Chan Pil Park

Dual-channel microreactor for gas-liquid syntheses.

A microreactor consisting of two microfluidic channels that are separated by a thin membrane is devised for intimate contact between gas and liquid phases. Gas flowing in one microchannel can diffuse into the liquid flowing in the other microchannel through the thin membrane. An oxidative Heck reaction carried out in the dual-channel (DC) microreactor, in which gaseous oxygen plays a key role in the catalytic reaction, shows the significant improvement that can be made over the traditional batch reactor and the conventional segmental microreactor in terms of yield, selectivity, and reaction time. It also allows independent control of the flow of the gaseous reagent. The proposed DC microreactor should prove to be a powerful tool for fully exploring gas-liquid microchemistry.

Monolithic and Flexible Polyimide Film Microreactors for Organic Microchemical Applications Fabricated by Laser Ablation

Glass, silicon, poly(dimethylsil-oxane) (PDMS), and poly(methylmethacrylate) (PMMA)have been used for the fabrication of miniaturized devices.Fabrication with glass or silicon substrates requires relativelycomplex processes, and the fabrication costs are high.Relatively cheap polymers such as PDMS or PMMA arenot suitable for application in organic chemical processesowing to their low chemical stability and easy swelling.

Triple-channel microreactor for biphasic gas-liquid reactions: Photosensitized oxygenations.

Summary A triple-channel microreactor fabricated by means of a soft-lithography technique was devised for efficient biphasic gas–liquid reactions. The excellent performance of the microreactor was demonstrated by carrying out photosensitized oxygenations of α-terpinene, citronellol, and allyl alcohols.

A Microchemical System with Continuous Recovery and Recirculation of Catalyst-Immobilized Magnetic Particles†

A microchemical system for continuous flow catalytic reactions with magnetic catalyst is presented. The automatic separation of catalyst particles and recirculation by the microchemical system makes it possible to realize fully the advantages a catalytic microreactor can offer. It would be applicable to various catalytic reactions with aid of already reported magnetic catalyst or new magnetic catalyst.

Low Pressure Ethenolysis of Renewable Methyl Oleate in a Microchemical System

A microchemical system for ethenolysis of renewable methyl oleate was developed, in which the dual-phase, microfluidic design enabled efficient diffusion of ethylene gas into liquid methyl oleate through an increased contact area. The increased mass transfer of ethylene favored the formation of desired commodity chemicals with significantly suppressed homometathesis when compared to the bulk system. In addition to higher selectivity and conversion, this system also provides the typical advantages of a microchemical system, including the possibility of convenient scale-up.

Green Diacetoxylation of Alkenes in a Microchemical System

The palladium-catalyzed diacetoxylation and trifluoromethanesulfonic acid-catalyzed diacetoxylation using inexpensive and environmentally friendly hydrogen peroxide and peracetic acid were successfully conducted with the help of microchemical technology. Excellent yield and selectivity were achieved in significantly shortened reaction times without the decomposition of explosive oxidants and further transformation of unstable products, offering a safe and efficient alternative to traditional methods for alkene diacetoxylation.

Continuous flow photooxygenation of monoterpenes

Photooxygenation of monoterpenes was conducted in two continuous flow reactors. The first, suitable for lab-scale research, had a maximum yield of 99.9%, and the second, focused on industrial applications, showed a daily output that was 270.0-fold higher than that in batch systems. The use of sunlight instead of an LED lamp gave 68.28% conversion.

Eco-efficient preparation of a N-doped graphene equivalent and its application to metal free selective oxidation reaction

Here, we demonstrate that graphene oxide (GO) can be converted to N-doped reduced GO (rGO) that could become a substitute for N-doped graphene. Simultaneous doping and reduction can be accomplished for this purpose by simply mixing GO with hydrazine and then continuously sonicating the solution at 65 °C. A high level of reduction is realized, as evidenced by a carbon to oxygen ratio of 20.7 that compares with the highest value of 15.3 ever reported in solution (water + hydrazine) methods. Nitrogen doping is possible up to 6.3 wt% and the extent of doping can be increased with increasing sonication time. Notably, the simple tuning process of N-doping in GO greatly enhanced the efficiency of the carbocatalyst for various kinds of metal free oxidation reactions and hence is proposed as a suitable candidate for future industrial applications.

Dynamically tunable nanoparticle engineering enabled by short contact-time microfluidic synthesis with a reactive gas

We present a membrane-based droplet microfluidic method that uses carbon monoxide (CO) gas as a reducing agent to synthesize plasmonic silica–gold nanoparticles, and demonstrate engineering of nanoparticle structure at short (1–5 s) gas–liquid contact times.

Microreactor-Mediated Benzylic Bromination in Concentrated Solar Radiation

Sunlight-induced bromination of benzylic compounds was conducted in a capillary microreactor, resulting in mono-brominated compounds with yields of up to 94 %. These reactions can be considered to be eco-friendly since they were carried out without an artificial light source or additional temperature control. In addition, up to 257.9 mmol could be produced daily using cost-effective molecular bromine, which leads to potential improvement of industrial processes.