phenol exam qs

Cards (7)

    • compound Y reacts with Br2, indicates presence of phenol group due to higher e- density
    • effervescence suggests release of CO2 gas, indicates presence of acidic functional group (carboxylic acid) acid + NaCO3 -> salt + H2O + CO2
    • so compound must contain phenol group and carboxylic acid
    • ANSWER: salicylic acid (C6H4(OH)(COOH)) which has 7 carbon atoms
  • b) paracetamol has a phenol group (-OH) which is slightly acidic and can react with bases to form phenoxide salts. this statement is true
    c) paracetamol contains an amide functional group (-CONH-) and a hydroxyl group (-OH) but it does not have a ketone functional group (C=O). this statement is not true as a ketone is bonded to 2 other carbons.
    d) paracetamol can undergo hydrolysis in the presence of aqueous acid, breaking down into acetic acid and p-aminophenol. this statement is true
    • lone pairs of e- on the oxygen (OH in quinol) (1 mark) partially delocalise into the ring (1 mark)
    • adding e- density to the ring therefore making it more reactive so no catalyst needed
    • therefore quinol more susceptible to attacks from an electrophile (1 mark)
  • the chemist observed that bromine decolourises when it reacts with phenol
    what other observation would she have made? what is the organic product formed?
    observation - white precipitate
    organic product - tribromophenol
  • explain relative resistance to bromination of benzene compared to phenol and compared to cyclohexene
    in benzene the π-electrons are delocalised
    low electron density of the π-electrons means benzene is unable to polarise Br2
  • explain relative resistance to bromination of benzene compared to phenol and compared to cyclohexene 

    in phenol, the lone pair of electrons on the oxygen of OH group is delocalised into the π - electron cloud
    the higher electron density in the ring means it can polarise Br2
  • explain relative resistance to bromination of benzene compared to phenol and compared to cyclohexene 


    in cyclohexene, the π-electrons are localised
    the high electron density of the π-electrons means it can polarise Br2