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61.
Synthesis of Pharmacologically Active Bis(indolyl) and Tris(indolyl) Derivatives Using Chlorotrimethylsilane 下载免费PDF全文
Nongthombam G. Singh Chingrishon Kathing Jims W. S. Rani Rishan L. Nongkhlaw 《中国化学会会志》2014,61(4):442-446
Chlorotrimethylsilane is found to be a comparatively fast and efficient catalyst for carrying out electrophilic substitution reactions of indoles with various aldehydes/ketones/triethylorthoformate, yielding excellent amount of bis(indolyl)methanes/tris(indolyl)methanes. The merits of this protocol are avoidance of any external energy source, minimal reaction time, simple and easy procedure and high yield under solvent free room temperature condition. The versatility of this method has been tested with various aldehydes/ketones and received satisfactory results. 相似文献
62.
One‐pot Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐ones Catalysed by Cupric Acetate under Solvent‐free Conditions 下载免费PDF全文
Chingrishon Kathing Jims World Star Rani Nongthombam Geetmani Singh Shokip Tumtin Ridaphun Nongrum Rishanlang Nongkhlaw 《中国化学会会志》2014,61(11):1254-1258
A solvent‐free synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones from aromatic aldehydes, β‐keto ester/acetyl acetone and urea catalysed by cupric acetate under thermal condition is reported as a simple and an efficient protocol. Compared with classical Biginelli reaction reported in 1893, this new method provides much improved modification in terms of yield and reaction time. The usage of milder catalyst, environmental friendly procedures and excellent yields within a very short time (5–15 min) are the advantages of the method in which the involvement of solvent‐free condition adds an edge to the method. Thus, the efficiency of the protocol enabled the rapid synthesis of 3,4‐dihydropyrimidin‐2(1H)‐one derivatives in a short duration. 相似文献
63.
Sumita Rani Mukesh Kumar Sumit Sharma Dinesh Kumar 《Journal of Sol-Gel Science and Technology》2014,71(3):470-476
Fine powders of zirconium oxide (ZrO2) were prepared using zirconium oxychloride by combustion method. The crystalline size of pure ZrO2 was in range of 14–45 nm. Graphene was incorporated in ZrO2 using graphene oxide as precursor and reducing it with hydrazine hydrate. X-Ray diffraction, Fourier transform infra-red spectroscopy, thermogravimetric analysis and Raman spectroscopy methods were used to characterize the samples. The role of graphene in structural transformation of ZrO2 to monoclinic phase was clearly observed. 相似文献
64.
A series of 2-(arylimino)-3-(hydroxyimino)butanes 3a–g, easily accessed by the condensation of variously substituted anilines 1a–g with biacetyl monoxime 2, were efficiently cyclized to afford 2,3-dimethylquinoxaline-1-oxides 4a–g using bis(acetoxy)phenyl-λ 3-iodane as an oxidant. This methodology utilizes a commercially available and environmental benign oxidant to achieve the title compounds in excellent yields under mild conditions.
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
65.
M. S. A. Rani N. S. Mohamed 《International Journal of Polymer Analysis and Characterization》2015,20(6):491-503
In the present work, an attempt has been made to prepare a new natural biopolymer blend electrolyte of carboxymethyl cellulose/chitosan impregnated with NH4NO3 by the solution casting technique. The conductivity for the system was measured by impedance spectroscopy. The incorporation of 40 wt.% NH4NO3 optimized the ambient temperature conductivity of the electrolyte up to 1.03 × 10?5 S cm?1. All electrolytes were found to follow the Arrhenius relationship. Dielectric studies confirmed that the electrolytes obey non-Debye behavior. The temperature dependence of the power law exponent s for the highest conducting film can be represented by the correlated barrier hopping model. 相似文献
66.
Amongst various carbon sources, xylan was found to be the sole inducer of endoxylanase production by Penicillium janthinellum MTCC 10889 in submerged cultivation. Endoxylanase synthesis by a xylan induced culture was initially repressed after a simultaneous addition of xylose, probably by the inducer exclusion mechanism, but it was resumed and achieved its highest level at a much later stage of growth (at 120 h). Xylose added after 30 h of growth cannot exert its full repressive effect. Although glucose was proved to be a more potent repressor than xylose, supplementation of salicin, an alcoholic β-glycoside containing d-glucose, with pure xylan resulted in an about 3.22 fold increase in the enzyme synthesis at 72 h followed by constant high production of the enzyme at least until the 144th h of growth. Inducing capacity of salicin in a xylan induced culture was significantly reduced when it was added after 30 h of growth. Addition of salicin and xylan help to partially overcome the repressive effect of xylose and glucose. Failure of salicin in recovering the endoxylanase synthesis in actinomycin D and cyclohexamide inhibited the xylan induced culture indicating that salicin cannot initiate the de novo synthesis of the enzyme. 相似文献
67.
A microwave-assisted, environmentally friendly, high-yielding, time-saving synthesis of medicinally important 3-substituted isocoumarins was carried out in a single step by direct condensation of homophthalic acid with aryol and acyl chlorides under solvent-free conditions without any solid support. The synthesised isocoumarins were structurally characterised by microanalysis, 1H NMR, EI, IR and UV. 相似文献
68.
The conversion of CO2 to useful chemicals, especially to atom economical products, is the best approach to utilize an excess of CO2 present in the atmosphere. In this study, a metal‐organic framework (ZIF‐8) is integrated with nanocrystalline zirconosilicate zeolite to develop an integrated porous catalyst for CO2 insertion reactions. The catalyst exhibits excellent activity for the CO2 insertion reaction of epoxide to produce cyclic carbonate in neat condition without the addition of any co‐catalyst. The catalyst is stable and recyclable during the cyclic carbonate synthesis. Further, the catalyst also exhibits very good activity in another CO2 insertion reaction to produce quinazoline‐2,4(1H, 3H)‐dione. 相似文献
69.
Ramandeep Kaur Heena Ripneel Kaur Aman Grover Susheela Rani Ashok Kumar Malik Abuzar Kabir Kenneth G. Furton 《Journal of separation science》2020,43(13):2626-2635
A simple, fast, and sensitive analytical protocol using fabric‐phase sorptive extraction followed by high performance liquid chromatography with ultraviolet detection has been developed and validated for the extraction of five parabens including methylparaben, ethylparaben, propylparaben, butylparaben, and benzylparaben. In the present work, sol‐gel polyethylene glycol coated fabric‐phase sorptive extraction membrane is used for the preconcentration of parabens (polar) from complex matrices. The use of fabric‐phase sorptive extraction membrane provides a high surface area which offers high sorbent loading, shortened equilibrium time, and overall decrease in the sample preparation time. Various factors affecting the performance of fabric‐phase sorptive extraction, including extraction time, eluting solvent, elution time, and pH of the sample matrix, were optimized. Separation was performed using a mobile phase consisting of water:acetonitrile (63:37; v/v) at an isocratic elution mode at a flow rate of 0.9 mL/min with wavelength at 254 nm. The calibration curves of the target analytes were prepared with good correlation coefficient values (r2 > 0.9955). The limit of detection values range from 0.252 to 0.580 ng/mL. Finally, the method was successfully applied to various cosmetics and personal care product samples such as rose water, deodorant, hair serum, and cream with extraction recoveries ranged between 88 and 122% with relative standard deviation <5%. 相似文献
70.
Liquid-phase esterification of acetic acid with n-butanol to n-butyl acetate is studied in the presence of a polymeric catalyst, that is, poly(o-methylene p-toluene sulfonic acid). The performance of the proposed catalyst is compared with the other commercially available homogeneous and heterogeneous catalysts in terms of its activity. Experiments are conducted in an isothermal stirred batch reactor to study the effects of speed of agitation, temperature, and catalyst loading on the rate of reaction. A concentration-based pseudo-homogeneous (PH) kinetic model and activity-based kinetic models such as PH, Eley-Rideal (ER), and Langmuir-Hinselwood-Hougen-Watson (LHHW) models are developed. All the models considered in this study resulted in similar percentage deviation close to 4%. Further, kinetic models are validated through additional experiments, and it is observed that the simple concentration-based PH model is able to predict experimental data with least deviation compared to activity-based PH, ER, and LHHW models. The developed kinetic models are also tested using the Fisher-Snedecor test (F-test) and are found to be acceptable. By incorporating both modeling data and validation data, the overall absolute average deviations of different models are found to be concentration-based PH model 4.354%, activity-based PH model 5.006%, ER I model 5.189%, ER II model 5.403%, ER III model 5.437%, and LHHW model 6.104%, illustrating the superiority of the simple concentration-based PH model. 相似文献