Journal of Flow Chemistry最新文献

Organolithium compounds have been used successfully in flow chemistry since the recent past. Most of the studies dealt with the use in halogen-lithium exchanges. So far, however, there has been a lack of use in substitution reactions. The use of flow microreactors makes the highly reactive organolithium compounds more controllable and thus creates new synthetic possibilities.

The synthesis of dithiocarbamates derivatives is important for their practical utilization as pharmaceuticals and for other purposes. Herein, we demonstrated the TfOH-catalyzed synthesis of dithiocarbamates via three-component reaction of α-diazoesters in good yields under continuous flow conditions. The reaction exhibits a wide substrate scope of diazo compounds and high functional group tolerance. This study provides a safe and mild protocol to form dithiocarbamates that complements TfOH-catalyzed S-H insertion reaction of diazo compounds and continuous flow synthesis strategies.

Phenols are vital building blocks for manufactured goods, agrochemicals, and medicine. As the demand to circumvent fossil fuels intensifies, so does the need to establish alternate sources of chemical feedstock, with many researchers looking to biomass. Lignin, a complex biopolymer found in plants, represents a relatively untapped renewable source of phenolic compounds. Examples of aromatic compounds derived from lignin include phenol, guaiacol (2-methoxyphenol), and catechol (2-hydroxyphenol). The development of new technologies and chemistry to upgrade or modify these compounds is crucial to realizing the potential of biomass as chemical feedstock. Over the last two decades, continuous flow technology has become an established tool for chemists to expand the capabilities of reaction control and to provide a means to probe novel reactions that might otherwise be difficult to study or accomplish via conventional means. Flow also imparts many advantages, such as superior mixing capabilities for gas/liquid reactions, increased efficiency for photochemical transformations, and improved scalability. This mini review will highlight research efforts reported in the last half-decade (since 2016) toward upgrading lignin-derived phenolic substrates using continuous flow technology. Recent developments focus on reactions requiring oxygenation, oxidation, hydrogenation, and deoxygenation to name a few.

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Water soluble biomimetic models of Riboflavin (B2 vitamin) and Folic acid (B8 vitamin) demonstrated to be good oxidant of formic acid at various pH. Their usage as anolyte mediators in a flow fuel cell to convert formic acid (or formate) into electricity is validated with measured power densities up to 16 mW.cm^− 2. These preliminary optimum conditions demonstrated a volumetric energy density of 0.68 Wh.L^− 1 when operating at 5 mA.cm^− 2 and neutral pH. These new conditions inspired from redox flow batteries processes permit to remove noble metals at both sides of the formate flow fuel cell.

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The direct conversion of glucose to 5-(hydroxymethyl)furfural (HMF) has been considered a challenging process. In this study, we developed a new method using gadolinium(III) trifluoromethanesulfonate (Gd(OTf)₃) in combination with Brønsted acidic ionic liquids as a catalytic system to search possibly more environmentally benign process. The reaction was carried out under a continuous-flow system. The one-step isomerization/dehydration of glucose to give the highest HMF with Gd(OTf)₃ together with DBU-based Brønsted acidic ionic liquid in a low-cost home-built continuous system. The plausible mechanism was proposed with the Lewis acidic sites of Gd(OTf)₃ for the isomerization step and DBU-based Brønsted acidic ionic liquid sites for the dehydration step. The recycling of catalytic system Gd(OTf)₃/DBU-based Brønsted acidic ionic liquid in DMSO was examined. Our findings provided a safe and environmental process for the continuous conversion of glucose into HMF. The use of continuous flow for HMF synthesis ensures that the current method can be applied to the large-scale process.

Biomass is a renewable, almost infinite reservoir of a large diversity of highly functionalized chemicals. The conversion of biomass toward biobased platform molecules through biorefineries generally still lacks economic viability. Profitability could be enhanced through the development of new market opportunities for these biobased platform chemicals. The fine chemical industry, and more specifically the manufacturing of pharmaceuticals is one of the sectors bearing significant potential for these biobased building blocks to rapidly emerge and make a difference. There are, however, still many challenges to be dealt with before this market can thrive. Continuous flow technology and its integration for the upgrading of biobased platform molecules for the manufacturing of pharmaceuticals is foreseen as a game-changer. This perspective reflects on the main challenges relative to chemical, process, regulatory and supply chain-related burdens still to be addressed. The implementation of integrated continuous flow processes and their automation into modular units will help for tackling with these challenges.

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We presented a microfluidic device for the preparation of monodisperse microdroplets with a small volume of samples or reagents, which is power-free, user-friendly and based only on a highly portable syringe. Our method requires only hand-operated syringes and sharpened capillaries without any complicated experimental setups, making the entire system portable and user-friendly for non-technical users. Vacuum is generated by pulling the plunger of the syringe on site, and fluid is generated by vacuum. The droplet size can be flexibly controlled by adjusting the size of micropores and capillary or vacuum degree. More potentially, microliter samples or reagents can also be prepared from it into emulsions. Unlike traditional methods, our device is self-activated, avoiding the need for external power supply while ensuring fewer samples or reagents consumption, simplifying operations and saving costs, facilitating immediate diagnostic testing or field trace substance detection.