Search results for "electrolysis"
showing 10 items of 109 documents
Eulerian two-fluid model of alkaline water electrolysis for hydrogen production
2020
Hydrogen storage is a promising technology for storage of renewable energy resources. Despite its high energy density potential, the development of hydrogen storage has been impeded, mainly due to its significant cost. Although its cost is governed mainly by electrical energy expense, especially for hydrogen produced with alkaline water electrolysis, it is also driven by the value of the cell tension. The most common means of electrolyzer improvement is the use of an electrocatalyst, which reduces the energy required for electrochemical reaction to take place. Another efficient means of electrolyzer improvement is to use the Computational Fluid Dynamics (CFD)-assisted design that allows the…
Deposition of Cu Nanoparticles on the Surface of Metallic Aluminum
2012
Deposition of Cu particles by electrolysis at constant electrode potential and by internal electrolysis methods was investigated. The composition of deposited material was confirmed by optical and scanning electron microscope methods. Combination of electrolysis at constant electrode potential with internal electrolysis method was found most effective for fabrication of nanoparticle arrays. Single crystalline Cu particles are fabricated by internal electrolysis, while polycrystalline ones obtained by combined chronopotentiometric and internal electrolysis methods. The formation mechanism of Cu nanoparticles is described.
Oxide anodes in electro-organic oxidation. Oxidation of maleic addon tungsten oxide anodes
1982
The electrochemical oxidation of maleic acid on tungsten anodes has been investigated. Glyoxal and carbon dioxide were the main products together with tartaric acid and acetaldehyde. Glyoxal is also obtained as the main product from the oxidation ofd-tartaric acid. Under the same conditions succinic acid is completely oxidized to carbon dioxide and water. The anodic dissolution of tungsten and the oxidation of water to oxygen become predominant in the final stages of the electrolyses.
Simple electrochemical reduction of nitrones to amines.
2018
Only electricity is needed for the transformation of nitrones to amines. Such a direct double reduction has not been reported by any sole chemical reagent in a single step process.
Twofold Electrochemical Amination of Naphthalene and Related Arenes
2017
The twofold, electrochemical amination reaction of polycyclic arenes, e.g. naphthalene (4), via Zincke intermediates is demonstrated for the first time. The installation of the nitrogen functionalities occurs regioselectively in positions 1 and 5 of naphthalene (4). The key for this electro-conversion is boron-doped diamond as anode material. The method of the multi-amination reaction is expanded to other aromatic substrates. A detailed study is provided, covering electrolysis parameters, e.g. anode material, electrolyte system, current density, separator, etc. Despite the moderate yields, this approach offers the first direct electro-synthetic access to diaminated products.
Electrochemical Formation of 3,5-Diimido-1,2-dithiolanes by Dehydrogenative Coupling
2018
A synthetic approach to the cyclic disulfide moiety of 3,5-diimido-1,2-dithiolane derivatives starting with readily available precursors including the electrochemical coupling of dithioanilides is developed. The electrochemical key step provides sustainable synthetic access in high yields, using a very simple electrolysis setup.
Simple and scalable electrochemical synthesis of 2,1-benzisoxazoles and quinoline N-oxides.
2019
Cathodic reduction of the nitro moiety and subsequent intramolecular cyclization affords different substituted 2,1-benzisoxazoles and quinoline N-oxides. This methodology allows the synthesis of two different types of heterocycles from common simple starting materials, using electrons as a sole reagent for this transformation. The electrolysis can be conducted in a very simple undivided electrolysis cell under constant current conditions. This permits working on a larger scale compared to other electrochemical methodologies and represents a significant advantage.
Electrochemical Screening for Electroorganic Synthesis
2015
Electrochemical screening is usually strongly focused on electroanalytical data, while the parameters of organic synthesis are mostly not used as selection criteria. Typical parameters would be indication of the formation of the product and the efficiency of the electroorganic conversion. The latter data indicate the stability of the product under electrolysis conditions and represent the key for the accumulation of the desired product. We survey the current methods for electroorganic screening. In particular, parallel electrolysis under more defined conditions is discussed in detail since it represents a powerful tool for the development of electroorganic syntheses and processes.
Selective and Scalable Dehydrogenative Electrochemical Synthesis of 3,3′,5,5′-Tetramethyl-2,2′-biphenol
2019
3,3′,5,5′-Tetramethyl-2,2′-biphenol is a compound of high technical significance, as it exhibits superior properties as building block for ligands in the transition-metal catalysis. However, side reactions and overoxidation are challenging issues in the conventional synthesis of this particular biphenol. Here, an electrochemical method is presented as powerful and sustainable alternative to conventional chemical strategies, which gives good yields up to 51%. Despite using inexpensive and well-available bromide-containing supporting electrolytes, the issue of bromination and general byproduct formation is effectively suppressed by adding water to the electrolyte. Additionally, the scalabilit…
Synthesis ofmeta-Terphenyl-2,2′′-diols by Anodic C−C Cross-Coupling Reactions
2016
The anodic C-C cross-coupling reaction is a versatile synthetic approach to symmetric and non-symmetric biphenols and arylated phenols. We herein present a metal-free electrosynthetic method that provides access to symmetric and non-symmetric meta-terphenyl-2,2''-diols in good yields and high selectivity. Symmetric derivatives can be obtained by direct electrolysis in an undivided cell. The synthesis of non-symmetric meta-terphenyl-2,2''-diols required two electrochemical steps. The reactions are easy to conduct and scalable. The method also features a broad substrate scope, and a large variety of functional groups are tolerated. The target molecules may serve as [OCO](3-) pincer ligands.