Carbonyls (Aldehydes, Ketones, Carboxylic Acids)

LiAlH4

• Used to reduce Carboxylic Acids

• Must be in dry ether as it is very reactive with water

• Forms the corresponding alcohol to the acid and water:

  • CH3COOH + 4[H] → CH3CH2OH + H2O

Carboxylic Acids

• RC=OOH groups

• weak acid as it dissociates with water slightly

• Can be created from nitriles + dilute HCl + water:

  • CH3CH2CN + HCl + 2H2O → CH3C=OOH + NH4Cl

NaBrH4

• Used to reduce carbonyls

• Turns aldehydes into primary alcohols (same for LiClH4)

• Turns ketones into secondary alcohols (same for LIClH4)

Nucleophilic Addition with HCN

• HCN is created in situ:

  • NaCN + H2SO4 → HCN + NaHSO4

• HCN is a nucleophile

• Forms a nitrile (CnHn2-1CN):

  • With reduction or adding [H], an amine is produced

  • With hydrolysis using dilute HCl and H2O, carboxylic acid is produced

• 2 Mechanisms:

  • C=O is breaks bond heterolytically whilst CN- donates electron pair to carbocation

  • Intermediate where both the O and CN is bonded to the carbocation

  • The left over H+ from HCN bonds with the O to create 2-hydroxynitrile