In naphth [ " a " ] azulene, a naphthalene ring is condensed at the 1, 2-positions of azulene.
12.
In naphth [ " a " ] azulene, a naphthalene ring is condensed at the 1, 2-positions of azulene.
13.
Subsequent work showed that the isomerization of azulene to naphthalene is not readily reversible ( the kcal / mol ) . and is as follows:
14.
The oldest characterized thermal rearrangement of an aromatic compound was that of the isomerization of azulene to naphthalene by Heilbronner et al . in 1947.
15.
Another notable feature of azulene is that it violates Kasha's rule by exhibiting fluorescence from an upper-excited state ( S 2 ?
16.
The isomerization of unsubstituted azulene to naphthalene was the first reported thermal transformation of an aromatic hydrocarbon, and has consequently been the most widely studied rearrangement.
17.
For example, the cyclopentadienyl anion and the cycloheptatrienylium cation are both considered to be aromatic ions, and the azulene molecule can be approximated as a combination of both.
18.
Azulene has a long history, dating back to the 15th century as the azure-blue chromophore obtained by steam distillation of wormwood and named in 1863 by Septimus Piesse.
19.
Likewise, since the characterization of the automerization of naphthalene by Scott in 1977, azulene, benz [ " a " ] anthracene and even benzene have been described.
20.
The diradical mechanism has been supported by Homolysis of the weakest bond in azulene occurs, followed by a hydrogen shift and ring closure so as to retain the aromaticity of the molecule.
