Aromatic Chemistry Flashcards
What is benzene’s formula
C6H6
What is another name for arenes
Aromatic compounds
What is benzenes most common reaction type
Electrophilic substitution
What is the structure and bond angle of benzene?
Flat hexagon
120
What is the bond length between the C’s in benzene
An intermediate between C-C and C=C
What happens to the 4th electron in the p orbital of each C atom in benzene?
It delocalises to form rings of electron density above and below the hexagon
Why is benzene stable
Because of the its delocalised ring of electrons
What evidence is there that benzene is more stable than cyclohexan-1,3,5-triene?
Hydrogenation of cyclohexene = -120
cyclohexan-1,3,5-triene = -360
Hydrogenation of Benzene = -208
Therefore benzene is 152 more stable
What is the electrophile for the nitrification of benzene and how is it obtained
NO2+
H2SO4 + HNO3 –> NO2+ + HSO4- + H2O
What are nitrobenzene’s used for?
The manufacture of explosives
The formation of aromatic amines
What catalyst is used in a Friedel-Crafts Reaction?
AlCl3
Why does benzene prefer substitution reactions to addition reactions?
Addition reactions would involve breaking the delocalisation and thereby losing stability
How do substituents with a positive inductive effect (e.g. alkyl groups) affect further substitution?
They release electrons into the delocalised electron ring making further substitution reactions more likely
How do substituents with a negative inductive effect (e.g. NH2) affect further substitution?
They remove electrons from the delocalised electron ring making further substitution reactions less likely
What 3 things must be referred to when comparing Benzene to cyclohextriene
Chemistry - Bromine water not s
decolourised
Shape - A regular hexagon where as cyclohextriene has double and single bonds so you’d expect different bond lengths
Stability - Cyclohexane = 120 kj mol to get to cyclohexane
Cyclohextriene is 360
Benzene is 208 so more stable
