1,3,5,7-cyclooctatetraene

Description

## 1,3,5,7-Cyclooctatetraene: A Curious Molecule with Potential

1,3,5,7-cyclooctatetraene (COT) is a fascinating organic molecule with the chemical formula C8H8. It consists of an eight-membered ring containing alternating single and double bonds.

**Here's why it's important for research:**

**1. A non-aromatic hydrocarbon:** Unlike its smaller ring counterparts like benzene, COT is **not aromatic**. This is because it doesn't follow Hückel's rule for aromaticity, which states that a planar, cyclic molecule must have a specific number of pi electrons (4n+2) to be aromatic. COT has 8 pi electrons, failing this rule.

**2. Unusual structure and bonding:** COT's non-aromatic nature results in its unique structure. It can exist in two conformations: a **tub-shaped** conformation, which is more stable, and a **planar** conformation, which is less stable. This non-planar shape further distinguishes it from other cyclic hydrocarbons.

**3. Chemical reactivity and applications:** The lack of aromaticity in COT makes it a valuable starting material for various chemical reactions and applications. It can readily undergo reactions like:
* **Hydrogenation:** It can easily be hydrogenated to cyclooctane, a saturated eight-membered ring.
* **Electrophilic attack:** It can undergo electrophilic attack at its double bonds due to its electron density.
* **Metal complexation:** It can form complexes with transition metals like uranium, creating interesting organometallic compounds.

**4. Model system for theoretical studies:** Its unusual structure and unique bonding make it an excellent model system for theoretical studies on the nature of aromaticity, bonding, and electron delocalization.

**5. Potential for new materials:** Research is ongoing to explore the potential of COT as a precursor for new materials with unique properties. For example, COT-based polymers have shown promise for applications in organic electronics.

**In summary:**

1,3,5,7-cyclooctatetraene's non-aromatic nature, unusual structure, and reactivity make it a valuable molecule for research in organic chemistry, theoretical chemistry, and materials science. It continues to be a source of interesting discoveries and advancements in various scientific fields.

1,3,5,7-cyclooctatetraene: structure in first source [Medical Subject Headings (MeSH), National Library of Medicine, extracted Dec-2023]

[8]annulene : An antiaromatic annulene that is cyclooctane having four double bonds at positions 1, 3, 5 and 7. [Chemical Entities of Biological Interest (ChEBI), Hastings J, Owen G, Dekker A, Ennis M, Kale N, Muthukrishnan V, Turner S, Swainston N, Mendes P, Steinbeck C. (2016). ChEBI in 2016: Improved services and an expanding collection of metabolites. Nucleic Acids Res]