Green Chemistry Metrics Research Articles

γCDCoBr2 complexes as catalysts in sulfide oxidation and its reused

γCDCoBr2 complexes synthesized in ethyl acetate or dichloromethane solvents or CoBr2 were used as catalysts in sulfoxidation reactions giving very good yields and high chemoselectivity. Sulfoxidation takes place in the presence of other functional groups such as –COOH, –NO2 or –CHO. A structure-reactivity analysis was carried out, correlating the Hammet σ parameters and the TOF values obtained in the oxidation reaction of the para-substituted arylmethylsulfides in the presence of each catalyst. Additionally, the effect of groups of different sizes attached to sulfur atom was analysed. Also, these reactions were evaluated using green chemistry metrics, good results were obtained in many cases. The solid complexes can be used several times, after three cycles the yield decreased only 7% (from 95 to 88%). Techniques as FT-IR and TGA were used to characterize used complexes after 1st and 6th cycles.

Sustainable TLC-densitometric method for pharmacokinetic study of the concurrently used ibuprofen and metronidazole: Green metric assessment

Combination therapy with metronidazole has been demonstrated to be superior in surgical site infections and pain treatment protocols. Ibuprofen, on the other hand, is an effective and safe medication with long duration of action for patients with post-operative pain.In this investigation, in vivo estimation of metronidazole and ibuprofen was performed, followed by a pharmacokinetic study using an ecological TLC-densitometric approach. Separation of drugs and the internal standard, furosemide from plasma matrix was performed using ethyl acetate: ethanol: ammonium hydroxide solution 33% (5:5:0.1, by volume) on TLC silica gel 60 F254 plates and scanning at 220.0 nm and 310 nm. The method was sensitive for metronidazole and ibuprofen in the ranges of 0.1–2.5 and 0.1–3.0 µg/band, respectively.Furthermore, the devised method’s performance was evaluated by analyzing various samples obtained from volunteers at different time intervals who received either a single medication or a combination of drugs. The information gathered was utilized to investigate the pharmacokinetic properties of both medicines. According to the findings of the pharmacokinetic study, co-administration of metronidazole and ibuprofen increased their maximum plasma concentrations and time required to reach this concentration. It was also discovered that ibuprofen greatly influenced the bioavailability and distribution of metronidazole. Accordingly, care should be taken when both medications are used simultaneously, especially for metronidazole, which requires dose regulation. Furthermore, different novel Green analytical chemistry metrics were applied to assess the suggested method, including GABI, RGB colored tool, AGREE, and hexagon. The results revealed that the developed analytical approach had a negligible environmental impact.

Reduced zwitterionic graphene oxide sheets decorated with nickel nanoparticles as magnetically and efficient catalyst for A3‐coupling reactions under optimized green experimental conditions

A Ni‐based supported reduced zwitterionic graphene oxide N,N‐bis(2‐pyridylmethyl)ethylenediamine 1,3‐propanesultone (GO‐BPED‐PS) material was prepared for the catalysis of A3‐coupling reactions under green experimental conditions. First, the in situ generation of nickel nanoparticles (NiNPs) onto the reduced zwitterionic GO‐BPED‐PS sheets was characterized by various techniques such as Fourier infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM) analysis. Moreover, the electron density map of NiNPs onto the reduced zwitterionic GO‐based sheets was produced through the X‐ray crystallographic analysis. Then, the as‐prepared reduced GO‐BPED‐PS NiNPs (rGO‐BPED‐PS@NiNPs) material was used as a heterogeneous catalyst for the three‐component coupling reaction (A3‐coupling reaction) of benzaldehyde, morpholine, and terminal alkynes. The experimental conditions were performed in order to obtain very good green chemistry metrics. In particular, we obtained a high catalytic efficiency when using γ‐valerolactone as solvent, a reaction time of 3 h and a temperature of 100°C. In addition, it was demonstrated that the rGO‐BPED‐PS@NiNPs catalyst could be recycled for 11 times without a significant decrease in its catalytic activity.

Zero waste, single step methods of fabrication of reduced graphene oxide decorated with gold nanoparticles

This paper reports a novel approach to the use of carbon, in the form of reduced graphene oxide, as a reducing agent for Au(III) chloride complex ions. This approach allows fabrication of a composite material Au@GOr in a single-step process. The reduction of Au(III) complex ions was performed using high pressure, 50 bar, and high temperature, 250°C, reactor. The average diameter of obtained gold nanoparticles was below 3 nm. The advantage of the reduced graphene oxide as the reducing agent is its high surface area. This accelerates the reaction rate significantly. The greenness and sustainability of the process are assessed by green chemistry metrics and circularity indicators recently applied for the first time to a nanomaterial synthesis. As a key green metrics, atom economy (AE) measures the degree of the incorporation of reactant atoms into the final product and in the case of the research presented scoring 99%.

Green assessment of polymer microparticles production processes: a critical review

The sustainability of polymer microparticle production processes was evaluated. A different viewpoint was provided to encourage researchers to use simple yet effective green chemistry metrics calculations in the development of these processes.

Visible-light-mediated synthesis of β-keto sulfones using g-C3N4 as a recyclable photocatalyst under sustainable conditions

Syntheses of β-keto sulfones have been reported using g-C3N4 as a recyclable photocatalyst along with green chemistry metrics and eco-scale evaluation.

Green Synthesis of Metal-Organic Framework Mil-101(Cr) – an Assessment by Quantitative Green Chemistry Metrics

Green Synthesis of Metal-Organic Framework Mil-101(Cr) – an Assessment by Quantitative Green Chemistry Metrics

L-Proline catalyzed one-pot three-component synthesis and evaluation for biological activities of tetrahydrobenzo[b]pyran: evaluation by green chemistry metrics

L-Proline catalyzed one-pot three-component synthesis and evaluation for biological activities of tetrahydrobenzo[b]pyran: evaluation by green chemistry metrics

Multicriteria Decision Analysis and Grouping of Analytical Procedures for Phthalates Determination in Disposable Baby Diapers

This study presents the application of one of the tools from the multicriteria decision analysis set (MCDA), the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). Selected green analytical chemistry metrics were used to rank analytical procedures for the phthalate determination in disposable baby diapers. Nine analytical procedures were assessed in order to find one that has the lowest environmental impact and the best analytical figures of merit. Nine different criteria, where weighting was based on the experts’ evaluation, were used in the procedures’ assessment. With the use of TOPSIS, an easy and straightforward technique, selection of the most appropriate procedure was made.

Thin Film Mechano-Energy Induced Slicing of Carbon Nanotubes under Flow

Controlling the length of CNTs is important for their applications. As-prepared CNTs are typically nonuniform in length and are entangled, but for applications in electronics and biomedical research in particular, specific lengths are desirable; this has attracted intensified research efforts. We have developed a versatile thin film microfluidic method, which is high in green chemistry metrics, for controlled disentangling and slicing both single-walled CNTs and multiwalled CNTs. The method uses the mechanoenergy generated in a biphasic immiscible mixture of water and o-xylene in a titled vortex fluidic device (VFD) operating at ambient temperature, without the need for using surfactants or other axillary reagents and without the need for applying external fields. Importantly, this simple method can achieve a yield of 93% under continuous flow conditions. The high shear in the dynamic thin film in the VFD is also effective for such processing under continuous flow conditions, such that the method is scalable.

A sustainable process for selective recovery of lithium as lithium phosphate from spent LiFePO4 batteries

This work demonstrates a novel, systematic and sustainable route for the treatment of cathode powder of spent LiFePO4 batteries. First time, lithium was selectively leached using formic acid as lixiviant with H2O2 as an oxidant. Effect of different parameters i.e., formic acid and H2O2 concentration, pulp density, temperature and time have been studied. The optimised leaching conditions were used for the selective leaching of Li and Li was precipitated as Li3PO4 in two steps, i.e., firstly, in situ precipitation at pH = 12.5, 60 °C and then at pH = 12.5, 90 °C using saturated Na3PO4 solution from the pregnant leach solution. The products were recovered with high purity (>99.5%) and X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) techniques were used for characterization. The overall study confirmed the suitability of the developed scheme for industrial application to provide economic and environmental benefits. Green chemistry metrics and the revenue generated from the developed process were calculated which revealed that the process is indeed green, sustainable, and economic.

Evaluation of ozone as an efficient and sustainable reagent for chalcopyrite leaching: Process optimization and oxidative mechanism

Chalcopyrite is the main copper-bearing mineral and is refractory to oxidative leaching. There are many investigations to optimize copper extraction from this mineral but most of the processes are energy intensive and environmental threatening. Ozone at low concentration is an efficient reagent for high extraction of copper from chalcopyrite, which is also ecofriendly. This paper presents a comprehensive investigation on the process optimization for both copper and iron extraction from chalcopyrite using ozone. The following variables were tested during 48-h leaching periods: temperature, ferric sulfate, ozone and sulfuric acid concentrations, solid/liquid ratio, and leaching time. Ozone leaching recovered 100% of the copper from chalcopyrite at 25 °C without addition of ferric. The overall reaction kinetics followed the shrinking core model by mixed control of diffusion through the product layer and chemical reactions. The proposed leaching mechanism was verified via various characterization techniques. Green chemistry metrics were evaluated, and the optimized process was demonstrated to be environmentally attractive. Ozone leaching appears to have strong potential as a “green” and technically feasible method to leach copper from chalcopyrite.

Ru-Catalyzed Selective Catalytic Methylation and Methylenation Reaction Employing Methanol as the C1 Source.

Methanol can be employed as a green and sustainable methylating agent to form C-C and C-N bonds via borrowing hydrogen (BH) methodology. Herein we explored the activity of the acridine-derived SNS-Ru pincer for the activation of methanol to apply it as a C1 building block in different reactions. Our catalytic system shows great success toward the β-C(sp3)-methylation reaction of 2-phenylethanols to provide good to excellent yields of the methylated products. We investigated the mechanistic details, kinetic progress, and temperature-dependent product distribution, which revealed the slow and steady generation of in situ formed aldehyde, is the key factor to get the higher yield of the β-methylated product. To establish the environmental benefit of this reaction, green chemistry metrics are calculated. Furthermore, dimerization of 2-naphthol via methylene linkage and formation of N-methylation of amine are also described in this study, which offers a wide range of substrate scope with a good to excellent yield.

Quantitative Sustainability Assessment of Flow Chemistry–From Simple Metrics to Holistic Assessment

Flow chemistry has changed chemical process designs toward process intensification and is generally considered as green methodology. In this connection, this perspective provides a more critical and holistic view about the sustainability of flow chemistry by introducing both simple and complex holistic tools for environmental quantitative assessment on sustainability and providing examples of how they were used for flow chemistry. The latter also shows a critical assessment of what flow chemistry can add to make chemical processes more sustainable. With the increasing complexity of assessment, green chemistry metrics, life cycle assessment methodology, and circular transition indicators are discussed. In this way, the sustainability of flow chemistry is assessed first on the level of a reaction only and then moving to a process level and beyond. Flow chemists are very aware of the principles of green chemistry and their simple metrics. Yet, they hardly use life cycle assessment, and quantitative circularity analysis has not been made. When those assessments are used, it is usually done by researchers with an ecology background. This perspective aims to make flow chemists aware of the opportunities that complex environmental assessment can provide and that protecting our planet requires a holistic sustainability consideration. The perspective critically states what each of the three types of assessments can do and what their limitations are.

A greener and cheaper approach towards synthesis of glycerol carbonate from bio waste glycerol using CaO–TiO2 Nanocatalysts

In this work we focused on clean catalytic approach of efficient CaO/TiO2 green nano particles derived from waste chicken eggshells with inorganic support TiO2 for glycerol carbonate synthesis. The designed nano catalysts were characterized using several chemical and spectrochemical techniques like XRD, FE-SEM, TGA-DSC, FT-IR BET-BJH methods. The corelation between the basic strength and catalytic activity of synthesized catalyst was tested by Hammett indicator method and found to be one of the important factors for glycerol carbonate synthesis. Under optimized condition of reaction parameters (Temp- 90 °C, time – 180min, DMC: gly molar ratio 4:1 and catalyst loading 3 wt% of glycerol used in reaction in gram) 3:1 CaO/TiO2 mixed oxide showed an excellent performance of 99.3% glycerol conversion and 93.7% of glycerol carbonate yield. The green metrics like Process mass intensity (PMI), and Environmental factor (E-factor), were well studied and obtained as 1.37 mg and 0.082 respectively for the transesterification process with 100% atom utilization (AU). The designed catalyst possessing ideal green chemistry metrics appreciate the manufacturing process of GLC both in industrial and lab scale. The utilization of waste eggshell not only a cheaper and green catalyst but also reduces the amount of waste and its treatment cost which is economically and ecologically friendly.

Dispirooxindole-pyrrolothiazoles: Synthesis, anti-cancer activity, molecular docking and green chemistry metrics evaluation

A modest library of a set of dispirooxindole-pyrrolothiazole derivatives 5a–n has been synthesized through multicomponent technique employing 1,3-dipolar cycloaddition reaction of azomethine ylide with novel dipolarophiles, 2,6-di (arylmethylidene) -4-methylcyclohexanones 4a–n without any catalyst. The reaction provides simple and efficient access to synthetically useful and biologically important dispirooxindole-pyrrolothiazoles in high yield (86–98%) with high degree of stereo-, regio-, and chemo-selectivities. All the synthesized compounds were characterized using popular spectral methods like IR, 1H NMR, 13C NMR and 2D NMR techniques. Further, the molecular structure of 5a was confirmed by single crystal XRD. The synthesized compounds were subjected to cytotoxicity evaluation using K562-leukemia cell line. Compound 5 k has been found to be an effective compound of this class in targeting K562-leukemia cell with IC50 value of 13.28 ± 0.11 µg/ml. From the molecular docking data, it is realized that these compounds 5a–n showed a binding energy between -8.1 and -10.8 kcal/mol and thereby inhibit Tyrosine Kinases. Smaller E-factor (0.13), high atom-economy (89.74%), percentage yield (98.00%), reaction mass efficiency (88.43%), and carbon efficiency (96.97%) are successful achieved for compound 5j.

Enviro-economical benign synthesis of glycerol carbonate from biowaste glycerol using industrial waste pond ash catalyst

The dramatic increase in biodiesel plant leads to oversupplied glycerol as its by product which requires industrial application for sustainability of biodiesel. The main focus of this study is the proper utilization of industrial waste pond ash for the preparation of various catalysts for the synthesis of glycerol carbonate . A series of catalysts were prepared by doping barium , lithium and potassium on the surface of pond ash collected from national thermal power plant (NTPC, Talcher, India). Among all the synthesized catalyst 20% Barium doped pond ash catalyst provided highest conversion of glycerol i.e. 98% and 94% glycerol carbonate yield respectively at mild reaction conditions. . 20% Ba doped pond ash catalyst was highly suitable for glycerol carbonate synthesis due to highest basic strength. The physicochemical properties of synthesized catalyst were studied through TGA-DSC, XRD, FT-IR spectra , SEM -EDX analysis . The catalytic performance as well as reaction parameters like temperature, time, DMC to glycerol molar ratio and catalyst loading percentage were optimized for better conversion of glycerol. Green metrics like E-factors , PMI are also studied to determine the sustainability and environmental impact of catalyst as well as transesterification reaction of glycerol. The overall evaluation of green chemistry for the work indicated that the synthesized catalyst is environmental benign in nature. • Synthesis of (Li,Ba,K) catalyst using industrial waste pond ash. • Green synthesis of glycerol carbonate using designed catalyst. • Screening of catalyst, optimization of parameters and reusability, deactivation mechanism. • Green chemistry metrics like E-factor, PMI were well studied. • Comparative study of 20%BaPA catalyst with other mixed metal oxide catalysts.

Red-Purple Photochromic Indigos from Green Chemistry: Mono-tBOC or Di-tBOC N-Substituted Indigos Displaying Excited State Proton Transfer or Photoisomerization.

In indigo, excited state proton transfer (ESPT) is known to be associated with the molecular mechanism responsible for highly efficient radiationless deactivation. When this route is blocked (partially or totally), new deactivation routes become available. Using new green chemistry procedures, with favorable green chemistry metrics, monosubstitution and disubstitution of N group(s) in indigo, by tert-butoxy carbonyl groups, N-(tert-butoxycarbonyl)indigo (NtBOCInd) and N,N'-(tert-butoxycarbonyl)indigo (N,N'tBOCInd), respectively, were synthetically accomplished. The compounds display red to purple colors depending on the solvent and substitution. Different excited-state deactivation pathways were observed and found to be structure- and solvent-dependent. Trans-cis photoisomerization was found to be absent with NtBOCInd and present with N,N'tBOCInd in nonpolar solvents. Time-resolved fluorescence experiments revealed single-exponential decays for the two compounds which, linked to time-dependent density functional theory (TDDFT) studies, show that with NtBOCInd ESPT is extremely fast and barrierless-predicted to be 1 kJ mol-1 in methylcyclohexane and 5 kJ mol-1 in dimethylsulfoxide-, which contrasts with ∼11 kJ mol-1 experimentally obtained for indigo. An alternative ESPT, competitive with the N-H···O═C intramolecular pathway, involving dimer units is also probed by TDDFT and found to be consistent with the experimentally observed time-resolved data. N,N'tBOCInd, where ESPT is precluded, shows solvent-dependent trans-cis/cis-trans photoisomerization and is surprisingly found to be more stable in the nonemissive cis conformation, whose deactivation to S0 is found to be solvent-dependent.

Sulfur Catalyzed Metal‐ and Solvent‐Free ABB'C Four‐Component Synthesis of N‐Arylidene‐2‐aryl‐imidazo[1‐2‐a]azin‐3‐amines via Strecker Reaction

AbstractAn efficient ABB'C four‐component Strecker reaction between 2‐aminopyridines, aromatic aldehydes and trimethylsilyl cyanide (TMSCN) was developed under metal‐ and solvent‐free conditions to access N‐arylidene‐2‐aryl‐imidazo[1,2‐a]azin‐3‐amines in high yields. This one‐pot reaction was carried out in the presence of elemental sulfur as catalyst using readily available starting material at room temperature. The reaction was tolerant to several substituted 2‐aminopyridines and aryl aldehydes and have good green chemistry metrics as compared to the reported methods.

Recent Advances in Environmental Analysis Towards Green Nanomaterials

Background: The protection of the ecology is an important task to control and restore the quality of environmental media through the reduction or prevention of the pollutants. Due to the growing awareness of safety, health and environmental issues, the use of non-toxic, clean and ecofriendly methods in the synthesis of nanoparticles has emerged out of necessity. Methods: In this article, the following concepts were considered: strategies of green chemistry, green chemistry metrics, waste management, green nanotechnology/nanoscience and characterization. Furthermore, the tables that include the covered topics were also presented in the manuscript. Results: The green synthesis of nanomaterials is a safe, energy-efficient and fast method which reduces the use of solvents, reagents, and preservatives that are hazardous to environment and human health. Conclusion: The fabrication of nanomaterials with green methods is a clean, safe, nontoxic and environmentally- friendly application which is necessary especially in large-scale operations.