Colour by design Flashcards
1
Q
What is the molecular formula of benzene
A
C6H6
2
Q
What is the Kekulé structure of benzene
A
Alternating single and double bonds that continuously flip between carbons
3
Q
What is the delocalised model of benzene?
A
Each carbon donates an electron from its p-orbital which all combine to form a ring of delocalised electrons
4
Q
What are the three pieces of evidence that support the delocalised model of benzene?
A
- X-ray diffraction shows that all the c-c bonds are the same length
- Bromine water and benzene do not react (no colour change) but bromine and alkene do not react. You would expect electrophilic addition to occur if benzene had a kekulé structure
- The enthalpy change of cyclehexene is -120kj/mol but benzene is -208k/mol (less than 3 x-120) so more energy must have been put into the bonds in benzene than if it were the kekulé structure.
5
Q
What is an arene
A
A group with a benzene ring
6
Q
Benzene + Nitronium ion
Conditions needed
A
Electrophilic substitution: Nitrobenzene
**
Warm with H2SO4 + HNO3
If you only want one NO2 group then you must keep temperatures under 55C
7
Q
Benzene and Sulfur trioxide
A
Electophilic addition: Benzenesulfonic acid
8
Q
A