Chemical Review and Letters
Volume:6 Issue: 2, Spring 2023

Thioethers are one of the most important family of organosulfur compounds that have shown lots of applications in pharmaceuticals, agrochemicals, polymeric materials and organic dyes. Interestingly, over 30 FDA-approved drugs contain at least one thioether motif in their structures and are used to treat a wide range of diseases, from depression to rheumatoid arthritis to acute coronary syndrome. Therefore, looking for novel, efficient, and straightforward methodologies for their synthesis from low cost, readily available, and non-toxic starting materials is very important in organic chemistry. In this context, the reactions between various electrophiles and sulfenylating agents has recently attracted more and more attention as a general and straightforward route for their synthesis. However, most of the existing sulfenylating agents had some disadvantages, such as a foul smell, high cost and being unstable to air and moisture. Recently, sulfinic esters have emerged as odor-less, easily accessible, stable and easy to handle sulfenylating agents and successfully applied in the synthesis of various aliphatic and aromatic thioethers, mainly through the site-selective functionalization of C–H bonds. The purpose of this review is to provide an overview of the available literature on the synthesis of thioethers using sulfinic esters as sulfenylating agents, with special emphasis on the mechanistic features of the reactions. Literature has been surveyed from 2016 to the end of 2022.

Hyoscine butyl bromide (HBB), also known as scopolamine butyl bromide, is an anticholinergic medication used to treat bladder spasms, renal colic, esophageal spasms, and crampy abdominal pain. A fast and simple spectrophotometric approach is developed for the determination of hyoscine butyl bromide in pure and pharmaceutical formulations using batch and flow injection methods. The proposed approach is based on the reduction of ferrate ion to ferrous ion by HBB and the subsequent formation of excess Fe(III)-thiocyanate complex which gave maximum absorbance at 478 nm. The experimental conditions of both methods for the assay were studied and optimized. The absorbance was found to decrease linearly with the drug concentration to give a calibration curve which obeys Beer’s law in the range of 0.5-200, and 5.0-200 μg/mL with a linear regression coefficient of 0.9964, and 0.9909 with detection limits of 1.40, and 2.10 µg/mL for both batch and rFIA methods, respectively. The proposed approaches were successively applied for the determination of the studied drugs in their different pharmaceutical dosage forms and gave an excellent per cent of recovery compared with the official international pharmacopoeia method.

Through the use of theoretical techniques, this study investigated the corrosion inhibition potentials of a few chosen nitrogen-based five membered ring heterocycles, such as 2-methyl-1H-imidazole (2MI), 2-methyl-oxazole (2MO), 2,4,5-trimethyl-thizole (2TT), and 3-methyl-4,5-dihydro-1H-pyrole (MPP), on the surface of mild steel. To determine the potentials of these compounds in corrosion inhibition and to suggest a mechanism for the process, quantum chemical parameters, Fukui indices, and quench molecular dynamic simulation approaches were used. The corrosion inhibition potentials of the examined compounds were discovered to be caused by the existence of numerous hetero atoms rich in n-electrons, pi-bonds, molecular shape, and charge distribution. The outcomes demonstrated that each molecule's adsorption or binding energy is negative and comparatively low, less than the +100kcal/mol threshold. It has also been discovered that, depending on the parameters examined, the 2TT molecule may be more efficient in preventing corrosion on the Fe(1 1 1) surface. This is owing to the sp3 sulfur heteroatom in its structure, which is probably less electronegative than other sp3 heteroatoms (oxygen and nitrogen) in the compounds, in addition to the sp2 nitrogen each of them contained. from the results, all of the investigated compounds have the capacity to prevent mild steel corrosion. The molecules adhere to the physical adsorption process, the mechanism, the expected adsorption/binding energies, and the molecule's examined properties all indicate that 2TT is substantially a stronger corrosion inhibitor on Fe(1 1 1), in the following order: 2TT >MDP > 2MI > 2MO.

In this research, the adsorption behavior of Fe-decorated porphyrin is investigated toward ethionamide (EA) using Density Functional Theory (DFT) calculations. Total energies, geometry optimizations were obtained and Density of State (DOS) analysis was performed at B3lyp level of theory with the 6-31G* basis set. The adsorption energy (Ead) between EA and the pristine, Si-, Ga- and Al-doped graphene is changed in the following order: Ga-Complex-N(ring) > Al- Complex-N(ring) > Si-Complex-N(ring) > Complex-S. The Ead of the Graphene-EA complex is -2.552 kcal/mol, which is low and shows that the adsorption is physical. The % ΔEg= -59.61% for Si-doped graphene EA shows the high sensitivity of the Si-doped graphene to the adsorption of EA. The Eg for Ga-doped graphene-EA decreases significantly from 2.35 to 1.11 eV and the rate of change is %ΔEg = -52.75%, showing the high sensitivity of Ga-doped graphene to the adsorption of EA. However, the high Ead of -36.66 kcal/mol shows that the Ga-doped graphene can be used as a suitable sensing device only at higher temperatures. The % ΔEg= -58.98 % for Al-doped graphene-EA indicates the high sensitivity of the Al-doped graphene to the adsorption of EA. The Ead of -34.53 kcal/mol can be used as a suitable sensing device only at higher temperatures.

Oxidation and decarboxylation are among the most important processes in organicsynthesis. The combination of these two fundamental processes provides a novel syntheticstrategy, that is, oxidative decarboxylation. Over the past few years, considerable attentionhas been focused on such an attractive research arena. This review offers an overview of theutility of oxidative decarboxylation in the synthesis of various aryl aldehydes and ketonesfrom the corresponding arylacetic acids. The review is divided into three major sections. Thefirst section focuses exclusively on metal-catalyzed reactions. The second section will discussmetal-free approaches. The third will cover photoredox-catalyzed decarboxylative oxidations.Literature has been surveyed from the year 1980 to 2022

Optimizing adsorption processes with the use of standard central composite designs (CCD) for the removal of contaminants from wastewater is becoming more popular. The use of standard CCD enables the variables under study to be randomized. However, some studies, particularly those conducted within industries, usually involve factors with some hard to change (HTC) levels and others with easy to change (ETC) levels, in which case the HTC factor cannot be totally randomized, resulting in a split-plot design. The optimum conditions for the removal of 4-bromophenol (4-BP) from synthetic wastewater onto BiFeO3 were investigated in this study using split plot CCD and three adsorption factors (pH, adsorbent dosage, and shaking time) were considered. The pH was considered the HTC factor because of the duration of time, acid and/or base required to change it, whereas the adsorbent dosage and contact time were the ETC variables. Adsorbent dosage of 0.60 g, pH of 7, and contact time of 167 minutes were found to be the optimum adsorption conditions at desirability of 1. The predicted and experimental adsorbed values were 88.02 % and 87.86 %, respectively, indicating that the experimental and predicted values were in good agreement. The equilibrium adsorption data was found to be best suited by the Langmuir isotherm model, yielding a monolayer adsorption capacity of 65.96 mg/g. Regression results, as well as qe experimental and qe calculated values, reveal that the pseudo-second-order model more closely represents the kinetics.

In this paper, a new aprotic N2O2-tetradentate Schiff base ligand and its mercury complexes were synthesized with a general formula of HgLX2 (X is Cl−, Br−, I−, N3−, NO3− and SCN−) and characterized by physical and spectral techniques such as IR, UV-Visible, 1H NMR, 13C NMR, ESI/MASS, molar conductivity, thermal analysis and melting point. In addition, nanostructured HgLI2 and HgLBr2 complexes were also synthesized and confirmed using SEM, EDX and XRD techniques. Thermal analysis of the ligand and complexes showed that these compounds decompose in 2-3 steps. Moreover, some thermo-kinetics activation parameters of the compounds were calculated at all the thermal decomposition steps. The biological properties of synthesized compounds were tested against two gram-positive and two Gram-negative bacteria. Also, Aspergillus oryzae and Candida albicans were selected for antifungal screening of the compounds. Further, the bactericidal effects of the compounds were depicted by SEM images of treated bacteria by the ligand and some mercury complexes. The ability of DNA cleavage of N2O2-tetradentate Schiff base ligand and its complexes was investigated by the agarose gel electrophoresis method. The results showed that Schiff base mercury complexes had higher antibacterial/antifungal activity as compared with the free ligand. HgLX2 compounds also showed a greater ability to cleavage of DNA than free ligand. Furthermore, the cytotoxicity properties of the ligand and some HgLX2 (X=Cl−, Br− and I−) complexes were evaluated against the PC3 cancer cells line by using MTT bioassay and nitric oxide level measurement as compared with cisplatin. Finally, the antioxidant activities of the titled compounds were measured by DPPH and FRAP methods.

Methyl ester is the name given to monoalkyl esters of vegetable and animal oils. Since methyl ester has fuel properties that are comparable to those of diesel fuel, it is becoming more popular as a substitute fuel for use in diesel engines. The amount of free fatty acids (FFA) in the oil determines how methyl ester is produced. In this study, the titration method was used to calculate the FFA values of the crude cottonseed oil (CCSO) and one-time Used Cottonseed Oil (UCSO), with values 0.56 % and 1.26 %, respectively. The UCSO is transformed into methyl ester by employing a heterogeneous alkali catalyzed transesterification reaction. It involves the addition of methanol to bleach and degummed UCSO in the presence of heterogeneous catalysts CaO-blend derived from calcinated eggshells and coconut shell blend. Reaction variables including the methanol-to-oil ratio, reaction temperature, reaction time and catalyst concentration control the transesterification process. The Box-Behnken design was employed to optimize the aforementioned parameters using the response surface methodology (RSM). Numerous factors that affect the generation of biodiesel have been plotted using the response surface plot and contour plot. An optimized UCSO methyl ester yield of 92.00 % was obtained at a 1:10.80 molar ratio, 2.5 wt. % catalyst concentration, 80 minute reaction time, and 60 °C reaction temperature. The experimental yield was 92.10 %, as determined by the optimized yield based on these parameters. This shows that the response surface methodology is a successful strategy for increasing the yield. The regression model proved successful, as observed by the error values between the predicted and actual outcomes being less than 1 % UCSOME conversion. For this study, adequate precision was 8.9518. As a result, the model can be utilized to explore the design space. Each succeeding cycle of reuse produced 91.60 %, 85.50 %, 81.60 %, 78.60 %, 74.20 %, and 72.87 % of the biodiesel. The measurements for viscosity, density, and flash point of UCSO were 33-36 mm2/s at 311 K, 911-916 kg/m3 at 288 K, and 504-510 K, respectively. UCSO methyl ester (UCSOME) had a viscosity between 3.6 and 3.7 mm2/s and a density between 875 and 880 at 311 K. While the flash points of the UCSOME are measured at 435–440 K as opposed to 504-510 K. The saponification value of cottonseed oil was 188.32 mg/g while that of biodiesel was 165.87 mg/g. Thus, biodiesel fatty acid methyl ester possesses a distinctive FTIR absorption of carbonyl (C=0) stretching vibrations near 1740-1744 cm-1 and C-O bending vibrations in the range of 1196 cm-1.

Recent trends in direct S-cyanation of thiols. This review article is related to Recent trends in direct S-cyanation of thiols

In present computational survey, we are compared and contrasted electronic effects of C20 and its C20-2nTinBn heterofullerenic derivatives with n = 1-5, at density functional theory (DFT). All nanocages are true minima and none of them collapses to deformed open cage as segregated nanostructure. Isolating five single hetero bonds of Ti—B via either one double bond of C═C or one carbon atom is a suitable method for reaching highly substituted stable heterofullerene i.e. pen-shell C10Ti5B5 since it prevents from weak homo bonding of Ti—Ti and B—B. The C1-C18Ti1B1 heterofullerene can avoid from the most strained directly fused five-pentagon configuration, but its open-shell electronic structure with highly pyramidalized titanium atom (126.59° i.e. 3-4 times relation to C20) may render it too reactive to be observed under typical experimental conditions. The calculated binding energy (B.E.) shows C10Ti5B5 as the most stable heterofullerene. Contrary on B.E., the absolute heat of atomization of heterofullerenes decreases as number of substituting Ti―B unit (n) increases. Hence, substitution effect on binding energy is more significant than heat of atomization. Compared to the previously reported material such Ti-decorated B38 nanofullerene as a suitable hydrogen storage with B.E. of 5.67 eV/atom, our studied C20-2nTinBn heterofullerenes show the higher B.E. with range of 12.25 to 38.03 eV/atom, the higher stability and the higher capacity for hydrogen storage. Interestingly, C18Ti1B1 heterofullerene must be not only kinetically stable against electronic excitations but also based on natural bond orbital (NBO) analysis, the highest charge transfer (CT) is take placed from πC=C bonds to the neighboring LP*B, LP*Ti and σ*Ti-B anti-bonds of it. Also, the exceptionally large value of nucleus-independent chemical shifts (NICS) is found for C18Ti1B1 compared to the archetypically aromatic benzene and [2.2]paracyclophane molecules.