Paired electrolysis has a limited
reaction scope for organic synthesis
because it is often not compatible with reactions involving short-lived
intermediates. We addressed this limitation using alternating current
electrolysis (ACE). Using trifluoromethylation of (hetero)arenes as
a model reaction, we showed that the yield was improved from 13% using
paired electrolysis to 84% using ACE. We have also developed a theory
for guiding the rational design of reaction parameters for future
applications of ACE.
Here,
we report a unique electrosynthetic method that enables the
selective one-electron oxidation of tertiary amines to generate α-amino
radical intermediates over two-electron oxidation to iminium cations,
providing easy access to arylation products by simply applying an
optimal alternating current (AC) frequency. More importantly, we have
discovered an electrochemical descriptor from cyclic voltammetry studies
to predict the optimal AC frequency for various amine substrates,
circumventing the time-consuming trial-and-error methods for optimizing
reaction conditions. This new development in AC electrolysis provides
an alternative strategy to solving challenging chemoselectivity problems
in synthetic organic chemistry.
Here, we report an electrochemical protocol for hydrogen isotope exchange (HIE) at α-C(sp3)-H amine sites. Tetrahydroisoquinoline and pyrrolidine are selected as two model substrates because of their different proton transfer...
Nanowire sensors are promising to deliver greater performance than conventional sensors due to their size confinement as well as low cost and power consumption. However, scalable assembly of nanowire sensors remains a big challenge, which requires the synthesis of uniform nanowires and organization of them. Here, we report a simple method to control the growth and organization of a promising nanowire material for gas sensing, tetrathiafulvalene bromide ((TTF)Br), by mass transfer in electrodeposition. We found that the use of Pt microdisk electrodes for electrodeposition of (TTF)Br wires resulted in wires with higher uniformity and larger aspect ratio (length to width) than their counterparts deposited on Pt films under the same deposition conditions. More interestingly, we found that the number of wires grown from a Pt microdisk electrode exhibited a limiting number of 3 or 4 per electrode when the electrode diameters are smaller than ∼1.4 μm. Both experimental and simulation results suggest that the morphological differences and the constant minimum wire density are caused by the different TTF flux distributions at a microdisk versus a film electrode. The results have significant implications for scalable manufacturing of nanowire-based sensing devices.
Here, we report a unique electrosynthetic method that enables selective one-electron oxidation of tertiary amines to generate α-amino radical intermediates over the two-electron oxidation to iminium cations, providing easy access to arylation products by simply applying an optimal alternating current (AC) frequency. More importantly, we have discovered an electrochemical descriptor from cyclic voltammetry studies to predict the optimal AC frequency for various amine substrates, circumventing the time-consuming trial-and-error methods for optimizing reaction conditions. This new development in AC electrolysis provides an alternative strategy to solving challenging chemoselectivity problems in synthetic organic chemistry.
Here, we report an electrochemical protocol for hydrogen isotope exchange (HIE) at -C(sp3)-H amine sites. Tetrahydroisoquinoline and pyrrolidine are selected as two model substrates because of their different proton transfer (PT) and hydrogen atom transfer (HAT) kinetics at the -C(sp3)-H amine sites, which are utilized to control the HIE reaction outcome at different applied alternating current (AC) frequencies. We found the highest deuterium incorporation for tetrahydroisoquinolines at 0 Hz (i.e., direct current (DC) electrolysis condition) and pyrrolidines at 0.5 Hz. Analysis of the product distribution and D incorporation at different frequencies reveals that HIE of tetrahydroisoquinolines is limited by its slow HAT, whereas HIE of pyrrolidines is limited by the overoxidation of its -amino radical intermediates. The AC-frequency-dependent HIE of amines can be potentially used to achieve elective labeling of -amine sites in one drug molecule, which will significantly impact the pharmaceutical industry.
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