phenols

• phenols are a class of aromatic compound with a hydroxyl group directly bonded to a benzene ring
• simplest member of the phenols is phenol, C6H5OH
• phenols

  
• acidic nature of phenols


  • phenol is slightly soluble in water and partially dissociates
  • phenol are therefore weak acids

  
• • phenol is more acidic than ethanol but less acidic than carboxylic acids
  • ethanol does not react with strong bases such as sodium hydroxide or weak bases such as sodium carbonate
  • phenol reacts with strong bases such as sodium hydroxide but not with weak bases such as sodium carbonate
  • carboxylic acids react with strong bases such as sodium hydroxide and weak bases such as sodium carbonate
• reacting phenol with sodium hydroxide


  • phenol reacts with sodium hydroxide to form a salt and water in a neutralisation reaction

  
• reacting phenol with bromine


  • phenol reacts with aqueous bromine in an electrophilic substitution reaction to form a white precipitate of 2,4,6-tribromophenol and hydrogen bromide

  
• with benzene only mono substituition and with phenol you can get tri substitution
• reacting phenol with nitric acid


  • phenol reacts with dilute nitric acid at room temperature yo form a mixture of 2-nitrophenol and 4-nitrophenol

  
• reason for increased activity of phenols


  • increased reactivity due to presence of a lone pair of electrons in the oxygen p-orbital of the hydroxyl group
  • the lone pair of electrons in the oxygen p-orbital of the hydroxyl group becomes delocalised in the delocalised ring of pi electrons of the benzene ring
  • electron density of ring is increased
  • able to polarise/attract electrophiles more easily