The Continuous Acid-Catalysed Etherification of Aliphatic Alcohols Using Stoichiometric Quantities of Dialkyl Carbonates

Catalytic reductive deoxygenation of esters to ethers driven by hydrosilane activation through non-covalent interactions with a fluorinated borate salt

A fluorinated borate BArF salt catalyses the reductive deoxygenation of esters to ethers by using hydrosilanes. Experimental and theoretical studies highlight the role of noncovalent interactions in the reaction mechanism.

Synthesis of Biomass-Derived Ethers for Use as Fuels and Lubricants

Ethers synthesized from biomass-derived compounds have exceptional properties as fuels, lubricants, and specialty chemicals and can serve as replacements for petroleum-derived products. Recent efforts have identified heterogeneous catalysts for the selective synthesis of ethers from alcohols, aldehydes, ketones, furans, esters, olefins, carboxylic acids, and other molecules derived from biomass. This Review highlights the scope of etherification reactions and provides insights into the choice of catalysts and reaction conditions best suited for producing targeted ethers from the available starting materials. First, the properties of ethers for specific applications and the methods by which synthons for ether synthesis can be obtained from biomass are discussed. Then the progress that has been made on the synthesis of ethers via the following methods is summarized: direct etherification of alcohols; reductive etherification of alcohols with aldehydes or ketones; etherification of furanic compounds, esters, and carboxylic acids; and the addition of alcohols to olefins. Next, the mechanisms of these reactions and catalyst properties required to promote them are discussed, with the goal of understanding how reaction conditions can be tuned to optimize catalyst activity and selectivity towards desired ethers. The Review closes by examining the tradeoffs between catalyst selectivity, activity, stability, and reaction conditions required to achieve the most economically and environmentally favorable routes to biomass-derived ethers.

The Hitchhiker's Guide to Flow Chemistry ∥

Flow chemistry involves the use of channels or tubing to conduct a reaction in a continuous stream rather than in a flask. Flow equipment provides chemists with unique control over reaction parameters enhancing reactivity or in some cases enabling new reactions. This relatively young technology has received a remarkable amount of attention in the past decade with many reports on what can be done in flow. Until recently, however, the question, "Should we do this in flow?" has merely been an afterthought. This review introduces readers to the basic principles and fundamentals of flow chemistry and critically discusses recent flow chemistry accounts.

Continuous-Flow O-Alkylation of Biobased Derivatives with Dialkyl Carbonates in the Presence of Magnesium-Aluminium Hydrotalcites as Catalyst Precursors

The base-catalysed reactions of OH-bearing biobased derivatives (BBDs) including glycerol formal, solketal, glycerol carbonate, furfuryl alcohol and tetrahydrofurfuryl alcohol with non-toxic dialkyl carbonates (dimethyl and diethyl carbonate) were explored under continuous-flow (CF) conditions in the presence of three Na-exchanged Y- and X-faujasites (FAUs) and four Mg-Al hydrotalcites (HTs). Compared to previous etherification protocols mediated by dialkyl carbonates, the reported procedure offers substantial improvements not only in terms of (chemo)selectivity but also for the recyclability of the catalysts, workup, ease of product purification and, importantly, process intensification. Characterisation studies proved that both HT30 and KW2000 hydrotalcites acted as catalyst precursors: during the thermal activation pre-treatments, the typical lamellar structure of the hydrotalcite was broken down gradually into a MgO-like phase (periclase) or rather a magnesia-alumina solid solution, which was the genuine catalytic phase.

Reductive Etherification of Fatty Acids or Esters with Alcohols using Molecular Hydrogen

In the presence of a catalyst system consisting of a ruthenium/triphos complex and the Brønsted acid trifluoromethanesulfonimide, mixtures of fatty acids and aliphatic alcohols are converted into the corresponding ethers at 70 bar H2 . The protocol allows the sustainable one-step synthesis of valuable long-chain ether fragrances, lubricants, and surfactants from renewable sources. The reaction protocol is extended to various fatty acids and esters both in pure form and as mixtures, for example, tall oil acids or rapeseed methyl ester (RME). Even the mixed triglyceride rapeseed oil was converted in one step.

Synthesis of ethyl hexyl ether over acidic ion-exchange resins for cleaner diesel fuel

Identifying the resin polymer zones where ethyl hexyl ether and by-products are preferentially formed in hexanol etherification with diethyl carbonate.