Classical and advanced chemical sciences
Thermal study of some novel bisphenol-C derivatives has been investigated using TG and DSC techniques under nitrogen atmosphere at the heating rate of 10 ºC min-1. The nature and position of the substituents affect DSC transition, thermal stability, and kinetic parameters. Melting transitions (57-237 oC) and heat of fusion (15-78 kJ mol-1) of the compounds have been determined from DSC curves. Bisphenol-C derivatives are thermally stable up to about 215-350 oC and followed either integral or fractional order degradation kinetics due to structural dissimilarity—different magnitudes of n, Ea and A suggested different degradation mechanisms. Large and negative magnitudes of ΔS* confirmed a highly ordered transition state, while large and positive magnitudes of ΔS* confirmed a less ordered transition state.
Keywords: Kinetic parameters; Bisphenol-C; Thermal decomposition; TG; DSC
In recent decades, the energy demand is ever increasing. Biomass energy is a viable option as an alternative due to reduced CO2 emissions and depletion of fossil fuels at a faster rate. Therefore, the substitution of non-renewable fossil resources by renewable biomass as a sustainable feedstock has been focused on researchers to develop useful green fuels and other platform chemicals such as biofuels, commodity chemicals, and new bio-based materials. For the conversion of sugars, several methodologies have been investigated through chemocatalysis from plant-derived biomass feedstocks. This review critically overviewed the latest advancement regarding reaction conditions, product yields, and selectivity on the conversion of C6-sugars into important chemicals like 5- hydroxymethylfurfural, levulinic acid, lactic acid, formic acid, glyceraldehyde, 1,3-dihydroxyacetone and furan-2,5-dicarboxylic acid, etc. This review describes green chemistry principles includes the main reactions used to convert renewable biomass into industrially important products that are applicable as raw materials with emphasis on preparative organic synthesis.
Keywords: Biomass; carbohydrates; solid catalysts; 5-hydroxymethylfurfural (HMF); value-added chemicals
The data on the specifics of synthesis of elemental silver nanoparticles (SNPs) having the shapes of various geometric shapes (pseudo spherical, prismatic, cubic, trigonal-pyramidal, etc.), obtained by using various plant and animal substrates, and fields of their possible use, have been systematized and generalized. The review covers mainly articles published in the current XXI century.
Keywords: silver nanoparticles (SNPs); geometric shape; biosynthesis; plants; animals
It has been observed that countries without universal policies of BCG vaccination are more severely affected compared to countries with long-established BCG vaccination policies. This has led researchers to investigate the possible relation between BCG and COVID-19. The authors have evaluated the current research regarding the role of the universal Bacille Calmette Guerin (BCG) vaccination policy of a country to the morbidity and mortality due to COVID-19/ SARS-CoV-2 in that country. It is believed that the BCG vaccine trains the immune system of the human body for non-mycobacterial pathogens through non-specific immunotherapeutic mechanisms. Most of the epidemiological studies point towards a positive correlation but barring a few, and they tend to ignore factors like lower testing rates in countries having universal BCG policy. BCG vaccination policy cannot be seen in isolation as the factors like climatic conditions, nutritional habits, genetic and ethnic aspects, social and cultural influence and age distribution also are responsible for the varied morbidity and mortality due to COVID-19. Multiple-dose BCG vaccine repurposing for SARS-CoV-2, however, should be explored. Clinical trials of the BCG vaccine to test its efficacy on SARS-CoV-2 are urgently needed before deducing unidirectional correlations.
Keywords: SARS-CoV-2; Universal BCG vaccination policy; COVID-19; Coronavirus; Morbidity; Mortality
A series of functionally substituted pyrazole compounds have been synthesized using classical chemistry. Here we synthesized trifluoromethyl containing pyrazole compound by condensation of arylhydrazine derivative with ethyl (2E)-2-(ethoxymethylidene)-4,4,4-trifluoro-3-oxobutanoate. Pyrazole moieties have essential pharmaceutical and agrochemical activities. Our research-based on trifluoromethyl-containing pyrazole compounds synthesis also helps to improve biological activities due to fluorine binding affinity properties.
Keywords: pyrazole; ethyl (2E)-2-(ethoxymethylidene)-4,4,4-trifluoro-3-oxobutanoate; arylhydrazine
Huge amount of coal fly ash, generated from power plants which contain trace toxic metals also like Pb, As, Hg, Ni, Cd and Ba etc., is considered as an environmental hazard worldwide. These toxic elements are leached into water, soil and ground water from coal fly ash and contaminate them. The leaching behaviour of trace toxic elements as a function of liquid/solid (L/S) ratio present in coal fly ash from three coal-fired power plants were studied by conducting US EPA leaching test methods (LEAF). The test has been conducted under a different range liquid to solid ratios. Most of trace elements show similar nature of liquid/solid partitioning (LSP) curve in the different coal fly ash samples in the leaching tests despite of elemental and mineralogical compositions and different ranks of coals fly ash. LSP curves of trace elements from fly ash samples in the L/S ratios tests (LEAF) shows some variations also. The present study is an assessment the leachability of trace elements in three coal fly ash samples collected from three power plants by LEAF at different L/S ratios.
Keywords: Thermal plant, leachate, coal fly ash, pollution, human health
Herein we report synthesis of 3-methyl-2-((2-styrylphenoxy)methyl)-4-(2,2,2-trifluoroethoxy)pyridine derivatives (9a-j) from 2-((3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl)methoxy)benzaldehyde (7) and appropriate acetophenone (8a-f) afford very good to excellent yield (80-95 %). The structure of newly synthesized compounds have been established on the basis of 1H-NMR, 13C-NMR, ESI-MS and elemental analysis. All compounds (9a-f) were screened for their in vitro antibacterial activity against Gram-positive bacteria (Streptococcus pneumoniae and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Vibrio cholerae) and antifungal activity against C. albicans and A. fumigatus by MIC method.
Keywords: Pyridine derivatives; chalcone; antimicrobial activity; antifungal activity
The work is devoted to the preparation of zinc complexes of tetra(4-octyloxyphenoxy)phthalocyanines, as well as its sulfonated derivatives and the study of their properties, primarily spectroscopic and luminescent. The compounds were synthesized and characterized by IR and electron spectroscopy, MALDI-TOF mass spectrometry and elemental analysis. Absorption spectra were obtained in the visible range in chloroform, DMF, water (for the sulfonated analogue). It was shown that in the studied concentration range the complexes exist in monomeric form. Sulfonated phthalocyaninates turned out to be aggregated only in an aqueous medium, which made it possible to study the fluorescent properties in an organic medium (namely, in DMSO). The introduction of a sulfonate groups was found to lead to quenching of fluorescence in comparison with an organo-soluble phthalocyaninate.
Keywords: Phthalocyanine; synthesis; metal complexes; fluorescence; absorption spectroscopy