Determination of 2-hydroxy-4-methoxybenzaldehyde in roots of Decalepis hamiltonii (Wight & Arn.) and Hemidesmus indicus R.Br

The roots of Decalepis hamiltonii and Hemidesmus indicus are aromatic and possess the crystalline compound 2-hydroxy-4-methoxybenzaldehyde as the major compound (> 90%) in their volatile oils. A gas chromatographic procedure was developed for the assay of 2-hydroxy-4-methoxybenzaldehyde in both fresh and dried roots of different origin. Benzyl butyrate was used as the internal standard. Among the methods tried, steam hydrodistillation was suitable for extraction of the volatile oils. The quantity of this aromatic compound varied from 0.03 to 0.54%.     

The use of fractional orders in the determination of birefringence of highly dispersive materials by the channelled spectrum method

The channelled spectrum employing polarized light interference is a very convenient method for the study of dispersion of birefringence. However, while using this method, the absolute order of the polarized light interference fringes cannot be determined easily. Approximate methods are therefore used to estimate the order. One of the approximations is that the dispersion of birefringence across neighbouring integer order fringes is negligible. In this paper, we show how this approximation can cause errors. A modification is reported whereby the error in the determination of absolute fringe order can be reduced using fractional orders instead of integer orders. The theoretical background for this method supported with computer simulation is presented. An experimental arrangement implementing these modifications is described. This method uses a Constant Deviation Spectrometer (CDS) and a Soleil Babinet Compensator (SBC).     

Reversal Diastereoselectivity Between the Organomagnesium and Organolithium Reagents on Chiral N-Tert-Butylsulfinylaldimines for the Preparation of Chiral Amines

The asymmetric synthesis of both the enantiomer of chiral amines from the single chiral source of N-tert-butylsulfinylaldimines (3) by simply changing the organometallic reagents through diastereoselective addition. An efficient enantioselective synthesis of chiral amines including (S)-3-methyl-1-(2-piperidin-1-yl-phenyl)butyl amine (6a), a key intermediate to prepare antidiabetic drug repaglinide (1), is reported.     

Correction to: Effect of Basil antioxidant additive on the performance,combustion and emission characteristics of used cooking oil biodiesel in CI engine

Journal of Thermal Analysis and Calorimetry - The solid–liquid equilibria (SLE) of two binary mixtures of organic stabilizers for energetic materials, viz....     

Block copolymerization initiated by Mn(III)-poly(ethylene glycol) redox system — general features and kinetics

The kinetics and mechanism of thermal polymerization of acrylonitrile initiated by Mn(III) pyrophosphate — poly(ethylene glycol) (PEG, molecular weight 6000) redox system in aqueous sulfuric acid medium was studied in the temperature range 30–60°C. The overall rates of polymerization and the disappearance of Mn³⁺ were determined. The polymerization was initiated by the organic free radical produced from the Mn³⁺-PEG reaction and the termination was by the metal ions. The rate of polymerization of acrylonitrile was found to be directly proportional to the square of the monomer concentration and first power of PEG concentration, and inversely proportional to the concentration of Mn³⁺. The rate of manganic ion disappearance was found to be directly proportional to manganic ion concentration and PEG concentration, and independent of the monomer concentration. Based on these observations, a plausible reaction scheme was suggested and suitable kinetic expressions were evaluated.     

Synthesis of dihydrochromeno[4,3-b]pyrrolo[3,2-f]quinolines via intramolecular aza Diels-Alder reaction

An efficient and convenient one-pot intramolecular aza Diels-Alder approach for the synthesis of dihydrochromeno[4,3-b]pyrrolo[3,2-f]quinolines has been reported. Particularly valuable features of this methodology include simple execution, inexpensive catalyst, and good product yields.     

苝类化合物研究与应用

苝类化合物具有大的共轭体系,易于进行结构修饰,可引入各种功能性基团,这种奇特结构赋予了苝类化合物优良的理化性质和特殊功能,在材料科学、超分子化学、生物、药学、医学等领域具有宽广的应用潜力,尤其在苝类有机光电材料已得到广泛的研究,取得了许多重要成就。尤其是近来越来越多的研究致力于开发苝类化合物其它可能的应用,已延伸到诸多领域,特别是相关生物医药的应用研究已成为近几年来异常活跃的新兴研究领域,引起广泛关注,进展迅速。本文结合课题组的研究工作,参考国内外近五年文献,首次系统地综述了苝类化合物在有机光电材料、纳米材料、生物医药光敏剂、生物荧光标记和成像、药物载体、人工诊断剂、人工离子受体和荧光分子探针等材料、生物、医药领域应用研究新进展。文中注重强化了化合物结构对苝类化合物性质和应用的影响。对未来苝类化合物研究与应用的发展趋势作了展望。     

Thermodynamics,structure and kinetics in the system Ga–O–N

Within the ternary system Ga–O–N we performed experimental and theoretical investigations on the thermodynamics, structure and kinetics of new stable and metastable compounds.We studied the ammonolysis of β-Ga₂O₃ at elevated temperatures by means of ex situ X-ray diffraction, ex situ neutron diffraction, and in situ X-ray absorption spectroscopy (XAS). From total diffraction pattern refinement with the Rietveld method we analyzed the anionic occupancy factors and the lattice parameters of β-Ga₂O₃ during the reaction. Within the detection limits of these methods, we can rule out the existence of a crystalline oxynitride phase that is not derived from wurtzite-type GaN. The nitrogen solubility in β-Ga₂O₃ was found to be below the detection limit of about 2–3 at.% in the anionic sublattice. The kinetics of the ammonolysis of β-Ga₂O₃ to α-GaN and of the oxidation of α-GaN to β-Ga₂O₃ was studied by means of in situ X-ray absorption spectroscopy. In both cases the reaction kinetics could be described well by fitting linear combinations of β-Ga₂O₃ and α-GaN spectra only, excluding that other crystalline or amorphous phases appear during these reactions. The kinetics of the ammonolysis can be described well by an extended Johnson–Mehl–Avrami–Kolmogorow model with nucleation and growth of GaN nuclei, while the oxidation kinetics can be modeled by a shrinking core model where Ga₂O₃ grows as a layer. Investigations by means of TEM and SEM support the assumptions in both models.To investigate the structure and energetics of spinel-type gallium oxynitrides (γ-galons) we performed first-principles calculations using density-functional theory. In addition to the ideal cubic γ-Ga₃O₃N we studied gallium deficient γ-galons within the Constant-Anion-Model.In highly non-stoichiometric, amorphous gallium oxide of approximate composition GaO_1.2 we found at a temperature around 670 K an insulator–metal transition, with a conductivity jump of seven orders of magnitude. We demonstrate through experimental studies and density-functional theory calculations that the conductivity jump takes place at a critical gallium concentration and is induced by crystallization of stoichiometric β-Ga₂O₃ within the metastable oxide matrix. By doping with nitrogen the critical temperature and the conductivity in the highly conducting state can be tuned.     

Synthesis, spectroscopic, redox, catalytic and antimicrobial properties of some ruthenium(II) Schiff base complexes

A new series of mixed ligand semicarbazone or thiosemicarbazone complexes of Ru(II) having the general formula [RuCO(EPh₃)(B)L] (where E = P or As; B = PPh₃, AsPh₃ or Pyridine; L = dibasic tridentate ligand derived by the condensation of ethylacetoacetate/methylacetoacetate and thiosemicarbazide/semicarbazide) have been synthesized and characterized by physico-chemical, spectroscopic and electrochemical studies. A comparative study on the catalysis of oxidation of benzyl alcohol, cyclohexanol, cinnamyl alcohol, n-butanol, n-propanol and iso-butyl alcohol has been done with N-methylmorpholine-N-oxide and molecular oxygen as co-oxidants. Catalytic activity studies of the complexes in coupling reactions have been carried out. The antibacterial properties of the complexes have also been examined.