Benzene (Chapter 15) Flashcards
1,2 Disubstitution
Ortho-
o–
1,3 Disubstitution
Meta-
m–
1,4 Disubstitution
Para-
p–
Phenol
Aniline
Benzaldehyde
Benzoic Acid
Styrene
Benzene
A six-carbon cyclic compound consisting of six equally overlapping p orbitals and six equal-length C—C bonds.
All carbons within the benzene ring are sp2-hybridized.
Benzene vs. 1,3,5–Hexatriene
Stabiilty Comparison
Benzene is more stable than 1,3,5-Hexatriene due to the “closure” of the six-membered carbon compound.
Six-membered cyclic π systems are more stable than acyclic π systems.
Aromatic System
Huckel’s Rule
A cyclic planar system of sp2-hybridized atoms containing (4n + 2)π electrons.
Aromatic systems are highly stabilized.
Antiaromatic System
Huckel’s Rule
A cyclic planar system of sp2-hybridized atoms containing (4n)π electrons.
Antiaromatic systems are highly destabilized (i.e. less stable than alkenes or dienes).
Nonaromatic System
- Non-planar
- Acyclic
- sp3-Hybridized Atoms
Nonaromatic systems are comparible in stability to alkenes and dienes.
1,3–Cyclobutadiene
- Highly Unstable (Antiaromatic + Ring Strain)
- Ability to Act as Alkene and Diene
- Alternating Single + Double Bonds
- Two Distinct Isomers (Rapid Isomerization through Symmetrical Transition State)
The two isomers of 1,3–Cyclobutadiene are not resonance structures (because atoms are moved during the isomerization process).
1,3,5,7–Cyclooctatetraene
- Non-Aromatic (Tub-Shaped)
- Non-Conjugated π Bonds
- Acts an Simple Alkene