Question

which of the following molecules are stabilized by delocalized π orbitals? select all correct answers.
(a) (b) (c) (d)
□ molecule a
□ molecule b
□ molecule c
□ molecule d

Explanation:

• Molecule a: It has a conjugated system of double bonds in a cyclic structure. In such systems, the π electrons are delocalized over the entire ring. This delocalization lowers the energy of the molecule (due to resonance) and stabilizes it.
• Molecule b: It has carbon - oxygen double bonds conjugated with carbon - carbon double bonds. The π electrons in the \(C = C\) and \(C=O\) bonds are delocalized. The oxygen atom can participate in resonance (using its lone pairs) which further delocalizes the π electrons and stabilizes the molecule.
• Molecule c: There is no conjugation of π bonds. The carbon - oxygen double bonds are separated by a \(CH_2\) group. So, the π electrons are localized around each \(C = O\) bond and there is no significant delocalization of π electrons.
• Molecule d: It has a conjugated diene system (\(C = C - C = C\)). The π electrons in the two \(C = C\) bonds are delocalized over the four - carbon chain. Delocalization of π electrons in conjugated dienes (due to resonance) stabilizes the molecule.

Answer:

molecule a, molecule b, molecule d