Which of the following compounds is antiaromatic?

• A. Cyclobutadiene
• B. Benzene
• C. Furan
• D. Cyclooctatetraene

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the criteria for aromaticity and antiaromaticity. A compound is aromatic if it is cyclic, planar, fully conjugated, and has \((4n + 2)\) π electrons (Hückel's rule). It is antiaromatic if it meets the first three criteria but has \$4n\( π electrons, where \)n$ is an integer.
2. Step 2: Analyze each compound for planarity, cyclic conjugation, and count the number of π electrons involved in the conjugated system.
3. Step 3: For cyclobutadiene, note that it is a four-membered ring with 4 π electrons and is planar and fully conjugated, which fits the \$4n\( π electron rule (with \)n=1$), indicating antiaromaticity.
4. Step 4: For benzene, it has 6 π electrons, is planar, cyclic, and fully conjugated, satisfying the \((4n + 2)\) rule (with \(n=1\)), so it is aromatic, not antiaromatic.
5. Step 5: For furan and cyclooctatetraene, consider their structures and electron counts: furan has a heteroatom contributing lone pair electrons and is aromatic, while cyclooctatetraene is non-planar and thus non-aromatic, not antiaromatic.