3.10 Aromatic chemistry Flashcards
1
Q
Explain why the structure of Benzene is more stable than the proposed Kekule structure (6)
A
- Bond length in Benzene is 139pm this is between the length of single and double C-C bonds so it cannot contain simple C-C or C=C bonds. Stability is due to delocalised electrons
- Enthalpy of hydrogenation of cyclohex-1-ene was -120kJ/mol (this is for one C=C) so expected value for hydrogenation of Benzene would be 120 X 3 = -360kJ/mol however the actual value is -208kJ/mol so more energy is required to break the bonds in benzene so it must be more stable
1
Q
Formula of Benzene
A
c6h6
2
Q
What was Kekule’s proposed structure of benzene
A
Cyclical 6 carbon compound with each carbon attached to 1 H. 3 double CC bonds and 3 single CC bonds which alternate
3
Q
In what orbital are the delocalised electrons in Benzene in?
A
P
4
Q
What type of reaction do arenes undergo
A
Electrophilic substitution
5
Q
Name the reaction that produces a strong electrophile for acylation
A
RCOCl + AlCl3 > RCO+ AlCl4-
6
Q
A