Solventless Synthesis Research Articles

Efficient, Facile, and Green Synthesis of Ruthenium Carboxylate Complexes by Manual Grinding

Recently, scientists have been developing sustainable processes, and in this context, mechanochemistry is commonly associated with green chemistry for its ability to reduce waste generation from chemical reactions. The well-known acetate complex, diacetate bis(triphenylphosphine) ruthenium(II) [Ru(OAc)2(PPh3)2], is a versatile precursor for preparing active complexes for several catalytic reactions. This report presents an efficient and straightforward manual grinding protocol for the sustainable synthesis of ruthenium carboxylate complexes starting from the commercially available [RuCl2(PPh3)3] and metal carboxylates. This work represents a novel and preliminary investigation into carboxylate precursors’ alternative solventless synthesis route based on manual grinding. To our knowledge, this is the first time [Ru(OAc)2(PPh3)2] has been prepared via a mechanochemical procedure. The synthesis method has also been investigated for other alkali metal carboxylates and yields ranging from 30 to 80% were obtained. A comparison of sustainability and environmental impact between conventional solution synthesis and the grinding route has been carried out using the E-factor and Mass Productivity. While for the acetate complex E-factor and MP were only slightly better compared with the solvent method (3 vs. 4 for E-factor and ~6 vs. 5 for MP), for benzoate higher results were found (1 vs. ~4 for E-factor and 10 vs. 5 for MP).

Development of Alkylamine-Coordinate Self-Reducible Metal Complex for Tailor-Made and Solventless Synthesis of Inorganic Nanoparticle

Development of Alkylamine-Coordinate Self-Reducible Metal Complex for Tailor-Made and Solventless Synthesis of Inorganic Nanoparticle

Solventless Synthesis of Zinc Sulphide Nanoparticles from Zinc Bis(diethyldithiocarbamate) as a Single Source Precursor.

This study explores the synthesis of nanoparticles through the thermal decomposition of single-source precursors, a method gaining popularity due to its low cost, minimal environmental toxicity, rapidity, scalability, and the ability to form nanoparticles with few defects. Zinc ethyl carbamate was synthesized and characterized using 1HNMR and infrared spectroscopy. Its purity was confirmed through microelemental analysis and melting point determination. The melting point of the complex was determined to be 165 °C. The thermogravimetric analyses indicated a one-step decomposition of zinc ethyl carbamate with a decomposition onset of of 200 °C, yielding a stable ZnS residue. Further thermal decomposition led to the formation of wurtzite phase ZnS nanoparticles, as evidenced by XRD. SEM micrographs displayed mixed spherical, and cubic unevenly sized, polydispersed nanoparticles, while EDX revealed approximately a 1 : 1 Zn to S ratio. Estimated band gap from the Tauc's plot gave 3.93 eV and 3.42 eV for the nanoparticles synthesized at 300 and 400 °C respectively. The wide difference in the band gaps may be as a result of the larger particles observed at 400 °C and the deformations in the sample as observed in the SEM.

Synthesis of Peptides by Reactive Extrusion. Application to the Continuous and Solventless Preparation of Aspartame.

AbstractThe solventless synthesis of peptides from unactivated amino acids was optimized in a twin‐screw extruder (TSE). The general method enabled the preparation of dipeptides and tripeptides with no epimerization. This flow mechanochemistry approach was applied to the synthesis of aspartame, a synthetic dipeptide, prepared in a continuous mode on large scale and with high productivity.

Solvent-Free Aerobic Oxidative Cleavage of Methyl Oleate to Biobased Aldehydes over Mechanochemically Synthesized Supported AgAu Nanoparticles.

The performance of mechanochemically synthesized supported bimetallic AgAu nanoalloy catalysts was evaluated in the oxidative cleavage of methyl oleate, a commonly available unsaturated bio-derived raw material. An extensive screening of supports (SiO2 , C, ZrO2 , Al2 O3 ), metallic ratios (Ag : Au), reaction times, temperatures, and use of solvents was carried out. The performance was optimized towards productivity and selectivity for the primary cleavage products (aldehydes and oxoesters). The optimal conditions were achieved in the absence of solvent, using Ag8 Au92 /SiO2 as catalyst, at 80 °C, reaction time of 1 h, substrate to catalyst=555 and 10 bar of molecular oxygen. A strong support effect was observed: the selectivity to aldehydes was best with silica as support, and to esters was best using zirconia. This shows not only that mechanochemical preparation of bimetallic catalysts is a powerful tool to generate useful catalyst compositions, but also that a safe, green, solventless synthesis of bio-derived products can be achieved by aerobic oxidative cleavage.

Glycerol Carbonate Solventless Synthesis Using Ethylene Carbonate, Glycerol and a Tunisian Smectite Clay: Activity, Stability and Kinetic Studies

Biodiesel is nowadays added in 5–10% v/v to diesel, and its production involves the parallel creation of a vast glycerol amount as a by-product. Despite its many applications, there is a surplus of glycerol (Gly) that has boosted the search for new applications of this compound, now transformed into an industrial synthesis intermediate or platform chemical. Its transcarbonation is a type of reaction that occurs under mild conditions, using weak or moderate basic catalysts, and allows the parallel production of glycols of industrial interest with high selectivity, such as ethylene glycol. In this research, we have studied the activity of a Tunisian clay rich in inorganic carbonates that give it a weak basic character. The raw clay (RC) has been fully characterized by XRD, FTIR, SEM-EDS and nitrogen porosimetry. Subsequently, it has been employed as a catalyst to react glycerol (G) with ethylene carbonate (EC) to obtain glycerol carbonate (GC) and ethylene glycol (EG). The main operating variables and their effects on glycerol conversion and initial reaction rate were analyzed: catalyst concentration (2–6% w/w glycerol), reagent molar ratio (EC:G 1.5:1 to 3:1), and temperature (80–110 °C). Then, an appropriate kinetic model was selected from the results obtained under various reaction conditions, including the total deactivation of order 1 of the catalyst. The kinetic constant activation energy in this reaction using Tunisian smectite was found to be around 183.3 kJ·mol−1. In the second phase of the investigation, we explored the reuse of smectite using the kinetic model to appreciate the effect of cycle-to-cycle deactivation. It can be seen that the kinetic constant of the main reaction generally decreases with the number of cycles at low temperature and goes through a maximum at high operating temperature, while the deactivation constant increases with the number of catalytic cycles. The catalyst shows more stability, in general, at higher temperatures.

Fabrication of SiC-Type Films Using Low-Energy Plasma-Enhanced Chemical Vapor Deposition (PECVD) and Subsequent Pyrolysis

Silicon carbide (SiC) is a promising material for a variety of applications in the biomedical, aerospace, and energy industries. Solution-phase techniques have long been used to deposit precursor films prior to pyrolysis into SiC, but they tend to face difficulties with substrate compatibility and the use of toxic solvents. In this study, we introduce a solventless synthesis route for fabricating SiC-type films by depositing an organosilicon copolymer poly(vinylphenyldimethylsilane-co-divinylbenzene) (p(VPDMS-co-DVB)) film using low-energy plasma chemical vapor deposition (PECVD) followed by subsequent pyrolysis. The chemical structure of the film was systematically studied in situ during pyrolysis as a function of temperature using diffuse reflection infrared Fourier transform spectroscopy (DRIFTS). The majority of the functional groups were found to have disappeared by a temperature of 800 °C, with most of the mass loss occurring between 350 and 520 °C. Thermogravimetric analysis (TGA) was used to measure the loss of mass as the pyrolysis temperature was increased, and the observed pyrolysis rates were compared to estimates of such rates from the DRIFTS analysis. Our proposed synthesis route provides a scalable and solventless method of producing SiC-type ceramic films for such applications as high-temperature sensors and membranes.

Green synthesis of organogelators from renewable natural sources for cosmetic and pharmaceutical applications

Organogels are semi-solid systems in which a three-dimensional network, composed by the organgelator fibers, immobilizes an organic liquid phase by twisting around it. They find application in different industrial fields as “soft” materials; their mechanical and chemical properties, together with their rheological behavior, make them excellent candidates in cosmetic and pharmaceutical technologies.The synthesis of organo-gelling agents often suffers of long procedures, unfriendly solvents and reagents, and complex work up. In this research we focused on an ecofriendly solventless synthesis using renewable sources, as starting materials, under microwave activation (MW). Using a simple mixture of reagents in dry media, under acidic conditions, 1,3:2,4-dibenzylidene sorbitol (DBS), a low-molecular-weight gelator, and some derivatives were obtained in good yield in less than ten minutes. The obtained products showed good gelling properties.

Investigating the vapour phase synthesis of copper terephthalate metal organic framework thin films by atomic/molecular layer deposition.

Solventless synthesis and processing of Metal Organic Frameworks (MOFs) is critical to implement these materials in applied technologies. Vapour phase synthesis of MOF thin films is particularly suitable for such applications, but challenging compared to the conventional solution based methods. It is therefore compelling to advance and widen the vapour phase synthesis of MOF thin films. Crystalline copper terephthalate MOF thin films are grown in the vapour phase by means of atomic and molecular layer deposition (ALD/MLD) on different kinds of substrates. Expanding from the pioneering work, the formation of the 3D phase is clearly evidenced for the first time and the adaptability of the process to several kinds of substrates is revealed. A directional film growth is observed at the early stage of the ALD/MLD process leading to oriented MOF crystallites on a surface, when isotropical growth proceeds with the increasing number of ALD/MLD cycles. Notably, this study primarily demonstrates a heteroepitaxial growth achievable in the vapour phase by using DMOF-1 single crystals as the starting surface with a lattice matching topology. Such an approach offers an appealing pathway to develop MOF on MOF superlattice materials in the vapour phase.

Amidation by reactive extrusion for the synthesis of active pharmaceutical ingredients teriflunomide and moclobemide.

The solventless synthesis of an amide was performed in a twin-screw extruder in the presence of a coupling agent, providing a high yielding and productive method. The reaction conditions were optimized to prepare APIs, teriflunomide and moclobemide.

Nano TiCl4/γ-Al2O3: An efficient heterogeneous solid acid catalyst for rapid and solvent-less synthesis of azo dyes based on 2-naphthol at room temperature

A green heterogeneous solid acid was prepared as an extremely efficient catalyst, through the reaction of γ-alumina with titanium tetrachloride. Nano TiCl4/γ-Al2O3 was characterized by fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), Brunner–Emmet–Teller (BET) surface area analysis, X-ray fluorescence (XRF) and thermal gravimetric analysis (TGA). Nano TiCl4/γ-Al2O3 was used for the synthesis of aryl diazonium salts as the starting reactant and then, diazo coupling with 2-naphthol produced the azo dyes in a solvent-free medium at room temperature (25 °C). The work-up of the reaction is easy, and the catalyst is removed from the products by simple filtration.

Solvent-free synthesis of NiCo2S4 having the metallic nature.

Nickel-cobalt sulfide (NiCo2S4) is a prominent member of bimetallic transition metal sulfides. It is being widely used for a variety of applications such as electrode material, photocatalysis, and energy storage devices (like pseudo capacitors, supercapacitors, solar cells, and fuel cells) due to its better electronic conductivity, manageable morphology, and high capacitance. This work presents the one-step solventless synthesis of NiCo2S4 sheet-like nanostructures and then explores their metallic nature. Scanning electron microscopy (SEM) and transmission electron microscopic (TEM) analysis show the sheet-like grown morphology. Few nanorods are also seen. Except for a recent study (Xia et al. 2015) that shows metallic behavior, most of the reports show that NiCo2S4 is a semiconductor with claimed bandgap between 1.21 and 2.4eV. In this study, we observe from UV-Vis and diffuse reflectance spectroscopy (DRS) that NiCo2S4 has a specific band gap value between 2.02 and 2.17eV. However, IV characteristics in the temperature range of 300-400K show that NiCo2S4 is a metal with a positive temperature coefficient of resistance consistent with a recent report. Furthermore, we see the ohmic conduction mechanism. The Arrhenius plot is drawn, and the activation energy is calculated to be 3.45meV. The metallic nature is attributed to the coupling of two metal species (nickel and cobalt), which accounts for its superior conductivity and performance in a variety of essential applications.

Development of a Tailored Sol-Gel Immobilized Biocatalyst for Sustainable Synthesis of the Food Aroma Ester n-Amyl Caproate in Continuous Solventless System.

This study reports the synthesis of a hybrid sol-gel material, based on organically modified silanes (ORMOSILs) with epoxy functional groups, and its application in the stabilization of lipase type B from Candida antarctica (CalB) through sol-gel entrapment. The key immobilization parameters in the sol-gel entrapment of lipase using epoxysilanes were optimized by the design of numerous experiments, demonstrating that glycidoxypropyl-trimethoxysilane can allow the formation of a matrix with excellent properties in view of the biocatalytic esterifications catalyzed by this lipase, at an enzyme loading of 25 g/mol of silane. The characterization of the immobilized biocatalyst and the correlation of its catalytic efficiency with the morphological and physicochemical properties of the sol-gel matrix was accomplished through scanning electron microscopy (SEM), fluorescence microscopy (FM), as well as thermogravimetric and differential thermal analysis (TGA/DTA). The operational and thermal stability of lipase were increased as a result of immobilization, with the entrapped lipase retaining 99% activity after 10 successive reaction cycles in the batch solventless synthesis of n-amyl caproate. A possible correlation of optimal productivity and yield was attempted for this immobilized lipase via the continuous flow synthesis of n-amyl caproate in a solventless system. The robustness and excellent biocatalytic efficiency of the optimized biocatalyst provide a promising solution for the synthesis of food-grade flavor esters, even at larger scales.

Solvent-Less Synthesis of Hybrid Molecules of 3-Formylchromones Catalyzed by Boric Acid

Abstract: In our effort to develop hybrid molecules, we conceived the synthesis of hydrazones from 3-formylchromone and carboxylic acid hydrazides in presence of boric acid as a green catalyst.

Acid functionalized hydrochar as heterogeneous catalysts for solventless synthesis of biofuel precursors

Synthesis of biofuel precursors via the hydroxyalkylation alkylation reaction by using acid functionalized hydrochar catalysts.

Solventless synthesis of ZIF-L and ZIF-8 with hydraulic press and high temperature

In recent years, alternative methods to conventional synthesis of MOFs (metal-organic frameworks) have emerged due to the problematic use of solvents for both the environment and human health. Here we present the synthesis of ZIFs (zeolitic imidazolate frameworks) at high pressure by means of a hydraulic press provided with a heating mechanism. By the optimization of parameters such as temperature, time and the addition of promotor NH4NO3, a considerable increase in the reaction yield was achieved in products, neither washed nor activated, obtained since the first minute of reaction. Depending on the operation conditions, ZIF-L appeared as competing phase with ZIF-8. Upon transformation of ZIF-L into ZIF-8 in presence of ethanol, a reaction yield of 58.2% was achieved to highly crystalline ZIF-8 with a BET specific surface area of 947 m2/g. This green, fast, versatile and improved method suggests a possible way to future synthesis of other MOFs and the possibility of their industrial implementation.

Cu{SC(O)OiPr}]96: A Giant Self-Assembled Copper(I) Supramolecular Wheel Exhibiting Photoluminescence Tuning and Correlations with Dynamic Solvation and Solventless Synthesis.

The hierarchical self-organization of structurally complex high-nuclearity metal clusters with metallosupramolecular wheel architectures that are obtained from the self-assembly of smaller solvated cluster units is rare and unique. Here, we use the potentially heteroditopic monothiocarbonate ligand and demonstrate for the first time the synthesis and structure of a solvated non-cyclic hexadecanuclear cluster [Cu{SC(O)OiPr}]16·2THF (1) that can simultaneously desolvate and self-assemble in solution and subsequently form a giant metallaring, [Cu{SC(O)OiPr}]96 (2). We also demonstrate a luminescent precursor to cluster (2) can be achieved through a solventless and rapid mechanochemical synthesis. Cluster (2) is the highest nuclearity copper(I) wheel and the largest metal cluster containing a heterodichalcogen (O, S) ligand reported to date. Cluster (2) also exhibits solid-state luminescence with relatively long emission lifetimes at 4.1, 13.9 (μs). The synthetic strategy described here opens new research avenues by replacing solvent molecules in stable {Cu16} clusters with designed building units that can form new hybrid and multifunctional finite supramolecular materials. This finding may lead to the development of novel high-nuclearity materials self-assembled in a facile manner with tunable optical properties.

Development of Low-Viscosity and High-Performance Biobased Monobenzoxazine from Tyrosol and Furfurylamine.

This work details the scalable and solventless synthesis of a potential fully biobased monobenzoxazine resin derived from tyrosol and furfurylamine. The structure of the monomer was studied by nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FTIR). The curing of the precursors was characterized by differential scanning calorimetry (DSC), rheological measurements, and thermogravimetric analysis (TGA). The properties of the resulting biobased polybenzoxazine were then determined by thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMA). A thermally stable resin was obtained with 5% and 10% weight-reduction-temperature (Td5 and Td10) values of 349 and 395 °C, respectively, and a char yield of 53%. Moreover, the low melting temperature, low viscosity, and excellent thermomechanical behavior make this fully biobased resin a promising candidate for coating applications.

Fesipmim]Cl as highly efficient and reusable catalyst for solventless synthesis of dihydropyridine derivatives through Hantzsch reaction

In the present investigation, magnetic ferrite nanoparticles (ferrite NPs) were synthesized and coated with silica (ferrite@SiO2NPs) by using the sol-gel method. After that, silica propylmethylimidazolium chloride ionic liquid [Sipmim]Cl was prepared and linked with the above-prepared ferrite@SiO2NPs to synthesize ferrite silica propylmethylimidazolium chloride [Fesipmim]Cl catalyst. The formation of [Fesipmim]Cl catalyst was confirmed by Fourier-transform infrared (FT-IR) spectroscopy analysis. X-ray diffraction (XRD) analysis confirmed the structure of ferrite NPs and ferrite@SiO2 NPs. Transmission electron microscopy (TEM) evidenced the successful formation of ferrite NPs and ferrite@SiO2 NPs. Scanning electron microscopy (SEM) results revealed the change in morphology of ferrite NPs, ferrite@SiO2NPs and [Fesipmim]Cl. The magnetic properties of [Fesipmim]Cl catalyst were measured by vibrating sample magnetometer (VSM). The efficiency of the [Fesipmim]Cl catalyst was checked by using it for the synthesis of different derivatives of dihydropyridine through Hantzsch reaction via a three-component coupling reaction of substituted benzaldehydes, ethyl/ methyl acetoacetate and ammonium acetate. The formation and structures of all the synthesized compounds were confirmed by FT-IR, 1HNMR, 13C NMR spectral analyses. The reusability of the catalyst [Fesipmim]Cl was checked up to seven cycles and found to have excellent activity up to five cycles.

Rapid ecosynthesis of TiO2@CuO@Chromite nanocatalyst for environmentally friendly applications: solventless cyanation of aldehydes and high efficient treatment of sewage waters

BackgroundDue to the large surface area of green-synthesized TiO2@CuO@Chromite nanocatalysts (NCs) and accumulations of bioactive phytochemicals on its surface, it was used for an efficient and safe synthesis of nitriles and also an environmentally friendly process of water treatment. For the first time, a rapid, economic, one-pot, solventless and safe protocol is presented for ecosynthesis of TiO2@CuO@Chromite nanocatalysts (NCs) to efficient, ligand-free and solventless synthesis of aromatic nitriles through the cyanation of aldehydes at room temperature. Furthermore, the eco-NCs were used as a potent adsorbent for physical and biological treatment of sewage waters collected around the natural and residential area of northern parts of the Soran city in Iraq at room temperature.ResultsThe structural elucidation of the NCs using the SEM (scanning electron microscopy), Cross-sectional EDS (electron dispersive spectroscopy), elemental mapping analysis, XRD (X-ray diffractions) and BET (Brunauer–Emmett–Teller) for detection of specific surface area of eco-NCs confirmed the formation of NCs with a large surface area. Application of green TiO2@CuO@Chromite NCs in solventless synthesis of aromatic nitriles shows high efficiency, time saving, economical aspect and ecofriendly and safe methodology. Also, the treatment process of sewage waters monitored using UV–Vis double beam spectrophotometer, optical microscopy and antibiogram tests demonstrated an efficient ability for the eco-NCs in physical and biological treatment of sewage samples.ConclusionsThe NCs employed in both ligand and solventless highly efficient and safe synthesis of aromatic nitriles through the cyanation of aldehydes at room temperature demonstrated the production of aryl nitriles in very good-to-excellent yields. This protocol indicated a green alternative to the existing methods since the reaction proceeds in solventless medium in the absence of any ligand and organic solvent with simple work-up procedure, low temperature, higher yield and shorter reaction time. Further, it was used in the physical and biological treatment of the real samples of sewage waters collected around the natural and residential area of northern parts of Iraq at room temperature, which shows a very good treatment ability in this process.