Phenol Flashcards
Why is phenol acidic?
Lone pair of O atom interacts with π ring system
O-H bond weakened
H+ lost more easily
Phenoxide ion is stabilised by the partial delocalisation of the -ve charge into the π system
Less attractive to H+ ions
Explain the bonding in phenol
OH group attached directly to the aromatic ring
Lone pair of O atom interacts with the π ring electron system
Ring density is enhanced (more attractive to nucleophiles)
C-O bond shortened and strengthened
O-H bond weakened so H+ ion easily lost
Describe the appearance of phenol
Colourless crystalline solid at room temp
Sparingly soluble in water
How is the phenoxide ion stabilised?
By the partial delocalisation of the -ve charge into the π system
Therefore less attractive to H+ ions
What happens when NaOH is reacted with phenol?
Sodium phenoxide and water is formed
Is phenol more or less susceptible to electrophilic substitution than benzene?
More-
The presence of the OH group bonded directly to the benzene ring increases the electron density of the ring
In which positions of the ring is phenol most susceptible to E S?
2,4 & 6
What is the product when bromine reacts with phenol?
A white ppt of tri bromo phenol is formed with 3HBr as misty fumes
Give the equation of bromine reacting with phenol
Phenol + 3Br2 –> 3HBr + 2,4,6tribromophenol
How is a phenolic ester made?
From reacting an acyl chloride with phenol in anhydrous conditions
What is the equation for the esterification of phenol?
CH3-COCl + phenol –> CH3-COOC6H5 + HCl
What is the bi-product of the esterification of phenol?
HCl
What happens when phenol is refluxed with Cr2O72-?
Nothing, phenol cannot be oxidised
Can phenol be halogenated with PCl5?
No, no reaction
What is the test for a phenolic OH group?
Neutralised FeCl3 solution will turn from brown/yellow to deep purple when added to the phenolic solution
