Reactions of Phenols

Question 1

Reactions that take place on the aromatic ring are

Answer 1

electrophilic substitutions

Question 2

What happens to the ortho and para positions

Answer 2

they become electron rich due to resonance effect caused by -OH group.

Question 3

Nitration

Answer 3

with dilute HNo3 at low temperature to yield a mixture of ortho and paranitrophenols

Question 4

How can the ortho and para isomers be separated

Answer 4

steam distillation as ortho is steam volatile due to intramolecular hydrogen bonding while p-nitrophenol is less volatile due to intermolecular hydrogen bonding

Question 5

iupac name of picric acid

Answer 5

2,4,6-trinitrophenol

Question 6

how is picric acid formed

Answer 6

phenol +h2so4 which yield phenol-2,4-disulphonic acid + hno3 to get 2,4,6-trinitrophenol

Question 7

halogenation with CHCL3 AND CS2

Answer 7

yield monohalidephenols(ortho and para)

Question 8

How is 2,4,6-tribromophenol prepared

Answer 8

phenol + bromowater forms 2,4,6-tribromophenol as white precipitate

Question 9

Kolbe’s reaction

Answer 9

phenoxide ion formed from treating phenol with NaOH is more reactive than phenol towards electrophilic substitution.

Question 10

which electrophile reacts in kolbe’s reaction

Answer 10

carbon dioxide, weak electrophile

Question 11

main product of kolbe’s reaction

Answer 11

orthohydroxybenzoic acid(salicyclic acid)

Question 12

Reimer-Tiemann reaction

Answer 12

Phenol + CHCl3(chloroform) and aq NaOH to form a -CHO group at ortho position of benzene. then it is hydrolysed to produce salicylaldehyde

Question 13

Reaction of phenol with zinc dust

Answer 13

phenol + Zinc forms benzene

Question 14

Oxidation of phenol

Answer 14

with chromic acid produces a diketone like benzoquinone.