Additive-controlled chemoselective inter-/intramolecular hydroamination via electrochemical PCET process.

Electrochemically generated amidyl radical species produced distinct inter- or intramolecular hydroamination reaction products via a proton-coupled electron transfer (PCET) mechanism. Cyclic voltammetry (CV) analysis indicated that the chemoselectivity was derived from the size of the hydrogen bond complex, which consisted of the carbamate substrate and phosphate base, and could be controlled using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as an additive. These results provide fundamental insights for the design of PCET-based redox reaction systems under electrochemical conditions.

Periodic cycles of seizure clustering and suppression in children with epilepsy strongly suggest focal cortical dysplasia.

AIM: We investigated characteristic seizure patterns in epilepsy caused by focal cortical dysplasia (FCD), which differ from epilepsy by other aetiologies in surgical cases with lesions on magnetic resonance imaging (MRI), then examined if these features were applicable to patients with epilepsy without any lesions on MRI. METHOD: We retrospectively studied clinicopathological features in 291 (143 females) children with epilepsy who had undergone resective surgery after comprehensive evaluation, including 277 cases with lesions on MRI (136 females, age at resection 0-17 years [mean 6 years 10 months, SD 5 years 7 months]) and 14 cases without any lesions on MRI (seven females, age 0-16 years [mean 7 years 8 months, SD 4 years 8 months]). RESULTS: Among 277 patients with lesions on MRI, 87 cases exhibited recurrent periodic cycles of seizure clustering (≥5 seizures/day for ≥1 week) and suppression (no seizures for ≥1 week); of these, 80 cases (92%) were pathologically diagnosed with FCD. Other pathologies included glial scar, hippocampal sclerosis, hemimegalencephaly, and cortical tuber in three, two, one, and one case respectively. All 14 patients without any lesions on MRI had significant recurrent periodic seizure cycles and FCD histopathologically. INTERPRETATION: Periodic seizure cycles characterized by clustering and suppression in patients with epilepsy strongly suggest the presence of FCD regardless of MRI findings, and comprehensive evaluations for epilepsy surgery should be proceeded.

Synthesis of piperidine and pyrrolidine derivatives by electroreductive cyclization of imine with terminal dihaloalkanes in a flow microreactor.

We have successfully synthesized piperidine and pyrrolidine derivatives by electroreductive cyclization using readily available imine and terminal dihaloalkanes in a flow microreactor. Reduction of the substrate imine on the cathode proceeded efficiently due to the large specific surface area of the microreactor. This method provided target compounds in good yields compared to a conventional batch-type reaction. Furthermore, piperidine and pyrrolidine derivatives could be obtained on preparative scale by continuous electrolysis for approximately 1 hour.

Bayesian optimization with constraint on passed charge for multiparameter screening of electrochemical reductive carboxylation in a flow microreactor.

Multiparameter screening of reductive carboxylation in an electrochemical flow microreactor was performed using a Bayesian optimization (BO) strategy. The developed algorithm features a constraint on passed charge for the electrochemical reaction, which led to suitable conditions being instantaneously found for the desired reaction. Analysis of the BO-suggested conditions underscored the physicochemical validity.

Triple-Phase Boundary in Anion-Exchange Membrane Reactor Enables Selective Electrosynthesis of Aldehyde from Primary Alcohol.

Invited for this month's cover is the group of Prof. Mahito Atobe at Yokohama National University, Japan. The image shows an anion-exchange membrane (AEM) reactor enabling selective oxidation of a primary alcohol to a corresponding aldehyde by the electrochemical reaction at the triple-phase boundary. The Communication itself is available at 10.1002/cssc.202102076.

Triple-phase Boundary in Anion-Exchange Membrane Reactor Enables Selective Electrosynthesis of Aldehyde from Primary Alcohol.

Oxidation of primary alcohol to the corresponding aldehyde remains a significant challenge, even with the state-of-the-art chemistry. Here, a novel electrochemical system was developed for the exclusive production of aldehyde from primary alcohol using an anion-exchange membrane (AEM) reactor. Oxidation proceeded on a gold catalyst under basic conditions, which largely enhanced the reaction rate. Despite the basic nature around the reaction sites, the oxidation of primary alcohols exclusively yielded the corresponding aldehyde, which was attributed to the unique three-phase interfacial reaction sites in the AEM reactor. In addition to benzyl alcohol, the oxidation of allylic and aliphatic alcohols was also demonstrated. Comparison of constant potential electrolysis with the AEM reactor or a conventional batch-type cell revealed the crucial role of the triple-phase boundary for the selectivity of the oxidation of alcohol.

Electrocatalytic hydrogenation of benzoic acids in a proton-exchange membrane reactor.

The highly efficient chemoselective electrocatalytic hydrogenation of benzoic acids (BAs) to cyclohexanecarboxylic acids (CCAs) was carried out in a proton-exchange membrane reactor under mild conditions without hydrogenation of the carboxyl group. Among the investigated catalysts, the PtRu alloy catalyst was found to be the most suitable for achieving high current efficiencies for production of CCAs. An electrochemical spillover mechanism on the PtRu alloy catalyst was also proposed.

Integrated Flow Synthesis of α-Amino Acids by In Situ Generation of Aldimines and Subsequent Electrochemical Carboxylation.

The synthesis of α-amino acids was carried out in a continuous flow system. In this system, aldimines were efficiently generated in situ via the dehydration-condensation of aldehydes with anilines in a desiccant bed column filled with 4 Å molecular sieves desiccant, followed by reaction with CO2 in an electrochemical flow microreactor to afford the α-amino acids in high to moderate yields. The present system can provide α-amino acids without using stoichiometric amounts of metal reagents or highly toxic cyanide reagents.

Electrosynthesis in Laminar Flow Using a Flow Microreactor.

Electrosynthesis and microflow synthesis have become essential tools in their own rights in modern organic synthesis. In this personal account, we summarize our works on the integrated use of these techniques, i. e., electrosynthesis in a flow microreactor. Our group has developed an electrochemical microflow system composed of a pair of electrodes that face each other to form a micrometer-scale gap for the flow path, through which solution passes in laminar flow. By the aid of laminar flow, unprecedented chemo- and electrochemical selectivity has been observed, which is not achievable with conventional batch-type electrochemical cells. In addition, we showcase various unique electrochemical systems and reactions achieved with the flow microreactor, including self-supported electrolysis, efficient paired electrolysis, in situ generation of active species and its flash use, the spaciotemporal control of electropolymerization, and combinatorial screening of the reaction conditions.

Electrochemical synthesis of microporous polyaniline films using foam templates prepared by ultrasonication.

We report a new soft template method for the synthesis of unique polyaniline (PANI) films with microporous structures. In this process, ultrasonication is used to foam an electrolyte solution containing a surfactant, which is subsequently employed as a soft template for PANI growth via the electrochemical polymerization of aniline. Analysis by scanning electron microscopy demonstrates that the resulting PANI films contain numerous micropores. These microporous PANI films exhibit faster charging (doping) and discharging (dedoping) current responses compared to ordinary flat films of the same material.

Size-controlled synthesis of polymer hollow nanoparticles using emulsion templates prepared by tandem acoustic emulsification.

We have developed a new emulsion template method for the synthesis of poly(methylmethacrylate) (PMMA) hollow nanoparticles with different sizes. This synthetic method involves sequential ultrasonic irradiation (20 kHz → 500 kHz → 1.6 MHz → 2.4 MHz → 5.0 MHz) for acoustic emulsification of a water-insoluble fluorous solvent such as perfluoromethylcyclohexane (PFMCH) in an aqueous medium, followed by monomer (methylmethacrylate (MMA)) adsorption on the surface of the PFMCH emulsion droplets and photopolymerization of the adsorbed MMA in the obtained emulsion solution. Since the size of the PFMCH droplet templates can be tuned according to the number of steps of tandem acoustic emulsification, the obtained PMMA particle size can also be controlled. The subsequent removal of the core fluorous solvent by the heat treatment yielded size-controlled PMMA hollow nanoparticles and monodisperse PMMA hollow nanoparticles of different sizes. Furthermore, we confirmed that the substances could go in or go out of the hollow particles through the shells. Such a nice permeability is important for applications such as nanoreactors and drug delivery systems.

Applications of Flow Microreactors in Electrosynthetic Processes.

The fundamental advantages and potential benefits of flow microreactor technology include extremely large surface-to-volume ratios, precise control over temperature and residence time, extremely fast molecular diffusion, and increased safety during reactive processes. These advantages and benefits can be applied to a wide range of electrosynthetic techniques, and so the integration of flow microreactors with electrosynthesis has received significant research interest from both academia and industry. This review presents an up-to-date overview of electrosynthetic processes in continuous-flow microreactors. In addition, the advantages of continuous-flow electrochemistry are discussed, along with a thorough comparison of microreactor-based processes and conventional batch reaction systems.

Cathodic Aromatic C,C Cross-Coupling Reaction via Single Electron Transfer Pathway.

We have successfully developed a novel cathodic cross-coupling reaction of aryl halides with arenes. Utilization of the cathodic single electron transfer (SET) mechanism for activation of aryl halides enables the cross-coupling reaction to proceed without the need for any transition metal catalysts or single electron donors in a mild condition. The SET from a cathode to an aryl halide initiates a radical chain by giving an anion radical of the aryl halide. The following propagation cycle also consists entirely of anion radical intermediates.

Electroresponsive Structurally Colored Materials: A Combination of Structural and Electrochromic Effects.

Electroresponsive structurally colored materials composed of ordered arrays of polyaniline@poly(methyl methacrylate) (PANI@PMMA) core-shell nanoparticles have been successfully prepared. The core-shell nanoparticles were synthesized by deposition of PANI shells on the surfaces of the PMMA cores by the oxidative polymerization of anilinium chloride. Ordered arrays were then fabricated by using the fluidic cell method. Because the ordered arrays and the PANI shells generate structural and electrochromic colors, respectively, these core-shell colloidal crystals exhibited colors resulting from the combined effects of these materials. The crystal colors depended greatly on the size of PANI@PMMA particles and could also be varied by the application of a voltage. The electrochromic colors of these arrays were found to be quite different from those exhibited by pure PANI films prepared by electrochemical oxidation.

An anodic aromatic C,C cross-coupling reaction using parallel laminar flow mode in a flow microreactor.

We have successfully demonstrated an efficient anodic aromatic C,C cross-coupling reaction using parallel laminar flow mode in a two-inlet flow microreactor. The model reaction proceeded effectively even in single flow-through operations and the desired cross-coupling product was obtained in much higher current yields compared to the reaction in a conventional batch type cell.

RETRACTED: Size-controlled spherical polymer nanoparticles: synthesis with tandem acoustic emulsification followed by soap-free emulsion polymerization and one-step fabrication of colloidal crystal films of various colors.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article was retracted at the request of the Editor. The above paper is essentially a duplicate of an original Article in "Size-Controlled Synthesis of Polymer Nanoparticles with Tandem Acoustic Emulsification Followed by Soap-Free Emulsion Polymerization" ACS Macro Lett., 2013, 2 (6), pp 482­484, 10.1021/mz4001817.

Size-Controlled Synthesis of Polymer Nanoparticles with Tandem Acoustic Emulsification Followed by Soap-Free Emulsion Polymerization.

We have developed a novel synthesis method for size-controlled polymer nanoparticles using soap-free emulsion polymerization. This new synthetic method involves sequential ultrasonic irradiation (20 kHz → 500 kHz → 1.6 MHz → 2.4 MHz) for acoustic emulsification of a water-insoluble monomer such as methylmethacrylate (MMA) in an aqueous medium, followed by emulsion polymerization in the obtained solution without using any surfactants. The sequential ultrasonication (tandem acoustic emulsification) could provide a clear and stable emulsified solution containing monomer droplets with relatively narrow size distribution in the nanometer range. The subsequent polymerization in this solution yielded size-controlled polymer nanoparticles. Furthermore, colloidal crystal films could be easily prepared from the as-polymerized nanoparticle solution using the fluidic-cell method.