Aromatic compounds

Question 1

Nitration of benzene conditions (3)

Answer 1

conc HNO3
CONC H2SO4
Temp above 50 degrees

Question 2

Compare the reagents and conditions for the nitration of phenol with those used for the nitration of benzene.

State and explain the effect of the –OH group on the reactivity of the benzene ring in phenol.

Answer 2

benzene conditions:
conc HNO3
CONC H2SO4
Temp above 50 degrees
-lone pair from O atom is delocalised into the ring
-so there is a greater electron density around phenol ring
-so benzene ring is phenol is activated
-and attracts electrophiles more

Question 3

Describe, with the aid of suitable diagrams showing orbital overlap, the difference in
bonding between structure A and structure B. A= old benzene B=new

Answer 3

p orbitals overlap to form pi bonds
A- pi bonds are localised between 2 C atoms
B- pi bonds are delocalised
drawn diagrams

Question 4

Why is the relative resistance to the bromination of benzine higher than for alkenes? 4

Answer 4

-In benzene electrons are delocalised
-in alkenes, pi bond is localised between 2 carbons
-benzene has lower electron density
-so benzine polarises bromine less.

Question 5

Why are acyl chlorides so useful?

Answer 5

They are very reactive and can be easily converted into carboxylic acid derivatives eg; esters, amides.

Question 6

explain how polymer lactic acid (PLA) breaks down and why the stitches dissolve 3

Answer 6

PLA is a polyester
Monomer is soluble because it can form hydrogen bonds TO water
Ester links on PLA are hydrolysed

Question 7

condensation polymer

Answer 7

monomers join together to form polymer chain and another product- h20