Substituent dependency of the dihydroazulene ⇄ vinylheptafulvene photochromism: steric and electronic effects of 9-anthryl compounds- new access to condensed hydropentalenes was written by Gierisch, Sebastian;Bauer, Walter;Burgemeister, Thomas;Daub, Joerg. And the article was included in Chemische Berichte in 1989.Electric Literature of C18H10N2 This article mentions the following:
The synthesis of 2-(9-anthryl)-1,8a-dihydro-1,1-azulenedicarbonitrile (I) from 8-methoxyheptafulvene (II) by [8+2] cycloaddition reaction via tetrahydroazulene III and elimination of MeOH is described. On irradiation with visible light I is transformed to the vinylheptafulvene IV, which reconverts to I under thermal conditions. The steric congestion caused by the 9-anthryl substituent determines the rate of the [8+2] cycloaddition reaction as well as the kinetics of the thermal back reaction IV → I and causes thermochromic behavior of I. By intramol. electrophilic substitution, III yields the condensed hydropentalene V, which on oxidation leads to the condensed polycycle VI. The stereochem. assignments of the 9-anthryl compounds were made mainly by one- and two-dimensional 1H-NMR spectroscopy. In the experiment, the researchers used many compounds, for example, 2-(Anthracen-9-ylmethylene)malononitrile (cas: 55490-87-4Electric Literature of C18H10N2).
2-(Anthracen-9-ylmethylene)malononitrile (cas: 55490-87-4) belongs to nitriles. There has been no report on the microbial biosynthesis of nitriles and the physiological function of such enzymes, nor was it not even known whether aliphatic and aromatic nitriles are biological compounds or just petrochemicals. Some nitriles are manufactured by heating carboxylic acids with ammonia in the presence of catalysts. This process is used to make nitriles from natural fats and oils, the products being used as softening agents in synthetic rubbers, plastics, and textiles and for making amines.Electric Literature of C18H10N2
Referemce:
Nitrile – Wikipedia,
Nitriles – Chemistry LibreTexts