Mini-Reviews in Organic Chemistry - Volume 17, Issue 7, 2020

Microbial Fuel Cells (MFCs) offer a sustainable solution for alternative energy production by employing microorganisms as catalysts for direct conversion of chemical energy of feedstock into electricity. Electricity from urine (urine-tricity) using MFCs is a promising cost-effective technology capable of serving multipurpose benefits - generation of electricity, waste alleviation, resource recovery and disinfection. As an abundant waste product from human and animal origin with high nutritional values, urine is considered to be a potential source for extraction of alternative energy in the coming days. However, developments to improve power generation from urine-fed MFCs at reasonable scales still face many challenges such as non-availability of sustainable materials, cathodic limitations, and low power density. The aim of this paper was to critically evaluate the state-of-the-art research and developments in urine-fed MFCs over the past decade (2008-2018) in terms of their construction (material selection and configuration), modes of operation (batch, continuous, cascade, etc.) and performance (power generation, nutrient recovery and waste treatment). This review identifies the preference for sources of urine for MFC application from human beings, cows and elephants. Among these, human urine-fed MFCs offer a variety of applications to practice in the real-world scenario. One key observation is that, effective disinfection can be achieved by optimizing the operating conditions and MFC configurations without compromising on performance. In essence, this review demarcates the scope of enhancing the reuse potential of urine for renewable energy generation and simultaneously achieving resource recovery.

Coumarin and oxadiazole moieties ubiquitously occur in a wide range of natural products and are valued for their varied and beneficial pharmacological activities. Herein, this review focuses on various documented techniques used by researchers to synthesize an assortment of biologically active coumarin-oxadiazole scaffolds. Also, the common techniques discussed are used to establish the wide-range of biological activities of the synthesized coumarin and oxadiozole derivatives, including; antioxidant, anthelmintic, antimicrobial, anti-tuberculosis, analgesic, anti-inflammatory, cytotoxicity and anticonvulsant. Additionally, the current, well-established drugs synthesized using coumarin-oxadiazole scaffolds are typically dispensed in regular clinical practice are also highlighted in this review paper.

Faujasite Y zeolites, due to their outstanding properties, have numerous applications in the chemical industries like petroleum refining, adsorption, FCC, petrochemical, aromatic alkylation, natural gas dehydration, separation, and environmental protection. The astonishing properties include high surface area, high porosity, high thermal stability and large ion-exchange capacity. In this review study, a summary of different synthesis techniques of this type of zeolite has been addressed. Different kinds of techniques like seeding, free template, organic template, increasing the alkali treatment and temperature control methods are described. Subsequently, because of its important role as a catalyst for different processes, the application of this zeolite was reviewed for different chemical processes.

A literature survey on C-methylation of organic substrates with methane as a methylating agent is analyzed. Of the substrates that undergo C-methylation are benzene, naphthalenes, toluene, alkanes, alkenes, acetonitrile, and other functionalized organic compounds. None of these methylation reactions occur in the absence of a catalyst. A direct introduction of a methyl group on the carbon sites of a molecule is concomitant with the formation of other products, as a result of either a possible rearrangement or a further reaction with methane. Mechanistically, the C-methylation with methane proceeds oxidatively. The products selectivities depend on several factors, mainly on the acid/ base character of the solid catalyst.

Cancer is a common disease that poses a serious threat to human health. Angiogenesis is essential for the growth and metabolism of tumors, providing oxygen and nutrition for the growth of cells and tissues. However, angiogenesis of tumors depends on the stimulation of growth factors. Vascular Endothelial Growth Factor (VEGFR) is the most unique factor. Therefore, VEGF/VEGFR targeting anticancer drugs are playing an increasingly significant role in clinical trials. In addition, it has been proved that chalcone, the precursor of natural flavonoids, has potential anti-tumor activity, especially anti-angiogenesis activity. This review summarizes the reports about the anti-angiogenesis of chalcone derivatives. Based on the chalcone skeleton, it is divided into substituted chalcones and modified chalcones. The anti-angiogenesis activities of natural or synthetic chalcones, benzene ring modified or connecting bridge modified chalcones are described in this review.

α,β-Unsaturated acids are well-known and useful reagents, and they have been applied in different fields due to their fascinating properties. The catalytic Knoevenagel condensation reaction is one of the most remarkable methods for the formation of C=C bonds. The multi-substituted alkenes can be obtained from the reaction of carbonyl and active methylene compounds in the presence of base catalysts, Brönsted catalysts, Lewis acid catalysts, or ionic liquids. In terms of providing both desirable structural diversity and compound libraries, Doebner-Knoevenagel condensation is the most efficient strategy. There is a high demand for an efficient, rapid, environment-friendly, and sustainable catalytic protocol under milder conditions for the stereoselective synthesis of Knoevenagel products, which can tolerate a wide variety of functions. Carrying out the transformations through alternative reagents, catalysts, or methods provides a valuable and broad space for selectivity. Herein, the recent advances in the synthesis of structurally diversified Knoevenagel products using nanocatalysts are reviewed.

Parthenium hysterophorus (Compositae), an obnoxious weed, was investigated thoroughly for its chemical constituents. We isolated a large number of pseudoguaianolides and other compounds. Many of the isolates are new natural products. Parthenin, the major pseudoguaianolide, was synthetically converted to its various analogues. Some of the constituents of the plant and of the prepared analogues were found to possess significant antibacterial and anticancer properties. Here, we review our phytochemical research on Parthenium hysterophorus informing of our work on the isolation, structure elucidation, synthetic modifications, and bioevaluation of its chemical constituents.

Raw materials from renewable natural resources for industrial applications are in high concern in recent industrial research. Researchers invest their time in the management of waste as well as the conversion of waste to wealth. In that line, the production of biofuels including biodiesel, and value-added products from non-edible oil sources as well as from the generated waste biomasses, are in the tilt of research in recent times. Preparation of different oleochemicals such as grease, resins, soap, lubricants, etc. from vegetable oils, and utilization of seed cake as fertilizer, animal feed, medicine, etc. are encouraged as a part of the generation of waste to wealth as per today’s environment is concerned. In recent days, various reports on the production of biodiesel and other oleochemicals from non-edible oil sources are published in various scientific journals. Yellow oleander (Thevetia peruviana) is a tropical shrub which produces a toxic non-edible fruit containing a high percentage of seed oil (up to 67%), protein (30-37%) as well as other medicinally important phytochemicals. It is attracting the researchers worldwide for the production of biodiesel, various oleochemicals, medicine, animal feed, etc. In this study, biodiesel and various value-added products synthesized from Thevetia peruviana oil and cake are reviewed to generate and popularize the potential use of yellow oleander seed for various industrial applications and accordingly, for substantial growth in cultivation for commercial-scale requirements.

Rubiaceae family belongs to the Gentianales, it contains 650 genera and 13,000 species and its worldwide distribution makes it the fourth largest angiosperms. Rubiaceae contains a large amount of anthraquinone compounds, especially in the roots. Anthraquinones are very important natural products with various bioactivities, including antibacterial, antiviral, cytotoxic and antitumor, which make it play an important role in recent research. In the previous study, many researchers have reported anthraquinones from Rubiaceae in different aspects. The present paper provides an overview of the bioactive properties of new naturally occurring anthraquinones and its structural diversity that have been isolated from the Rubiaceae family in recent years. The article covers the literature from 2007 to 2018, overall 95 new anthraquinones.

The depletion of fossil fuel requires the search for alternative renewable feedstock and environmentally friendly methods for the production of high value-added compounds and fuels. In this context, the efficient use of biomass has emerged as a significant research field as it represents an alternative green and renewable carbon source. Various technologies have been explored for this purpose and heterogeneous photocatalysis represents a valid alternative to the catalytic methods since it can be carried out under mild experimental conditions without the addition of harmful oxidizing agents. Different biomass components have been used as the starting materials, and many valuable chemicals have been obtained with different selectivity depending on some experimental conditions as, for instance, type of photocatalyst, solvent, and physico-chemical features of the catalysts. Moreover, by carrying out the reaction in de-aerated systems, in addition to high added value compounds, hydrogen can be obtained in the gaseous phase. In particular, photocatalytic conversion of lignocellulose, carbohydrates, 5-hydroxymethyl-2-furfural and glycerol (considering only the partial oxidation products) is reported.