Modern Electrochemical Aspects for the Synthesis of Value‐Added Organic Products

The use of electricity instead of stoichiometric amounts of oxidizers or reducing agents in synthesis is very appealing for economic and ecological reasons, and represents a major driving force for research efforts in this area. To use electron transfer at the electrode for a successful transformation in organic synthesis, the intermediate radical (cation/anion) has to be stabilized. Its combination with other approaches in organic chemistry or concepts of contemporary synthesis allows the establishment of powerful synthetic methods. The aim in the 21st Century will be to use as little fossil carbon as possible and, for this reason, the use of renewable sources is becoming increasingly impo…

Elektrifizierung der organischen Synthese

Structure and luminescence properties of supramolecular polymers of amphiphilic aromatic thioether–peptide conjugates in water

We present the preparation of luminophore–peptide conjugates that self-assemble into supramolecular polymers in neutral buffer. To this end, we have prepared a small library of six conjugates with varying substitution patterns of the aromatic thioethers, as well as varying amino acid sequences. The latter have allowed us to tune the thermodynamic driving force for self-assembly and probe their photoluminescent properties either in the monomeric or polymeric state, while fully avoiding selective solvent techniques or organic solvent mixtures. All of the supramolecular structures were characterised with transmission electron microscopy, circular dichroism measurements, as well as steady-state…

Moderne Aspekte der Elektrochemie zur Synthese hochwertiger organischer Produkte

Adsorption and separation of black liquor-derived phenol derivatives using anion exchange resins

Abstract Kraft black liquor is the major waste stream of the paper pulping industry. This stream is usually directly incinerated in such facilities for energy production and recycling of the inorganic chemicals involved. However, lignin and other low molecular organic fragments dissolved in black liquor give rise to a large variety of aromatic fine chemicals. Energetic use of black liquor and its components prevents the removal of these valuable compounds from the waste stream. We present an easy protocol for adsorption and selective desorption of low molecular phenol derivatives from black liquor depending on the composition of the desorption system. Furthermore, adsorption experiments in …

Electro-conversion as sustainable method for the fine chemical production from the biopolymer lignin

Lignin, one of the most abundant polymers in nature, qualifies itself by the polyphenolic structure as potential renewable feedstock for the production of bio-based aromatic fine chemicals. However, the natural complexity and degradation stability of lignin make the depolymerization a highly challenging task. Several efforts have been pursued for the selective degradation of the biopolymer into suitable compounds. However, there are only a few technical approaches for the degradation of lignin to aromatic fine chemicals. Organic electrosynthesis is the synthetic method that enables the direct use of electricity for the production of valuable compounds. Moreover, electro-organic synthesis re…

Electrochemical Amination of Less-Activated Alkylated Arenes Using Boron-Doped Diamond Anodes

The anodic C–H amination of aromatic compounds is a powerful and versatile method for the synthesis of aniline derivatives. By using boron-doped diamond (BDD) anodes, a method initially described by Yoshida et al. for electron-rich arenes was expanded to less-activated aromatic systems e.g., simple alkylated benzene derivatives. Anodes based on sp3 carbon seem to be the key for the electrochemical amination reaction. The corresponding primary anilines are obtained in good yields. Despite the cationic intermediates of the electrolytic reaction tert-butyl moieties are tolerated.

Development of a Method for Anodic Degradation of Lignin for the Analysis of Paleo‐Vegetation Proxies in Speleothems

ChemInform Abstract: Electrochemical Amination of Less-Activated Alkylated Arenes Using Boron-Doped Diamond Anodes.

Comprehensive valorisation of technically relevant organosolv lignins via anodic oxidation

Lignin represents the largest renewable feedstock of aromatic moieties in nature. However, its valorisation towards organic chemicals poses a challenging task. We herein report the selective electrochemical depolymerisation of several technically relevant organosolv lignins to aromatic fine chemicals with a simple two-electrode arrangement using caustic soda as electrolyte. Vanillin, syringaldehyde, the corresponding ketones and guaiacol were obtained with a combined maximum of 7.8 wt% isolated yield. Deeper insight in the process was provided by FT-IR, HSQC NMR and 31P NMR analyses of the lignins.

Anodic Degradation of Lignin at Active Transition Metal-based Alloys and Performance-enhanced Anodes

High-Temperature Electrolysis of Kraft Lignin for Selective Vanillin Formation

Lignin represents the largest renewable resource of aromatic moieties on earth and harbors a huge potential as a sustainable feedstock for the synthesis of biobased aromatic fine chemicals. Due to the complex, heterogeneous, and robust chemical structure of the biopolymer, the valorization is associated with significant challenges. Unfortunately, technical lignins, which are a large side stream of the pulp and paper industries, are mainly thermally exploited. In this study, technical Kraft lignin was selectively electrochemically depolymerized to the aroma chemical vanillin. Using electricity, toxic and/or expensive oxidizers could be replaced. The electrodegradation of Kraft lignin was per…

Electrifying Organic Synthesis

Abstract The direct synthetic organic use of electricity is currently experiencing a renaissance. More synthetically oriented laboratories working in this area are exploiting both novel and more traditional concepts, paving the way to broader applications of this niche technology. As only electrons serve as reagents, the generation of reagent waste is efficiently avoided. Moreover, stoichiometric reagents can be regenerated and allow a transformation to be conducted in an electrocatalytic fashion. However, the application of electroorganic transformations is more than minimizing the waste footprint, it rather gives rise to inherently safe processes, reduces the number of steps of many synth…