Aromatics

Question 1

What is a benzene ring called if it is on a molecule ?

Answer 1

Pheny - molecule name

Question 2

Describe the structure of kekule benzene.

Answer 2

6 Carbon ring with 3 double bonds ( hexa-1,3,5-triene)

Question 3

Compare how kekule benzene and benzene reacts with bromine.

Answer 3

Kekule benzene reacts making solution go from orange to colourless
Benzene does not react unless at high temp with catalyst

Question 4

Talk about how enthalpy of hydrogenation proved how benzene does not have the same structure as kekule benzene.

Answer 4

delta h of Hydrogenation of cyclohexene is -120
delta h of hydrogenation for cyclodiene is -240
but when benzene reacts with hydrogen its delta H isnt -360 as expected it is -208

Question 5

How does x ray crystallography prove structure of benzene isn’t the same as kekule benzene ?

Answer 5

Single bonds are loger than double bonds but bonds in benzene are a intermediate of the two bond lengths.

Question 6

Describe the structure of benzene.

Answer 6

Planar 6 carbon ring bonded to one H each
P orbitals in each carbon overlap to form a ring of delocalised electrons

Question 7

Why is benzene very stable ?

Answer 7

Because of the ring of delocalised electrons

Question 8

What is the catalyst and how is the electrophile in nitration of benzene produced ?

Answer 8

H2SO4

HNO3 + H2SO4 -> H2O + NO2+ + HSO4-

Question 9

Outline the mechanism for the nitration of benzene

Answer 9

Question 10

What is the catalyst and how is the electrophile in the acylation of benzene produced ?

Answer 10

AlCl3

AlCl3 + Acyl chloride ( aldehyde but instead of CHO CClO) - > AlCL4

Question 11

Outline the mechanism for the acylation of benzene.

Answer 11