Synthesis of α‐Benzylthiobenzimidazoleacetonitriles and Their Chemoselective Reduction of the Double Bond with NaBH4

Condensation of 2‐((1H‐benzimidazol‐2‐yl)thio)acetonitre 1 with aromatic aldehydes in methanol containing piperidine gave the corresponding 2‐((1H‐benzimidazol‐2‐yl)thio)‐3‐arylacrylonitrile 2 , which on treatment with NaBH₄ in ethanol unexpectedly and chemoselectively gave 2‐((1H‐benzimidazol‐2‐yl)thio)‐3‐arylpropanenitrile 3 by the reduction of the double bond of 2 . 3 on methylation with dimethyl sulfate containing K₂CO₃ as a base and tetrabutylammonium bromide as PTC gave 2‐((1‐methylbenzimidazol‐2‐yl)thio)‐3‐arylpropanenitrile 6 . The latter could also be prepared in an alternative way by reaction of 1 with dimethyl sulfate giving the intermediary 2‐((1‐methylbenzimidazol‐2‐yl)thio)acetonitrile 4 , followed by condensation with aromatic aldehydes yielding 5 and subsequent reduction of 5 with NaBH₄ in methanol. 6 could be directly synthesized by treatment of 4 with benzyl chloride in DMF and triethylamine as a base at 60°C for 5 h.     

Solvent Extraction Separation of Iridium(III) from Rhodium(III) by N-n-Octylaniline

The use ofN-n-octylaniline for the extraction of iridium(III) from malonate media is studied at pH 8.5. Iridium(III) extracted in the organic phase was stripped with 2.0 M hydrochloric acid and was determined spectrophotometrically by the stannous chloride–hydrobromic acid method at 385 nm. The extraction system is studied as a function of the equilibration time, diluent, reagent concentration and diverse ions. Experimental data have been analyzed graphically to determine the stoichiometry of the extracted species. It was found that the extraction of iridium(III) proceeds by an anion exchange mechanism and transforms into the extracted species [RR"NH₂ ⁺Ir(C₃H₂O₄)₂ ^–]_org. The method is simple, rapid, and selective and has been devised for the sequential separation of iridium(III) from rhodium(III), not only from each other, but also from other accompanying Platinum Group Metals (PGMs), Au(III), and base metals.     

A bio-oriented anthranilic acid catalyzed synthesis of quinazolin-8 (4H)-one derivatives: Evaluation by green chemistry metrics

An environmental friendly synthetic route has been investigated for the synthesis of quinazolin-8 (4H)-one derivatives in the presence of anthranilic acid as a catalyst. The zwitter ion formed in course of reaction may a play key role in the desired transformations leading good to excellent yields. Evaluation of the present protocol by green chemistry metrics demonstrated that it is highly efficient and eco-compatible.     

Pattern Formation in Growing Sandpiles with Multiple Sources or Sinks

Adding sand grains at a single site in the Abelian sandpile models produces beautiful but complex patterns. We study the effect of sink sites on such patterns. Sinks change the scaling of the diameter of the pattern with the number N of sand grains added. For example, in two dimensions, in the presence of a sink site, the diameter of the pattern grows as $\sqrt{(N/\log N)}$ for large N, whereas it grows as $\sqrt{N}$ if there are no sink sites. In the presence of a line of sink sites, this rate reduces to N ^1/3. We determine the growth rates for various sink geometries along with the case when there are two lines of sink sites forming a wedge, and generalizations to higher dimensions. We characterize the asymptotic pattern in the large N limit for one such case, the two-dimensional F-lattice with a single source adjacent to a line of sink sites. The characterization is done in terms of the positions of different spatial features in the pattern. For this lattice, we also provide an exact characterization of the pattern with two sources, when the line joining them is along one of the axes of the lattice.     

Relaxation of the folding of globulin around heme of hemoglobin of Homo sapiens by the food-grade additive molecule chlorophyllin

Abstract  

Binding of chlorophyllin (Chln), a food-grade additive molecule with hemoglobin (Hb), has been studied by photophysical and photochemical methods with a view to unravel the biochemical transport pathway of it. The binding affinity constant and binding sites between Chln and Hb are determined and found to be 3.3 × 10⁵ M⁻¹ and 15 (on tryptophan basis), respectively. Fluorimetric quenching experiments entail that Chln is bound in the vicinity of the tryptophan residue of Hb. Circular dichroism studies suggest that Chln induces a change in the α-helical content of Hb. Chlorophyllin is bound in the vicinity of the tryptophan residue of hemoglobin, which has been confirmed from spectrofluorimetric studies, when a quenching in the tryptophan fluorescence occurs because of the chlorophyllin-induced exposure of the tryptophan residue to hydrophillic zone. The cyclic voltammetric studies indicate that the redox reaction of Fe^II of Hb is inhibited shielding of it by the Chln molecule.     

“Seems Bad Turns Good” – traces of precursor in dicationic ionic liquid lead to analytical application

Research on Chemical Intermediates - We explored a geminal dicationic ionic liquid (DCIL), 1′-(propane-1,3-diyl)bis(4-aminopyridin-1-ium) dibromide, [C3(Amp)2][Br]2, as a fluorescent probe...