Video Experimental Relacionado

Updated: Mar 21, 2026

[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst

[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst

Published on: May 21, 2019

Activación de las olefinas inducida por la luz visible utilizando fotooxidantes de racimo 3D ricos en boro aromático

Marco S Messina^1,2, Jonathan C Axtell¹, Yiqun Wang¹

¹Department of Chemistry and Biochemistry, University of California, Los Angeles , 607 Charles E. Young Drive East, Los Angeles, California 90095-1569, United States.

Journal of the American Chemical Society

|May 18, 2016

Resumen

Los nuevos reactivos fotorreductivos libres de metales basados en grupos de dodecaborato pueden iniciar la polimerización de monómeros de estireno e isobutileno utilizando luz visible. Estos compuestos estables en el aire ofrecen una alternativa sostenible para iniciar transformaciones químicas.

Área de la Ciencia:

Química inorgánica
Ciencias de los materiales
La fotoquímica

Sus antecedentes:

Los grupos de dodecaborato icosaédrico perfuncionalizado (B12 ((OCH2Ar) 12) se exploran para nuevas aplicaciones fotoquímicas.
La transferencia de carga entre los sustituyentes de bencilo y el núcleo del clúster de boro permite la fotoexcitación.

Objetivo del estudio:

Introducir una nueva clase de reactivos fotorreductivos sin metales.
Para demostrar su utilidad en el inicio de reacciones de polimerización.

Principales métodos:

Fotoexcitación de los racimos B12 ((OCH2Ar) 12 utilizando un LED azul.
Estudios de transferencia de electrones con varios monómeros de estireno y isobutileno.
Iniciación y caracterización de la polimerización.

Principales resultados:

Los grupos fotoexcitados exhiben altos potenciales de reducción del estado excitado (hasta 3 V).
Iniciación eficiente de la polimerización observada para estirenos ricos en electrones y deficientes en electrones a bajas cargas de catalizador (0,005 mol%).
Producción de poli (isobutileno) muy ramificado a partir de isobutileno.

Conclusiones:

Los grupos B12 (OCH2Ar) 12 representan una nueva clase de reactivos fotorreductivos estables en el aire y libres de metales.
Estos reactivos pueden mediar efectivamente la polimerización de las olefinas a través de la transferencia de electrones fotoinducida.
Este descubrimiento abre nuevas vías para la catálisis fotorredóxica sostenible.

Más Videos Relacionados

Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

Published on: April 22, 2016

Light-driven Enzymatic Decarboxylation

Light-driven Enzymatic Decarboxylation

Published on: May 22, 2016

Videos de Conceptos Relacionados

Cycloaddition Reactions: MO Requirements for Photochemical Activation

Cycloaddition Reactions: MO Requirements for Photochemical Activation

Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.

Photochemical Electrocyclic Reactions: Stereochemistry

Photochemical Electrocyclic Reactions: Stereochemistry

The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation

ortho–para-Directing Activators: –CH3, –OH, –&NoBreak;NH2, –OCH3

ortho–para-Directing Activators: –CH₃, –OH, –⁠NH₂, –OCH₃

All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...

Hydroboration-Oxidation of Alkenes

Hydroboration-Oxidation of Alkenes

In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.

Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide

Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide

Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.

Cycloaddition Reactions: MO Requirements for Thermal Activation

Cycloaddition Reactions: MO Requirements for Thermal Activation

Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.