Aromatic Compounds Flashcards
What are aromatic compounds?
Cyclic compounds, containing some number of conjugated double bonds and have an unusually large resonance energy
What structure did the kekulé structure fail to explain?
1,2-dichlorobenzene
What is the hybridization of the carbons in benzene?
Sp2 hybridized
What the shape of benzene?+ What are the CCC bond angles?
CCC bond angles are 120 degrees and benzene is a planar structure
What is the length of carbon-carbon lengths in benzene?
139pm, intermediate between single and double carbon bonds
What happens to the electrons in the overlapping p orbitals in benzene?
These 6 pi electrons are delocalised over the six carbons
What are annulenes?
Cyclic hydrocarbons with alternating single and double bonds
What are nonaromatic compounds?
Cyclic compounds that do not have a continuous , overlapping ring of p orbitals and may be nonplanar
What are antiaromatic compounds?
Compounds that are cyclic, conjugated with overlapping p orbitals around the ring but the delocalized pi electrons over the ring increases its electronic energy
What is hekules’s rule?
If the number of pi electrons in a cyclic system is (4N+2) the system is aromatic
If the number of pi electrons is (4N) in the system then it is antiaromatic
What does the ortho- name mean in relationship to the structure of the molecule
1,2-disubstituted
What does the meta- prefix mean in relationship mean in relationship to the structure of the molecule?
1,3-disubstitued
Shaft does the para- prefix mean in relationship to the structure of the molecule?
1,4-disubstituted
What are the aromatic requirements
- cyclic structure with conjugated pi bonds
- each atom in the ring must have an unhybridized p orbital
- the unhybridized p orbitals must overlap continuously around the ring
- delocalization of the pi electrons over the ring must lower the electronic energy
What are the requirements for heckule’s rule to apply?
Must be aromatic or antiaromatic- cyclic compound with a continuous ring of. Overlapping p orbitals
