Question

Which of the following is an incorrect description of benzene? A) The CCC bond angles are all equal to 120 ∘. B) The molecule is planar. C) The molecule is a 6-membered ring containing alternating single and double carbon-carbon bonds. D) The molecule is aromatic. E) The molecule can be drawn as a resonance hybrid of two Kekule structures. 5. Circle and name the aromatic heterocycles in the following structure, which has been found to be effective aga fflammatory diseases including Alzheimer's disease and rheumatoid arthritis (J. Med. Chem. 2007, 4728).

Answer 1

Benzene is a planar molecule with a 6-membered ring containing alternating single and double carbon-carbon bonds. The CCC bond angles are slightly distorted, not equal to 120 degrees. The molecule is aromatic and can be drawn as a resonance hybrid of two Kekule structures.

Step-by-step explanation:

An incorrect description of benzene is option A) The CCC bond angles are all equal to 120 ∘. In reality, the bond angles in benzene are slightly distorted from the ideal 120 ∘ angle due to the delocalization of the π electrons. The actual bond angles are approximately 120.7 ∘.

Benzene is a planar molecule, as described in option B. It consists of a cyclic, hexagonal ring of six carbon atoms bonded together with alternating single and double bonds, as stated in option C. Benzene is indeed an aromatic molecule, as mentioned in option D. Aromatic compounds, including benzene, exhibit special stability due to their delocalized π electrons.

Option E is correct. Benzene can be represented as a resonance hybrid of two Kekule structures, where the double bonds are continuously shifting around the ring. This resonance allows for the delocalization of the π electrons, giving benzene its unique properties.