C6 Flashcards
What are the length of single and double bond
Single bond = 1.54a
Double bond = 1.34a
1a=
1x10-10 m
Bonding in benzene
All bonds have the same lengths l.39 a, all bonds are partial double bunds
Aromatic molecules have 4 key properties
Less reactive than expected
Reacts with substitution as opposed to addition
Have lower than expected enthalpy of hydro generation
Have bond lengths intermediate between double and single
The orbital description of benzene
The carbon atoms are sp 2 hybridised
The p orbital overlap leading to extended pi system
The orbital description of benzene
The carbon atoms are sp 2 hybridised
The p orbital overlap leading to extended pi system
What are the rules for a molecule to be aromatic
It should be cyclic
It must be planar
It should be completely conjugated
What are the rules for a molecule to be aromatic
It should be cyclic
It must be planar
It should be completely conjugated
The magic numbers ( must have to be aromatic)
( 4n+2)
Magic numbers 2,6,10,14
What if the molecule has 4n electrons and meets the other criteria
Its an anti - aromatic and destabilised
What does the anti aromacity do
Destabilises the molecule and forces it to adopt a non-planar geometry
Pyridine-like nitrogen’s
Contribute to one p electron to the pi system
Pyrrole-like nitrogen’s
Contribute to 2p electrons to the pi system
