Clean Synthesis Research Articles

Clean synthesis of ZnCo2O4@ZnCo-LDHs yolk–shell nanospheres composed of ultra-thin nanosheets with enhanced electrocatalytic properties

ZnCo2O4@ZnCo-LDHs yolk–shell nanospheres are prepared by a clean approach via controlled hydrolysis of mixed metal glycolates. The structures exhibit good oxygen evolution reaction activity.

Visible-light-initiated one-pot clean synthesis of nitrone from nitrobenzene and benzyl alcohol over CdS photocatalyst

The controlled visible-light mediated conversion of nitroaromatics to versatile nitrogen-containing intermediates is of great significance but still remains a challenge. Herein, we report for the first time a facile visible-light-initiated one-pot strategy for clean and efficient synthesis of nitrone from nitrobenzene and benzyl alcohol. It integrates the controlled photocatalytic reduction of nitrobenzene to phenylhydroxylamine by photogenerated electrons with the selective photocatalytic oxidation of benzyl alcohol to benzaldehyde by photoinduced holes over a low-cost CdS photocatalyst with a suitable reduction capability, followed by spontaneous condensation of the as-formed hydroxylamine and aldehyde at ambient pressure and room temperature. Furthermore, by modulating cocatalyst and illumination time, for the conversion of the same reactants, the other two useful nitrogen-containing compounds, imine and secondary amine, were also successfully synthesized. The reaction mechanisms for flexible synthesis of the three target products are proposed.

Facile synthesis of Nd2Sn2O7-SnO2 nanostructures by novel and environment-friendly approach for the photodegradation and removal of organic pollutants in water

A simple and clean synthesis for Nd2Sn2O7-SnO2 nanocomposites as high-efficiency visible-light responsive photocatalyst is described applying extract of pineapple, for the first time. As novel and non-toxic biofuel, extract of pineapple, is employed to fabricate Nd2Sn2O7-SnO2 nanocomposites through an environment-friendly procedure. The findings denote that the applied biofuel can play a meaningful role as capping agent during preparation of Nd2Sn2O7-SnO2 nanocomposites. Depending on the applied dosage of pineapple extract as well as time for fabrication, the grain size, photocatalytic yield and morphology of Nd2Sn2O7-SnO2 structures changed. A suite of identification methods like XRD, TEM, EDS, DRS, BET and FESEM are utilized for investigation of the produced Nd2Sn2O7-SnO2 nanocomposites. Nd2Sn2O7-SnO2 structures are utilized as visible-light responsive photocatalyst to degrade the rhodamine B and eosin Y contaminants. The produced Nd2Sn2O7-SnO2 nanocomposites have been found to be very effective as visible-light responsive photocatalyst to degrade contaminants which may bring to environmental pollution.

Metal-Organic Framework MIL-101(Cr) as an Efficient Heterogeneous Catalyst for Clean Synthesis of Benzoazoles.

A metal–organic framework [MIL-101(Cr)] was used as an efficient heterogeneous catalyst in the synthesis of benzoazoles (benzimidazole, benzothiazole, and benzoxazole), and quantitative conversion of products were obtained under optimized reaction conditions. The catalyst could be simply extracted from the reaction mixture, providing an efficient and clean synthetic methodology for the synthesis of benzoazoles. The MIL-101(Cr) catalyst could be reused without a remarkable decrease in its catalytic efficiency.

Environment-friendly synthesis of diethyl carbonate via ethyl carbamate alcoholysis over cerium oxide catalyst

A series of cerium oxide catalysts were prepared by simply calcination of nitrate cerium, and used for clean synthesis of diethyl carbonate (DEC) by ethyl carbamate (EC) alcoholysis. 51% conversion and 82% selectivity were obtained with catalyst CeO2-600. Almost the same activity as the fresh sample could be regained if the used catalyst was recalcined at 600 °C. XPS, XRD, CO2-TPD and BET study suggested that high surface area and the presence of abundant basic sites are important to achieve a higher catalytic performance.

Clean synthesis of coumarin-3-carboxylic acids using water extract of rice straw husk

Here, the authors report a novel methodology for the synthesis of coumarin-3-carboxylic acids by using water extract of rice straw ash, which is a simple method for obtaining the final product. Coumarin-3-carboxylic acids have been synthesized from several substituted salicylaldehydes and Meldrum’s acid as starting materials in outstanding yields (72–94%) in 220–320 min at room temperature.

Catalyst systems for the clean synthesis of nitrogen-containing fine chemicals based on the building and transformation of carbonyl-containing molecules

The clean synthesis of nitrogen-containing fine chemicals with wide applications in organic and pharmaceutical chemistry has attracted lots of attention. Meanwhile, the sustainable development for chemical industry is based on the clean conversion of fossil resource derived basic chemicals such as hydrocarbon, alcohols, CO, CO2 and amines. Therefore, it is very important to synthesize the nitrogen-containing fine chemicals by the effective and clean conversion of fossil resource derived basic chemicals. The synthesis of nitrogen-containing fine chemicals via building, activation and transformation of carbonyl-containing molecules is an effective way to realize it. The key point is to establish a highly active catalyst system for building and transformation of carbonyl-containing molecules. Our group has focused on the clean synthesis of the nitrogen-containing fine chemicals based on the building and transformation of carbonyl-containing molecules since 2008. Here, the main progress from our group in the catalytic amination based on the activation and conversion of C1 carbonyl molecules, the building of the intermediate containing carbonyl, and the establishment of the catalytic system bridging homogeneous and heterogeneous catalysis based on a catalytic cycle between C=O and CH–OH has been summarized.

Solid acids accelerate the photocatalytic hydrogen peroxide synthesis over a hybrid catalyst of titania nanotube with carbon dot

Photocatalytic synthesis of hydrogen peroxide (H2O2) from water and oxygen is an alternative route for clean energy storage and chemical synthesis, but still having problems with insufficient H2O2 productivity and solar-to-chemical energy conversion efficiency. Herein, we reported a hybrid catalyst of proton-form titania nanotube with carbon dot (HTNT-CD) that is highly efficient for the production of H2O2 under visible-light irradiation (λ > 420 nm, H2O2 productivity at 3.42 mmol gcat−1⋅h−1), outperforming the titania catalysts containing noble metals and the carbon nitride catalysts reported previously. Multiple studies demonstrate that the protons on the HTNT-CD are crucial for the production of H2O2 by efficiently accelerating the half reaction of molecular oxygen reduction to form H2O2, and effectively hindering H2O2 decomposition under the irradiation conditions. This HTNT-CD catalyst gives solar-to-H2O2 apparent energy conversion efficiency at 5.2%, which is even 4.9 times of that (1.06%) over the catalyst derived from commercial P25 and CDs. More importantly, the HTNT-CD is stable, giving high H2O2 productivity in the continuous recycle tests.

UV‐Assisted High‐Efficient Synthesis of α‐Ketoamides Using Air Promoted by a Non‐Metal Catalyst in Aqueous Solution

AbstractThe front cover artwork for issue 21/2018 is provided by the group of Prof. Bo Wang at the Key Laboratory of Advanced Materials of Tropical Island Resources, and State Key Lab of Marine Resource Utilizations in South China Sea, both from Hainan University (China). The image shows the formation of O3 under UV light, represented as a ray of sunlight. In water, O3 transforms into O2⋅‐, which acts as oxidant for the efficient and clean synthesis of α‐ketoamides at room temperature. See the Full Paper itself at https://doi.org/10.1002/cctc.201801365.

Activated‐Carbon‐Supported Calcium Oxide: A Selective and Efficient Catalyst for Nitrile‐Containing Diaryl Ether Synthesis

AbstractActivated‐carbon‐supported calcium oxide (CaO@AC) was prepared from AC and a suspension derived from CaO and ammonium carbonate. After calcination under nitrogen, high purity CaO@AC was obtained. The nature of non‐aggregation and high purity of CaO@AC enabled a clean and selective synthesis protocol for nitrile‐containing diaryl ethers. Various functional groups including methoxyl, amino, carboxyl, allyl and nitro were well‐tolerated, and products were obtained in excellent yields and purities. Asymmetric substitutions could be achieved via simple adjustment of reaction conditions, and transetherification was greatly suppressed to 10−3–10−4 scale. In addition, a mechanism for suppression in transetherification was proposed and discussed.

Microwave Irradiation Synthesis and Anti-breast Carcinoma of 6-ethoxy-2-(2-methoxy- benzylideneamino)benzothiazole and its Metal Complexes

Efficient and clean synthesis of Schiff base as a new ligand, 6-ethoxy-2-(2-methoxy benzylideneamino)benzothiazole has been synthesized in equimolar reaction of 2-amino-6-ethoxy-benzothiazole with 2-methoxy benzaldehyde using microwave technique. The prepared Schiff base was reacted with some transition metal ions Ni(II), Cu(II), Pd(II), Ag(I) and Au(III) in equimolar ratio (M:L, 1:1) using microwave technique. The stereochemistry and the bonding characteristics of the ligand and its complexes were achieved based on elemental analysis, FT-IR, UV-Vis., 1HNMR and ESR as well as Thermo-Gravimetric Analysis (TGA). The thermal dehydration and decomposition of Ni(II), Cu(II) and Ag(I) complexes were studied kinetically using the integral method applying the Coats–Redfern and Horowitz Metzger equations. The reactivity of ligand and its Au(III) complex were studied against breast carcinoma cell. The antimicrobial activity of ligand and its Ag(I) complex studied against the bacterial (positive and negative) grams and fungal strains.

Clean synthesis of epoxy plasticizer with quaternary ammonium phosphotungstate as catalyst from a byproduct of cashew nut processing

The toxic petroleum-based phthalates account 80% of the total plasticizer consumption in China. Conventional methods for preparing epoxy plasticizers produces a large amount of waste water. Furthermore, cardanol (a byproduct of cashew nut processing) has the potential to be an economic alternative for producing fine chemical products. Here we reported a strategy for acid-free catalytic production of epoxy plasticizer using renewable waste material cardanol as starting material and quaternary ammonium phosphotungstate as catalyst. The optimum epoxidation reaction parameters were investigated and the epoxy value of epoxidized cardanol based plasticizer was 5.2% at optimal reaction conditions. Remarkably, the catalyst was recycled and the percent recovery in the first recycle was 89.0%. Performances of plasticized PVC films showed that epoxidized cardanol based plasticizer improved thermal stability and decreased the glass transition temperature of PVC. Plasticizing efficiency of epoxidized cardanol based plasticizer reached 82.2%. Epoxidized cardanol based plasticizer is biologically safe without acute toxicity and showed more excellent solvent resistance and lower volatilization than dioctyl phthalate. In conclusion, a cleaner environment-friendly plasticizer derived from a waste material was produced by acid-free catalysis. The strategy introduced renewable waste material cardanol into the environment-friendly plasticizer production to substitute dioctyl phthalate and had potential application value to reduce pollution and improve human health.

Clean Synthesis of Epoxidized Tung Oil Derivatives via Phase Transfer Catalyst and Thiol–ene Reaction: A Detailed Study

Introducing renewable tung oil into the environment-friendly plasticizer production via clean and efficient strategies to substitute toxic dioctyl phthalate (DOP) holds potential application value ...

Cleaner synthesis and systematical characterization of sustainable poly(isosorbide-co-ethylene terephthalate) by environ-benign and highly active catalysts

It remains a great challenge to cost-efficiently and cleanly synthesize sustainable polyesters based on both biomass-derived comonomers and biogenic catalysts because of the lack of clean, biogenic, and active catalysts so far. This work would like to address the tough problems of cleaner manufacturing and processing of the polyesters. We report the first example of the sustainable copolyesters from starch-based isosorbide/ethylene glycol and terephthalic acid by a highly active but environmentally benign Ti-Mg catalyst designed in our laboratory replacing current toxic catalysts. The optimal content of the Ti-Mg catalyst for productively synthesizing the copolyesters is down to 5 ppm that is just 1/30–1/75 content of traditional toxic catalysts including Sb2O3, GeO2, and pyridine reported heretofore. The copolyesters obtained by the Ti-Mg catalyst possess higher molecular weight up to Mn 25150, better performance, and are much more environmentally benign than most of similar copolyesters reported up to now. The copolyesters retain transparency owing to their irregular chain structure and random chain sequence and thus remain as a stable amorphous structure even after experiencing heating/cooling cycles. The Ti-Mg catalyst demonstrates 41–46 times higher catalytic activity than Sb2O3 catalyst and is active enough to catalyse the direct polycondensation between OH and COOH by eliminating water that is clearly distinguished from toxic methanol and corrosive HCl produced by polycondensation between OH and COOCH3/COCl catalyzed with toxic Sb2O3/pyridine catalysts, achieving cost-efficient and cleaner synthesis of the copolyesters without toxic residues. A systematic environmental analysis of the Ti-Mg catalyst, the copolyesters, raw materials and catalytic process, has been estimated, signifying that the Ti-Mg catalyst replacing current Sb2O3, GeO2, and pyridine accomplishes the cleaner production of most polyesters without toxic discharge or other harmful environmental impacts.

Green synthesis of highly recyclable CuO/ eggshell nanocomposite to efficient removal of aromatic containing compounds and reduction of 4-nitrophenol at room temperature

The CuO/ eggshell nanocomposite (NCs) was green synthesized using the extract of the pomegranate dried peel in a green root as a novel adsorbent nanocatalyst to efficient removal of aromatic compounds of crude oil sample from Shiwashok oil field in Iraqi Kurdistan as a model. Also, it was employed to reduction of 4-nitrophenole (4-NP) to 4-aminophenol (4-AP) at room temperature. The characterization of nanocomposite was using FE-SEM, EDS, elemental mapping and XRD analytical techniques. The spectrophotometrically results strongly demonstrated the excellent ability of nanocomposite on removing the aromatic containing compounds from the light crude oil sample and also reduction of 4-NP. Furthermore, the biosynthesized nano-adsorbent is quite active and stable for many cycles in both reactions. Facile and clean synthesis, simple preparation procedure, alterable supports, low cost and highly efficiency are the best features of this method.

Catalyst: Possible Consequences of the N-Methyl Pyrrolidone REACH Restriction

The authors work at the Green Chemistry Centre of Excellence (GCCE) at the University of York and are all currently involved in the H2020-BBI-funded project ReSolve for the development of safer bio-based solvents. Solvent applications for dihydrolevoglucosenone (Cyrene) and 2,2,5,5-tetramethyloxloane (TMO) are among their prominent discoveries. Dr. James Sherwood leads the Alternative Solvents Technology Platform at the GCCE. His research interests include solvent effects in organic synthesis and the substitution of hazardous solvents with novel bio-based solvents. Dr. Thomas Farmer is leader of the Clean Synthesis Technology Platform in the GCCE. Tom works on the development of greener synthetic methods and the uses of bio-derived platform molecules. Prof. James Clark is the director of the GCCE and winner of the 2018 RSC Green Chemistry Award. He has published over 500 articles and is a member of the UK Government’s Chemical Stakeholder Forum.

The clean synthesis and confirmatory structural characterization of new 2-amino-4,8-dihydropyrano[3,2-b]pyran-3-cyano based on Kojic acid

A valuable and clean method was developed for the synthesis of the group of different novel 2-amino-4,8-dihydropyrano[3,2-b]pyran-3-carbonitriles containing a 2-aminopyran moiety by using of azido kojic acid and various 2-arylidinemalononitriles in the presence of NH4Cl as a catalyst in a green solvent (ethanol) with excellent yields. All structures were analyzed by FT-IR, 1H, 13C NMR spectroscopy, and representatively, one compound was analyzed by X-ray crystallography technique. Crystallographic analyses indicated that of this compound a dimer formed via two weak intermolecular hydrogen bonds with d(N···O) distances of 2.927 A and made a 14-membered ring with centrosymmetric (Ci) form.

A Convenient, Clean and Expeditious Synthesis of bis(heterocyclyl)methanes Over High Surface Area Zirconium Phosphate Catalyst in Water: A Green Approach

A Convenient, Clean and Expeditious Synthesis of bis(heterocyclyl)methanes Over High Surface Area Zirconium Phosphate Catalyst in Water: A Green Approach

In vivo Acute Cytotoxicity Study of Poly(2-amino ethyl methacrylate-co-methylene bis-acrylamide) Magnetic Composite Synthesized in Supercritical CO2

With magnetic ferrite nanoparticles (FNPs) gaining interest in biotechnological fields and methacrylates being used as synthetic polymer for therapeutics loading and conjugation, we attempt to make novel magnetic composite by supercritical CO2 assisted entrapment of FNPs into in situ synthesized polymeric mesh of 2-amino ethyl methacrylate (AEMA) cross linked with methylene bis-acrylamide (MBA) at90±1 oC and pressure of 1200 psivia 2,2-azobisisobutyronitrile (AIBN) initiated radical polymerization. Particle thus obtained was characterized by using proton nuclear magnetic resonance (1H NMR), X-ray diffraction (XRD), thermal gravimetric-derivative thermogravimetric-differential thermal analysis (TG-DTGDTA), atomic force microscopy (AFM), and vibrating sample magnetometer (VSM). 1H NMR of Copolymer (without FNPs embedded) demonstrated distinct peaks verifying AEMA moieties flanked by MBA moieties with free amino group. Though the particle showed less saturation magnetization than that of as synthesized FNPs, it still maintained similar magnetic profile. AFM results showed average grain size of polymeric magnetic composites (PMCs) to be 80 nm with less agglomeration. TGA results verify the thermal stability of the compound upto 200 oC. In vivo acute cytotoxicity was profiled by administrating four different concentrations of FNPs, Copolymer and PMCs (FNPs embedded) into Sprague Dawley albino rat intraperitonally for 14 days and measuring various hematological, biochemical and serum enzymatic parameters along with histological examinations. Overall, PMCs showed no significance change in these parameters compared to normal saline administered control which signifies biocompatible nature of the composite. Hence, clean synthesis of FNPs embedded biocompatible amino functional magnetic composite has been achieved which holds potential in number of applications like drug loading, enzyme immobilizations, targeted therapy, etc.

Exploring the excellent photophysical and electrochemical properties of graphene quantum dots for complementary sensing of uranium

Graphene quantum dots (GQDs) possessing excellent photophysical and electrochemical properties have been exposed here, for the first time, to develop the low cost, non-toxic, metal-free, sustainable real-life adaptable sensors for strategically important and environmentally concerned metals such as uranium(U). The Förster resonance energy transfer involving f-orbitals of U as well as the nonspecific electrostatic association between GQDs and ions of U quench the photoluminescence of the GQDs resulting into photophysical detection of U in a pure solution down to 0.56 μg L−1. The electrochemically reduced GQDs are also found to be more electrocatalytically active than gold and it could detect U down to 2 μg L−1 in aqueous solution having high ionic strengths. This complementary dual-purpose sensor is applicable to determine U in pure solution as well as in the presence of other metal ions in the ground water. Further, we have re-evaluated the kinetic models viz. Nicholson and Klingler-Kochi equations from their respective roots and unambiguously showed neither of the equations is suitable for universal kinetic analysis in electrochemistry. We have persuasively proposed a universal electrodic equation eliminating the perplexities of the traditional kinetic equations. This article paves the unconventional way for environmentally clean synthesis of GQDs possessing excellent photophysical and electrochemical properties expected from the complementary sensor.