Synthesis of oxalate doped polyaniline and its corrosion protection performance

It is known that dopants present in polyaniline (PANI) play an important role in corrosion protection of mild steel since the dopant ions form a secondary layer with iron. Since oxalate ions form a stable iron oxalate layer on mild steel, a study has been made on the corrosion protection performance of steel by vinyl coating containing oxalate doped PANI in acid and neutral media. Electrochemical impedance spectroscopy (EIS) studies have shown that the oxalate doped PANI is able to protect mild steel in sodium chloride solution since the impedance values are maintained at 10¹⁰ Ω cm² even after 100 days of exposure.     

Influence of sol–gel derived lithium cobalt phosphate in alkaline rechargeable battery

A lithium cobalt phosphate (LiCoPO₄) cathode was synthesised by citric acid assisted sol?Cgel method and its electrochemical behaviour in alkaline secondary battery (using novel lithium hydroxide as the electrolyte) is reported. The sol?Cgel method using metal acetate precursors with citric acid as a chelating agent influenced the particle size and the homogeneity while yielding a single phase LiCoPO₄ at a considerably lower temperature and shortened heating time, compared to that of the conventional solid state reaction. The cyclic voltammogram of LiCoPO₄ showed a reversible redox process implying that de-intercalation and intercalation of lithium can occur in aqueous electrolyte. This was supported by X-ray diffraction (XRD) and Infra-red (IR) studies. The charge?Cdischarge performance of the Zn/LiCoPO₄ battery showed good capacity retention (after 25 cycles it delivered 90?% of its initial capacity). This enhanced capacity retention was attributed to the synergistic effect of particle homogeneity, reduced Li⁺ diffusion path and stability of the non-reactive aqueous electrolyte between the electrode and the electrolyte interface.     

Radical‐Mediated Three‐Component Coupling of Alkenes

A tandem radical process involving conjugate addition to an activated alkene followed by allylation is reported. B‐Alkylcatecholboranes, easily available via hydroboration of the corresponding alkenes, were used to generate the initial radicals. These radicals add efficiently to electrophilic alkenes such as phenyl vinyl sulfone, N‐phenylmaleimide, and dialkyl fumarate. In the last step of this one‐pot process, the radical adducts react with the allylic sulfones. The whole process can be considered as a unique and selective coupling of three different alkenes.     

Synthesis of some new indolizines

The reaction between 4‐dimethylaminopyridine (DMAP) and 2‐bromoacetophenone(s) readily gives 1‐ [2‐(4‐substitutedphenyl)‐2‐oxoethyl]‐4‐(dimethylamino)pyridinium bromide ( 1–14 ). Action of aqueous NaOH on 1–8 generates the corresponding pyridinium ylide ( 15–22 ), which is isolated as a colored stable crystalline solid. Addition of 15–22 to dimethylacetylene dicarboxylate (DMAD) gives dimethyl 3‐(substitutedbenzoyl)‐7‐(dimethylamino)indolizine‐1,2‐dicarboxylate ( 23–30 ) in 46–62% yield.     

1‐[(4‐Chloro­benzoyl)­methyl]‐4‐(N,N‐di­methyl­amino)­pyridinium bromide sesquihydrate and 1‐[(4‐bromo­benzoyl)­methyl]‐4‐(N,N‐di­methyl­amino)­pyridinium bromide sesquihydrate

The title compounds, C₁₅H₁₆ClN₂O⁺·Br⁻·1.5H₂O and C₁₅H₁₆BrN₂O⁺·Br⁻·1.5H₂O, are isomorphous. The benzene ring is oriented nearly normal to the pyridine ring in both compounds. The molecular packing is mainly influenced by intermolecular O—H⋯O and O—H⋯Br interactions, as well as weak intramolecular C—H⋯O interactions. The H₂OBr⁻ units form an extended water–bromide chain, with a bridging water mol­ecule on a twofold axis.     

3‐(4‐Chloro­benzoyl)‐7‐(N,N‐di­methyl­amino)‐1‐phenyl­indolizine and 3‐(2,4‐di­chloro­benzoyl)‐7‐(N,N‐di­methyl­amino)‐1‐phenyl­indolizine

In both of the title compounds, C₂₃H₁₉ClN₂O, (I), and C₂₃H₁₈Cl₂N₂O, (II), the molecular packing is influenced by weak intermolecular C—H⋯O and C—H⋯π interactions, but despite the chemical similarity of the compounds, the packing in (II) is entirely different from that observed in (I).     

Rapid four-component reactions in water: synthesis of pyranopyrazoles

An environmentally benign four-component reaction in aqueous medium at room temperature has been developed for the synthesis of 6-amino-5-cyano-3-methyl-4-aryl/heteroaryl-2H,4H-dihydropyrano[2,3-c]pyrazoles.     

The Chemical Composition and Biological Activities of Essential Oil from Korean Native Thyme Bak-Ri-Hyang (Thymus quinquecostatus Celak.)

Thymus quinquecostatus Celak. (Korean name: bak-ri-hyang) is an important medicinal and aromatic herb in Korea, which is named for the spread of its fragrance over a distance of approximately 40 km. In traditional Korean systems of medicine, T. quinquecostatus has been used to treat cancer, constipation, hepatic disease, arteriosclerosis, poor circulation in women, constipation, and menstrual irregularities. At present, T. quinquecostatus is used only for ornamental and ground cover purposes. A literature search was conducted to retrieve information regarding the essential oil composition and biological properties of T. quinquecostatus from PubMed, Science Direct, Wiley, Springer, Taylor and Francis, Wiley, and other literature databases. T. quinquecostatus can be divided into different chemotypes, such as γ-terpinene, thymol, phenol, carvacrol, and geraniol, according to the presence of major components in its essential oil. Further, the essential oil from T. quinquecostatus has been reported to possess various therapeutic properties such as antioxidant, antimicrobial, anticancer, anti-inflammatory, analgesic, sleep prolonging, soothing, skin protection and whitening, anti-aging, anti-obesity, and anti-acne properties. In conclusion, this review will be helpful for utilizing the T. quinquecostatus plant in different industries including food, pharmaceuticals, pesticides, perfumery, and cosmetics.