Sulfuric acid immobilized on silica: an efficient reusable catalyst for selective hydrolysis of the terminal O-isopropylidene group of sugar derivatives

Sulfuric acid immobilized on silica proved to be an efficient catalyst for selective hydrolysis of the terminal O-isopropylidene group of sugar derivatives. The method is very simple and economic for large-scale synthesis in which the catalyst is recovered and reused for several runs. Reactions with di-O-isopropylidene derivatives of d-glucose, d-mannose, d-fructose and l-sorbose led to the formation of the corresponding mono-O-isopropylidene derivatives in good to excellent yields.     

An Efficient and Convenient Synthesis of Imidazolines and Benzimidazoles via Oxidation of Carbon‐Nitrogen Bond in Water Media

The metal coordination complex K₄[Fe(CN)₆] is an efficient and environmentally benign catalyst for the synthesis of imidazolines and benzimidazoles from various aldehydes and 1,2‐diamines in aqueous medium at room temperature. This protocol gives excellent yield of product with desired purity.     

Oxadiazole: Synthesis,characterization and biological activities

The synthesis of novel achiral and chiral amides incorporating 1,3,4-oxadiazole ring are reported. All the synthesized amides are characterized ¹H, ¹³C, FTIR and elemental analysis techniques. Synthesized compounds are screened for microbial and cytotoxic activities.     

Robust sample average approximation

Mathematical Programming - Sample average approximation (SAA) is a widely popular approach to data-driven decision-making under uncertainty. Under mild assumptions, SAA is both tractable and enjoys...     

Compositional dependence of structural parameters,polyhedral distortion and magnetic properties of gallium ferrite

We show the effect of composition on the structure, polyhedral distortion and magnetic characteristics of pure phase polycrystalline Ga_2?xFe_xO₃ (GFO) for compositions between 0.8≤x≤1.3. X-ray analysis reveals that lattice parameters of GFO exhibit a linear dependence on Fe content in single phase region indicating manifestation of Vegard's law. Upon changing the composition, a rather small change in the overall unit cell volume (～1%) appears to be an outcome of a competition between changing trends of various polyhedra. Increasing Fe content of the samples also leads to stretching of the bonds as indicated by the Raman peak shifts. Further, low temperature magnetic measurements show that the coercivity of the samples is maximum for Ga:Fe ratio of 1:1 driven by a competition between decreasing crystallite size and increasing magnetic anisotropy.     

Severe climate sway in coherent CDMA-OSSB-FSO transmission system

Free space optics (FSO) link at high transmission rate is delimited due to its perceptivity to diversified surroundings especially in hilly regions. A demonstration of CDMA-FSO coherent detection system is reported in this work to achieve a prolonged 10 Gbps-FSO link with acceptable SNR under the impact profound haze, rain and fog environment. Further, the work is extended to weigh the proposed CO-CDMA-OSSB-FSO transmission system against OFDM-OSSB-FSO direct detection system 0045 and 0050.     

Silica-supported boric acid with ionic liquid: a novel recyclable catalytic system for one-pot three-component Mannich reaction

A rapid and efficient silica-supported boric acid/ionic liquid ([bmim][PF?]), catalyzed, one-pot three-component Mannich reaction has been carried out to synthesize β-amino carbonyl compounds at room temperature. The reaction afforded desired products in excellent yields with moderate to good diastereoselectivity. The method provides a novel modification of three-component Mannich reaction in terms of mild reaction conditions, clean reaction profiles, low amount of catalyst, recyclability of catalyst and a simple workup procedure. The present report first time describes the preparation of H?BO?-SiO? catalyst and its use with [bmim][PF?], to synthesize Mannich products. The catalyst can be reused at least seven times.     

Mesogenic quinazolone derivatives: synthesis and characterisation

Two new mesogenic homologous series of quinazolone derivatives have been synthesised by condensation of 4-n-alkoxybenzoyloxy benzaldehyde (for series I) / 4-n-alkoxy-3-methoxybenzoyloxy benzaldehyde (for series II) with 3-amino-2-methyl quinazolone in alcohol. The synthesised compounds are characterised by a combination of elemental analysis and standard spectroscopic methods. In series I, all the synthesised members exhibit the nematic mesophase. An enantiotropic smectic A phase is observed from the n-decyloxy derivative onward to the last homologue synthesised. Methoxy to n-propyloxy derivatives of series II are non-mesogenic, whereas the rest of the members exhibit a monotropic nematic mesophase. The mesomorphic properties of the present series I and II are compared with each other and with the other structurally related mesogenic homologous series to evaluate the effect of lateral methoxy substituent and quinazolone moiety on mesomorphism.     

Porous‐Organic‐Framework‐Templated Nitrogen‐Rich Porous Carbon as a More Proficient Electrocatalyst than Pt/C for the Electrochemical Reduction of Oxygen

Porous nitrogen‐rich carbon (POF‐C‐1000) that was synthesized by using a porous organic framework (POF) as a self‐sacrificing host template in a nanocasting process possessed a high degree of graphitization in an ordered structural arrangement with large domains and well‐ordered arrays of carbon sheets. POF‐C‐1000 exhibits favorable electrocatalytic activity for the oxygen‐reduction reaction (ORR) with a clear positive shift of about 40 mV in the onset potential compared to that of a traditional, commercially available Pt/C catalyst. In addition, irrespective of its moderate surface area (785 m² g^?1), POF‐C‐1000 showed a reasonable H₂ adsorption of 1.6 wt % (77 K) and a CO₂ uptake of 3.5 mmol g^?1 (273 K).