Azulene

• Cyclopentacyclohepten
• Bicyclo [ 5.3.0 ] decapentaene

Black - violet crystals

Fixed

99 ° C.

242 ° C

Practically insoluble in water

0.80 ( 2 ) D ( 2.7 × 10-30 C · m)

Template: Infobox chemical / molecular formula search available

Azulene ( from the Spanish azul "blue" ) or Cyclopentacyclohepten is a blue crystalline aromatic hydrocarbon. It is an isomer of naphthalene and has for a hydrocarbon is a strikingly high dipole moment.

History

Back in the 15th century you could win at the steam distillation of chamomile a deep blue essential oil, which is anti-inflammatory. It was not until 1915, by Alfred E. Sherndal by the action of acid, the isolated azulene as a carrier of this blue color. However, established by Sherndal tricyclic ( triple ring ) aromatic structural formula proved to be false. 1926 was Leopold Ružička the correct sum formula. Only in 1936 could be clarified by Alexander Peacock and Placidius A. Plattner, the structure of this compound.

Plattner set on 1941 empirical rules for predicting the hue depending on the substitution pattern. 1955 Azulensysteme easily accessible by the developed by Klaus Hafner and Karl Ziegler Ziegler- Hafner synthesis. Nevertheless, the mid- 1970s were known only 60 compounds with a Azulensystem. Mid -1990s, doubled by synthesis of 50 Azulencarbonsäureestern this number. By NMR spectroscopy wrong certain features were to be corrected.

Properties

Physical Properties

Azulene is insoluble in water; in organic solvents it dissolves with a deep blue color. The solid is irritating.

Chemical Properties

Hydrocarbons, which are formally derived from azulene are called Azulene; they are colored blue to purple. One example is the blue 6-tert- Butylazulen. The color can be explained by a charge transfer between the two rings. Azulene is metastable. With years of storage, it isomerizes to naphthalene.

Occurrence

The most famous natural Azulenverbindung, " Proazulen C" ( matricin ), occurs in chamomile and goes at 80 to 90 ° C in chamazulene (1,4- dimethyl-7 - ethylazulen ) over. These azulenes is dehydrated Sesquiterpenderivate.

Use

Azulene derivatives from natural sources are often used in cosmetic products.