Azulene

Description

Azulene (pronounced “as you lean”) is an aromatic hydrocarbon that contains no six-membered rings. It is an isomer of naphthalene and has a similar odor, but instead of white, its crystals are dark blue. (Azul?is the Spanish word for blue.)
Blue-colored compounds with the azulene structure have been known for six centuries. Azulene itself was synthesized from octahydronaphthalene by B. Susz, A. S. Pfau, and P. A. Plattner in 1937 and from indane by Plattner and G. Magyar in 1942.
Azulene’s 10–π-electron system qualifies it as an aromatic compound. Similarly to aromatics that contain benzene rings, it undergoes reactions such as Friedel–Crafts substitutions. And like the cyclopentadienyl anion and the cycloheptatrienyl cation, it forms π-complexes with metals such as molybdenum and iron.

Chemical properties

Azulene is a blue crystalline compound with the chemical formula C10H8 and a melting point of 99°C. It contains afive-membered ring fused to a seven-membered ring and has aromatic properties. When heated it is converted into naphthalene.

The Uses of Azulene

azulene is renowned as an anti-inflammatory, calming, and soothing agent. excellent for sensitive skin, azulene is a german chamomile derivative with a characteristic deep blue color. Careful, it stains!

The Uses of Azulene

Azulene is used as an additive in ointments. It is an active ingredient in cosmetics, shaving creams and other topicals. It is used as antioxidant and in anti-inflammatory activities. It is involved in the colorimetric determination of furfural. It acts as ligand for low valent metals and forms pi complexes with both cyclopentadienyl and cylcloheptatrienyl ligands in organometallic chemistry. It is also used as precursor for the preparation of (azulene)Mo2 (CO)6 and (azulene)Fe2 (CO)5.

Definition

ChEBI: Azulene is a mancude carbobicyclic parent consisting of a cycloheptatriene and cyclopentadiene rings. It has a role as a plant metabolite and a volatile oil component. It is an ortho-fused bicyclic arene, a member of azulenes and a mancude carbobicyclic parent.

Synthesis Reference(s)

Journal of the American Chemical Society, 75, p. 2386, 1953 DOI: 10.1021/ja01106a030
Tetrahedron Letters, 23, p. 495, 1982 DOI: 10.1016/S0040-4039(00)86871-9

Safety Profile

Poison by intraperitoneal,intravenous, and subcutaneous routes. When heated todecomposition it emits acrid smoke and irritating vapors.

Purification Methods

Crystallise azulene from EtOH. It has UV max 270nm (log 4.72) in hexane. [Platner & Magyar Helv Chim Acta 25 581 1942, Beilstein 5 IV 1636.]