Photochemistry of Anthracene-9,10-endoperoxide

Abstract

The wavelength dependence of the photochemistry of anthracene-9,10-endoperoxide (APO) in acetonitrile was quantitatively investigated at 5 degrees C, with excitation varied from 240 to 450 nm. Anthracene (AC) and a diepoxide (DE) were identified as the main primary photoproducts. After short exposure times DE was at all wavelengths the dominating photoproduct, while AC was only formed for lambda <or= 320 nm. The maximum AC quantum yield of 29% was reached at 270 nm. Anthraquinone (AQ) and a bicyclic acetal (BA) were identified as the main secondary products. Formation of AQ and BA occurred both from DE and from ground-state APO. Formation of BA from ground-state APO involved excited DE or BA itself, while formation of BA from DE required UV excitation of DE. Room-temperature thermolysis of APO only produced AQ. For lambda <or= 310 nm the total photochemistry quantum yield was, within error margins, constant and close to unity. Between 300 and 450 nm, the tail of the APO absorption spectrum, a more or less monotonic decrease of the total photochemistry quantum yield was observed.

9D nonadiabatic quantum dynamics through a four-state conical intersection: Investigating the homolysis of the O–O bond in anthracene-9,10-endoperoxide

“…This result is in agreement with the recently calculated energy paths 13 and the available experiments that found that 1 O 2 is obtained after excitation to states higher than the S 1 . 9 The present quantum dynamic simulations cannot provide the pathways to form rearrangement products due to the limited consideration of DOFs. Such rearrangements of the molecule require much more complicated DOFs, which are impossible to be described by a simple model Hamilton operator.…”

“…1) it has been established that the cycloreversion is preferred after excitation to higher lying singlet states S n (n ≥ 2), whereas excitation to the S 1 exclusively entails the O-O cleavage. 9 The S 1 of APO was found to correspond to a π * OO → σ * OO transition. 10,11 This assignment is in agreement with considerations of the orbitals contributing to a Diels-Alder type of reaction.…”

EPR Study of the Thermal Decomposition of Transannular Peroxide of Anthracene

“…In contrary to the latter mentioned polymer matrix crosslinking reactions, depending on the reaction conditions, a vigorous degradation of polysaccharide hyaluronic acid by singlet oxygen liberated from POA was reported earlier [8]. The possibility of endoperoxides to release these reactive species by unimolecular decomposition makes them interesting candidates for in vivo site-specific oxidative targeting with singlet oxygen at the present time [6,9]. The complex oxygen photosensitization in the presence of water soluble anthracene-1-sulphonate was studied by means of EPR spin trapping method [10].…”

“…These thermally and photo chemically reactive substances (depending on the reaction conditions) are decomposed to the original hydrocarbon and simultaneously liberate singlet oxygen ( 1 O 2 ), or decompose by the disruption of the O-O bonds, thus producing highly reactive biradical, or finally by the transformation into the other types of peroxides [4]. For instance, for anthracene-9,10-endoperoxide (POA) it has been found, that its photochemical excitation to S n , with n ≥ 2 leads to cycloreversion, producing anthracene and 1 O 2 , whereas excitation to the S 1 state would initially cause homolytic O-O cleavage, eventually resulting in a diepoxide rearrangement product [5,6].…”

An Overview of Selective Oxidation of Alcohols: Catalysts, Oxidants and Reaction Mechanisms

“…In contrast, the superoxo radical (d) was rapidly reduced by the e -at the para position of the triazine ring on g-C 3 N 4 , producing the 1,4-endoperoxide species (f) [81]. Protonation of the endoperoxide species produced H 2 O 2 [80,82] and completed the photocatalytic cycle.…”