43042-33-7Relevant articles and documents
High-capacity organic cathode active materials of 2,2′-bis-p-benzoquinone derivatives for rechargeable batteries
Yokoji, Takato,Kameyama, Yuki,Maruyama, Norihiko,Matsubara, Hiroshi
supporting information, p. 5457 - 5466 (2016/05/24)
Rechargeable batteries using organic cathode materials are expected to afford high mass energy densities since these materials can undergo multiple electron redox reactions per molecule. Although the batteries using benzoquinone (BQ) derivatives as organic cathode active materials exhibited high theoretical capacity, their practical capacities and cycle retention were far from satisfactory. To overcome these problems, dimeric BQ derivatives based on the 2,2′-bis-p-benzoquinone (BBQ) framework were synthesized, and the charge-discharge behaviour of the prepared cells using BBQs as the cathode active materials was investigated. BBQ-based cells exhibited excellent performance compared to those based on BQ monomers. For example, the BBQ cell afforded a high initial capacity of 358 A h kg-1 (more than twice that of current lithium-ion batteries that use LiCoO2 as the cathode active material) and a high cycle retention of 198 A h kg-1 at 50 cycles. Electrochemical measurements and density functional theory (DFT) calculations indicated that three electron-redox reactions generally occur in BBQ derivatives, although (OMe)2-BBQ appeared to undergo a four-electron redox reaction.
Photochemistry of methoxyhydroquinone and methoxy-p-benzoquinone in solution related to the photoyellowing of the lignocellulosics
Bearnais-Barbry, Stephane,Bonneau, Roland,Castellan, Alain
, p. 542 - 548 (2007/10/03)
The photoreactivity of methoxy-p-benzoquinone (MQ) and methoxyhydroquinone (MHQ) in dilute solution (10-4-10-3 M) was studied using continuous irradiation and laser flash photolysis (LFP). The quinone irradiated in degassed tetrahydrofuran (THF) gives MHQ and an adduct with the solvent. Only the formation of hydroquinone is observed in ethanol, and hydroxylation is evidenced in water, whereas the compound is stable in CCl4. The bis-quinone, 4,4′-dimethoxybiphenyl-2,5,2′,5′-bisquinone, and the dibenzofurane-quinone, 8-hydroxy-3,7-dimethoxydibenzofuran-1,4-quinone, are formed in the presence of MHQ, whereas the reactivity is low with ethylconiferyl alcohol. When MHQ is irradiated selectively in degassed THF, the formation of MQ and of the bis-hydroquinone, 4,4′-dimethoxy-2,5,2′,5′-tetrahydroxy-biphenyl, are observed. The dimer is oxidized photochemically or thermally into the mono- or bis-quinones, the process being accelerated in alkaline medium. The formation of the dimers is strongly favored by the contiguous presence of quinone and hydroquinone. When MHQ is selectively irradiated in the presence of trans-ethylconiferaldehyde (EtC), quinone formation and isomerization of EtC are observed. LFP experiments, performed with a selective excitation of MQ, indicate that the triplet state of the quinone is strongly quenched by MHQ to conduce to a semiquinone radical. The interaction between 3MQ* and MQ is mainly driven by an electron transfer process according to the similar value of the quenching rate constant found with another electron donor compound such as 1,4-dimethoxybenzene. By contrast, no strong quenching of 3EtC* by MHQ was observed. It is proposed that the photochemistry of the couple MQ/MHQ is governed by the formation of encounter complex between either 3MQ* and MHQ or 3MHQ* and MQ. Consequently, the fast part of the photoyellowing of lignocellulosics does not appear to involve the couple MHQ/MQ or MHQ/etherified coniferaldehyde, but more likely a combination of oxidation of the hydroquinone by ground-state oxygen and photohydration of the formed quinone from its triplet state, giving inter-alia more colored o-quinonoid type molecules.
