Electrogenerated Fe(I) Porphyrins: Efficient Electrocatalysts for Reductive Dechlorination of DDT in N,N′‐Dimethylformamide

Two iron(I) porphyrins were electrogenerated and then utilized as catalysts for the reductive dechlorination of 1,1‐bis(4‐chlorophenyl)‐2,2,2‐trichloroethane (DDT) in N,N′‐dimethylformamide. No reaction is observed between DDT and the Fe(III) or Fe(II) forms of the porphyrin, but the electrogenerated Fe(I) porphyrin efficiently catalyzes the electroreduction of DDT to give (1,1‐bis(4‐chlorophenyl)‐2,2‐dichloroethane) DDD, (1,1‐bis(4‐chlorophenyl)‐2,2‐dichloroethylene) DDE and (1,1‐bis(4‐chlorophenyl)‐2‐dichloroethane) DDMU as determined by GC‐MS analysis. The reductive dechlorination was monitored by electrochemistry, controlled potential electrolysis and spectroelectrochemistry and a mechanism for the reaction involving the reduced porphyrins and DDT is proposed. Comparisons are also made between the catalytic properties of metalloporphyrins containing iron, cobalt and manganese central metal ions under the same solution conditions.     

Optimization of mobile phase for the determination of Esomeprazole and related compounds and investigation of stress degradation by LC–MS

In this study, the objective was to investigate the degradation behavior of Esomeprazole under different recommended stress conditions according to International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use [1] by HPLC. Our research showed that the effect of mobile phase species on separation was significant for the determination of Esomeprazole and its related compounds. Successful separation of the drug from its related impurities and degradation products formed under different stress conditions was achieved using ammonium acetate buffer/ACN by a gradient elution. Compared with phosphate buffer/ACN, ammonium acetate buffer/ACN under same pH and gradient showed a great improvement in resolution due to the change of elution order. The drug was subjected to stress conditions including acidic, alkaline, oxidative, photolytic, and thermal conditions. Extensive degradation occurred in acidic and oxidative conditions, while mild degradation was observed in alkaline and photolytic conditions. Besides, it turned out the drug was extremely stable under thermal condition. The stability‐indicating LC–UV method was validated with respect to linearity, precision, accuracy, specificity, and robustness. The LC–MS method was also adopted for the characterization of degradation products. Based on the m/z values and fragmentation patterns, the degradation pathway of the drug has been proposed.     

Wang Resin Bound Addition Reactions Under Microwave Irradiation

The addition reaction process of Wang resin bound amines with isocyanates was monitored directly using a FTIR method. It showed that the reaction process was greatly enhanced under microwave irradiation.     

Hydrogen Peroxide–Promoted Transformation of Thioureas/Thiosemicarbazides to Related Ureas/Semicarbazides at Room Temperature via Grinding

A novel and environmentally benign synthetic method for ureas through hydrogen peroxide–promoted desulfurization of thioureas at room tepemperature via grinding is reported. As compared with the traditional method, this one is manipulatively simple and the oxidant is low cost, highly active, and environmentally friendly.     

Cascade reaction for 3-pyrrolines and pyrroles from nitroallylic acetates and N-mesyl 2-aminoethanones

Cascade reactions of nitroallylic acetates with methanesulfonyl 2-aminoethanones affords either the 3-pyrrolines or the pyrroles in one pot depending on reaction solvents and temperature. A possible mechanism for the entire sequence is proposed.     

Study of the effect of laser treatment on the initial oxidation behaviour of Al‐coated NiCrAlY bond‐coat

In this study, the initial oxidation behaviour of laser‐treated Al/NiCrAlY bond‐coat is investigated. Two approaches, (i) Al film sputtering on the surface of bond‐coat and (ii) laser treatment, have been taken to enhance the oxidation resistance of NiCrAlY bond‐coat. Experimental results showed that after laser treatment, the Al/NiCrAlY bond‐coat exhibited a columnar dendritic microstructure without cracks and voids. A dense and continuous α‐Al₂O₃/Cr₂O₃ multilayer was found to form on the bond‐coat surface. Results on the cyclic oxidation at 1200 °C (for time ≤ 204 h) revealed that the laser‐treated Al/NiCrAlY bond‐coat exhibited better oxidation resistance compared to as‐sprayed NiCrAlY, Al/NiCrAlY and laser‐remelted NiCrAlY bond‐coat. The formation of θ‐Al₂O₃, NiO, Cr₂O₃ and NiCr₂O₄ spinel oxides was observed to be suppressed due to the preformed α‐Al₂O₃ scale during initial oxidation on the surface of laser pre‐oxidized Al/NiCrAlY bond‐coat. Copyright © 2013 John Wiley & Sons, Ltd.     

Microfluidic-directed assembly of uniform fluorescent supraballs from CdTe nanocrystals-loaded acrylosilane microemulsion

We report herein a facile approach of fabricating fluorescent supraballs from CdTe nanocrystals (NCs)-loaded acrylosilane microemulsion by a simple microfluidic strategy. Initially, core–shell acrylosilane microemulsion with poly(methylmethacrylate-co-butylacrylate-co-vinyltri(isopropoxy)silane) (poly (MMA-co-BA-co-VPS)) as the core and poly(methylmethacrylate-co-butylacrylate-co-vinyltri(isopropoxy)silane-co-acrylamide) (poly(MMA-co-BA-co-VPS-co-AM)) as the shell were synthesized by differential microemulsion polymerization. Subsequently, CdTe NCs were assembled with these acrylosilane microemulsion particles in the presence of N′-(ethylcarbonimidoyl)-N, N-dimethylpropane-1, 3-diaminemonohydrochloride. Eventually, we fabricated uniformly distributed fluorescent supraballs using the as-prepared CdTe-loaded acrylosilane microemulsion as the discontinuous phase, and methylsilicone oil as the continuous phase by means of a microfluidic device. These fluorescent supraballs display unique colors and favorable fluorescence, which might be useful in optoelectronic applications, such as fluorescent switches, light-emitting diode displays, and illuminations.