Classical and advanced chemical sciences
A new, specific, and robust normal phase liquid chromatographic (NP-LC) method for the determination of structurally similar impurities (isomers) of Vortioxetine hydrobromide has been developed and validated. An excellent chromatographic resolution between the structurally similar impurities (isomers) and Vortioxetine hydrobromide was achieved on Chiralpak-ADH (250 x 4.6 mm ID), 5 μ column. The mobile phase used of n-hexane, ethanol, diethylamine, and trifluoroacetic acid in the ratio (75:25:0.05:0.05, v/v/v/v) and the flow rate was maintained at 1.0 mLmin-1. UV detection was carried out at 235 nm. The resolution between all positional isomers and Vortioxetine hydrobromide was found not less than 2. An effect of column oven temperature on the resolution was also studied and found to be ≥ 2.0. Three structurally similar impurities (Isomer-1, Isomer-2, and Isomer-3) have been detected in the test sample of Vortioxetine hydrobromide by advanced NP-LC method. Further, these isomeric impurities were characterized by mass spectrometry, 1H NMR and FT-IR spectral data. The developed method was validated as per ICH guidelines and found to be specific, robust, and selective. The developed NP-LC method was successfully applied to the analysis of drug substance and drug product samples of Vortioxetine hydrobromide.
Keywords: Vortioxetine; positional isomers; isomeric impurities; HPLC method; normal phase
We have found that ninhydrin reacted with N-hydroxyurea and N-alkoxyureas in acetic acid with the predominant formation of diastereomers of 1,3a,8a-trihydroxy-1,3,3a,8a-tetrahydroindeno[1,2-d]imidazole-2,8-dione and 1-alkoxy-3a,8a-dihydroxy-1,3,3a,8a-tetrahydroindeno[1,2-d]imidazole-2,8- diones, respectively. with sic-orientation of 3a,8a-HO-groups. The X-ray structural analysis of 1,3aS,8aR-trihydroxy-1,3,3a,8a-tetrahydroindeno[1,2-d]imidazole-2,8- dione and 1-n-butyloxy-3aS,8aR-dihydroxy-1,3,3a,8a-tetrahydro- indeno[1,2-d]imidazole-2,8-dione has demonstrated their specific structural features.
Keywords: Ninhydrin, N-hydroxyurea, N-alkoxyureas, synthesis, structure, C–C bond elongation
A new series of thiazole compounds are synthesized and theirs anticancer activity was tested against breast cancer cells MCF7. The starting ethyl 2-(4-hydroxyphenyl)-4-methylthiazole-5-carboxylate was alkylated by alkyl bromides in DMF. The resulted ethyl 4-methyl-2-(4-(alkyloxy)phenyl)thiazole- 5-carboxylate compounds were refluxed with hydrazine hydrate in ethanol to afford 4-methyl-2-(4-(alkyloxy)phenyl)thiazole-5-carbohydrazide compounds. These hydrazides were reacted with various cyclizing reagents to give various 1,3,4-oxadiazole and pyrazole-ring containing thiazole compounds. The antiproliferative activity was calculated on the basis of IC50 values. The (5-amino-3-phenyl-1H-pyrazol-1-yl)(4-methyl-2-(4-(ethoxy)phenyl)thiazol-5-yl) methanone has comparable activity with standard Paclitaxel.
Keywords: Synthesis, anti-proliferative, thiazole, oxadiazole, pyrazole.
The kinetics of complex formation of dopamine, (-)3-(3,4-dihydroxyphenyl)-L- alanine ( Levodopa or LD), with Fe(II) and Fe(III) has been studied spectrophotometrically. The reactions were carried out at a pH range of 3.0 to 9.2, at 25 ± 1oC.Complex formation was not observed below pH 4.0. These investigations showed that the Fe(II) and Fe(III) complexes have identical spectra, indicative of same oxidation state of iron in these complexes. Fe(III)-LD complexation was studied only in non-buffered media. The reaction was very fast, and hence was studied using stopped flow technique. This reaction shows a linear dependence on [LD]. While, in case of Fe(II) complexation, a saturation pathway is followed. Rate laws have been deduced.
Keywords: Kinetics; mechanism; dopamine; UV-Vis spectrophotometry; pH effect
Materials and environmental chemistry
Global energy consumption is on the rise due to increasing industrial capacity of nations. This has made humans to be over reliant on fossil fuel for energy production. Diminishing fossil fuel reserve and long-term increase in average climate temperature has given rise to energy shortage and environmental degradation. Renewable energy is an alternative that will offer clean, sustainable and efficient energy. Solar, wind and hydro have all been explored in this regard. Biodiesel is another promising resource with great potential. It is diesel produced from organic sources containing free fatty acids through the transesterification reaction process that utilizes alcohols and catalysts. Research has been undertaken over the years to improve the efficiency of biodiesel production aimed at reducing complexities and cost. The type of catalysts used influences reaction conditions and biodiesel yield. Heterogeneous nanocatalyst has shown great potential in eradicating complexities and reducing cost. This review will focus on most recent research works that have used nanocatalyst to produce biodiesel. Possible areas of research can be explored for advancement in biodiesel production using nanotechnology.
Keywords: Nanocatalyst, transesterification, biodiesel, catalyst characterization, homogenous catalysts
In this paper, the liquid-solid extraction of neodymium(III) by sodium bentonite and magnetic activated carbon was reported. Neodymium (Nd) is a key element that widely applied in high-tech industries; various parameters, such as: the time, metal concentration, ionic strength, effect of initial pH etc., have been studied to assess the efficiency of sodium bentonite and magnetic activated carbon for the removal of Nd(III). Optimal extraction yield was achieved at pH equal to 9.1 for sodium bentonite and in the range of pHi from 3.1 to 9.2 for the magnetic activated carbon. The time needed for magnetic activated carbon to absorb the maximum of Nd(III) is 100 min and 60 min for sodium bentonite. The experimental capacity obtained was 528 mg g-1 for magnetic activated carbon and 503 mg g-1 for sodium bentonite. In order to validate the performance of this extractants, kinetics and diffusional studies were also developed throughout this study. Adsorption equilibrium data were calculated for Langmuir and Freundlich isotherms. It was found that the sorption of Nd(III) on sodium and magnetic activated carbon was better suited to the Freundlich adsorption model.
Keywords: Neodymium, sodium bentonite, magnetic activated carbon removal, kinetics