Ring opening of epoxides with alcohols using Fe(Cp)2BF4 as catalyst

Fe(Cp)₂BF₄ is an efficient catalyst for the alcoholysis of aromatic, aliphatic, and cyclic epoxides giving excellent yields of the corresponding β-alkoxy alcohols under ambient conditions. The methanolysis of styrene oxide using Fe(Cp)₂BF₄ as a catalyst (5 mol %) gave excellent yield of 2-methoxy-2-phenylethanol with complete regio-selectivity. The ring opening of cyclic epoxides gave 77–97% yields of trans-β-methoxy alcohols, in 0.5–6 h. The use of 1,2-epoxyhexane and 1,2-epoxydodecane as substrates gave both regioisomers in excellent yields. The first order rate of reaction with respect to catalyst was observed for the kinetics of ring opening of 1,2-epoxyhexane with methanol.     

Application of oxetane ring opening toward stereoselective synthesis of zincophorin fragment

A stereoselective synthesis of the C1–C11 fragment of zincophorin was achieved by using an intramolecular oxetane ring opening reaction as the key step. The oxetane moiety was synthesized by employing a desymmetrization protocol developed at our group and a non-Evans syn aldol as the key steps toward the synthesis.     

Base mediated synthesis of α-aminated aroyl/acetylnaphthalenes through [4+2] annulations

We have developed a base promoted simple, efficient and alternative approach for the synthesis of 4-amino-3-aroyl//heteroaroyl/acetyl-2-methylsulfanyl-naphthalene-1-carbonitriles by reaction of easily accessible 3,3-bis(methylthio)-1-aryl/heteroaryl/acetylprop-2-en-1-one and 2-cyanomethyl-benzonitrile. Reaction of 1-(2-halo/methoxy-phenyl)-3,3-bis(methylthio)prop-2-en-1-one and 2-cyanomethyl-benzonitrile under basic conditions also afforded 6-(methylthio)-7-oxo-7,12-dihydrobenzo[c]acridine-5-carbonitrile along with usual product. Structure of the synthesized product has been confirmed by single X-ray crystallography.     

Visible-light-promoted aerobic oxidative cyclization to access 1,3,4-oxadiazoles from aldehydes and acylhydrazides

A novel and practical access to symmetrical and unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles directly from aldehydes and acylhydrazides using visible light irradiation under an air atmosphere in the presence of eosin Y as an organophotoredox catalyst at rt is reported. This is the first example of oxidative cyclization of acylhydrazones employing air and visible light as inexpensive, readily available, non-toxic, and sustainable reagents.     

Stereoselective total synthesis of oplopandiol,oploxyne A,and oploxyne B

A stereoselective total synthesis of oplopandiol, oploxyne A, and (−)-oploxyne B is described. The key reactions include Sharpless asymmetric epoxidation, d-proline catalyzed aminoxylation, Cadiot–Chodkiewicz cross-coupling reaction, m-CPBA induced substrate-controlled stereoselective epoxidation, and Lewis acid catalyzed stereo- and regioselective ring-opening of epoxide.     

Experimental and Theoretical Studies on Synthesized Compounds as Corrosion Inhibitor for Mild Steel in Hydrochloric Acid Solution

Imidazole derivatives, namely, 1-((1-(piperazinomethyl)-1H-benzoimidazol-2-yl)methyl)-2-phenylhydrazine (PBIP), and 1-((1-(morpholinomethyl)-1H-benzoimidazol-2-yl)methyl)-2-phenylhydrazine (MBIP) were synthesized and investigated as inhibitors for mild steel corrosion in 15% HCl solution using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques. It was found that the inhibition efficiency of both the inhibitors increases with increase in concentration of inhibitors and decreases with increase in temperature. The inhibitors, PBIP and MBIP, show corrosion inhibition efficiency of 92.6% and 91.4% at 300 ppm concentration, respectively, at 303 K. Polarization studies showed that both the studied inhibitors were of mixed type in nature. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were performed for surface study of uninhibited and inhibited mild steel samples. The semi-empirical AM1 method was employed for theoretical calculations.     

Levels and effects of natural radionuclides in soil samples of Garhwal Himalaya

Distribution of natural radionuclide gives significant parameter to assess the presence of gamma radioactivity and its radiological effect in our environment. Natural radionuclides are present in the form of ²²⁶Ra, ²³²Th and ⁴⁰K in soil, rocks, water, air, and building materials. Distribution of natural radionuclides depends on the type of minerals present in the soil and rocks. For this purpose gamma spectrometer is used as tool for finding the concentration of these radionuclides. The activity concentration of naturally occurring radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in these soil samples were found to vary from of 8 ± 1 Bq/kg to 50 ± 10 Bq/kg with an average 20 Bq/kg, 7 ± 1–88 ± 16 Bq/kg with an Average 26 Bq/kg and 115 ± 18–885 ± 132 Bq/kg with an average 329 Bq/kg, respectively. In this paper, we are presenting the radiological effect due to distribution of natural radionuclide present in soil of Garhwal Himalaya.     

Multivariate statistical analysis approach to assess groundwater quality in two selected mandals of Vizianagaram district,Andhra Pradesh,India

Groundwater quality is the major concern all over the world. Natural processes and manmade activities are the prime reasons for the contamination of available water resources. It is crucial to assess the quality of groundwater in areas surrounded by various industries. The present study was carried out to assess the groundwater quality during pre-monsoon and post monsoon seasons of 2016, in two mandals of Vizianagaram district of Andhra Pradesh via multivariate statistical analysis and water quality index method. The present work gains importance in light of the construction of proposed international airport at Bhohapuram and the existence of various industries in Pusapatirega mandal. A total of thirty-seven villages, eighteen from Bhogapuram mandal and seventeen from Pusapatirega mandal were selected for the present study. Factor analysis, linear regression analysis, correlation matrix analysis and cluster analysis tools were used to emphasize the parameters influencing quality of water in the chosen study area. From the analysis reports, it was found that the groundwater of the two mandals under investigation was strongly influenced by EC, TDS, total hardness(TH), Ca⁺², Mg⁺² and K⁺. During the two seasons under study, the water quality index value was found to be greater than 100 indicating that the water is unfit for human consumption. Concentration of Ca⁺², Mg⁺² and K⁺ were found to be beyond the permissible limits prescribed by BIS (2012). Dissolution of calcium and magnesium bearing minerals, mixing of industrial and household wastes may be the reasons for elevated concentration levels of these parameters.     

Nelumbo nucifera leaves as source of water-repellent wax: Extraction through polar and non-polar organic solvents

Nelumbo nucifera leaves are rich source of natural wax possessing super-hydrophobic properties. It provides protection to them from ecological turbulences and climatic wear and tear. In this study, various experiments have been conducted to observe the yield of extraction and the determination of various functional groups, which are present in natural wax, derived from Nelumbo nucifera leaves. The natural wax has been extracted from lotus leaves through non-polar (hexane) and polar (ethanol) solvent via different extraction methods. The superhydrophobic wax has been successfully extracted with hexane. Whereas, ethanol did not extract the water-repellent wax of lotus leaf. Considering the cumulative amount, i.e. (desired + undesired), the maceration shows the extraction of 2.9% (%w/w, through hexane) and 10.2% (%w/w, through ethanol), while it was found 2.5% (%w/w, cycle period 15 min) and 9.0% (%w/w, cycle period 26 min) respectively, in case of Soxhlet extraction technique. For this specific case of natural wax recovery from biomass (lotus leaf), the maceration (traditional method) resulted a little bit superior extraction yield in comparison to the Soxhlet extraction method for extraction of crude wax. In the case of non-polar solvent (hexane), an extraction yield of 1.97% (%w/w) through maceration method was observed while in the case of non-polar solvent (ethanol), an extraction yield of 1.62% (%w/w) through Soxhlet extraction was observed. The TLC analysis on both types of extracts was performed. For the detection of various hydrocarbon chains in the crude wax extracts, FTIR was also performed. Topography of wax surface and wax-coated waterproof fabric was compared through SEM.     

Hydrothermal processing of waste pine wood into industrially useful products

An ongoing major outbreak of mountain pine beetle in Western Canada has provided a clear opportunity to utilize waste pinewood as a source of renewable energy. Therefore hydrothermal processing of waste pinewood as a feedstock for bio-oil and biochar production using subcritical and supercritical water technology was carried out in semi-batch mode to investigate the effect of pressure (200–400 bar) and temperature (300–400 °C) on the yield and composition of bio-oil. The pinewood samples have very high cellulose and hemicellulose content but low ash content and are thus a formidable feedstock for bioenergy production. The optimum conditions for the hydrothermal processing of the pinewood in a tubular reactor were found to be 400 °C and 250 bars with respect to biochar and bio-oil yield based on the highest calorific value analysis. Detailed characterization of bio-oil and biochar was performed using GCMS, NMR, SEM, calorific value, and elemental analysis, respectively. The critical components of bio-oil were found to be phenols, methoxyphenols, hydroxymethyl furfural (HMF), and vanillin, whereas as compared to the raw pine wood, the biochar was considerably lower H:C and O:C ratios than those of the unprocessed pinewood. The analyses of bio-oil by means of GCMS and ¹H NMR showed that it was mainly composed of heterocyclic compounds, phenols, aldehydes and acids.