Aromatic chem

Question 1

Bonding
What is their shape?
What are their bonds an intermediate between?
What is benzene described as?
What are the bond angles?
Can it undergo addition?
What is the shape around each carbon? What are the bonds?
In what orbital is the lone e?
What do they overlap to form? What is this known as? What does this allow the electrons to be?

Answer 1

Planar hexagon 
C-C and C=C
Resonance Hybrid
120
No 
Trigonal planar
2  covalent bonds with surrounding Cs,one with H and a lone e
2p
Delocalised ring 
II ring
More spread out

Question 2

What are compound with delocalised e’s more than all pairing?
What is this difference known as?(3)

Answer 2

More stable
Resonance energy
Delocalisation energy
Stabilisation energy

Question 3

Delocalisation Stability
What do enthalpies of hydrogenation indicate?
How does it do this?
Which is more stable benzene or the hypothetical cyclohexatriene?

Answer 3

Benzene does not have 3 double bonds

Enthalpies of hydrogenation for is less than 3 times that of C6H10 but if it had 3 double bonds it would be double

Benzene

Question 4

What kind of effect does cyclic delocalisation have?

Therefore what does it undergo with difficulty?

Answer 4

Stabilising

Addition

Question 5

Catalytic Hydrogenation
What is the catalyst? What temperature?
What does it convert benzene into?

Answer 5

Nickel 200c

Cyclohexane

Question 6

Physical properties
What is it at room temp?
Why are they Imiscible with water?

Answer 6

Colourless liquid

Non polar vdw only

Question 7

Electrophillic subsitution
What does the II ring have that attracts electrophiles?
What does the intermediate lose to reform stable delocalised ring?

Answer 7

High negative charge density

H+

Question 8

Nitration
What is the NO2+ formed by?
Equation for formation of H2SO4 from HSO4- and H+

Uses of aromatic nitrocompounds
What are the two uses?
Which are especially good as explosives?
What happens when they are heated? Why?
What is NO2 easily reduced to?
What is it reduced by?(2)
What is the product?

Answer 8

Protonation of HNO3 by H2SO4
HSO4- + H+ > H2SO4
Explosives and aromatic amine manufacture
Those with several nitro groups
Decompose with explosive violence bc energetically unstable
HNO3-
Catalytic hydrogenation or metal acid combo
Useful intermediate

Question 9

Friedal Crafts Acylation
What is formed?
What are these useful as?
How is the AlCl3 reformed? Equation

Answer 9

Acyl substituted arene
Intermediates
AlCl4- + H+ > AlCl3 + HCl

Question 10

What are arenes?

Why are they described as aromatic?

Answer 10

Group of cyclical compounds

Because they are naturally fragrant