Title: Benzylic Hydroperoxidation via Visible-Light-Induced Csp3−H Activation
A highly efficient benzylic hydroperoxidation has been realized through a visible-light-induced Csp3−H activation. We believe that this reaction undergoes a direct HAT mechanism catalyzed by eosin Y. This approach features the use of a metal-free catalyst (eosin Y), an energy-economical light source (blue LED), and a sustainable oxidant (molecular oxygen). Primary, secondary, and tertiary hydroperoxides as well as silyl, benzyl, and acyl peroxides were successfully prepared with good yields and excellent functional group compatibility. more »« less
Lessard, Jacob J.; Scheutz, Georg M.; Korpusik, Angie B.; Olson, Rebecca A.; Figg, C. Adrian; Sumerlin, Brent S.
(, Polymer Chemistry)
null
(Ed.)
We describe a self-catalyzing photoredox polymerization system for the modular generation of macromolecular photocatalysts. Specifically, we designed a photoactive eosin Y-derived monomer that can induce photoelectron/energy transfer, while simultaneously partaking in reversible addition–fragmentation chain transfer polymerization as a monomer, affording polymer catalysts with tunable eosin Y incorporations.
Freeburne, Sarah; Pester, Christian W
(, Polymer Chemistry)
This article describes the synthesis and characterization of a UV-crosslinked Eosin Y-photocatalytic gel and studies its performance in the oxidation of thioanisole in batch and flow reactors.
Photoinduced atom transfer radical polymerization (photo-ATRP) has risen to the forefront of modern polymer chemistry as a powerful tool giving access to well-defined materials with complex architecture. However, most photo-ATRP systems can only generate radicals under biocidal UV light and are oxygen-sensitive, hindering their practical use in the synthesis of polymer biohybrids. Herein, inspired by the photoinduced electron transfer-reversible addition–fragmentation chain transfer (PET-RAFT) polymerization, we demonstrate a dual photoredox/copper catalysis that allows open-air ATRP under green light irradiation. Eosin Y was used as an organic photoredox catalyst (PC) in combination with a copper complex (X–Cu II /L). The role of PC was to trigger and drive the polymerization, while X–Cu II /L acted as a deactivator, providing a well-controlled polymerization. The excited PC was oxidatively quenched by X–Cu II /L, generating Cu I /L activator and PC˙ + . The ATRP ligand (L) used in excess then reduced the PC˙ + , closing the photocatalytic cycle. The continuous reduction of X–Cu II /L back to Cu I /L by excited PC provided high oxygen tolerance. As a result, a well-controlled and rapid ATRP could proceed even in an open vessel despite continuous oxygen diffusion. This method allowed the synthesis of polymers with narrow molecular weight distributions and controlled molecular weights using Cu catalyst and PC at ppm levels in both aqueous and organic media. A detailed comparison of photo-ATRP with PET-RAFT polymerization revealed the superiority of dual photoredox/copper catalysis under biologically relevant conditions. The kinetic studies and fluorescence measurements indicated that in the absence of the X–Cu II /L complex, green light irradiation caused faster photobleaching of eosin Y, leading to inhibition of PET-RAFT polymerization. Importantly, PET-RAFT polymerizations showed significantly higher dispersity values (1.14 ≤ Đ ≤ 4.01) in contrast to photo-ATRP (1.15 ≤ Đ ≤ 1.22) under identical conditions.
Inoa, Joan; Dominici, Grecia; Eldabagh, Reem; Foley, Jonathan J.; Xing, Yalan
(, Synthesis)
null
(Ed.)
Abstract In recent years, advancements in photocatalysis have allowed for a plethora of chemical transformations under milder conditions. Many of these photochemical reactions utilize hydrogen atom transfer processes to obtain desired products. Hydrogen atom transfer processes can follow one of two unique pathways: the first, a direct path and the second, an indirect path. In this paper, we highlight the ability of eosin Y to act as a direct hydrogen atom transfer catalyst from both synthetic and computational chemistry perspectives.
The imaging and quantification of stained red blood cells (RBCs) are important for identifying RBCs in hematology and for diagnosing diseased RBCs or parasites in cytopathology. Romanowsky staining has been used traditionally to produce hues in blood cells using a mixture of anionic eosin Y and cationic methylene blue and azure B. While Romanowsky stains have been widely used in cytopathology, end-users have experienced problems with varying results in staining due to the premature precipitation or evaporation of methanol, leading to the inherent inconsistency of solution-based Romanowsky staining. Herein, we demonstrate that the staining and destaining of blood smears are controllable by the contact time of agarose gel stamps. While the extent of staining and destaining is discernable by the hue values of stamped red blood cells in micrographs, the quantification of adsorbed and desorbed Romanowsky dye molecules (in particular, eosin Y, methylene blue and azure B) from and to the agarose gel stamps needs a model that can explain the sorption process. We found predictable sorption of the Romanowsky dye molecules from the pseudo-second-order kinetic model for adsorption and the one phase decay model for desorption. Thus, the method of agarose gel stamping demonstrated here could be an alternative to solution-based Romanowsky staining with the predictable quantity of sorption and timing of contact.
@article{osti_10212793,
place = {Country unknown/Code not available},
title = {Benzylic Hydroperoxidation via Visible-Light-Induced Csp3−H Activation},
url = {https://par.nsf.gov/biblio/10212793},
DOI = {10.1021/acs.joc.0c00385},
abstractNote = {A highly efficient benzylic hydroperoxidation has been realized through a visible-light-induced Csp3−H activation. We believe that this reaction undergoes a direct HAT mechanism catalyzed by eosin Y. This approach features the use of a metal-free catalyst (eosin Y), an energy-economical light source (blue LED), and a sustainable oxidant (molecular oxygen). Primary, secondary, and tertiary hydroperoxides as well as silyl, benzyl, and acyl peroxides were successfully prepared with good yields and excellent functional group compatibility.},
journal = {Journal of organic chemistry},
volume = {85},
author = {Inoa, Joan and Patel, Mansi and Dominici, Grecia and Eldabagh, Reem and Patel, Anjali and Lee, John and Xing, Yalan},
editor = {null}
}
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