Synthesis Chemistry Research Articles

Methide Affinity Scale: Key Thermodynamic Data Underpinning Catalysis, Organic Synthesis, and Organometallic and Polymer Chemistry.

Methide transfer reactions play important roles in many areas of chemistry, including the Grignard reaction, in the transmetalation steps of metal-catalyzed cross-coupling reactions, and in the generation of cationic metal polymerization catalysts. Methide affinities (MAs) are the key thermodynamic quantity that underpin such reactions, and yet comprehensive methide affinity scales are poorly developed. Here, B3LYP-D3BJ/def2-TZVP calculations are used to calculate the energy changes (MAs) for cations (MeZ → Z+ + Me-), neutrals (MeY- → Y + Me-), and anions (MeX2- → X- + Me-) derived from permethyl species of all group s and p elements. The MAs range from 2525.8 for the singlet cation F+ to -820.4 kJ/mol for the tetramethylborate anion, Me4B-. The cations show the clearest trends: the MAs in all cases decrease going down the group, while moving across a period, the MAs increase from group 1 to group 2 and then decrease for group 3, remaining about the same or with a modest increase moving to group 4, and then continue to increase across a period to a maximum for the halogens (group 17). The anions and dianions are sensitive to hypervalency; those elements that cannot expand the octet have very unfavorable MAs (e.g., MA of Me4C requires the formation of Me5C- and of Me4B- requires the formation of Me5B2-). To address whether the anion MeY- and dianion MeZ2- are stable, the vertical detachment energies of the anions and dianions were calculated. All of the anions are thermodynamically stable with respect to electron loss, except for Me4N-, while the dianions are all thermodynamically unstable with respect to electron loss. The kinetic stability of the dianions with respect to methide and electron loss was also evaluated for the lowest MAs. The only dianions that might be kinetically stable and observable in the gas phase are Me4Ca2-, Me4Sr2-, and Me4Ba2-. The dianion CF3CaF32- is predicted to be both thermodynamically and kinetically stable in the gas phase.

Palladium N-Heterocyclic Carbene-Catalyzed Aminations: An Outline.

Amination reactions play a pivotal role in synthetic organic chemistry, facilitating the generation of nitrogen-containing scaffolds with broad applications in drug synthesis, material production, polymer formation, and the generation of amino acids and peptides. Amination offers the potential to fine tune the properties of natural products and produce functional materials for various applications. Palladium N-heterocyclic carbene (Pd-NHC) emerges as an innovative and highly effective catalyst in this context. Under favorable reaction conditions, this robust and simple catalyst efficiently facilitates the synthesis of a diverse range of compounds with varying complexity and utility. Pd-NHC complexes exhibit significant σ-electron donating potential, enhancing the ease of the oxidative addition process in their mechanistic pathway. Their steric topography further contributes to a rapid reductive elimination. These complexes demonstrate remarkable stability, a result of the strong Pd-ligand bond. The wide variety of Pd-NHC complexes has proven highly efficient in catalyzing reactions across a spectrum of complexities, from simple to intricate. The domain of aminations catalyzed by Pd-NHC has undergone significant diversification, presenting new opportunities, particularly in the realms of material chemistry and natural product synthesis. This review outlines the advancements in Pd-NHC-catalyzed amination reactions, covering literature up to date.

A critical analysis of extracts of okra seeds and amla offering green chemistry for synthesis of zinc oxide nanoparticles and their promising role in reducing crude oil viscosity

To produce zinc oxide (ZnO) nanoparticles, aqueous solution growth offers cost and energy advantages over gas phase methods making the process green, but the quality of the ZnO nanoparticles could be compromised. It is often exaggerated that plant extracts can make the solution growth process even more ‘green’, but its overall impact requires careful evaluation. In this study, the effectiveness of plant extracts obtained from okra seeds and amla and their impact on ZnO nanoparticle production are investigated. Results showed that certain chemicals like phenolic compounds from amla can exhibit significant antioxidant activity. Extraction in water at room temperature is advantageous for the green synthesis, but may require greater amount of plant part or longer extraction time. Characterization techniques including FT-IR spectroscopy, UV–vis spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) are employed. There are possibilities of some impurity caused by remnants of precursor for ZnO, indicating requirement for additional purification stages. SEM analysis reveals distinct morphologies influenced by plant extracts, with particle sizes ranging from sub-100 nm to several microns. Elemental composition of synthesized ZnO are consistent with that of commercial ones. Apart from synthesizing ZnO nanoparticles, their impact on the viscosity of Arab Medium Crude Oil is also investigated. Dispersion of the ZnO particles in the oil reveals up to 70% reduction in viscosity.

Exploring acylselenourea diselenides: Synthesis, spectroscopy, and structural characterization of phenyl-substituted N,N'-diselanediyl

Acylselenourea diselenides, with the formula [RC(O)NC(Se)NR2]2, are underexplored organoselenated compounds with potential applications in medicinal chemistry, coordination, and organic synthesis. This article presents a comprehensive study on the synthesis, spectroscopy, and structural characterization of the novel diselenide N,N'-diselanediyl-bis-((diphenylamino)methanylylidene)-dibenzamide, i.e., R = Phenyl. The compound was synthesized by a one-pot bimolecular oxidation between the tautomeric forms of the selenourea intermediate PhC(O)NHC(Se)N(Ph)2. The total yield of the reaction was moderate (40 %), with losses attributed to the formation of amorphous red selenium. Spectroscopic analysis, including FT-IR, 1H NMR, and 13C NMR, confirmed the molecular identity of the compound. The crystal structure of diselenide was determined by single-crystal X-ray diffraction analysis, which revealed the formation of a centrosymmetric dimer through a bidirectional hydrogen bond of the C=O···H-Ph type. Hirshfeld surface (HS) analysis and topological study of electron density (ρ) provided detailed information on the strength of the intermolecular and intramolecular interactions in the crystal structure.

Visible Light-Enhanced [3 + 2] Cycloaddition of N,N-Disubstituted Hydrazines with Organo-Cyanamides: Access to Polysubstituted 1,2,4-Triazol-3-amines.

Visible light-enhanced [3 + 2] cycloaddition of N,N-disubstituted hydrazines with N-cyano-N-aryl-p-toluenesulfonamides is an efficient reaction pathway to polysubstituted 1,2,4-triazol-3-amines. The reaction is performed under mild conditions without the addition of any transition metals. This strategy involves a C(sp3)-H bond activation, a cyano cycloaddition, and the formation of two new C═N bonds. The protocol shows the advantages of good functional group tolerance and broad substrate scope. The late-stage modification experiments provide practical applications in the field of organic synthesis and medicinal chemistry.

Assessing sustainability and green chemistry in synthesis of a Vanillin-based vitrimer at scale: Enabling sustainable manufacturing of recyclable carbon fiber composites

Sustainable manufacturing of carbon fibre (CFs) reinforced polymer (CFRP) composites featured technically by low-cost and rapid manufacturing techniques, use of renewable materials, and non-destructive recycling process. By developing an inherently recyclable thermoset, this research bridges between these three components of sustainable manufacturing by focusing on a fast cured vanillin-based Schiff base polyimide network in all-solid state. In this study, a multifunctional vanillin-based monomer was synthesised at scale in water which can be cured using a diamine without requiring any organic solvent. A CFRP was fabricated using this newly developed Schiff base polymer using compression moulding technique, and its mechanical and thermal/fire performance were compared to a CFRP made of a commercially available automotive grade epoxy resin. The resulting Schiff base CFRP composite demonstrated exceptional fire retardancy, complemented by remarkable tensile strength and modulus values of 427 MPa and 45 GPa, respectively. These characteristics meet the criteria for a broad spectrum of high-performance applications. In contrast to conventional CF reclaiming processes, a novel and efficient chemical recycling approach was introduced, enabling the delamination of CF layers containing the Schiff base network without requiring the separation and purification of the polymer matrix. This approach facilitates the low-cost remanufacturing of new CFRP composites with mechanical performance comparable to the original composite. Finally, green chemistry matrices as well as simplified life cycle assessment (LCA)-like approaches, including the EcoScale and GREEN MOTION rates, were employed to evaluate the efficiency and environmental impact of the CFRP manufacturing process.

Continuous flow synthesis of metal nanowires: protocols, engineering aspects of scale-up and applications.

This review comprehensively covers the translation from batch to continuous flow synthesis of metal nanowires (i.e., silver, copper, gold, and platinum nanowires) and their diverse applications across various sectors. Metal nanowires have attracted significant attention owing to their versatility and feasibility for large-scale synthesis. The efficacy of flow chemistry in nanomaterial synthesis has been extensively demonstrated over the past few decades. Continuous flow synthesis offers scalability, high throughput screening, and robust and reproducible synthesis procedures, making it a promising technology. Silver nanowires, widely used in flexible electronics, transparent conductive films, and sensors, have benefited from advancements in continuous flow synthesis aimed at achieving high aspect ratios and uniform diameters, though challenges in preventing agglomeration during large-scale production remain. Copper nanowires, considered as a cost-effective alternative to silver nanowires for conductive materials, have benefited from continuous flow synthesis methods that minimize oxidation and enhance stability, yet scaling up these processes requires precise control of reducing environments and copper ion concentration. A critical evaluation of various metal nanowire ink formulations is conducted, aiming to identify formulations that exhibit superior properties with lower metal solid content. This study delves into the intricacies of continuous flow synthesis methods for metal nanowires, emphasizing the exploration of engineering considerations essential for the design of continuous flow reactors. Furthermore, challenges associated with large-scale synthesis are addressed, highlighting the process-related issues.

Revisiting the phosphonium salt chemistry for P-doped carbon synthesis: toward high phosphorus contents and beyond the phosphate environment.

The introduction of phosphorus and nitrogen atoms in carbo-catalysts is a common way to tune the electronic density, and thereby the reactivity, of the material, as well as to introduce surface reactive sites. Numerous environments are reported for the N atoms, but the P-doping chemistry is less explored and focuses on surface POx groups. A one-step synthesis of P/N-doped carbonaceous materials is presented here, using affordable and industrially available urea and tetrakis(hydroxymethyl)phosphonium chloride (THPC) as the N and P sources, respectively. In contrast to most of the synthetic pathways toward P-doped carbonaceous materials, the THPC precursor only displays P-C bonds along the carbon backbone. This resulted in unusual phosphorus environments for the materials obtained from direct thermal treatment of THPC-urea, presumably of type C-P-N according to 31P NMR and XPS. Alternatively, the in situ polymerization and calcination of the precursors were run in calcium chloride hydrate, used as a combined reaction medium and porogen agent. Following this salt-templating strategy led to particularly high phosphorus contents (up to 18 wt%), associated with porosities up to 600 m2 g-1. The so-formed P/N-doped porous materials were employed as metal-free catalysts for the mild oxidative dehydrogenation of N-heterocycles to N-heteroarenes at room temperature and in air.

Enhanced condensation kinetics in aqueous microdroplets driven by coupled surface reactions and gas-phase partitioning.

Although aqueous microdroplets have been shown to exhibit enhanced chemical reactivity compared to bulk solutions, mechanisms for these enhancements are not completely understood. Here we combine experimental measurements and kinetic modeling to show the strong coupling of interfacial reactions and gas/droplet partitioning in the condensation reaction of pyruvic acid (PA) to yield zymonic acid (ZA) in acidic aqueous microdroplets. Experimental analysis of single microdroplets reveals the substantial influence of evaporation of PA and partitioning of water on the size-, relative humidity (RH)- and temperature-dependent sigmoidal reaction kinetics for the condensation reaction. A newly developed diffusion-reaction-partitioning model is used to simulate the complex kinetics observed in the microdroplets. The model can quantitatively predict the size and compositional changes as the reaction proceeds under different environmental conditions, and provides insights into how microdroplet reactivity is controlled by coupled interfacial reactions and the gas-phase partitioning of PA and water. Importantly, the kinetic model best fits the data when an autocatalytic step is included in the mechanism, i.e. a reaction step where the product, ZA, catalyzes the interfacial condensation reaction. Overall, the dynamic nature of aqueous microdroplet chemistry and the coupling of interfacial chemistry with gas-phase partitioning are demonstrated. Furthermore, autocatalysis of small organic molecules at the air-water interface for aqueous microdroplets, shown here for the first time, has implications for several fields including prebiotic chemistry, atmospheric chemistry and chemical synthesis.

Development of novel transition metal-catalyzed synthetic approaches for the synthesis of a dihydrobenzofuran nucleus: a review.

The synthesis of dihydrobenzofuran scaffolds bears pivotal significance in the field of medicinal chemistry and organic synthesis. These heterocyclic scaffolds hold immense prospects owing to their significant pharmaceutical applications as they are extensively employed as essential precursors for constructing complex organic frameworks. Their versatility and importance make them an interesting subject of study for researchers in the scientific community. While exploring their synthesis, researchers have unveiled various novel and efficient pathways for assembling the dihydrobenzofuran core. In the wake of extensive data being continuously reported each year, we have outlined the recent updates (post 2020) on novel methodological accomplishments employing the efficient catalytic role of several transition metals to forge dihydrobenzofuran functionalities.

Cell-resistant wavelength-shifting molecular beacons made of L-DNA and a clickable L-configured uridine.

Wavelength-shifting molecular beacons were prepared from L-DNA. The clickable anchor for the two dyes, Cy3 and Cy5, was 2'-O-propargyl-L-uridine and was synthesized from L-ribose. Four clickable molecular beacons were prepared and double-modified with the azide dyes by a combination of click chemistry on a solid support for Cy3 during DNA synthesis and postsynthetic click chemistry for Cy5 in solution. Cy3 and Cy5 successfully formed a FRET pair in the beacons, and the closed form (red fluorescence) and the open form (green fluorescence) can be distinguished by the two-color fluorescence readout. Two molecular beacons were identified to show the greatest fluorescence contrast in temperature-dependent fluorescence measurements. The stability of the L-configured molecular beacons was demonstrated after several heating and cooling cycles as well as in the cell lysate. In comparison, D-configured molecular beacons showed a rapid decrease of fluorescence contrast in the cell lysate, which is caused by the opening of the beacons, probably due to degradation. This was confirmed in cell experiments using confocal microscopy. The L-configured molecular beacons are potential intracellular thermometers for future applications.

Recent developments in the synthesis and applications of terpyridine-based metal complexes: a systematic review.

Terpyridine-based metal complexes have emerged as versatile and indispensable building blocks in the realm of modern chemistry, offering a plethora of applications spanning from materials science to catalysis and beyond. This comprehensive review article delves into the multifaceted world of terpyridine complexes, presenting an overview of their synthesis, structural diversity, and coordination chemistry principles. Focusing on their diverse functionalities, we explore their pivotal roles in catalysis, supramolecular chemistry, luminescent materials, and nanoscience. Furthermore, we highlight the burgeoning applications of terpyridine complexes in sustainable energy technologies, biomimetic systems, and medicinal chemistry, underscoring their remarkable adaptability to address pressing challenges in these fields. By elucidating the pivotal role of terpyridine complexes as versatile building blocks, this review provides valuable insights into their current state-of-the-art applications and future potential, thus inspiring continued innovation and exploration in this exciting area of research.

Recent studies on the reaction of [X6O19]8− (X = Nb, Ta) polyanions under acidic conditions

This review focuses on the recent studies on the reaction of [X6O19]8− (X = Nb, Ta) under acidic conditions, highlighting the synthesis and structural chemistry of mixed-addendum niobotungstates/tantalotungstates and hetero-peroxo-PONb/Ta clusters.

An overview: dinuclear palladium complexes for organic synthesis

From materials science and polymer chemistry to organic synthesis and medicinal chemistry, cross-coupling has influenced many scientific fields.

Recent advances in the synthesis of N-heterocycles from α-amino acids mediated by iodine

The synthesis of N-heterocycles has received extensive attention from scientists considering their important role in organic synthesis, pharmaceuticals, and material chemistry. α-Amino acids (α-AAS), both natural and non-natural, are structurally...

Rapid and efficient mechanosynthesis of alkali and alkaline earth molybdates

Mechanochemistry provides a convenient and efficient route for synthesizing high purity alkali and alkaline earth heptamolybdates and trimolybdates in high yields.

M-Ge-Si thermolytic molecular precursors and models for germanium-doped transition metal sites on silica.

The synthesis, thermolysis, and surface organometallic chemistry of thermolytic molecular precursors based on a new germanosilicate ligand platform, -OGe[OSi(OtBu)3]3, is described. Use of this ligand is demonstrated with preparation of complexes containing the first-row transition metals Cr, Mn, and Fe. The thermolysis and grafting behavior of the synthesized complexes, Fe{OGe[OSi(OtBu)3]3}2 (FeGe), Mn{OGe[OSi(OtBu)3]3}2(THF)2 (MnGe) and Cr{OGe[OSi(OtBu)3]3}2(THF)2 (CrGe), was evaluated using a combination of thermogravimetric analysis; nuclear magnetic resonance (NMR), ultraviolet-visible (UV-Vis), and electron paramagnetic resonance (EPR) spectroscopies; and single-crystal X-ray diffraction (XRD). Grafting of the precursors onto SBA-15 mesoporous silica and subsequent calcination in air led to substantial changes in transition metal coordination environments and oxidation states, the implications of which are discussed in the context of low-coordinate and low oxidation state thermolytic molecular precursors.

Radical hydroboration for the synthesis of organoboron compounds.

Organoboron compounds demonstrate diverse applications in the fields of organic synthesis, materials science, and medicinal chemistry. Compared to the conventional hydroboration reaction, radical hydroboration serves as an alternative approach for the synthesis of organoborons via different mechanisms. In radical hydroboration, a boryl radical is initially generated from homolytic cleavage of a B-H or a B-B bond, which is then added to an unsaturated double bond to deliver a carbon radical. Subsequent hydrogen atom transfer or reduction of the carbon radical to form a carbanion followed by protonation gave the final product. Over the past few years, numerous efforts have been made for efficient synthesis of boryl radicals and the expansion of substrate scope of the radical hydroboration reaction. Here, we discuss the recent advancement of radical hydroboration and its associated mechanisms. Numerous radical hydroboration strategies employing N-heterocyclic carbene borane, bis(pinacolato)diboron and pinacolborane as the boron source were illustrated. Thermochemical, photochemical and electrochemical strategies for the generation of boryl radicals were also discussed in detail.

Professor (Dr) Sukh Dev: an iconic scientist with an innate sixth sense who radicalized natural product synthesis & organic chemistry.

Harry Kochat, J. S. Yadav, Vinod K. Singh and S. S. V. Ramasastry introduce the special Organic & Biomolecular Chemistry themed collection celebrating the 100th birthday of Professor Sukh Dev.

Photo-induced radical transformations of tosyl cyanide.

Tosyl cyanide is a commonly used reagent for cyanation and sulfonylation in organic synthesis and pharmaceutical chemistry. The photocatalytic transformations of tosyl cyanide are generally conducted under mild conditions. This minireview summarizes the recent progress of radical-involved transformations of tosyl cyanide via photo-induced cyanation or sulfonylcyanation.