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Benzene, Aromaticity, and Benzene Derivatives
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
Initial reaction with sodium leads to a one-electron transfer and formation of a resonance-stabilized radical anion. Two resonance contributors are shown with the negative charge and radical not on the carbon bearing the electron rich oxygen of the OCH3 group. In other words, these resonance contributors are formed so that the OCH3 group is on a sp2-hybridized carbon. Note that electronic repulsion of the two electron-rich centers leads to separation of the negative charge and radical to the more stable 1,4-position rather than having those electron-rich centers proximal to each other in a 1,2-position. This charge separation sets the 1,4-relationship of the alkene units and leads to formation of the final cyclohexa-1,4-diene product. An acid–base reaction with ethanol, which is a strong acid in the medium, leads to protonation of the carbanion and formation of the radical shown. A second reaction with sodium leads to another carbanion, which rapidly reacts with ethanol to give the final product, 1-methoxycyclohexa-1,4-diene. Why does the OCH3 group in the preceding question reside on a sp2-carbon in the final product?
Application of Nanomaterials for Lithium Ion Batteries
Published in Hieng Kiat Jun, Nanomaterials in Energy Devices, 2017
The ‘low-population’ and ‘high-population’ conditions generally refer to the concentration of EC in the electrolyte relative to other solvent components (The detailed explanation of other solvent components is described later). However, it can also refer to a lower or higher concentration of other Li-coordinated solvent molecules within the immediate environment relative to the reacting solvent molecules. It is thought that Li ion is solvated by one or more solvent molecule in the electrolyte. Coordination of a solvent molecule with a Li ion facilitates its reduction because this results in a negative-free energy change for the first reduction reaction. There is an energy barrier associated with the ring-opening step that has to be overcome to form the SEI layer. When the Li-coordinated cyclic carbonate adsorbs on the carbon surface, that additional coordination gives strain to the surface ring structure. This facilitates the reduction of the cyclic molecule and the ring-opening step by lowering the activation energy barrier for reaction (Wang et al. 2003, Marom et al. 2011). The Li-coordination would stabilize the radical anion that would then form, which undergoes a second 1-electron reduction. The affinity of electron for the anion is predicted to be much lower than the uncharged molecule, so it is reasonable to expect that the second reaction may not immediately proceed after the first reduction. Because these reactions should take place at the carbon surface, the radical anion can be stabilized by the active surface of the carbon. Once the second reduction occurs, the molecule can either react with a Li ion under ‘low-population’ conditions or with another Li-coordinated molecule under ‘high-population’ conditions. Both pathways result in the generation of ethene and either lithium carbonate or the alkyl carbonate. These lithium carbonate and/or alkyl carbonate are thought to be the main components of SEI.
Superficial sonication synthesis of a highly sunshine active metal modified ZnO photocatalyst and its multiple applications
Published in Inorganic and Nano-Metal Chemistry, 2022
P. Dhatshanamurthi, B. Subash, K. Jayamoorthy, R. Sasikala, P. Vijaya, M. Shanthi
The pathway of the charge isolation and photocatalytic reaction for SrO/Ag/ZnO heterogeneous photocatalyst is displayed in Scheme 1. When the semiconductor is excited by sunlight, a valence band electron (VB) moves to the conduction band (CB) and leaves positive a hole in the valence bond.[38] The recombination of electron-holes is sure to reduce the photocatalytic phenomenon of semiconductors. However, the existence of “Silver” captures the electron from CB of Zinc oxide, reducing the reentry of the electron to hole. The capturing feature of “Silver” yields enormous superoxide radical anion, and meanwhile valance band holes of zinc oxide reacts with H2O to yield hydroxyl radical (•OH) which is more reactive. The superoxide radical anion (O•−) and •OH enhances the degradation of dye.[28,39]
Synthesis, characterization, and biological activity of Cu(II) and Co(II) complexes of novel N1 ,N2-bis(4-methyl quinolin-2-yl)benzene-1,2-diamine: CuO and CoO nanoparticles derived from their metal complexes for photocatalytic activity
Published in Inorganic and Nano-Metal Chemistry, 2021
N. Venugopal, G. Krishnamurthy, H. S. Bhojyanaik, M. Madhukar Naik, N. Sunilkumar
The photocatalytic degradation in the presence of UV light + CuO and CoO oxide catalysts, the interaction between oxides and ultraviolet radiation produces holes (h+) and electrons (e−) on the surface of the catalyst. Where the holes act as powerful oxidants and electrons as powerful reluctant. The generated electrons on oxide react with oxygen to give the negative radical anion of oxygen (O2−·) which reacts with water to exhibit superoxide radical (OOH⋅). In the other hand, hydroxyl radicals are produced by the decomposition of water or by the reaction of hole with OH‒, behave as a reactive intermediate for degradation. The superoxide radical and hydroxide radicals efficiently increased the degradation of dye molecules.[46]
The effect of NADPH oxidase inhibitor diphenyleneiodonium (DPI) and glutathione (GSH) on Isatis cappadocica, under Arsenic (As) toxicity
Published in International Journal of Phytoremediation, 2021
Zahra Souri, Naser Karimi, Parvaiz Ahmad
In plant cells, the production of ROS is regulated through the photosynthetic rate, respiration, photorespiration, NADPH oxidases (NOXs) and other metabolite producing systems (Foyer and Noctor 2003; Marino et al.2012). Amongst these systems, NADPH oxidase in the plasma membrane plays a main role (Chen et al.2013). In addition, NOXs have been suggested as main components of ROS-generating in plants growing under stressful condition (Wang et al.2013; Sytykiewicz 2016; Wang et al.2016). NOXs reduced oxygen to the superoxide radical anion (O2•−) using NADPH (as electrons donor) (Jakubowska et al.2015). O2•− is an unstable superoxide radical which is quickly dismutated to H2O2 by superoxide dismutase (SOD) (Jakubowska et al.2015). Diphenyleneiodonium chloride (DPI) is a general flavoprotein inhibitor, commonly used to inhibit NOXs (Kaur et al.2014). In general, the application of DPI used to investigate the redox status and antioxidant responses in plant cells, under stress conditions. However, at present, there is dearth of information pertaining to the effects of DPI on plants growth and their responses under heavy metal stress.