3.3.8.1 aldehydes and ketones

• aldehyde functional group 


  -CHO (C=O)
• how are aldehydes produced?

  initial oxidation and distillation of primary alcohols
• what are aldehydes oxidised further into, in the presence of K2Cr2O7/H+?

  carboxylic acids
• production of carboxylic acids

  
• Ketones functional group 


  -C=O, carbonyl group
• how are ketones produced?

  oxidation of secondary alcohols with K2Cr2O7/H+
• formation of ketones

  
• testing for ketones


  no further oxidation of ketones - produce NVC with Tollens' reagent and Fehling's solution
• reduction 


  all the oxidation reactions involved in the production of aldehydes/ketons can be reversed via reduction reactions
• reducing agent used


  NaBH4 - used in nucleophilic addition
• nucleophilic addition - ketones

  
• role of NaBH4 in nucleophilic addition mechanism

  provides the H- (with lone pair) nucleophile
• nucleophilic addition H+ role

  H+ ions required so the reaction takes place under aqueous conditions
• hydroxynitriles 


  formed from a nucleophilic addition reaction with a cyanide nucleophile
• nucleophilic addition mechanism with cyanide ions

  
• cyanide reagents 


  KCN or HCN
• why is HCN not often used?

  hard to store as a gas and reacts to produce dangerous by-products
• what is a common product with hydroxynitriles

  optical isomers - contain chiral carbon centre
• what causes different enantiomers to be produced?

  cyanide nucleophile can attack from either above or below the double bond
• naming hydroxynitriles 


  the carbon on the nitrile group is included in the carbon chain and is carbon number 1