Inorganic Chemistry
Recent Advances in Organocatalytic Synthesis and Catalytic Activity of Substituted Pyrrolidines
The emergence of enantioselective organocatalysis as a potent synthetic chemistry strategy that supports metal-catalyzed transformations has resulted in the creation of novel procedures for the synthesis of various chiral molecules. Organocatalysis is a desirable method for creating complex molecular structures due to its many benefits including its ease of use wide availability of catalysts and low toxicity. Chemists are actively exploring synthetic methodologies and looking into the applications of pyrrolidine-based organocatalysts. The application of organocatalysts spans a wide range of reaction types highlighting their ability to participate in a variety of catalytic processes. The current study offers a succinct summary of the principal strategic methods for producing pyrrolidine-based organocatalysts and demonstrating their usefulness in organic transformations.
Laser Synthesis of Catalytically Active Materials for Organic Synthesis and Sensor Technology
Introduction: The catalytic activity of metallic nanomaterials depends on their surface morphology. A widely known method is the laser synthesis of metal nanostructures by depositing on dielectric surfaces from aqueous solutions containing metal complexes. The article analyzes the factors that favor the production of conductive catalytic and sensory-active deposits by laser method. It is shown that the two main factors is the presence of a large number of charged defects on heterophase surfaces and the structure of metal-containing complexes in solution. This is typical for mono- and bimetallic alloys the components of which interact with the laser beams according to the autocatalytic type. Using the example of laser deposition from solutions of Co Ni Fe Zn and Ag salts with homo- and heterophase dielectrics the sensory and catalytic properties of the deposits are compared by impedance spectroscopy and voltammetry. It has been shown that heterophase precipitation significantly enhances the catalysis response. Background: It is known that the highest catalytic activity exhibits nanostructured and highly porous materials with a large specific surface area and materials containing surface heterogeneity in the form of charged acid-base centers. Such materials are necessary for the creation of new catalysts for organic synthesis and for the creation of new sensor materials for enzyme-free microbiosensors. Active development of new methods for the synthesis of such materials is underway. But not all of them give the expected result. Methods: Laser synthesis methods have the best prospects including the method of laser-induced metal deposition. This is the laser synthesis of metal nanostructures by depositing dielectric surfaces from aqueous solutions containing metal complexes. Results: Ц#144;rticle analyzes the factors that favor the production of conductive catalytic and sensory-active deposits by laser method. It is shown that the two main factors are the presence of a large number of charged defects on heterophase surfaces and the structure of a metal-contained complex in solution. This is typical for mono- and bimetallic alloys the components of which interact with the laser beam according to the autocatalytic type. Using the example of laser deposition from solutions of Co Ni Fe Zn and Ag salts with homo- and heterophase dielectrics the sensory and catalytic properties of the deposits are compared by impedance spectroscopy and voltammetry. Conclusion: It has been shown that heterophase precipitation significantly enhances the catalysis response. It is shown that the laser deposition reaction has an autocatalytic mechanism in a dynamic mode. The results of autocatalysis can be used in a stationary mode to create a microbiosensor for glucose as well as to create a technology for laser refining rare metals and hydrogen energy in a dynamic mode.
Synthesis and Anti TB Screening of α-Acyloxy Carboxamides via Passerini MCRs Prompted by GaCl3 and PEG-400 Media
Aims: The Isocyanides based Multi-component reactions (IMCRs) and Passerini reactions were performed by using GaCl3 and PEG-400 media to generate a library of new scaffolds. Background: The Isocyanides Multi-component reactions (IMCRs) have proven their importance due to their major advantages in synthetic and medicinal areas. Among various IMCRs Passerini stands for their pertinency in the novel adducts articulation and generates an amide functionality which shows unbeatable efficiency towards the generation of lead scaffolds. In the research fields PEG is acting as a versatile greener solvent due to its beneficial economic advantages. In general chiral-based separation is always a headache for the chemist and researchers tend to generate routes with major products such as single isomers. Most MCRs studied with metal-based synthesis and rather use Au or Pt-based catalyst Gallium that has been widely explored in chiral Lewis acid catalysis organo-catalysis or cooperative catalysis to generate a library of compounds with high stereoselectivity with mild reaction conditions. Objective: To find diverse scaffolds in the field of organic chemistry using easily accessible metal catalysts. Methods: In this article Enantiomerically pure 2-(((1H-benzo[d][123]triazol-1-yl)methyl)amino)-2-oxo-1-substitutedphenylethyl pyrazine-2-carboxylate (4a-4j) produced through a three-component passerine coupling reaction under GaCl3 as a Lewis acid-promoted conditions with diastereoseletivity ranging from moderate to good. Results: The designed approach exhibited an in situ single-step-economical path to enantiomerically pure α-acyloxy carboxamides with pyrazine and 1H-benzo[d][123]triazole fragments employing the greener way of media through “PEG-400”. In an anti-TB screening against H37Rv the withdrawing groups showed excellent activity compared to the donating groups. Conclusion: It was expected that the Lewis acid-PEG pairs could serve as the best catalytic transformations in eco-friendly ways and enrich the pure enantiomer of the adduct. On the medicinal side the isolated library of compounds was screened for their biological activity against “Mycobacterium Tuberculosis H37Rv” and 4f featuring “4-F” as a substituent was found to be most active (MIC: 12.5 μg/mL).
Green Synthesis of Au-Ni Bimetallic Nanoparticles using Aqueous Extract of Coccinia grandis (L.) Voigt and their Catalytic Activity in Oxidation of Alcohols
Background: In recent years bimetallic nanoparticles have gained remarkable attention due to their excellent physical and chemical properties. Especially bimetallic nanoparticles are found to be highly efficient as catalysts in many important organic transformations. Objective: The objective of the present work involves green synthesis of Au-Ni bimetallic nanoparticles using plant extract as the bio-reductant and to evaluate their catalytic efficiency in oxidation of alcohols. Methods: The experiment involves a simple and eco-friendly protocol for synthesis of Au-Ni bimetallic as well as their corresponding monometallic nanoparticles that involves the use of aqueous fruit seed extract of Coccinia grandis(L.) Voigt as the bio-reductant and tannic acid as the bio-stabilizer. The synthesized nanoparticles were characterized by using XRD TEM FTIR TGA etc. and their catalytic activity was evaluated for oxidation of alcohols. Results: The synthesized bimetallic nanoparticles have shown excellent catalytic activity towards aqueous phase oxidation of alcohols to aldehydes under ambient reaction conditions. Furthermore the results have revealed better effective performance of the bimetallic nanoparticles over the corresponding monometallic nanoparticles of gold and nickel establishing the synergic influence of the two metals. Another attractive feature of this work is that the Au-Ni bimetallic nanoparticles could be recycled and reused up to four catalytic cycles without any significant decline in product yield. Conclusion: The green synthesized bimetallic Au-Ni nanoparticles have shown excellent catalytic activity toward the oxidation of alcohols in aqueous media under ambient reaction conditions. In addition the nanoparticles are found to be successfully recyclable upto four catalytic cycles.
Manganese-Iron Mixed Oxides of Spinel Structure as Soot Combustion Catalysts
Background: An abatement of emission of particulate matter (mainly soot) is a challenge for the scientific community. An active and cheap catalytic system for soot combustion can help solve this problem. Objective: The aim of this study was to investigate the influence of the composition of a series of Mn3-xFexO4 (x = 0 - 3) oxides of spinel structure on their catalytic properties in soot combustion. Methods: Samples were synthesized by coprecipitation followed by a consecutive thermal treatment. Their structure was verified by X-ray diffraction and Raman spectroscopy. The obtained catalysts were tested in model soot oxidation (Printex U) in both tight and loose contact modes. Results: It was found that different mechanisms of soot combustion occurred dependently on a chosen contact mode. Conclusion: It was confirmed that in the case of tight contact (TC) a coexistence of divalent manganese and iron species was decisive for the catalytic activity whereas a presence of trivalent manganese centers was crucial in the case of loose contact (LC). Mn1.2Fe1.8O4 was found to be the most active catalyst.
Validation of Inhibitory Activity of Thiazolidine-4-carboxylic Acid Derivatives against Novel Influenza Neuraminidase Enzyme
Background: Neuraminidase enzymes are a large family found in a range of organisms. The best-known neuraminidase is viral neuraminidase a drug target for the prevention of the spread of influenza infection. The viral neuraminidases are frequently used as antigenic determinants found on the surface of the influenza virus. Objective: Thiazolidine derivatives have been synthesized and explored previously and further compounds have been designed on the basis of leading compounds. This research aimed to validate those previously synthesized compounds and a new series of compounds. Methods: A series of 28 compounds of thiazolidine-4-carboxylic acid derivatives were studied and evaluated for their ability to inhibit the neuraminidase (NA) of the influenza A virus. Twenty-eight compounds were differentiated into a training set of 21 compounds and a test set of 07 compounds. Results: The validated compounds demonstrated moderate inhibitory activity against influenza A neuraminidase. The most potent compound was acetaminophen mercapturate (C13H16N2O5S) (MW: 312.34). S-(5-acetamido-2-hydroxyphenyl)-N-acetyl-L-cysteine is an S-substituted N-acetyl-Lcysteine in which the S-substituent is specified as 5-acetamido-2-hydroxyphenyl. It acts as a drug metabolite a human urinary metabolite and a rat metabolite. It is a member of acetamides an organic sulphide a member of phenols and an S-substituted N-acetyl-L-cysteine. It derives from “paracetamol”. Conclusion: Validation of inhibitory activity of thiazolidine-4-carboxylic acid derivatives as novel influenza NA shows drug discovery of a more potent and reliable drug for the influenza virus.
The Co-catalyst Effects of Mn(II), Zn(II), and Cr(III) Chlorides on Acidic Ionic Liquid Catalyzed Synthesis of Value-added Products from Cellulose in Aqueous Ethanol
Background: Catalytic depolymerization and processing of cellulose can be used to produce value-added renewable feedstock chemicals. Objective: This study aimed to develop an acidic ionic liquid-metal ion chloride catalyst system-based single-reactor method for processing cellulose into value-added products. Methods: The effect of metal chlorides as co-catalysts on 1-(1-propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyzed degradation of cellulose in 40% (v/v) aq. ethanol was studied by measuring levulinic acid ethyl levulinate and 5-hydroxymethylfurfural yields. Results: In experiments with Mn(II) and Zn(II) chloride co-catalysts at 160 and 170°C for 12 h the initial yields of ethyl levulinate and 5-hydroxymethylfurfural improved from ~ 7% to ~ 12-15% due to co-catalytic effects. The highest enhancements in ethyl levulinate yields were observed with CrCl3 where the yield increased from 6 to 27% with the addition of a 10 mol% co-catalyst. Conclusion: All three transition metal chlorides studied caused improvements in yields of secondary products ethyl levulinate and 5-hydroxymethylfurfural in acidic ionic liquid catalyzed degradation of cellulose in aqueous ethanol. The most significant enhancements in ethyl levulinate yields were observed with CrCl3 as a co-catalyst.
Photocatalytic Multi-Component Reactions: An Emerging Avenue
In recent years photocatalytic multi-component reactions have emerged as a cuttingedge innovation in the field of organic synthesis. These reactions allow the simultaneous transformation of multiple reactants which not only saves time and resources but also provides access to a diverse range of complex molecules. The use of photocatalysts in these reactions provides several advantages including mild reaction conditions high selectivity and high functional group tolerance. Moreover the integration of renewable energy sources such as visible light as a driving force for these reactions further adds to their sustainability. This innovation has opened up new avenues for the synthesis of complex molecules and holds great promise for the development of sustainable and efficient chemical processes. This review gives a broad understanding of photocatalyzed multi- component reaction protocols developed with wide applications in synthetic organic chemistry. These green efficient and straightforward reactions utilize recyclable photocatalyst solvent-free or catalyst-free conditions for the synthesis of compounds with biological significance in a costeffective fashion. They are easily purified due to the minimum or no by-product formation. The review is divided into sections based on the type of photocatalysts involved and covers literature up to 2022.
Asymmetric Synthesis of Spirooxindole Lactones by Ammonium-tethered Chiral Organocatalysts catalyzed Michael Addition/Cyclization of 3- hydroxyoxindoles with α,β-unsaturated Aldehydes
The ammonium-tethered pyrrolidine-based organocatalyst catalyzed asymmetric Michael addition/cyclization reaction of αβ-unsaturated aldehydes with 3-hydroxyoxindole in aqueous media was developed giving the spirooxidole lactones in high yields with high enantioselectivities. Background: The asymmetric Michael addition/cyclization reaction of 3-hydroxyoxindoles with αβ- unsaturated aldehydes is an important method for the synthesis of chiral spirooxindole derivatives which are found in a wide range of biologically active natural products and pharmaceutical agents. Objective: Organocatalyzed asymmetric Michael addition/cyclization reactions are one of the most powerful and effective approaches for the construction of complex molecules from relatively simple starting materials. However a major problem associated with these organocatalytic system is that high catalyst loading and organic solvents are required. In the present work our objective was to develop a water-compatible organocatalyst that aimed at lowering catalyst loading and being active in an aqueous system. Methods: In a typical experiment To a solution of catalyst 2a (0.008 mmol) and PhCO2H (0.096 mmol) in 0.5 mL of a mixture solvent iPrOH/H2O (1:3) was added αβ-unsaturated aldehyde (0.4 mmol) and 3-hydroxyoxindole (0.8 mmol). The reaction mixture was proceeded at room temperature for 16 hours and then was extracted with 10 mL dichloromethane to give the cyclized hemiacetal which was subjected to the direct oxidation with pyridinium chlorochromate (PCC 1.2 mmol) for 16 hours to give the desired spirooxindole lactones. Results: The reactions successfully gave spirooxindole lactones in high to excellent yields (81-95%) with moderate to excellent enantioselectivities (up to 99% ee). However the diastereoselectivities were poor ranging from 1:1.1 to 1:2.3. Conclusion: The asymmetric Michael addition/cyclization reaction of αβ-unsaturated aldehydes with 3-hydroxyoxindole using ammonium-tethered pyrrolidine-based organocatalyst has been developed. The reaction was performed in aqueous media with low catalyst loading (2 mol%) and provided the spirooxidole lactones in high yields (81-95%) with high enantioselectivities (ee: up to 99%).
Application of Photo-inactive Ru(edta) Complexes in Photocatalytic Small Molecules Transformation over Semiconductor Surface - A Perspective
Photocatalytic transformation of small substrate molecules to useful products through an environmentally benign and economically viable pathway is a challenging area of research of continual importance. This review focuses on our perception of the application of ruthenium(III) complexes comprising ‘edta’ ligand (edta4- = ethylenediaminetetraacetate) as a ‘redox mediator’ or ‘relay’ in photocatalytic electron transfer reaction pertaining to the conversion of small substrate molecules viz. hydrazine to ammonia bicarbonate to formate dioxygen to hydrogen peroxide. In this article the prospect of [RuIII(edta)(H2O)]- and [RuIII(edta)(pz)]- to act as ‘redox mediator’ or ‘molecular catalysts’ in photocatalytic transformations of aforesaid small molecules are assessed systematically.
One Pot Synthesis of Oximes from Carbonyl Compounds Catalysed by Vanadium(V) Complex
Background: An eco-friendly catalyst was synthesized in good yield and characterized by various physicochemical techniques. The catalytic performance of the environmentally benign complex was investigated via slurry synthesis of oximes. The catalytic studies were successfully carried out using a simple protocol. The fascinating advantage of this protocol is cost effectiveness simple work up good yield short reactions time and milder reaction conditions. Methods: The complex was prepared by reaction of vanadium pentoxide with hydrazone ligand in 1:1 molar ratios and to this reaction mixture potassium carbonate (0.14 g 1 mmol) was added and ground till fine yellow colour powder appeared. Oximations were carried out by reacting the substrates 15 % H2O2 ammonia and vanadium(V) complex. The reaction was taken in a mortar and ground till a fine powder appeared. After completion of the reaction the crude product was extracted using dichloromethane/ water in 1:2 v/v evaporated and dried under vacuum. Results: We synthesized different varieties of oximes using our newly synthesized complex as a catalyst. The products were characterized by 1H NMR and 13C NMR spectroscopy. The completion of the reaction was monitored by checking the complete disappearance of the aldehyde proton and the appearance of oxime protons. We also grew some single crystals of the products to provide further supporting evidences about the formation of products. Conclusion: Oximation of various carbonyl compounds was prepared quantitatively under the slurry condition using {[K(H-2O)3][V(O)2L]}2 as a catalyst. The catalytic reactions can be carried out under mild conditions with ease of scalability and straightforward work-up procedure which makes the present protocols greener and better alternative methods for the synthesis of oximes.
Recent Advances in Direct Pyridine C-H Activation Strategies
Background: Pyridine is one of the most ubiquitous hetero-aromatic moieties in pharmaceutical chemistry and it has enormous importance in a plethora of fields. From a synthetic chemistry standpoint pyridine moiety has been used as a directing group in C-H activation strategies to functionalize various rings. However this unique feature to participate as a directing group hinders developing methodologies to carry out C-H activation on the pyridine ring itself. One of the simplest solutions is to block the activity of ring nitrogen at the cost of two extra steps. Here in this review along with the blocking we will briefly mention some interesting ways to get around this problem and the remaining challenges ahead. Objective: The coordinating ability of pyridine N poses a big challenge toward C-H functionalization on the pyridine ring. This review summarizes some of the recent methods towards this challenge. Methods: Some key ideas towards that goal have been described. Here the C-H activation strategies are categorised as follows: (1) Pyridine N-oxide mediated C-H activation (2) Dimerization of C-H activation of pyridine (3) Direct Pyridine C2-H activation (4) Direct Pyridine C3-H activation and (5) Direct Pyridine C4-H activation. Results: Several methods have been highlighted that can be utilised to prepare C-H functionalized products with regiospecificity that subsequently may be manipulated into interesting products which are difficult to attain easily. Conclusion: This review explores various new direct C-H activation methods on pyridine which attempts to fill the void of traditional synthetic protocols in regard to regioselective pyridine functionalization. This review also explores the limitations of current methodologies which must be wiped off to attain a mature state in need of the pharmaceutical industry.
Studying Different Thermodynamic Properties of Binary Liquid Mixture of Ethyl Acetate with 1-Alkanols at 303.15K
Experimental values of ultrasonic velocity (u) density (ρ) and viscosity (η) for the binary mixtures of ethyl acetate with 1-alkanols have been measured at 303.15 K over the entire mole fraction range. Using these data the excess isentropic compressibility (βEs) excess intermolecular free length (LEf) excess molar volume (VEm) excess free volume (VEf) and excess available volume (VEa) have been calculated. These parameters were used to study the nature and extent of intermolecular interaction between component molecules present in the binary mixtures. Excess values of isentropic compressibility intermolecular free length molar volume free volume and available volume were plotted against the mole fraction of ethyl acetate over the whole composition range. From the properties of these excess parameters the nature and strength of the interactions in these binary systems are discussed.
Simultaneous Adsorptive/photocatalytic Removal of Organic Dyes and Hexavalent Chromium in Single and Binary Component Systems by Manganese Ferrite Nanoparticles
Background: As a major source of pollutant the effluents of dye based industries are mostly associated with several toxic heavy metals. Limited efforts have been made on simultaneous removal of both dyes and heavy metals from these effluents through adsorption/ photocatalysis processes. Spinel ferrites with narrow band gap and high stability are suitable for further exploitation in this regard. Objective: Synthesis and characterisation of manganese ferrite nanoparticle and to assess its efficiency towards removal of organic dyes and hexavalent chromium in single and binary component systems are the objectives of this study. Methods: Manganese ferrite nanoparticle (MF NPs) prepared by coprecipitation was characterised systematically by X-ray diffraction scanning electron microscopy transmission electron microscopy UV-Visible diffuse reflectance and magnetic measurement. Adsorptive and photocatalytic performances of the material under visible light were evaluated using aqueous solutions of different dyes and Cr(VI). Results: Characterisation by various techniques revealed the formation of cubic MF nanoparticles with narrow band gap (1.78 eV) and moderate saturation magnetization (38.5 emu/g). In comparison the anionic dyes and Cr(VI) were better adsorbed on MF while photoactivity was more pronounced in the case of cationic dye. Conclusion: MF NPs displayed potential for photo-degradation/reduction of different dyes and Cr(VI) individually or simultaneously under visible light. The catalyst can be recovered magnetically from the reaction mixture for recycling and further use.
Recent Trends and Prospects in the Iron-catalyzed Amination Reactions
Iron-catalyzed C–H amination reactions have emerged as a potent tool in synthetic organic chemistry in recent years. These reactions are eco-friendly highly catalytic efficient and show good functional group tolerance. The organonitrogen products of the reaction have found wide applications in agricultural chemistry medicinal chemistry industrial chemistry and natural product synthesis. This review focuses on the recent progress in iron-catalyzed C–H amination reactions and covers literature from 2019-2021.
Alumina Supported Nickel-iron-ruthenium based Catalyst for Dry Reforming of Methane
Introduction: Alumina-supported nickel-iron-ruthenium-based catalyst with a high surface area (200 m2 g-1) was synthesized via an impregnation method and tested for dry reforming of methane. Methods: The prepared catalyst was characterized by different analytical techniques such as Xray diffraction X-ray fluorescence N2 sorption environmental scanning electron microscopy and X-ray photoelectron spectroscopy (XPS). Result: The results revealed that the catalyst contains 2.5 wt.% Ni 2 wt.% Fe and 1.8 wt.% Ru. Conclusion: The catalytic tests showed that the prepared sample exhibits remarkable catalytic activity towards methane dry reforming with high conversion of methane and carbon dioxide reaching up to 92% and 89% respectively at 800°C.
Recent Advances in Palladium-catalyzed Borylation
The synthesis of organoboron compounds was accomplished using borylation catalyzed by palladium. This reaction is ubiquitous due to its widespread utility in coupling reactions and allied applications in synthesis. The attraction of borylation in organic synthesis has been attributed to moderate conditions associated with the reactions and tolerance to different types of functional groups. Their applications spread across pharmaceutical medical agricultural and other fields. This review summarizes the recent advances in palladium-catalyzed borylation halides and covers literature from (2012-2021).
Wet Air Oxidation of Phenol on Oxides of Fe(III), Mn(IV), Ti(IV) and Goethite
Background: Phenol and its derivatives exist in water bodies due to the discharge of polluted wastewater from industrial agricultural and domestic activities into water bodies. Various industries like pharmaceutical petrochemical and coal processing industries discharge phenolic compounds into water bodies. Phenol and substituted phenols are quite toxic to humans. Objective: Oxidative destruction of phenol in water was carried out at ambient temperature by using laboratory-synthesized goethite and commercial Fe2O3 TiO2 and MnO2 as catalysts in the presence and the absence ofH2O2. Methods: The reactions were carried out in a batch reactor in 100 mL conical flasks. After mixing the reactants (Phenol and H2O2) and the catalyst in appropriate amounts the flasks were capped and the contents were agitated in a water bath shaker (NSW India) at a constant temperature of 300 K for a predetermined time interval. Results: The results have been characterized in terms of percentage destruction of the Phenol. The catalyst Goethite was able to bring about 15.8 to 23.5% destruction as the reactant-H2O2 mole ratio was increased from 1:1 to 1:20 with a fixed catalyst load of 0.2 gL-1. The total conversion of phenol increases smoothly with an increase in the reaction time from 60 to 300 min in all cases except Fe2O3 in which case the reaction does not advance after 60 min. Interestingly the catalyst MnO2 brings about 94.4 % oxidative conversion of phenol with the same loading in the absence of H2O2 i.e. in wet air oxidation. It is also found that a 1:1 mixture of MnO2 + TiO2 gives 100 % conversion for a catalyst load of ≥ 6 gL-1 in the absence of H2O2. Conclusion: It is found that phenol could be completely oxidized to harmless end products at room temperature. For this purpose MnO2 has been found to be the most active catalyst among the ones tested whether H2O2 is present or not in the reaction mixture. The three oxides Fe2O3 goethite and TiO2 can perform better only in the presence of H2O2.