The acetosolv extraction, allylation and subsequent cross-linking of wheat straw lignin to thermoset biomaterials is herein described. The extraction temperature proved to be of great importance for the quality of the resulting lignin, with moderate temperature being key for preservation of β-O-4’ linkages. The allylation of the acetosolv lignin was carried out using three different synthetic strategies, resulting in selective installation of either benzylic or phenolic allyl ethers, or unselective allylation of various hydroxyl groups via etherification and carboxyallylation. The different allylation protocols employed either allyl alcohol, allyl chloride, or diallylcarbonate as allyl precursors, with the latter resulting in the highest degree of functionalization. Selected allylated acetosolv lignins were cross-linked using a thiol-ene approach and the lignin with the highest density of allyl groups was found to form a cross-linked thermoset material with properties comparable to kraft lignin-based analogues.

An efficient reaction at the counter electrode is of key importance for the success of net oxidative and net reductive electrochemical transformations. For electrooxidative processes, cathodic proton reduction to H 2 serves as the benchmark counter reaction. In contrast, net reductive electrochemical transformations have less attractive oxidative counter reactions to choose from and commonly rely on dissolution of a sacrificial anode that effectively results in stoichiometric metal consumption for the processes. In this study, we demonstrate that anodic borohydride oxidation has great potential to successfully replace the use of such sacrificial anodes for a variety of electroreductive organic transformations. This anodic transformation effectively serves as the inverse of cathodic proton reduction, producing H 2 using inert carbon‐based electrode materials.

Hole scavenger plays a crucial role in the photocatalytic hydrogen evolution reaction (HER), yet the principle guiding its selection remains controversial. In our study, we evaluate the photocatalytic HER performance of ZnIn2S4 (ZIS) with ten commonly used hole scavengers, and surprisingly find that the HER efficiency is dependent on the coordination interaction between the hole scavenger and the photocatalyst, rather than the commonly recognized redox potential of the scavengers. This coordination interaction can be quantitatively interpreted using the adsorption energy (AE) as a key metric. Notably, a scaling relationship is established between the calculated AE and the experimentally observed photocatalytic H2 evolution rate (Hrate). Among the ten investigated hole scavengers, triethanolamine demonstrates the strongest coordination interaction with ZIS, leading to the highest photocatalytic Hrate of 226.67 μmol h–1. As such, this work offers a valuable guideline for the rational selection of hole scavengers in a given photocatalytic system.

Herein, we present an electrochemical desulfurative protocol for the formation of alkyl boronic esters from thioethers. The paired electrolytic transformation utilizes HBpin as coupling partner and proceeds with inert electrodes. The transformation features mild conditions, broad substrate scope and excellent functional group tolerance, as illustrated by late-stage functionalization of pharmaceutical compounds and natural products. Furthermore, the protocol is scalable, successfully producing gram quantities of borylated product.

Zirconocene triflate is a powerful moisture-tolerant catalyst for activation of C O bonds in carboxylic acids and alcohols in the absence of water scavenging techniques. Herein, an overview of the use of this robust metal complex for direct amidation, esterification, and etherification is presented, along with a discussion on mechanistic aspects of the transformations and the catalyst class.

Alcohols are one of the most common organic compound classes among natural and synthetic products. Thus, methods for direct removal of C−OH groups without the need for wasteful pre-functionalization are of great synthetic interest to unlock the full synthetic potential of the compound class. Herein, electroreductive C−OH bond activation and subsequent deoxygenative C−H and C−C bond formation of benzylic and propargylic alcohols are demonstrated along with mechanistic insights. Experimental and theoretical studies indicate that the reductive C−OH bond cleavage furnishes an open shell intermediate that undergoes a radical-polar crossover to the corresponding carbanion that subsequently undergoes protonation to furnish alkane products. Furthermore, we demonstrate that the carbanion can be trapped with CO2 to form arylacetic acids. The cathodic transformations are efficiently balanced by the anodic oxidation of sub-stoichiometric borohydride additives, a strategy that serves as a highly attractive alternative to the use of sacrificial metal anodes.

Thioethers are highly prevalent functional groups in organic compounds of natural and synthetic origin but remain remarkably underexplored as starting materials in desulfurative transformations. As such, new synthetic methods are highly desirable to unlock the potential of the compound class. In this vein, electrochemistry is an ideal tool to enable new reactivity and selectivity under mild conditions. Herein, we demonstrate the efficient use of aryl alkyl thioethers as alkyl radical precursors in electroreductive transformations, along with mechanistic details. The transformations proceed with complete selectivity for C(sp3)−S bond cleavage, orthogonal to that of established transition metal-catalyzed two-electron routes. We showcase a hydrodesulfurization protocol with broad functional group tolerance, the first example of desulfurative C(sp3)−C(sp3) bond formation in Giese-type cross-coupling and the first protocol for electrocarboxylation of synthetic relevance with thioethers as starting materials. Finally, the compound class is shown to outcompete their well-established sulfone analogues as alkyl radical precursors, demonstrating their synthetic potential for future desulfurative transformations in a one-electron manifold.

Alcohols and their derivatives are ubiquitous and versatile motifs in organic synthesis. Deoxygenative transformations of these compounds are often challenging due to the thermodynamic penalty associated with the cleavage of the C−O bond. However, electrochemically driven redox events have been shown to facilitate the C−O bond cleavage in alcohols and their derivatives either through direct electron transfer or through the use of electron transfer mediators and electroactive catalysts. Herein, a comprehensive overview of preparative electrochemically mediated protocols for C−O bond activation and functionalization is detailed, including direct and indirect electrosynthetic methods, as well as photoelectrochemical strategies.

Through glycerol electrooxidation, we demonstrate the viability of using a PdNi catalyst electrodeposited on Ni foam to facilitate industrially relevant rates of hydrogen generation while concurrently providing valuable organic chemicals as glycerol oxidation products. This electrocatalyst, in a solution of 2 M NaOH and 1 M glycerol at 80 °C, enabled current densities above 2000 mA cm⁻² (in a voltammetric sweep) to be obtained in atmospheres of both air and N₂. Repeated potential cycling under an aerated atmosphere to these exceptional current densities indicated a high stability of the catalyst. Through steady state polarisation curves, 1000 mA cm⁻² was reached below an anodic potential of 0.8 V vs RHE. Chronoamperometry showed glycerate and lactate being the major oxidation products, with increased selectivity for lactate at the expense of glycerate in aerated systems. Aerated atmospheres were demonstrated to consistently increase the apparent Faradaic efficiency to >100%, as determined by the concentration of oxidation products in solution. The excellent performance of PdNi/Ni in aerated solutions suggests that O₂ removal from the electrolyte is not needed for an industrial glycerol electrooxidation process, and that combining electrochemical and chemical glycerol oxidation, in the presence of dissolved O₂, presents an important process advantage.