Catalysis Of Organic Reactions Research Articles

Iodo-Bodipys as visible-light-absorbing dual-functional photoredox catalysts for preparation of highly functionalized organic compounds by formation of C–C bonds via reductive and oxidative quenching catalytic mechanisms

Iodo-Bodipys were used as organic catalysts for three different photoredox catalytic organic reactions, i.e. the aza-Henry reaction of tetrahydroisoquinoline, oxidation/[3 + 2] cycloaddition/oxidative aromatization tandem reaction between tetrahydroisoquinolines and maleimides, and C–H arylation of heteroarenes with diazonium salts. The organic photocatalysts act as either electron acceptors (reductive quenching) or electron donors (oxidative quenching) in the single electron transfer (SET) of the catalytic cycles. Different from the widely used Ru(bpy)3[PF6]2, Ir(ppy)3, or halo-xanthane photocatalysts (Eosin Y or Rose Bengal), the new organic photocatalysts show strong absorption of visible light and long-lived triplet excited states, which are beneficial for SET, a crucial step for photoredox catalytic organic reactions. Moreover, the molecular structures of the new photocatalysts can be easily modified, as a result the absorption wavelength of the photocatalysts was readily tuned from 529 nm to 630 nm. The three different types of organic reactions are accelerated with the new organic photocatalysts (typical reaction times 1–2 h) compared to that catalyzed by Ru(bpy)3[PF6]2 or Ir(ppy)3 (reaction time: 12–72 h). The C–H arylation of thiophene with phenyl diazonium salts was used to prepare new Bodipy derivatives that show large Stokes shift. Our results are useful for designing of new organic catalysts for photoredox catalytic organic reactions to prepare highly functionalize organic compounds.

Promoting the catalytic efficiency of a catalyst by a solvothermal method

A solvothermal method has been successfully introduced and applied to catalytic organic reactions. This method provides an easy way to promote catalyst efficiency. Several classical coupling reactions and aminations of aryl halides were performed using common catalysts such as commercial Pd/C and CuI using this method.

Porous material-immobilized iodo-Bodipy as an efficient photocatalyst for photoredox catalytic organic reaction to prepare pyrrolo[2,1-a]isoquinoline

Iodo-Bodipy immobilized on porous silica was used as an efficient recyclable photocatalyst for photoredox catalytic tandem oxidation-[3+2] cycloaddition reactions of tetrahydroisoquinoline with N-phenylmaleimides to prepare pyrrolo[2,1-a]isoquinoline.

Small Gold Clusters Formed in Solution Give Reaction Turnover Numbers of 10 7 at Room Temperature

Very small gold clusters (3 to 10 atoms) formed from conventional gold salts and complexes can catalyze various organic reactions at room temperature, even when present at concentrations of parts per billion. Absorption and emission ultraviolet-visible spectroscopy and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry revealed that, for example, the ester-assisted hydration of alkynes began only when clusters of three to five gold atoms were formed. The turnover numbers and turnover frequencies associated with these catalyzed reactions can be as high as 10(7) and 10(5) per hour, respectively.

ChemInform Abstract: Alternatives to Free Molecular Halogens as Chemoselective Reactants: Catalysis of Organic Reactions with Reusable Complexes of Halogen Metal Salts

AbstractReview: 44 refs.

Polyethylene as a Nonvolatile Solid Cosolvent Phase for Catalyst Separation and Recovery

The studies described here show that a relatively low molecular weight, narrow polydispersity polyethylene (PE) wax (Polywax) can serve as a nontoxic and nonvolatile alternative to alkane solvents in monophasic catalytic organic reactions where catalysts and products are separated under biphasic conditions. In this application, a polymer that is a solid at room temperature substitutes for a conventional alkane solvent at ca. 80 °C. In addition to the advantages of being a nonvolatile, nontoxic, reusable solvent, this hydrocarbon polymer solvent, like heptane, can sequester nonpolar soluble polymer-bound catalysts after a reaction and separate them from products. The extent of this separation and its generality were studied using polyisobutylene (PIB)- and poly(4-dodecylstyrene)-bound dyes and PE-bound Pd allylic substitution catalysts, PIB-bound Pd cross-coupling catalysts, and PE- and PIB-bound metathesis catalysts. Catalytic reactions were effected using single-phase reaction mixtures containing Polywax with toluene, THF, or THF/DMF at ca. 80 °C. These solutions either separate into two liquid phases on addition of a perturbing agent or separate as a solid/liquid mixture on cooling. The hydrocarbon polymer-bound dyes or catalysts either separate into the hot liquid Polywax phase or coprecipitate with Polywax and are subsequently isolated as a nonvolatile Polywax solid phase that contains the dye or the recyclable catalyst.

ChemInform Abstract: Manganese Compounds in the Catalysis of Organic Reactions

AbstractReview: 215 refs.

Catalysis of Organic Reactions

This special issue of Topics in Catalysis is devoted to discussions of catalysis applied particularly to the preparation of organic compounds and documents the proceedings of the 24th Biennial Conference of the Organic Reactions Catalysis Society (ORCS), held in Annapolis, Maryland from April 15th through April 19th, 2012. ORCS seeks to advance practical applications of catalysis for making organic compounds by fostering discussions, providing opportunities for members to present their work, and facilitating dissemination of scientific knowledge. At the 24th meeting, we celebrated two Paul N. Rylander award winners. The Paul N. Rylander Award is sponsored by BASF and is awarded annually to researchers who have made significant contributions in the application of catalysis in organic reactions. The 2011 winner, Thomas A. Puckette of the Eastman Chemical Company, was honored for his contribution to low-pressure Rh hydroformylation reactions and the development of previously undiscovered ligands. The 2012 winner, Melanie S. Sanford of the University of Michigan, was honored for her work in Pd-catalyzed C–H activation reactions. The two awardees reflect the essence of ORCS. Professor Sanford, through basic research, has been opening new paths for industrially relevant compounds while diminishing the environmental impact of their manufacture. Dr. Puckette’s research has been in an industrial setting where he has specialized in pioneering new pathways for catalyst systems operating at commercial scale. Dr. Puckette’s research has focused on the development of ligands that, prior to his work, were carefully avoided to prevent poisoning. The connection between fundamental and applied research in furthering catalysis deployed throughout the world is the vision of ORCS. Bringing the two worlds together is what makes ORCS, as a society, unique. The 24th biennial conference was organized into six major symposia as follows:

Monophosphine-Cyclopalladated Ferrocenylpyrimidine Complex: Synthesis, Crystal Structure and Reusable Catalytic System for Coupling Reaction of Aryl Chlorides in PEG-400

Since the first report on the use of palladacycles for the Suzuki and Heck reactions by Herrmann, Beller and coworkers in 1995, a wide variety of known and new palladacycles have been successfully used in the coupling reactions. Employing aryl chlorides for this reaction has been focused because aryl chlorides are cheaper and more available than their bromides and iodide counterparts. However, only a few palladacycles have proved to be efficient for the activation of notoriously unreactive aryl chlorides. In most cases the catalysts employed need to be used in relatively high loadings, and poor recovery, which negated the advantages associated with the use of aryl chlorides. PEGs [poly(ethylene glycol)] have clear advantages as a solvent in organic synthesis because they are cheap, steady, readily available, and nontoxic. Recently, liquid PEGs have been adopted as a new approach for catalyst recycling, in a broad range of catalytic organic reactions. We have also found biaryl phosphine adducts of cyclopalladated ferrocenylpyrimidine are very efficient for the amination of aryl chlorides in PEG-400. These adducts combine the stability induced by the presence of a palladacycle framework with the high activity commonly associated with phosphine ligands, and were far more active than the corresponding dimeric palladacycle. As a continuation of our interest in the synthesis and application of cyclopalladated complexes, we have prepared a new phosphine adduct of palladacycle 2 from the reaction of cyclopalladated ferrocenylpyrimidine dimer 1 with commercially available 2-dicyclohexylphosphanyl-2'-(N,N-dimethylamino)biphenyl (DCPAB) (Scheme 1) and examined its activity in the coupling reactions. Complex 2 is airand moisture-stable, both in solid state and in solution. It is very soluble in chloroform, dichloromethane and acetone, but insoluble in petroleum ether and n-hexane. The new complex was fully characterized by elemental analysis, IR, H NMR and ESI-MS. These spectra were well consistent with the title complex. Moreover, the molecular structure of 2 has been ascertained by means of X-ray studies. The molecule of 2 together with selected bond distances and angles is shown in Figure 1. The Pd atom is in a slightly distorted square-planar environment bonded to the phosphorus atom, the chlorine atom, the pyrimidinyl nitrogen atom and the carbon atom of the ferrocenyl moiety. The Pd–P bond length of 2 is similar to those of the related DCPAB-palladacycles, while the above bond length of 2 is longer than those of the related PPh3-palladacycles possibly due to the steric bulk of the DCPAB ligand. 16-18 In the crystal of 2 there exist two types of intermolecular C–H···Cl hydrogen bonds, which link the molecules into a 2D

Manganese compounds in the catalysis of organic reactions

The review summarizes published data on the use of manganese compounds as catalysts in oxidation of alkanes, alcohols, aldehydes, sulfides, and amines and carbometalation, cross coupling, telomerization, chlorination, hydrosilylation, hydrohydrazination, and other reactions.

Alternatives to free molecular halogens as chemoselective reactants: Catalysis of organic reactions with reusable complexes of halogen metal salts

Organometallic complexes of halogen metallic salts have been used as catalysts in different organic reactions, mainly the oxidation of organic compounds. Their use has not only allowed the reduction of the amounts of catalyst (since they can be reused) but also a lower generation of byproducts and wastes. The different reaction media developed through the research were analyzed by several green parameters, and the best results were obtained with complexes that have cyclodextrins as organic ligands. The proposed methodology is an alternative to use of molecular halogen as oxidant or catalyst when halogens are significant chemoselective reactants.

The Boron Imprint into Combined Catalytic Organic Reactions

Combined reactions through organoboron intermediates belong to the class of sequential reactions whereby the advantages are clear in terms of efficiency and selectivity. The goal to prepare target molecules from simple substrates requires strategic steps and very selective formation of new bonds. The addition of boryl units to unsaturated substrates can be performed chemo-, regio- and stereoselectively, therefore the organoboron intermediates might be easily transformed into the functionalized molecules, with total retention of configuration. Taking advantage of these protocols, here we describe the most recent advances in combined reactions through B chemistry. Keywords: Cross-coupling, bis(pinacolato)diboron, bis(catecholato)diboron, boration, dimerization, cyclization, Organic Reactions, organic synthesis, building blocks, organoboronic esters, reductive elimination, oxidative addition, Transition metal-catalyzed, atom-economical manner, crystalline materials

CYCLODEXTRIN-STABILIZED METAL NANOPARTICLES: SYNTHESIS AND CHARACTERIZATION

A simple and novel method of synthesis of gold and silver nanoparticles from their salt solutions by amino acid reduction in the presence of β-Cyclodextrin as capping and stabilizing agent has been successfully carried out. Characterization is done by UV spectroscopy and High-Resolution Transmission Electron Micrograph (HRTEM) imaging. The size of the nanomaterials is found to lie in the range 5–100 nm. The aqueous solutions of metal nanomaterials are stable for months, indicating the encapsulation of them in the nanocavity of β-Cyclodextrin. This report is new and novel as it is a combination of nanoscience with Supramolecular Chemistry. Cyclodextrin-capped metal nanoparticles will exhibit selectivity in properties derived from host–guest phenomena on their surfaces and are novel nanocatalysts for catalytic organic reactions in aqueous solution. Cyclodextrins are found to be very effective and eco-friendly alternatives to surfactants and polymer matrices as stabilizers.

ChemInform Abstract: Catalysis of Organic Reactions by Mineral Surfaces

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Catalysis of Organic Reactions by Inorganic Solids

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Catalysis of Organic Reactions by Mineral Surfaces

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Performance of a Biomimetic Oxidation Catalyst Immobilized on Silicon Wafers: Comparison with Its Gold Congener

With the aim of extending the usefulness of an existing biomimetic catalytic system, cobalt porphyrin catalytic units with thiol linkers were heterogenized via chemical grafting to silicon wafers and utilized for the catalytic oxidation of hydroquinone to p-benzoquinone. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to analyze the morphology and composition of the heterogeneous catalyst. The results of the catalytic oxidation of hydroquinone obtained with porphyrins grafted on silicon were compared with those obtained earlier with the same catalyst in homogeneous phase and immobilized on gold. It was found that the catalysis could run over 400 h, without showing any sign of deactivation. The measured catalytic activity is at least 10 times higher than that measured under homogeneous conditions, but also 10 times lower than that observed with the catalytic unit immobilized on gold. The reasons of this discrepancy are discussed in term of substrate influence and overlayer organization. The silicon-immobilized catalyst has potential as an advanced functional material with applications in oxidative heterogeneous catalysis of organic reactions, as it combines long-term relatively high activity with low cost.

The Precious Metal Loop, Costs from an Operating Company Perspective

An operating company’s view of processes using PGM catalysts is, “What is the manufacturing process that will make specification product at a profit?” To evaluate those manufacturing economics, the “Precious Metal Loop” (Cline LW Jr, Precious metal recovery and the precious metal loop. Catalysis of organic reactions. Marcel Dekker Inc., New York, 1995) steps (A) buy the catalyst, (B) make the product, (C) ship spent catalyst to a refiner, and (D) receive the PGM settlement, represents that expense. This paper presents a description of each step of the loop, important values such as process losses and refining losses as a function of the metal and the metal’s ash concentration, detailed examples and a discussion to assess the manufacturing economics.

Catalysis of Organic Reactions

Catalysis of Organic Reactions

Solubility of trifluoroethoxyphthalocyanines and -subphthalocyanines in liquid and supercritical carbon dioxide

Abstract In an analysis of the solubility of a wide range of phthalocyanines (Pcs) and its analogues (SubPcs) in liquid and/or supercritical CO2, compounds with trifluoroethoxy substituents were found to exhibit high solubility. To our knowledge, this is the first example of Pc compounds soluble in 100% CO2. This unprecedented unique property of trifluoroethoxy substituted Pcs might have particular applications in catalysis in organic reactions as well as dyes for solar cells by CO2 delivering coatings.