Current Green Chemistry - Volume 11, Issue 1, 2024

The modern world of chemistry needs to find a sustainable solution for the remediation of heavy metals. The method of solving heavy metal problems using abundant and easily available ways is an integral part of green chemistry. This approach stimulates innovation among scientists. These procedures increase performance and decrease the consumption of non-renewable resources, minimizing negative impacts on the environment and less use of harmful chemicals. In this review, we have included some natural ways for the remediation of heavy metals such as Biochar, Clay, Zeolites, and Microorganismbased methods. We have also incorporated the mechanism of action of each of these procedures for the betterment of the reader.

Benzofuran, a versatile heterocyclic compound, has gained considerable attention in recent years due to its diverse biological activities, distinctive structural characteristics, broad synthetic approaches, and extensive applications. The growing potential inherent in benzofuran encourages many researchers to address the challenges of the synthesis of its framework. This comprehensive review aims to provide a detailed overview of the recent advancements in the synthesis of diverse benzofuran derivatives, highlighting innovative strategies, synthetic methodologies, and significant breakthroughs in the field. The synthetic methodologies are classified as metalcatalyzed routes, green-solvent-based routes, microwave-assisted methods, catalyst-free and solvent- free methods, and a miscellaneous group of routes. This categorization in review provides an easy means for the reader to rationally select the best possible synthetic method for benzofuran derivatives. In addition, it explores the use of different solvents and catalysts in benzofuran synthesis, which serves as a valuable resource for chemists, researchers, and scientists involved in pharmaceutical and allied sciences. Overall, this review provides a comprehensive overview of the synthesis of benzofuran scaffolds and complies with all the significant developments in the synthetic routes of benzofuran, which will be useful for researchers interested in the development of new benzofuran-based molecules.

Advancement in green synthetic methodologies has brought a revolution in heterocyclic synthesis. Green synthesis has bypassed the classical procedures involving toxic/hazardous solvents or catalysts and improved the current environmental safety standards by many folds. Green chemistry research has continuously made significant contributions to the development of heterocyclic scaffolds both at laboratory and commercial scales. Researchers are continuously developing and exploring the principles of green chemistry for the development of novel therapeutic agents. Quinoxaline lies in the category of versatile heterocyclic motifs, which possesses a wide diversity in its derivatives as well as a broad profile of its therapeutic potential. In the past decades, many new green synthetic protocols have been developed and employed successfully for the synthesis of quinoxaline derivatives. These include the use of reusable nanocatalysts, polymers, various green solvents, tonsils, catalysts, water as a catalyst, microwave irradiation, ultrasonic waves, non-toxic metal catalysts, surfactants, etc. The present review focuses on various green synthetic procedures reported for quinoxalines along with the specializations and applications of the reactions.

Pharmaceutical contamination, resulting from the discharge of active pharmaceutical ingredients (APIs) and other related compounds into the water, has become a growing concern due to its potential adverse effects on ecosystems and human health. This review article aims to examine the many facets of pharmaceutical contamination and highlight the most recent developments in its remediation. The effects of pharmaceuticals, sources, and pathways of pharmaceutical contamination, as well as the difficulties in detecting and evaluating its toxicities, have been included in the present manuscript. Nowadays various remediation strategies are employed to mitigate pharmaceutical contamination in water. Conventional wastewater treatment techniques, including activated sludge processes and membrane filtration, are effective in removing a portion of the pharmaceutical compounds. However, advanced oxidation processes such as ozonation and photocatalysis have shown promising results in enhancing the degradation of recalcitrant APIs. Nanotechnology-based approaches, such as the use of nanoparticles for adsorption and degradation, and bioremediation methods utilizing microbial degradation, enzymatic processes, and phytoremediation, offer potential future directions for efficient and sustainable remediation. This review describes the most recent developments, current status, and potential research directions with the future prospects of pharmaceutical pollutants.

Introduction: Dominating use of chemical processes for reducing indigo at several small-scale production houses formed the ground for initiating this study. Conventional textile processing hubs still use sodium hydrosulphite as a reducing agent irrespective of the source of indigo, whether natural or synthetic ignoring the unfavourable consequences of their disposal and elimination from effluent.Methods: The paper addresses the critical environmental issues related to the conventional reduction of indigo and studies already undertaken. It examines the indigo dyeing process of cotton using natural, chemical and eco-friendly reducing agents in combination with calcium hydroxide for a comparative study. Identification of natural indigo through High-Performance Liquid Chromatography was undertaken for further experimentation. Under specific parameters, the study examined the effect of Thiourea dioxide and natural reducing agents in indigo dyeing replacing Sodium hydrosulphite. The difference in weight, strength, and colour parameters such as K/S (HUNTERLAB), CIELab values and colourfastness are measured. The experimental results showed weight gain in all fabrics after indigo dyeing. There is a decrease in weft strength only in tamarind, iron, jaggery and dextrose vats. Iron vat showed a higher colour yield out of all reducing agents due to forming metal complexes with the cotton fabric, which influenced colour depth and highest relative colour strength % (114.11) and ΔC (8.48).Results: Thiourea dioxide showed the next highest relative colour strength % (96.59) and lowest ΔH values (8.54) concerning the values of the hydro process. Structural changes of fiber were studied by using SEM (Scanning Electron Microscope) after using different reducing agents, which revealed superior surface topography of samples dyed using thiox. The colour difference showed no significant effect on the colourfastness of alternative reducing agents.Conclusion: Thiox can be a perfect substitution for hydro in indigo dyeing as it was found practical and feasible for implementation even by small-scale units in India.

Introduction: A simple and eco-friendly synthesis of novel substituted pyrimido[1,6- a]pyrimidine, pyrimido[1,2-g]purine, and pyrimido[2,1-e]purine was accomplished by refluxing of nucleobases (cytosine, adenine or guanine) and dibenzalacetone (DBA) in water using NaOH as a catalyst.Methods: The molecular structures of the resulting products were characterized by infrared spectroscopy (FT-IR), mass spectrometry, and proton (¹H) and carbon (¹³C) nuclear magnetic resonance (NMR).Results: The antibacterial activity of the newly fused heterocycles was assayed against the Gram-positive bacterium Staphylococcus aureus (ATCC 6538) and Gram-negative Escherichia coli (ATCC 8737) using gentamicin as a standard commercially available antibiotic.Conclusion: In addition, the antioxidant capacity was screened using the 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH•) and the 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS+•) radicals scavenging assay.