3.10 Aromatic Compounds Flashcards
What’s the formula of Benzene?
C6H6
What type of structure does benzene have?
Planar cyclic structure
From which orbital does the unpaired electron from a carbon come from in benzene?
P orbital
Name two pieces of evidence to prove benzenes structure
- C-C bonds same length (in between length for C=C and C-C)
- Benzene less exothermic enthalpy of hydrogenation than expected
What’s the name of the theoretical structure of what Benzene ‘should’ be?
Cyclohexa-1,3,5-triene
State two features of why Benzene undergoes substitution and not addition
- Benzene ring = area of high electron density
- Addition reactions would destroy the ring
What is formed when Benzene reacts with NO2+?
Nitrobenzene
What are some uses of nitrobenzene? (2)
- Can be reduced to form aromatic amines
- Can be used in explosives (TNT)
What are the conditions needed for the nitration of benzene?
Heat with concentrated nitric acid and sulphuric acid
What is the role of sulphuric acid in the nitration of Benzene?
Catalyst
Give the equation for the formation of the NO2+ electrophile
HNO3 + 2H2SO4 ~> NO2+ + 2HSO4- + H3O+
HNO3 acts as base
How are electrophiles able to be made stronger?
Halogen carrier (a strong catalyst)
What is the role of AlCl3?
Halogen carrier
How does AlCl3 make the acyl chloride electrophile stronger?
AlCl3 accepts lone pair from acyl chloride, becoming AlCl4-
Electrophile then has carbocation (stronger electrophile)
What are the reactants in Friedel-Crafts Acylation?
Benzene + Acyl chloride
With anhydrous ammonium chloride catalyst
Give the mechanism for Friedel-Crafts Acylation
Give the mechanism for the nitration of benzene
