Module 6 - Benzene Flashcards
Who discovered the first model for the benzene ring?
Kekule
What did Kekule suggest the structure of Benzene was?
alternating single and double bonds acting like an unsaturated alkene
describe the formation of the modern Benzene ring
- each carbon atom forms three sigma bonds using sp2 orbitals
- sideways overlap of P orbitals causing electrons to be delocalised forming a pi system
- pi system made of 2 electron clouds above and below ring
give 3 pieces of evidence for the bonding in benzene
- lack of reactivity of benzene towards electrophillic addition
- thermodynamic stability of benzene
- bond lengths of benzene are all the same
what is the length of the bonds in benzene?
between a double and a single bond
expain what happens when bromine water is added to benzene and why
no reaction
Bromine does not undergo the electrophillic addition reaction
why is benzne less reactive compared to alkenes?
- double bond is localised in alkenes
- double bond is declocalised in benzene
- Benzene ring less dense so electrophiles less attracted
give reagents for the nitration of benzene
CONC HNO3 + CONC H2SO4 (cat)
give conditons for nitration of benzene
reflux, < 50 degrees
reagent for formation of halogenarene
AlCl3 + halogen (Cl2, Br2)
condition for formation of halogenarene
reflux
reagents for alkylation of benzene
haloalkane + AlCl3
conditons for alkylation of benzene
Reflux
give 3 electron donating arene groups
CH3, OH, NH2
Give an electron withdrawing arene group
NO2
