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Microwave Synthetic Technology
Published in Banik Bimal Krishna, Bandyopadhyay Debasish, Advances in Microwave Chemistry, 2018
Biswa Mohan Sahoo, Bimal Krishna Banik, Jnyanaranjan Pa
Some new 2-substituted benzimidazole derivatives were synthesized from the microwave irradiation method by condensation of 2-nitroaniline with different carboxylic acids (aliphatic, aromatic and hetrocyclic) by Kuldeep et al. The compounds synthesized are identified by 1HNMR and FT-IR (Fourier-transform infrared spectroscopy) spectroscopic techniques. All compounds studied in this work are screened for their in vitro antimicrobial activities against the standard strains: Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Bacillus pumilus, Candida albicans and Aspergillus niger using agar well diffusion method. The diameter (in mm) of zone of inhibition is determined by the agar well diffusion method. Compound 2-pyridin-3-yl-1Hbenzimidazole (1f) is found to be the most active antimicrobial compound amongst the series. Compounds 2-(2-chloro-4-nitro-phenyl)-1H-benzimidazole (1a), 2-(1H-benzimidazol-2-yl)-6-nitro-benzoic acid (1e) also showed good antimicrobial activity [119].
Physical Properties of Individual Groundwater Chemicals
Published in John H. Montgomery, Thomas Roy Crompton, Environmental Chemicals Desk Reference, 2017
John H. Montgomery, Thomas Roy Crompton
Biological. Under aerobic and anaerobic conditions using a sewage inoculum, 2-nitroaniline degraded to 2-methylbenzimidazole and 2-nitroacetanilide (Hallas and Alexander, 1983). A Pseudomonas sp. strain P6, isolated from a Matapeake silt loam, did not grow on 2-nitroaniline as the sole source of carbon. However, in the presence of 4-nitroaniline, approximately 50% of the applied 2-nitroaniline metabolized to nonvolatile products which could not be identified by HPLC (Zeyer and Kearney, 1983). In activated sludge inoculum, following a 20-day adaptation period, no degradation was observed (Pitter, 1976).
Biopolymers as Supports for Heterogeneous Catalysis: Focus on Chitosan, a Promising Aminopolysaccharide
Published in Arup K. SenGupta, Ion Exchange and Solvent Extraction, 2007
Eric Guibal, Thierry Vincent, Francisco Peirano Blondet
Palladium catalyst supported on SiO2-chitosan composite has been prepared using the conventional two-step procedure (chitosan precipitation on silica particles, followed by metal binding in ethanol under reflux).379 The catalyst is tested for the hydrogenation of a series of chloro-nitrobenzenes in solvent under 1 bar H2 pressure (Figure 4.32). The reaction is specific and the side-reaction is not obtained (i.e., the substrates are not dehalogenated): p-, m-, o-chloronitrobenzene, and 4-chloro-1,3 dinitrobenzene are quantitatively converted to p-, m-, o-chloroaniline and 4-chloro-3-aminoaniline, respectively. The initial hydrogenation rates are found to be comparable for the different substrates, but it depends on the chitosan:Pd molar ratio (based on glucosamine monomer group), reaching a maximum around 50. The catalytic activity is comparable at using methanol, ethanol cyclohexane, or toluene as the solvent, while the hydrogenation rate strongly decreases in tetrahydrofuran. The optimum temperature is close to 45°C. Han et al. used the same SiO2-chitosan composite for the preparation of a series of nonnoble single metallic [Ni, Cu, Cr, Co, Fe(II), and Fe(III)] or bimetallic (Cu/Zn, Cu/Cr) catalysts; they tested their catalytic activity for the hydrogenation of nitrobenzene to aniline in ethanol under 15 bar pressure.333 Single-metal catalysts are poorly reactive compared to bimetallic catalysts: the yield of the reaction increases from 10% to 96–100% when combining Cu and Zn or Cr as catalytic active sites. The reaction requires working at high temperature: the conversion yield sharply increases above 120°C. The highest yield is obtained when using chitosan (on monomer unit basis):Cu molar ratio close to 12 (maintaining the Cu:Zn molar ratio constant at 1:1). The solvent influences conversion yield and solvents can be classified according to: ethanol > methanol > water ≫ tetrahydrofuran (THF) Å 1,4-dioxane. The catalyst has also been successfully tested for the hydrogenation of 2-nitroanisole, 1-chloro-4-nitrobenzene, 2-nitroaniline, and 2-nitrotoluene to 2-anisidine, 4-chloroaniline, 1,4-phenylenediamine, and 2-toluidin, respectively. In this case, again, no by-products are obtained, indicating that a side reaction is not involved and that the reaction is highly selective.\ Example of hydrogenation of nitro-aromatic compound.
Synthesis of a simplified iron(III) tetraamido macrocyclic ligand (FeIII-TAML) catalyst and its catalytic activity for degradation of dye wastewater by H2O2
Published in Journal of Coordination Chemistry, 2020
Shunlai Li, Liaoyuan Wang, Run Zhou, Cheng Zhou, Hongguang Du
The synthesis of FeIII-TAML catalyst B has been reported [21, 22], but its synthesis route is complex (Figure 3), involving the protection and deprotection of amino groups, which increases the cost of synthesis. To simplify the route and reduce the cost, we redesigned the synthetic route (Figure 4). The improved route uses 2-nitroaniline as a raw material, and 2-nitroaniline reacts with dimethylmalonyl dichloride to form amide intermediate B1. The two nitro groups of B1 are reduced to the amino group, and the resulting intermediate B2 is further reacted with oxalyl chloride to give TAML (B3). Finally, TAML complexes with the iron salt in the presence of n-BuLi to form FeIII-TAML (B4). The total yield of the improved synthetic route was increased from 30.1% to 49.5% compared with the reported route.