The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
M Swaminathan - One of the best experts on this subject based on the ideXlab platform.
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nano n tio2 mediated selective photocatalytic synthesis of quinaldines from Nitrobenzenes
RSC Advances, 2012Co-Authors: K Selvam, M SwaminathanAbstract:N-Doped TiO2 using a new nitrogen precursor hydrazine hydrate was synthesized by a simple wet method. This photocatalyst was characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area, high resolution transmission electron microscopy (HR-TEM), UV-Vis diffused reflectance spectra (DRS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). N-Doping does not change the phase of TiO2. It is found that the size of N-TiO2 is 15.6 nm with 134.72 m² g−1 surface area. XPS analysis reveals the presence of anionic nitrogen in TiO2 as O–Ti–N. Substitution of N in place of oxygen in the TiO2 lattice causes a decrease in oxygen vacancies which inhibits the recombination of electron–hole pairs. This catalyst was used for the selective one-pot synthesis of quinaldines from Nitrobenzenes in ethanol under UV and visible light. N-TiO2 on irradiation induces a combined redox reaction with nitrobenzene and alcohol and this is followed by condensation-cyclization of aniline with oxidation products to give quinaldines. N-Doped TiO2 is found to be more efficient than metal doped TiO2 in quinaldine synthesis under visible light. Higher activity of the N-TiO2 could be attributed to its stronger absorbance of visible light.
Jim C Spain - One of the best experts on this subject based on the ideXlab platform.
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oxidative pathway for the biodegradation of nitrobenzene by comamonas sp strain js765
Applied and Environmental Microbiology, 1995Co-Authors: Shirley F Nishino, Jim C SpainAbstract:Previous studies have shown that the biodegradation of nitrobenzene by Pseudomonas pseudoalcaligenes JS45 proceeds by the reduction of nitrobenzene through nitrosobenzene and hydroxylaminobenzene, followed by rearrangement to 2-aminophenol, which then undergoes meta ring cleavage. We report here the isolation of a Comamonas sp. that uses an oxidative pathway for the complete mineralization of nitrobenzene. The isolate, designated strain JS765, uses nitrobenzene as a sole source of carbon, nitrogen, and energy. Nitrobenzene-grown cells oxidized nitrobenzene, with the stoichiometric release of nitrite. Extracts of nitrobenzene-grown JS765 showed high levels of catechol 2,3-dioxygenase activity that were not abolished by heating the cell extracts to 60(deg)C for 10 min. The ring cleavage product had an absorbance maximum at 375 nm, consistent with that of 2-hydroxymuconic semialdehyde. Both NAD-dependent dehydrogenase and NAD-independent hydrolase activities towards 2-hydroxymuconic semialdehyde were induced in extracts of nitrobenzene-grown cells. Catechol accumulated in the reaction mixture when cells preincubated with 3-chlorocatechol were incubated with nitrobenzene. Conversion of nitrobenzene to catechol by induced cells in the presence of 3-chlorocatechol and (sup18)O(inf2) demonstrated the simultaneous incorporation of two atoms of oxygen, which indicated that the initial reaction was dioxygenation. The results indicate that the catabolic pathway involves an initial dioxygenase attack on nitrobenzene with the release of nitrite and formation of catechol, which is subsequently degraded by a meta cleavage pathway.
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Degradation of nitrobenzene by a Pseudomonas pseudoalcaligenes.
Applied and environmental microbiology, 1993Co-Authors: Shirley F Nishino, Jim C SpainAbstract:A Pseudomonas pseudoalcaligenes able to use nitrobenzene as the sole source of carbon, nitrogen, and energy was isolated from soil and groundwater contaminated with nitrobenzene. The range of aromatic substrates able to support growth was limited to nitrobenzene, hydroxylaminobenzene, and 2-aminophenol. Washed suspensions of nitrobenzene-grown cells removed nitrobenzene from culture fluids with the concomitant release of ammonia. Nitrobenzene, nitrosobenzene, hydroxylaminobenzene, and 2-aminophenol stimulated oxygen uptake in resting cells and in extracts of nitrobenzene-grown cells. Under aerobic and anaerobic conditions, crude extracts converted nitrobenzene to 2-aminophenol with oxidation of 2 mol of NADPH. Ring cleavage, which required ferrous iron, produced a transient yellow product with a maximum A380. In the presence of NAD, the product disappeared and NADH was produced. In the absence of NAD, the ring fission product was spontaneously converted to picolinic acid, which was not further metabolized. These results indicate that the catabolic pathway involves the reduction of nitrobenzene to nitrosobenzene and then to hydroxylaminobenzene; each of these steps requires 1 mol of NADPH. An enzyme-mediated Bamberger-like rearrangement converts hydroxylaminobenzene to 2-aminophenol, which then undergoes meta ring cleavage to 2-aminomuconic semialdehyde. The mechanism for release of ammonia and subsequent metabolism are under investigation.
Chenho Tung - One of the best experts on this subject based on the ideXlab platform.
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highly efficient and selective photocatalytic hydrogenation of functionalized Nitrobenzenes
Green Chemistry, 2014Co-Authors: Xiujie Yang, Bin Chen, Liqiang Zheng, Chenho TungAbstract:We report a simple but efficient photocatalytic nitrobenzene reduction method employing eosin Y as the photocatalyst and TEOA as the reducing agent. With green LED light irradiation, the nitro group in the Nitrobenzenes containing other reducible groups was chemoselectively reduced into an amino group, and the corresponding anilines were isolated in quantitative yields. The photoinduced electron transfer mechanism suggests that the high chemoselectivity originates from the better electron-withdrawing ability of the nitro group.
K Selvam - One of the best experts on this subject based on the ideXlab platform.
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nano n tio2 mediated selective photocatalytic synthesis of quinaldines from Nitrobenzenes
RSC Advances, 2012Co-Authors: K Selvam, M SwaminathanAbstract:N-Doped TiO2 using a new nitrogen precursor hydrazine hydrate was synthesized by a simple wet method. This photocatalyst was characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area, high resolution transmission electron microscopy (HR-TEM), UV-Vis diffused reflectance spectra (DRS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). N-Doping does not change the phase of TiO2. It is found that the size of N-TiO2 is 15.6 nm with 134.72 m² g−1 surface area. XPS analysis reveals the presence of anionic nitrogen in TiO2 as O–Ti–N. Substitution of N in place of oxygen in the TiO2 lattice causes a decrease in oxygen vacancies which inhibits the recombination of electron–hole pairs. This catalyst was used for the selective one-pot synthesis of quinaldines from Nitrobenzenes in ethanol under UV and visible light. N-TiO2 on irradiation induces a combined redox reaction with nitrobenzene and alcohol and this is followed by condensation-cyclization of aniline with oxidation products to give quinaldines. N-Doped TiO2 is found to be more efficient than metal doped TiO2 in quinaldine synthesis under visible light. Higher activity of the N-TiO2 could be attributed to its stronger absorbance of visible light.
Sidi Mohamed Mekelleche - One of the best experts on this subject based on the ideXlab platform.
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qsar study of the toxicity of Nitrobenzenes to tetrahymena pyriformis using quantum chemical descriptors
Arabian Journal of Chemistry, 2016Co-Authors: Khadidja Bellifa, Sidi Mohamed MekellecheAbstract:Abstract Quantitative Structure–Activity Relationship (QSAR) models are useful in understanding how chemical structure relates to the biological activity and the toxicity of natural and synthetic chemicals. The present study shows that Parr’s electrophilicity index ω in combination of two other descriptors, namely, the LUMO energy and the hydrophobicity index log P , prove their utility for the prediction of the toxicity of a series constituted by 50 nitrobenzene derivatives. The QSAR models are developed using the Multiple Linear Regression (MLR) method. It turns out that the best model, which its stability is confirmed using the leave-1/3-of-set-out validation, is able to describe about 87% of the variance of the experimental toxicity. The satisfactory obtained results show that Parr’s electrophilicity index is a useful quantum chemical descriptor for the toxicity modeling of nitrobenzene derivatives. Finally, the elaborated model shows that the most toxic Nitrobenzenes are characterized by large hydrophobicities and high electrophilicity powers and could be efficiently applied for the estimation of the toxicity of Nitrobenzenes for which the experimental measures are unavailable.
