reactions of phenol Flashcards
describe the structure of phenol
benzene ring with OH group
what makes phenol an acid?
- donates a proton to water in aqueous solution
- due to delocalisation of oxygens negative charge around ring
- making the phenate ion more stable
what does the equilibrium sign show in a phenol reaction?
- weak acid
- only partly dissociates into ions and hydrogen bonds with water
what does phenol react with?
- reactive metals
- alkalis
why doesn’t phenol react with carbonates?
very weak acid
how can a phenol and carboxylic acid be distinguished?
- react with carbonate
- carboxylic acid will produce effervescence
- phenol will not react
why does phenol undergo electrophilic substitution more easily than benzene?
- no halogen carrier needed for halogen substitution
- dilute nitric acid is used for nitration instead of conc HNO3 and conc H2SO4
why is phenol more reactive than benzene?
- phenol has 2 lone pairs around the oxygen
- one of these is delocalised around the ring
- increasing the electron density in the pi system
- due to the increased electron density, the electrophile can be polarised without a halogen carrier or other catalyst
what happens if bromine water is added to a solution of phenol in water?
- water is decolourised
- white precipitate forms
- smells of antiseptic
- precipitate is 2,4,6 tribromophenol
what is the difference between decolourisation of bromine water due to a C=C bond and due to a phenol?
phenol also produces the white precipitate
describe the reaction of phenol with dilute nitric acid
- reacts at room temperature
- produces 2-nitrophenol and 4-nitrophenol
- this is mononitration
pH of phenol solution
4-5
equation for the dissociation of phenol
C6H5OH (aq) –> H+ + C6H4O-
reaction between sodium carbonate and phenol
- very little reaction
- phenols are too weak to react with carbonates
reaction between sodium hydroxide and phenol
- smell diminishes
C6H5OH + NaOH –> C6H5ONa + H2O
