2213-67-4Relevant articles and documents
Products and mechanisms of photochemical transformations of o-quinones
Shurygina,Kurskii, Yu.A.,Druzhkov,Chesnokov,Abakumov
, p. 234 - 238 (2011/11/06)
The photochemical transformations of quinones by the action of light at λ > 500 nm, namely, the photodecarbonylation and photoreduction reactions were studied with the use of a series of o-benzoquinones and 9,10-phenanthrenequinone as examples. The two-stage mechanism of the decarbonylation reaction of o-benzoquinones was established. At the first stage, rearrangement of a photoexcited quinone molecule into a bicyclic compound that spontaneously decomposes in the dark reaction into cyclopentadienone and CO takes place. It has been found that the formation of the photoreduction products of both o-benzoquinones and 9,10-phenanthrenequinone in the presence of various H donors (N,N-dimethylanilines and polymethylbenzenes) follows the same mechanism. In the first step, a phenol ether is produced, which subsequently undergoes quantitative transformation into pyrocatechol or ketol via the heterolytic mechanism. The stability of phenol ethers is determined by the structure and redox properties of the reactants.
Photoreduction of o-benzoquinones in the presence of p-bromo-N,N- dimethylaniline
Chesnokov,Cherkasov,Abakumov,Kurskii,Shurygina,Mamysheva,Shavyrin
, p. 718 - 724 (2007/10/03)
Photoreduction of o-benzoquinones in the presence of p-bromo-N,N- dimethylaniline under irradiation (λ, > 500 nm) affords the corresponding pyrocatechols and hydroxyphenyl ethers. The latter are unstable and, in turn, decompose in the dark reaction to pyrocatechols. The ratio between pyrocatechol and hydroxyphenyl ether formed upon the photoreaction is determined by the structure of o-quinone, namely, the presence and bulk of substituents in positions 3 and 6 of the ring. The yield of pyrocatechol is maximal (60-65%) if the substituents are the same (H and H, But and But) or insignificantly differ (Pri and But), regardless of its bulk.
