr2O7^2- + 8H+3CH3CO2H + 4H2O + 2Cr3+
  • What happens with potassium dichromate during oxidation?
    Orange dichromate reduces to green Cr3+
  • What reagents can oxidize aldehydes besides potassium dichromate?
    Fehling’s solution or Tollen’s reagent
  • What is observed when aldehydes react with Fehling’s solution?
    Blue Cu2+ ions change to red Cu2O precipitate
  • What is observed when aldehydes react with Tollen’s reagent?
    A silver mirror forms inside the test tube
  • What is formed when carbonyls react with hydrogen cyanide?
    hydroxynitriles
  • What reagents are used to form a hydroxynitrile from a carbonyl?
    Potassium/sodium/hydrogen cyanide and dilute sulfuric acid
  • What conditions are required for the reaction of carbonyls with hydrogen cyanide?
    Room temperature and pressure
  • What is the mechanism for the reaction of carbonyls with hydrogen cyanide?
    Nucleophilic addition
  • What happens to the CN group when naming hydroxynitriles?
    CN becomes part of the main chain
  • What is the result of adding HCN to unsymmetrical carbonyls?
    A racemate forms with no optical activity
  • Why are KCN and NaCN preferred over HCN for reactions?
    They completely ionize, providing more CN- ions
  • What is the risk associated with KCN and NaCN?
    They are still toxic due to cyanide ions
  • What supplies the H+ ions?
    sulfuric acid
  • What happens during the nucleophilic addition of HCN to carbonyls?
    CN- ions attack the positive carbon