Classical chemical sciences
The spectral and quantum-chemical studies of phosphonium ylides derivatives of 2-oxazoline-5-one with both conjugated and non-conjugated substituents were performed. It was found that considerable positive charge is located at phosphorus atom, whereas the substantial negative charge is fixed at sulphur atom. It has been found from the calculations and 13C NMR spectral data that introducing of the non-conjugated and conjugated substituents in the position 2 of the oxazole cycle in thiaphosphonium ylides causes only small change in the molecular equilibrium geometry and in charge distribution in oxazole moiety, whereas spectral characteristics of substituted derivatives are very sensitive to the nature of the lowest electron transitions which reflects in changes of their absorption maxima.
Keywords: phosphonium ylides, derivatives of 2-oxazoline-5-one, charge distribution, molecular geometry, 13C NMR spectroscopy, electron transitions, absorption spectra
The paper aimed to quantify the saponins expressed in escin, the major bioactive constituent of Aesculus hippocastanum, from five different pharmaceutical formulations: two types of tablets, and one type of gel, tincture, and glycerol-hydroalcoholic extract. The products are part of over the counter drugs and dietary supplements categories. Two spectrophotometric methods were used to quantify the escin, after separation from the other active ingredients and excipients. The first method, calibration curve method, is based on the reaction between the oxidized triterpenoid saponins and vanillin and records the absorbance at 560 nm. The limit of detection, limit of quantification, and the RSD values were calculated. The second method is based on the molar absorptivity of escin. Both methods have proved to be suitable for the determination of escin in different products.
Keywords: Escin, quantification, UV-Vis spectrophotometric methods, tablets, gel, tincture, glycerol-hydroalcoholic extract
A simple and green one pot protocol for the synthesis of pyranopyrazoles using ultrasonication waves in aqueous medium has been developed. Advantages of this method are it provides operational simplicity and environment-friendly green approach.
Keywords: pyranopyrazoles; one pot reaction; catalysis; ultrasound waves; aqueous medium
Elemental sulfur obtained during oxidative leaching of sulfides at low temperature will contain mercury and gold and both can be effectively recovered using sodium sulfide. Other metals go into solution.
Keywords: Sodium sulfide; Oxidative leaching; Sulfide ores; Surface active agents; Gold; Mercury
Materials and environmental chemistry
Two LED-UV based photochemical flow reactors have been compared. One was a commercially available LED-UV flow reactor designed for water disinfection or sterilization and the other one was a home-made LED-UV flow reactor designed for analogous purposes. The photochemical performances of two mentioned flow reactors working both at about 275 nm were evaluated using uridine actinometry through the determination of the pseudo-first order kinetics rate constant of uridine photolysis and through the measurement of the incident light I absorbed by the actinometer solution. From these data, the energy released to the solution by the LED-UV sources was determined. Furthermore, a third LED-UV reactor working at 360 nm was evaluated with uridine actinometer. As expected in the latter case uridine was not photolyzed and the reactor was found unsuitable for water disinfection.
Keywords: actinometry; uridine; UV-LED; flow reactors; photochemistry
Tungstocobalate, (CoIIIW12O40)5-, intercalated ZnAl-layered double hydroxide (ZnAl-CoW12) was prepared via rehydration of calcined ZnAl-LDH under nitrogen atmosphere. Characterization by chemical analysis together with powder XRD, FT-IR, TG-DTA and UV-VIS DRS provided evidence of intercalation of CoIIIW12O405- (58 wt. %) in the interlayer of LDH. The catalytic activity of ZnAl-CoW12 was evaluated for hydrogen peroxide mediated decolourisarion of methyl orange and oxidation of benzaldehyde to benzoic acid under varying reaction conditions. ZnAl-CoW12 was found effective for both the reactions and stable under the experimental conditions for repetitive use without any noticeable decrease in activity.
Keywords: Tungstocobalate; layered double hydroxide; intercalation; dye decolourisation; benzaldehyde oxidation
Chemical and biological aspects of life
Hypertension is a serious challenge worldwide. It is one of the most prevalent conditions seen today by researchers in both developed and underdeveloped countries. Depending upon progression of systolic and diastolic blood pressure it is classified into prehypertension, stage 1 and 2 hypertension. Modification in the lifestyle is an initial stage but pharmacological treatment is necessary when it become difficult to control it. In regular practice, drug therapy is being selected from diuretics, β-blockers, calcium channel blockers and renin angiotensin system inhibitors either alone or in combination for both initial and maintenance therapy. Choice of drug depends upon favorable effects in specific clinical setting. This article is all about the reasons and treatments of hypertension. The article elaborates the common reasons which lead to raise the blood pressure in a normal individual. It also reviews the studies related to the effect of different factors of our daily life on the blood pressure.
Keywords: Systolic, diastolic, cardiovascular, cerebrovascular, angiotensin
Before now, two compounds namely, 3-ethoxy-3,7-dimethyl-1,6-octadiene (ethyl linalool) and 1,2-benzenedicarboxylic acid diethyl ester (diethyl phthalate) have been isolated from the ethyl acetate fraction of Pycnanthus angolensis by column chromatography. In this study, the preparative thin-layer chromatography (p-TLC) of two previously obtained residues was carried out. The chemical and biological properties of the compounds obtained there from were evaluated. This exercise led to two isolates (NG-1b and NG-3b) whose identities have been revealed to be ethyl cinnamate (cinnamic acid, ethyl ester) and 9-oximino-2,7-diethoxy fluorene (2,7-diethoxy-9H-fluoren-9-one oxime) respectively using the MS and IR spectral techniques. The compounds were surprisingly strongly bacteriostatic against Escherichia coli but recorded no activity against Staphylococcus aureus and Candida albicans.
Keywords: Chemical, biological, properties, chromatography, Pycnanthus angolensis