Flashcards in 3.10 Aromatic Deck (10):
The rule of cyclics
All benzene are cyclic compounds; but not all cyclic compounds are benzene
What is benzene?
Flat hexagon of carbon atoms
Delocalised rings of electrons
What is the thermochemical evidence of Benzene structure?
Cyclohexene + H2 → ∆H -120
Expected + H2 → ∆H -360
Benzene + H2 → ∆H -208
so we learn that benzene is 152 kJ more stable than predicted due to delocalised field
What is delocalisation of Benzene?
overlapping of electron density
sandwiched between 2 rings
How does bond length affect stability?
c=c is most stable 0.134
(B) c-c is 0.140
c-c is 0.154, the weakest
What is electrophilic substitution?
Using benzene delocalised ring to donate electrons
How to prepare the Nitration of Benzene species?
H2SO4 + HNO3 → H2NO3+ + HSO4-
H2NO3+ → NO2+ +H2O
We use NO2+
H2SO4 is a catalyst as it is replenished at the end by H+ from benzene
What is nitrobenzene used for?
What is Friedel Craft acylation?
Adding a carbonyl group to benzene, with AlCl3 as a catalyst
RCOCl + AlCl3 → RCO+ + AlCl4-