Ionic liquids-assisted greener preparation of silver nanoparticles

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Synthesis of 4,4′-diaminotriphenylmethane derivatives using H3PW12O40 and HZSM5 zeolite under solvent-free conditions

An efficient and very simple method for synthesis of 4,4′-diaminotriphenylmethane and its derivatives has been achieved via reaction of various substituted aromatic aldehydes containing both electron-donating and electron-withdrawing groups with various anilines having electron-withdrawing and electron-donating groups in the presence of catalytic amounts of HZSM5 zeolite and H₃PW₁₂O₄₀ under solvent-free conditions. The reaction proceed with shorter reaction time and higher yield compared to the results obtained in different solvents. Anilines having electron-donating groups in comparison with those having electrondonating group performed this transformation in better yields. Also the results show that the steric hindrance plays an important role in this transformation. Reusability is an advantage of the HZSM5 zeolite, while it showed lesser activity than H₃PW₁₂O₄₀. The one-pot reaction, simple work up, high yields, use of efficient catalytic amount and eco-friendly reagents are the advantages of the proposed method. All products were characterized using ¹H NMR, ¹³C NMR and IR.     

Multivariate curve resolution-particle swarm optimization: A high-throughput approach to exploit pure information from multi-component hyphenated chromatographic signals

Multivariate curve resolution-particle swarm optimization (MCR-PSO) algorithm is proposed to exploit pure chromatographic and spectroscopic information from multi-component hyphenated chromatographic signals. This new MCR method is based on rotation of mathematically unique PCA solutions into the chemically meaningful MCR solutions. To obtain a proper rotation matrix, an objective function based on non-fulfillment of constraints is defined and is optimized using particle swarm optimization (PSO) algorithm. Initial values of rotation matrix are calculated using local rank analysis and heuristic evolving latent projection (HELP) method. The ability of MCR-PSO in resolving the chromatographic data is evaluated using simulated gas chromatography–mass spectrometry (GC–MS) and high-performance liquid chromatography–diode array detection (HPLC–DAD) data. To present a comprehensive study, different number of components and various levels of noise under proper constraints of non-negativity, unimodality and spectral normalization are considered. Calculation of the extent of rotational ambiguity in MCR solutions for different chromatographic systems using MCR-BANDS method showed that MCR-PSO solutions are always in the range of feasible solutions like true solutions. In addition, the performance of MCR-PSO is compared with other popular MCR methods of multivariate curve resolution-objective function minimization (MCR-FMIN) and multivariate curve resolution-alternating least squares (MCR-ALS). The results showed that MCR-PSO solutions are rather similar or better (in some cases) than other MCR methods in terms of statistical parameters. Finally MCR-PSO is successfully applied in the resolution of real GC–MS data. It should be pointed out that in addition to multivariate resolution of hyphenated chromatographic signals, MCR-PSO algorithm can be straightforwardly applied to other types of separation, spectroscopic and electrochemical data.     

Reductive amination of aldehydes and ketones using sodium borohydride in the presence of silica chloride under solvent free conditions

<正>A simple and convenient procedure for the preparation of amines from aldehydes and ketones with sodium borohydride activated by silica chloride as a catalyst under solvent-free conditions is described.A variety of aliphatic and aromatic aldehydes,ketones and amines when mixed with NaBH_4/silica chloride at room temperature,afforded excellent yield of the corresponding amines.