Recyclable Reaction Research Articles

Sustainable synthesis and manufacturing of silver powder-based metal clay for zero-waste technology applications

In this work, information on the metal clay technique is presented. Silver clays with different metal powder content were produced, and their selected properties were examined. The research part was divided into two parts. In the first part, silver powder was produced by solid state hydrogen reduction. The average particle size of the resulting silver powder falls within the range of 0.5 to 4.5 μm. Next, seven silver clays with different powder to binder ratios were made. Then, samples for testing were prepared from the commercially available silver clay. In the second part, tests of the samples were carried out. The susceptibility of clays to shaping, density, hardness and roughness were examined. A sample with 1% methylcellulose showed a roughness of less than 1 μm. The shrinkage value ranged from more than 30% to less than 5% for the highest and lowest methylcellulose clays, respectively. Tensile strength ranged from 90 to 100 MPa for samples with lower methylcellulose content in the clay and from 30 to 80 MPa for samples with higher methylcellulose content. The highest electrical conductivity was achieved for samples with the lowest content of methylcellulose, reaching almost 80% of the conductivity of bulk silver. The microstructure of the powders and the produced samples were tested. Recycling reactions of reactants have been postulated, to obtain sustainable production by-design. A holistic sustainability assessment is quantified using circular and green metrics as well as life cycle assessment. A material circularity indicator (MCI) of 0.50 and an E-factor of 0.29 were determined, generating environmentally relatively harmless water (84%) and green gases such as O2 and H2 (7%) as waste/by-products. The cost of producing 1 kg of silver powder utilizing the closed-loop technology presented in this paper amounts to €1103.45.

Recent Developments in Direct C-H Functionalization of Quinoxalin-2(1H)-Ones via Heterogeneous Catalysis Reactions.

In recent years, Web of Science has published nearly one hundred reports per year on quinoxalin-2(1H)-ones, which have attracted great interest due to their wide applications in pharmaceutical and materials fields, especially in recyclable heterogeneous catalytic reactions for direct C-H functionalisation. This review summarises for the first time the methods and reaction mechanisms of heterogeneous catalytic reactions of quinoxalin-2(1H)-ones, including six major types of heterogeneous catalysts involved. The heterogeneous reactions of quinoxalin-2(1H)-ones are summarised by classifying different types of catalytic materials (graphitic phase carbon nitride, MOF, COF, ion exchange resin, piezoelectric materials, and microsphere catalysis). In addition, this review discusses the future development of heterogeneous catalytic reactions of quinoxalin-2(1H)-ones, including the construction of C-B/Si/P/RF/X/Se bonds by heterogeneous catalytic reactions, the enrichment of heterogeneous catalysts such as metal oxides, graphene-based composites, doped metal nanoparticles, and molecular sieve-based porous materials, asymmetric synthesis, and other areas. The aim of this review is to contribute to the development of green and sustainable heterogeneous reaction methods for quinoxalin-2(1H)-ones with applications in materials chemistry and pharmacology.

Synergy of ultra-low-loaded ruthenium with alumina stimulating the catalytic hydrogenation of levulinic acid into γ-valerolactone

Herein we report an efficient and recyclable catalyst combining extremely low-loaded Ru and abundant alumina supported on nitrogen-doped carbon (NC) for hydrogenation of cellulose-derived levulinic acid (LA) into valuable γ-valerolactone (GVL). The as-fabricated Ru0.18/Al2O3/NC shows extraordinarily catalytic efficiency in transforming LA to GVL under solvent-free conditions, achieving up to a 1.77 × 105 turnover number (TON) and a 26400 h−1 turnover frequency (TOF) in a single batch reaction, which is far better than other heterogeneous catalysts and comparable to the best optimized homogenous catalysts. This catalyst demonstrates a good stability and reusability, whose catalytic performance can be maintained in 22 times recycled reactions, thus reaching a 106-level value of total TONs. These results highlight the importance of the synergistic effects between infrequent Ru and abundant alumina, and provide an up-and-coming way to design more active and stable low Ru loading catalyst for such a transformation.

A novel photoelectrochemical aptasensor based on nitrogen vacancies g-C3N5/TiO2 heterostructure and endonuclease assisted recycling amplification for ultrasensitive analysis of 17β-estradiol

Herein, we developed nitrogen vacancies g-C3N5/TiO2 heterostructure modified electrode for sensitive photoelectrochemical (PEC) sensing of 17β-estradiol (E2) based on target-triggered Endonuclease assisted recycling and horseradish peroxidase (HRP)-induced biocatalytic precipitation (BCP) cascade signal amplification strategies. The nitrogen vacancies g-C3N5 (NV-g-C3N5) was produced with thermal polycondensation method and employed as a photoactive material. Since the synergy effect between the TiO2 and NV-g-C3N5 can reduce the photo-induced electron-hole recombination and expedite the spatial charge separation, NV-g-C3N5/TiO2 heterostructure showed higher PEC activity. HRP-labeled Assistant DNA (HRP-AD) hybridized with Substrate DNA (SD) on the electrode in the absence of E2, and precipitation generated by HRP catalyzed could quench the photocurrent of the electrode. In the presence of E2, the target triggered Endonuclease assisted recycling reaction and achieved the conversion of the E2 to a massive output of template DNA (tDNA). Owing to tDNA strong affinity to the SD, HRP-AD was released from the electrode, gradually terminating the BCP reaction and restoring the photocurrent. The PEC aptasensor for E2 detection exhibited a broad linear range from 0.01 pM to 100 pM, with a detection limit of 0.0087 pM, and could be used to detect E2 in bioanalysis of environmental samples.

Photocatalytic Dehydrogenation of N-Heterocycles Promoted by Radicals from Graphene Oxide

Abstract Visible light-induced photocatalytic dehydrogenation of N-heterocycles was achieved by graphene oxide (GO). Unlike previously reported thermally induced GO-promoted reactions, this system generates radicals and molecular hydrogen, which are confirmed by electron spin resonance and gas chromatography. A metal-free, oxidant-free, and recyclable photocatalytic reaction were achieved by a carbon-based system for the first time.

An ultrasound assisted, ionic liquid-molecular iodine synergy driven efficient green synthesis of pyrrolobenzodiazepine-triazole hybrids as potential anticancer agents.

Herein, we report an efficient and eco-friendly, ultrasound assisted synthetic strategy for the construction of diversified pyrrolobenzodiazepine-triazole hybrids, which are potentially pharmaceutically important scaffolds, via a domino reaction involving intermolecular electrophilic substitution followed by intramolecular Huisgen 1,3-dipolar azide-alkyne cycloaddition. The USP of the reported protocol is the use of benign and inexpensive, recyclable molecular iodine-ionic liquid synergistic catalytic system cum reaction media for achieving the synthesis. The other salient features of this method are the use of mild reaction conditions, high yield and atom economy, operational simplicity, broad substrate scope and easy workup and purification. All the synthesized compounds were evaluated for in vitro anti-proliferative activity against various cancer cell lines. From among the synthesized title compounds, 9,9-dimethyl-8-phenyl-9H-benzo [b]pyrrolo [1,2-d][1,2,3]triazolo[5,1-g][1,4]diazepine (7) was found most to be the most active compound exhibiting IC50 value of 6.60, 5.45, 7.85, 11.21, 12.24, 10.12, and 11.32µM against MCF-7, MDA-MB-231, HeLa, SKOV-3, A549, HCT-116 and DLD-1 cell lines, respectively. Further the compounds were found to be non-toxic against normal human embryonic kidney (HEK-293) cell line.

Versatile application of strong Brønsted acid deep eutectic solvent as recyclable reaction media and catalysts in organic synthesis

Deep eutectic solvents (DESs) will be one of the most promising alternatives to conventional organic solvents. Hitherto, little attention has been dedicated to their applications in organic synthesis about strongly acid DESs. Herein, strong Brønsted acid DESs based on PTSA/PEG4000 were developed and used firstly to synthesize three significant compounds, namely 3,4-dihydrochromans, dihydrocoumarins and indolo[3,2-a]carbazoles, as reaction media and catalysts, and all of desired products were obtained in high yields in a short time. Furthermore, the yield of 3,4-dihydrochroman has not significant loss after five runs revealed that the PTSA/PEG4000 DES has ideal activity and recyclability. The PTSA/PEG4000 DES was characterized by FT-IR and TGA, and the obtained results also verified uniformity structure and the good stability of DES before and after reaction. More importantly, the eco-friendly and sustainable strategy minimized the utilization of organic solvents to a certain extent because crude products can be readily extracted by green solvent n-hexane, avoiding a series of issues introduced by conventional organic solvents.

Characterization of cool flame products during the low temperature oxidation of n-pentylbenzene

Radical chain recycling reactions represent a general topic in the chemistry of combustion, atmosphere, polymerization and so on. The nature and amount of OH radicals that generated by hydroperoxides during the oxidation of alkanes have been proven to drive the overall reactivity by enhancing the chain recycling steps. While low temperature oxidation kinetics of alkanes have been widely investigated, the comprehensive intermediates distribution during the low temperature oxidation of n-alkylbenzenes remains unexplored. This work selects n-pentylbenzene as a simple representative to investigate the low temperature oxidation kinetics of n-alkylbenzenes, especially intermediates and reactions that control the reactivity. The experiments were performed with a jet-stirred reactor coupled with the synchrotron vacuum ultraviolet radiation photoionization mass spectrometry (SVUV-PIMS). Around 70 intermediates, including phenyl hydroperoxides and highly oxygenated molecules (HOMs) were detected. By combining theoretical calculations and kinetic analysis, potential compositions and structures of key intermediates were identified and categorized into groups by their characteristic molecular formulae and chemical functionalities, such as C11H16On, C11H14On, C11H10On. Fingerprint hydroperoxides, including phenyl alkyl hydroperoxides, ketohydroperoxides, olefinic hydroperoxides, ketodihydroperoxides, were revealed to be formed from the characteristic first, second and third O2 addition and sequential reactions. These hydroperoxides play a dominant role in driving the low temperature oxidation reactivity by generating active OH radicals. The present experimental evidence, including the negative temperature coefficient behavior of n-alkylbenzenes as well as featured HOMs from the third O2 addition, extend the conceptual reaction schemes proposed in alkanes towards the oxidation of n-alkylbenzenes.

Dealkylation properties of alkylphenols over hierarchical ZSM-5 synthesized by desilication with TPAOH

In order to improve the catalytic performance of zeolite catalysts in alkylphenol dealkylation, TPAOH was used to introduce mesoporous structure to ZSM-5 zeolite in weak base NH4OH, and the content and dimension of mesoporous were changed by TPAOH concentration. The catalytic activity and lifetime of hierarchical zeolite were studied. The results showed that the phenol selectivity of hierarchical zeolite was slightly reduced, but the phenol yield was relatively stable. Higher TPAOH concentration expanded the introduced mesoporous structure, resulting in increased complexity of the catalytic products, including a certain amount of cresol, xylene, etc. Due to the mesoporous structure, the catalytic stability of hierarchical zeolite ZSM-5-0.3 was most significantly improved. Compared to commercial ZSM-5, the mixed phenol conversion rate of the first recycle reaction increased from 30.7% to 78.2%. By N2 adsorption-desorption tests, it was clear that coke deposition was located in the micropores of zeolite. The formation of mesoporous shortens the diffusion path of reactants in zeolite and thus reduced the formation of coke deposition. ZSM-5 zeolite still had good dealkylation performance in coal tar, and hierarchical zeolite had more significant catalytic stability.

Ultrasensitive detection of carcinoembryonic antigen based on exonuclease Ⅲ-assisted recycling and hybridization chain reaction strategies

In this work, we developed a novel ratiometric electrochemical aptasensor for the sensitive detection of carcinoembryonic antigen (CEA). Upon the addition of CEA, the specific binding between CEA and hairpin probe 1 (HP1) could trigger the Exo Ⅲ cleavage reaction and release large amounts of single stranded DNA (S1), which then hybridized with thiolated ferrocene-labeled hairpin probe 3 (Fc-HP3) on the electrode surface. Exo Ⅲ then cyclically digested the resulting duplexes to generate Fc-HP3 fragments on the electrode, accompanying the Fc molecules far away from the electrode surface and the Fc oxidation peak current signal (IFc) decreased. The HCR process was triggered by the Fc-HP3 fragment as an initiator, producing many long DNA sequences for electroactive probe methylene blue (MB) intercalation; thus, the MB oxidation peak current signal (IMB) increased. The IMB/IFc ratio was proportional to the logarithm value of CEA concentration from 100 fg mL−1 to 50 ng mL−1, with a lower detection limit of 30.5 fg mL−1. Furthermore, the aptasensor exhibited good selectivity and stability, with satisfactory reproducibility. Additionally, the developed aptasensor effectively measured CEA in real serum samples, verifying its practical application in biological samples.

Bifunctional Y-shaped probe combined with dual amplification for colorimetric sensing and molecular logic operation of two miRNAs

The abnormal expression of miRNA is closely related to various human diseases. In particular, the sensitivity detection of miRNA expression level is of great significance for the early diagnosis and prognosis of cancer. In this paper, we designed a Y-shaped DNA probe, using miRNA-21 and miRNA-141 as the dual input signals of AND logic gate. By combining with EXO III assisted target recycle and DNA hybridization chain reaction (HCR), we have realized dual signal amplification for detection of two miRNAs. In short, the Y-shaped DNA probe consists of two parts: the miRNA target binding region and the HCR initiator. When the two miRNAs are present at the same time, the target binding region specifically recognizes the target to generate two circulators, and then the HCR initiator is released. The EXO III specific cleavage two circulator, and release the target again which achieves the first step of signal amplification. After that, HCR was started by the split initiator generated in the first stage of continuous cycle, and the second step of signal amplification was realized. Thanks to the sensitive color change of gold nanoparticles in response to salt, we achieved ultra-high sensitivity for visual detection of miRNA-21 and miRNA-141. Under optimal conditions, the detection limit of both miRNA is 3 pM and the linear range is 10 pM to 0.4 nM. The method we designed could be applied in early detection and diagnosis of cancer.

Synthesis of new macrocyclic triperoxides

An efficient method has been developed for the synthesis of dialkyl hexaoxadispiroalkanedicarboxylates by the recyclization reaction of heptaoxadispiroalkanes with alkyl malonates (malonic acid dimethyl ester, malonic acid diethyl ester, malonic acid diisopropyl ester) under the action of lanthanide catalysts.

Rapid hydrolysis of PET in high-concentration alcohol aqueous solution by pore formation and spontaneous separation of terephthalate

Recovery of terephthalic acid (TPA) from waste polyethylene terephthalate (PET) should overcome the long-existing issues of low operation efficiency or massive wastewater generation during the hydrolysis and subsequent separation process to balance economics and environmental friendliness. Here, a high-concentration ethanol aqueous solution of 90 vol% is developed to achieve high-efficiency hydrolysis of PET by selectively cleaving C-O bonds and spontaneous separation of terephthalate using KOH as catalyst at 80 °C for 60 min. More than 98 % of TPA is recovered. It was attributed to the accelerated diffusion of the solvent in a reflux state due to the pore formation in PET and improved wettability between the solvent and PET. Notably, the terephthalate precipitated automatically from the reaction system due to low solubility in the solvent and separated by simple filtration, which avoids a large amount of waste water and acid in the following neutralization of terephthalate. The high efficiency of recycled reaction solution remained within several successive runs. The hydrolysis system is also applicable for degradation of other polymers containing ester groups and shows combined advantages of simplicity, high efficiency and eco-friendliness.

Micelle-Derived Palladium Nanoparticles for Suzuki–Miyaura Coupling Reactions in Water at Room Temperature

Despite the wide utility of colloidal palladium (Pd) nanoparticle (NP)-catalyzed Suzuki–Miyaura cross-coupling reactions in laboratory and industrial synthesis, the easy construction of colloidal Pd NPs and the detailed role of surfactants remain the focus of attention. Here, we present a simple and sustainable strategy to construct a nanoreactor by connecting micelles with Pd NPs. The strategy enables us to employ a pH-induced morphological transition of sugar-based surfactant aggregates, such as worm-like, spherical, and tubular micelles, to investigate the solubilization of organic substrates. Pd NPs are mainly synthesized by the reduction of phenylboronic acid, further stabilized by the sugar-based surfactant micelles. A kinetic model is established, and the apparent activation energy of this reaction in aqueous micellar solutions is determined to be 46.7 kJ/mol. Notably, the recycled aqueous reaction mixture containing the micelles and Pd NPs can be reused.

Recyclization reaction of <i>S</i>-, <i>N</i>-containing cyclic peroxides with aromatic amines

The recyclization reaction of tetraoxathiaspiroalkanes and tetraoxathiocanes with primary amines ( o , p -fluoroanilines, m , p -chloroanilines, o -toluidine, o , p -anisidines, ammonium chloride) to obtain cycloazadiperoxides under the action of samarium nitrate crystal hydrate as a catalyst was studied. The possibility of recycling N -( tert -butyl)hexaoxaazadispirocycloalkanes with arylamines to the corresponding azatriperoxides was shown. It was found that the rate of the recyclization reaction depends on the nature of the central heteroatom in the heterocycle (S > N > O).

A fluorometric graphene oxide-based assay for determination of agrB gene transcription in methicillin-resistant Staphylococcus aureus by coupling exonuclease III-assisted target recycling and hybridization chain reaction

Schematic representation of the graphene oxide-based fluorometric bioassay for determination of agrB gene transcription in MRSA by coupling exonuclease III-assisted target recycling and hybridization chain reaction.

Polyethylene glycol (PEG-400) as a recyclable and biodegradable reaction medium for green synthesis of 2-amino-4H-chromenes

A helpful manufactured course to the one-pot green synthesis of 2-amino-4H-chromenes through a tandem Knoevenagel-Michael cyclocondensation reaction of aldehydes, malononitrile, and resorcinol in polyethylene glycol (PEG-400) as accessible and biodegradable media have been detailed. All responses are completed in a brief time and the items are gotten in fabulous yields. The striking highlights of this eco-friendly approach are biodegradable media, fabulous yields, simple work-up without requires for column chromatographic separation, and no poisonous organic solvents, evasion of harmful reagents, one-pot strategy, and effortlessness of operation. Additionally, PEG-400 is exceedingly steady and can be reused for four sequential runs without major basic changes or misfortune of movement, which has been exceptionally advantageous in tending to natural concerns.

Cu-catalysed Chan–Evans–Lam reaction meets deep eutectic solvents: efficient and selective C–N bond formation under aerobic conditions at room temperature

The Cu(ii)-catalysed Chan–Evans–Lam amination between organoboron compounds and primary amines can be conducted and scaled up in Deep Eutectic Solvents as recyclable and sustainable reaction media, and in the absence of external ligands.

Kinetics of hypochlorous acid reactions with organic and chloride-containing tropospheric aerosol.

Chlorine plays an important role in tropospheric oxidation processes, in both marine and continental environments. Although modeling studies have explored the importance of halogen chemistry, uncertainty remains in associated chemical mechanisms and fundamental kinetics parameters. Prior kinetics measurements of multiphase halogen recycling reactions have been largely performed with dilute, bulk solutions, leaving unexplored more realistic chemical systems which have high solute concentrations and are internally mixed with both halide and organic components. Here, we address the multiphase kinetics of gaseous HOCl using an aerosol flow tube and aerosol mass spectrometer to study its reactions with particulate chloride, using atmospherically relevant particle acidity, solute concentrations, and ionic strength. We also investigate the chemistry that results when biomass burning (BB) aerosol components and chloride are internally mixed. Using pH-buffered deliquesced particles, we show that the rate constant for reaction of dissolved HOCl with H+ and Cl- at high relative humidity (RH) (80-85%) is within a factor of two of the literature value for bulk phase conditions. However, at lower RH values (60-70%) where the particles are considerably more concentrated, the rate constant for chloride loss from the particles is an order of magnitude higher. For pure organic compounds commonly found in biomass burning (BB) aerosol, such as coniferaldehyde, salicylic acid and furfural, an increase in the aerosol chlorine content occurs with HOCl exposure, indicating the formation of organochlorine species. Together, these independent findings explain results for internally mixed aerosol particles with both chloride and BB components present where we observed behavior consistent with both chloride loss and organochlorine formation occurring simultaneously upon HOCl exposure. Our results indicate that chlorine recycling via HOCl uptake by chloride-containing particles will occur in the atmosphere efficiently over a wide range of RH conditions, even when reactive organic compounds are present in the same particles as chloride. Simultaneously, formation of organochlorine compounds, which are commonly toxic, is likely occurring when reactive organic components are present.

Pulsed light influences several metabolic routes, delaying ripening and improving the postharvest quality of acerola

• Pulsed light reduced acerola climacteric respiration and delayed ethylene peak. • Pulsed light-treated acerola was firmer and lost less weight. • Pulsed light enhanced polyamines by stimulating synthesis and inhibiting degradation. • Pulsed light increased vitamin C by reducing degradation and improving recycling. This study investigated how pulsed light (PL) postharvest treatment influences acerola ripening physiology and quality, thus physiologically mature acerola ‘Okinawa’ were treated with PL (0.6 J.cm −2 ) and stored for 16 days at 10 °C. Compared to untreated, PL-treated acerola showed a 5% reduction in climacteric respiration with 78.65 mol CO 2 kg −1 h −1 and a one-day delay in ethylene peak of 2.65 µL C 2 H 4 kg −1 h −1 . PL-treated acerola also showed 13% lower weight loss and was 12% firmer probably due to the enhanced antioxidant enzymes that reduced hydrogen peroxide content with lower membrane lipid peroxidation, in addition to inhibition of cell wall hydrolysis. The higher polyamine levels induced by PL may be explained by the greater synthesis, inhibition of degradation, and enhancement of back-conversion reactions. PL treatment would have increased the total vitamin C by 33% as a result of lower degradation and more efficient recycling reactions, while polyphenols would have increased 10% by reducing oxidation and enhancing synthesis. Although the storage period exerted the main influence on ‘Okinawa’ acerola, results indicate that PL delayed ripening and promoted quality as an elicitor of antioxidant metabolism thus representing a hormetic phenomenon. Proposed mode of action of pulsed light (0.6 J.cm −2 ) on the physiology of ‘Okinawa’ acerola.