Mechanism of Evolution of Koneramine Complexes from One‐Pot Reactions: Snapshots of Intermediates Offer Facile Routes to New Dipicolylamines

Koneramines (L^ROR′, R=Ph or Ts; R′=Me, iPr) and their complexes were found to emerge from the system of pyridine‐2‐carboxaldehyde and N‐phenyl/tosylethylenediamine when a primary or secondary alcohol was used as solvent. Imidazolidinylpyridines (L^R, R=Ph or Ts) became major emergents whereas hemi‐aminals (L^ROH, R=Ph or Ts) are minor emergents of the system when tertiary butanol was used as the solvent; the bulky tertiary butyl group prevented the addition of alcohol to the iminium ion that diverted the equilibrium towards imidazolidinylpyridines. By playing with the components of the reaction mixture, crystals of the metastable intermediates bound to copper(II) and/or zinc(II) were obtained and the structures were determined by X‐ray diffraction analysis. The reported results shed light on how to control the emergents of the multicomponent reaction mixture that forms koneramines. Reactivity studies of the intermediates pave the way for a new type of koneramine complexes that are new dipicolylamines where the two pyridine moieties of the resulting koneramine are not the same.     

Investigations on temperature dependent structural evolution of NaPO3 glass

The understanding of molecular level structural information of phosphate glasses is very much essential. The unique microwave-absorbing ability of NaH₂PO₄·2H₂O was found to be very useful for preparing crystal and glassy sodium super ionic conductors (Nasicon's) as a component of batch mixtures. In this work NaPO₃ glass was prepared by both conventional melt quench and microwave heating from NaH₂PO₄·2H₂O as a starting material. The structure of NaPO₃ glass and their structural evolution upon heating through glass transition were probed by combination of complementary techniques like differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR) and thermo-Raman spectroscopy.This revised version was published online in November 2005 with corrections to the Cover Date.     

Ultrasound‐Assisted Pechmann Condensation of Phenols With β‐Ketoesters to Form Coumarins,in the Presence of Bismuth(III) Chloride Catalyst

Ultrasound was found to synergistically accelerate the condensation of phenol with β‐ketoesters in the presence of BiCl₃. In the absence of ultrasound, under the same conditions, the reaction was found to be slow. Thus, the reaction can be carried out in the presence of ultrasound at room temperature (28–30°C), with a considerable reduction of reaction time, with high yield and high purity of coumarins.     

Thermal decomposition mechanism of synthesized copper octoate

Present study describes the synthesis and characterization of copper octoate. Attenuated total reflectance–Fourier transformation infra red (ATR–FTIR) and energy dispersive X-ray (EDX) spectrometric techniques have been used for the characterization of the synthesized compound. The surface morphology of the compound has been studied using scanning electron microscopy (SEM). Thermal behavior and decomposition mechanism of copper octoate has been explained on the basis of simultaneous thermo-gravimetry–differential thermal analysis–evolved gas analysis (TG–DTA–EGA) and high temperature X-ray diffraction (HTXRD) measurements. Copper octoate is stable up to 250 °C. The decomposition process consists of two overlapping steps. A plausible decomposition mechanism is proposed and details of the studies carried out are being discussed here.     

Oxazoline-based antimicrobial oligomers: synthesis by CROP using supercritical CO2

A method using supercritical CO(2) to obtain biocompatible 2-oxazoline-based oligomers quaternized with different amines is described. The synthesized oligo(2-oxazoline)s display partial carbamic-acid insertion at one end. The syntheses of quaternary oligo(2-bisoxazoline)s and linear oligoethylenimine hydrochlorides are reported. Oligo(2-methyl-2-oxazoline) and oligo(2-bisoxazoline) quaternized with N,N-dimethyldodecylamine are the most efficient biocidal agents showing fast killing rates against Staphylococcus aureus and Escherichia coli. Linear oligoethylenimine hydrochloride shows the lowest MIC values but higher killing times against both bacteria. Based on the antimicrobial activity studies, a cooperative action of carbamic acid with the ammonium end group is proposed.     

Proconcentration of trace elements from high-purity thorium and uranium on Chelex-100 and determination by graphite furnace atomic absorption spectrometry with Zeeman-effect background correction

Preconcentration of trace impurities form large-sized samples of uranium metal and thorium oxide using a small column of Chelex-100 followed by their determination using graphite furnace atomic absorption spectrometry (GFAAS) is reported. A 0.5–10-g amount of the sample (uranium metal or thorium oxide) was dissolved, complexed with ammonium carbonate and subjected to the ion-exchange procedure. The retained analytes were eluted with 2–4 M nitric acid and brought to a small volume for a final dilution to 10-25 ml for their determination using GFAAS. The validity of the separation procedure and recoveries at μg kg⁻¹ levels was checked by standard addition; the recoveries were> 95%.     

Purification of arsenic contaminated ground water using hydrated manganese dioxide

An analytical methodology has been developed for the separation of arsenic from ground water using inorganic material in neutral medium. The separation procedure involves the quantitative retention of arsenic on hydrated manganese dioxide, in neutral medium. The validity of the separation procedure has been checked by a standard addition method and radiotracer studies. Neutron activation analysis (NAA), a powerful measurement technique, has been used for the quantitative determination of arsenic.     

Asymmetric synthesis of A-240610.0 via a new atropselective approach for axially chiral biaryls with chirality transfer

A new approach for atropselective preparation of axially chiral biaryl was developed. This process proceeded through a chirality transfer from a stereogenic center of a secondary alcohol to the stereogenic axis via regioselective intramolecular silyl group migration. This methodology allowed for the preparation of a single atropisomer 2 in good yield (85%) with high diastereoselectivity (99:1), which subsequently led to the successful development of an efficient asymmetric synthesis of A-240610.0, 1.     

Mechanochemical Synthesis and Reactivity of a Stable Nickel Borohydride

We report the solvent-assisted mechanochemically synthesised mononuclear Ni(II) borohydride complex supported by a macrocyclic tetradentate ligand. It was characterised as stable high-spin [(L^Me)Ni(η²-BH₄)]⁺ cation in solid-state and in solution by various physicochemical methods and capable of transferring hydride. The stoichiometric reactivity of [(L^Me)Ni(η²-BH₄)]⁺ cation was examined with trityl cation, alkyl halide, disulphide, thiol, carboxylic acid and enol at room temperature.