scholarly journals C-H Activation/Functionalization via Metalla-Electrocatalysis

2021 ◽  
Author(s):  
Guilherme M. Martins ◽  
Najoua Sbei ◽  
Geórgia C. Zimmer ◽  
Nisar Ahmed
Keyword(s):  
Green Chemistry ◽  
Control Strategy ◽  
Scale Up ◽  
Reaction Times ◽  
Metal Catalysts ◽  
Side Reactions ◽  
Potential Range ◽  
Efficient Strategy ◽  
Indirect Electrolysis ◽  
Chemical Oxidants

In conventional methods, C−H activations are largely involved in the use of stoichiometric amounts of toxic and expensive metal & chemical oxidants, conceding the overall sustainable nature. Meanwhile, undesired byproducts are generated, that is problematic in the scale up process. However, electrochemical C−H activation via catalyst control strategy using metals as mediators (instead electrochemical substrate control strategy) has been identified as a more efficient strategy toward selective functionalizations. Thus, indirect electrolysis makes the potential range more pleasant, and less side reactions can occur. Herein, we summarize the metalla-electrocatalysis process for activations of inert C−H bonds and functionalization. These Metalla-electrocatalyzed C−H bond functionalizations are presented in term of C−C and C−X (X = O, N, P and halogens) bonds formation. The electrooxidative C−H transformations in the presence of metal catalysts are described by better chemoselectivities with broad tolerance of sensitive functionalities. Moreover, in the future to enhance sustainability and green chemistry concerns, integration of metalla-electrocatalysis with flow and photochemistry will enable safe and efficient scale-up and may even improve reaction times, kinetics and yields.

Microwave Irradiated Acetylation of p-Anisidine: A Step towards Green Chemistry

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Mousumi Chakraborty ◽  
Vaishali Umrigar ◽  
Parimal A. Parikh
Keyword(s):  
Acetic Acid ◽  
Reaction Time ◽  
Green Chemistry ◽  
Acetic Anhydride ◽  
Microwave Irradiation ◽  
Organic Solvent ◽  
Reaction Times ◽  
Microwave Energy ◽  
Operating Parameters ◽  
Feed Composition

The present study aims at assessing the effect of microwave irradiation against thermal heat on the production of N-acetyl-p-anisidine by acetylation of p-anisidine. The acetylation of p-anisidine under microwave irradiation produces N-acetyl-p-anisidine in shorter reaction times, which offers a benefit to the laboratories as well as industries. It also eliminates the use of excess solvent. Effects of operating parameters such as reaction time, feed composition, and microwave energy and reaction temperature on selectivity to the desired product have been investigated. The results indicate as high as a 98% conversion of N-acetyl-p-anisidine can be achieved within 12-15 minutes using acetic acid. The use of acetic acid as an acetylating agent against conventionally used acetic anhydride eliminates the handling of explosive acetic anhydride and also the energy intensive distillation step for separation of acetic acid. Organic solvent like acetic anhydride are not only hazardous to the environment, they are also expensive and flammable.

scholarly journals Barium Dichloride as a Powerful and Inexpensive Catalyst for the Pechmann Condensation without Using Solvent

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Saeed Khodabakhshi
Keyword(s):  
Green Chemistry ◽  
Organic Solvents ◽  
Condensation Reaction ◽  
Reaction Times ◽  
Solvent Free ◽  
Coumarin Derivatives ◽  
Inexpensive Method ◽  
Keto Esters ◽  
Pechmann Condensation ◽  
Solvent Free Conditions

Various coumarin derivatives have been efficiently synthesized via barium dichloride-catalyzed Pechmann condensation reaction of various phenols and β-keto esters under solvent-free conditions. This novel and inexpensive method has advantages such as short reaction times, excellent product yields, and avoidance of organic solvents in agreement with green chemistry principles.

Metathetical Degradation and Depolymerization of Unsaturated Polymers

1997 ◽  
Vol 70 (3) ◽  
pp. 519-529 ◽  
Author(s):  
J. C. Marmo ◽  
K. B. Wagener
Keyword(s):  
Molecular Weight ◽  
Transition Metal ◽  
Catalytic System ◽  
Lewis Acid ◽  
Catalyst System ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Side Reactions

Abstract The employment of transition metal catalysts has been a viable route in the degradation and depolymerization of unsaturated polymers. Initially, unsaturated polymers were degraded with a catalytic system containing a transition metal and a Lewis acid cocatalyst (WCl6/SnBu4). Degradation chemistry was effective in reducing the molecular weight of the polymer, however, the classical catalyst system induces side reactions which generates ill-defined products. These side reactions were obviated by using a preformed alkylidene without a Lewis acid cocatalyst, and perfectly difunctional telechelics were synthesized.

scholarly journals Diels–Alder reactions of myrcene using intensified continuous-flow reactors

2017 ◽  
Vol 13 ◽  
pp. 120-126 ◽  
Author(s):  
Christian H Hornung ◽  
Miguel Á Álvarez-Diéguez ◽  
Thomas M Kohl ◽  
John Tsanaktsidis
Keyword(s):  
Continuous Flow ◽  
Flow Reactor ◽  
Scale Up ◽  
Reaction Times ◽  
Alder Reaction ◽  
Diels Alder ◽  
Flow Reactors ◽  
Diels Alder Reaction ◽  
Naturally Occurring ◽  
Continuous Flow Reactors

This work describes the Diels–Alder reaction of the naturally occurring substituted butadiene, myrcene, with a range of different naturally occurring and synthetic dienophiles. The synthesis of the Diels–Alder adduct from myrcene and acrylic acid, containing surfactant properties, was scaled-up in a plate-type continuous-flow reactor with a volume of 105 mL to a throughput of 2.79 kg of the final product per day. This continuous-flow approach provides a facile alternative scale-up route to conventional batch processing, and it helps to intensify the synthesis protocol by applying higher reaction temperatures and shorter reaction times.

scholarly journals An Oxidation Study of Phthalimide-Derived Hydroxylactams

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 548
Author(s):  
Bernard L. Adjei ◽  
Frederick A. Luzzio
Keyword(s):  
Silica Gel ◽  
Systematic Study ◽  
Special Interest ◽  
Scale Up ◽  
Reaction Times ◽  
Pyridinium Chlorochromate ◽  
Oxidation Study ◽  
Full Conversion ◽  
Oxidation System

A systematic study of the oxidation of 3-hydroxy-2-substituted isoindolin-1-ones (hydroxylactams) and their conversion to the corresponding phthalimides was undertaken using three oxidants. Of special interest was the introduction of nickel peroxide (NiO2) as an oxidation system for hydroxylactams and comparison of its performance with the commonly used pyridinium chlorochromate (PCC) and iodoxybenzoic acid (IBX) reagents. Using a range of hydroxylactams, optimal conversions of these substrates to the corresponding imides was achieved with 50 equivalents of freshly prepared NiO2 in refluxing toluene over 5–32 h reaction times. By comparison, oxidations of the same substrates using PCC/silica gel (three equivalents) and IBX (three equivalents) required oxidation times of 1–3 h for full conversion but required lengthier purification. While nominal amounts (~25 mg) of substrate hydroxylactams were used to ascertain conversion, scale-up procedures using all three methods gave good to excellent isolated yields of imides.

Microwave-Assisted Ruthenium-Catalyzed Reactions

2009 ◽  
Vol 62 (3) ◽  
pp. 184 ◽  
Author(s):  
François Nicks ◽  
Yannick Borguet ◽  
Sébastien Delfosse ◽  
Dario Bicchielli ◽  
Lionel Delaude ◽  
...  
Keyword(s):  
Reaction Times ◽  
Transfer Hydrogenation ◽  
Conventional Heating ◽  
Organic Chemical ◽  
Side Reactions ◽  
Chemical Transformations ◽  
Exchange Reactions ◽  
Present Contribution ◽  
Hydrogenation Reactions ◽  
Catalyzed Reactions

Since the first reports on the use of microwave irradiation to accelerate organic chemical transformations, a plethora of papers has been published in this field. In most examples, microwave heating has been shown to dramatically reduce reaction times, increase product yields, and enhance product purity by reducing unwanted side reactions compared with conventional heating methods. The present contribution aims at illustrating the advantages of this technology in homogeneous catalysis by ruthenium complexes and, when data are available, at comparing microwave-heated and conventionally heated experiments. Selected examples refer to olefin metathesis, isomerization reactions, 1,3-dipolar cycloadditions, atom transfer radical reactions, transfer hydrogenation reactions, and H/D exchange reactions.

scholarly journals Green Chemistry Approach for Efficient Synthesis of Schiff Bases of Isatin Derivatives and Evaluation of Their Antibacterial Activities

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Jnyanaranjan Panda ◽  
V. Jagannath Patro ◽  
Biswa Mohan Sahoo ◽  
Jitendriya Mishra
Keyword(s):  
Green Chemistry ◽  
Schiff Bases ◽  
Reaction Times ◽  
Antibacterial Activities ◽  
Primary Amines ◽  
Microwave Assisted Synthesis ◽  
Azomethine Group ◽  
Microwave Assisted ◽  
Isatin Derivatives

Microwave-assisted organic synthesis, a green chemistry approach, is nowadays widely used in the drug synthesis. Microwave-assisted synthesis improves both throughput and turnaround time for medicinal chemists by offering the benefits of drastically reduced reaction times, increased yields, and pure products. Schiff bases are the important class of organic compounds due to their flexibility, and structural diversities due to the presence of azomethine group which is helpful for elucidating the mechanism of transformation and rasemination reaction in biological system. This novel compound could also act as valuable ligands for the development of new chemical entities. In the present work, some Schiff bases of Isatin derivatives was synthesized using microwave heating method. Schiff base of Isatin were synthesized by condensation of the keto group of Isatin with different aromatic primary amines. They were characterized by means of spectral data and subsequently subjected to the in vitro antibacterial activities against gram positive and gram negative strains of microbes. It was observed that the compound with electron withdrawing substituents exhibited good antibacterial activities against almost all the micro organisms.

Ferric hydrogensulphate as a recyclable catalyst for the synthesis of fluorescein derivatives

2011 ◽  
Vol 65 (4) ◽  
Author(s):  
Hossein Eshghi ◽  
Narges Mirzaie
Keyword(s):  
Phthalic Anhydride ◽  
Scale Up ◽  
Reaction Times ◽  
Catalytic Amount ◽  
Recyclable Catalyst ◽  
Environmentally Benign ◽  
Absorption And Emission ◽  
Emission Properties ◽  
Benign Nature ◽  
High Yields

AbstractPolycondensation reactions of phenols with phthalic anhydride were carried out in the presence of ferric hydrogensulphate under melt conditions. The reactions proceeded in short reaction times by using a catalytic amount of Fe(HSO4)3 and the corresponding fluorescein derivatives were obtained in high yields. The simplicity, scale-up, along with the use of an inexpensive, non-toxic, recyclable catalyst of an environmentally benign nature, are other remarkable features of the procedure. The absorption and emission properties of these fluorescein derivatives were studied.

scholarly journals Electrosynthesis of 3,3′,5,5’-Tetramethyl-2,2′-biphenol in Flow

2020 ◽  
Author(s):  
Maximilian Selt ◽  
Barbara Gleede ◽  
Robert Franke ◽  
Andreas Stenglein ◽  
Siegfried R. Waldvogel
Keyword(s):  
Scale Up ◽  
Transition Metal Catalysis ◽  
Side Reactions ◽  
Narrow Gap ◽  
Metal Catalysis ◽  
Gap Flow ◽  
Electrolysis Cells ◽  
Efficient Alternative ◽  
Synthetic Approaches ◽  
Work Up

Abstract3,3′,5,5’-Tetramethyl-2,2′-biphenol is well known as an outstanding building block for ligands in transition-metal catalysis and is therefore of particular industrial interest. The electro-organic method is a powerful, sustainable, and efficient alternative to conventional synthetic approaches to obtain symmetric and non-symmetric biphenols. Here, we report the successive scale-up of the dehydrogenative anodic homocoupling of 2,4-dimethylphenol (4) from laboratory scale to the technically relevant scale in highly modular narrow gap flow electrolysis cells. The electrosynthesis was optimized in a manner that allows it to be easily adopted to different scales such as laboratory, semitechnical and technical scale. This includes not only the synthesis itself and its optimization but also a work-up strategy of the desired biphenols for larger scale. Furthermore, the challenges such as side reactions, heat development and gas evolution that arose during optimization are also discussed in detail. We have succeeded in obtaining yields of up to 62% of the desired biphenol.

Ultrasound-Promoted and Base-Mediated Regioselective Bromination of Imidazo[1,2-a]pyridines with Pyridinium Tribromide

Synthesis ◽  
2020 ◽  
Vol 52 (18) ◽  
pp. 2713-2720
Author(s):  
Qing-Wen Gui ◽  
Hongmei Jiang ◽  
Dingyi Guo ◽  
Yixin Zhang ◽  
Qin-Peng Shen ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Scale Up ◽  
High Energy ◽  
Metal Catalysts ◽  
Reaction Conditions ◽  
High Energy Efficiency ◽  
Operational Simplicity

By using pyridinium tribromide as the bromo source, an efficient­ and practical protocol for the synthesis of C3-brominated imidazo­[1,2-a]pyridines through ultrasound-promoted and Na2CO3-mediated regioselective bromination of imidazo[1,2-a]pyridines has been developed. This method effectively avoids the use of metal catalysts and harsh reaction conditions, and shows attractive characteristics such as operational simplicity, broad substrate scope with good to excellent yields, ease of scale-up and high energy efficiency.

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