Topic
Nitrobenzene
About: Nitrobenzene is a research topic. Over the lifetime, 5285 publications have been published within this topic receiving 83368 citations. The topic is also known as: essence of mirbane & nitrobenzol.
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TL;DR: In this article, the properties of supported zinc acetate catalysts on different supports have been examined for the catalytic synthesis of methylene diphenyl-4,4‘-diisocyanate (MDI) consisting of three steps.
Abstract: The catalytic synthesis of methylene diphenyl-4,4‘-diisocyanate (MDI) consists of three steps. Starting from the catalytic reaction of aniline and dimethyl carbonate (DMC), methyl phenyl carbamate (MPC) is formed. Then MPC condenses with formaldehyde to produce dimethyl methylene diphenyl-4,4‘-dicarbamate (MDC). Last, MDC is decomposed to MDI. For the first step, the properties of supported zinc acetate catalysts on different supports have been examined. Supported zinc acetate catalyst on activated carbon (AC) or α-Al2O3 shows good catalytic properties. Over Zn(OAc)2/AC catalyst, MPC yield reaches 78% and the selectivity is 98%. For the second step, when zinc chloride is used as a catalyst and nitrobenzene as a solvent, MDC yield can reach 87.4%. The catalytic activity of AC-supported ZnCl2 catalyst, which is calculated based on 1 mol of ZnCl2, is much higher than that of homogeneous ZnCl2. For the third step, zinc powder and its organic salts show higher catalytic activity; MDI yield is 87.3% over zinc p...
48 citations
TL;DR: The hydrogenation of nitroarenes is one of the most important strategies to produce the corresponding anilines and dicyclohexylamines, both of which are the fundamental raw materials in the synthesized synthesis as discussed by the authors.
Abstract: The hydrogenation of nitroarenes is one of the most important strategies to produce the corresponding anilines and dicyclohexylamines, both of which are the fundamental raw materials in the synthes...
48 citations
TL;DR: It was established that the developed methodology allows for the production of NPs with different morphologies and compositions in a safe and simple manner and a detailed reduction pathway mechanism for the catalytic reduction of 4-nitrophenol and nitrobenzene has been proposed.
48 citations
TL;DR: In this article, a comparison of degradation dynamics of five aromatic compounds (phenol, chlorobenzene, nitrobenzene, 4-chlorophenol, and pentachlorophenol) in aqueous solutions by non-catalytic UV, MW, and combined MW/UV remediation techniques in the presence of H2O2 is presented.
Abstract: Advanced oxidation processes have emerged as potentially powerful methods to transform organic pollutants in aqueous solutions into non-toxic substances. In this work, a comparison of degradation dynamics of five aromatic compounds (phenol, chlorobenzene, nitrobenzene, 4-chlorophenol, and pentachlorophenol) in aqueous solutions by non-catalytic UV, MW, and combined MW/UV remediation techniques in the presence of H2O2 is presented. Relative degradation rate constants have been monitored and the major products were identified. The combined degradation effect of UV and MW radiation was found larger than the sum of isolated effects in all cases studied. It is concluded that such an overall efficiency increase is essentially based on a thermal enhancement of subsequent oxidation reactions of the primary photoreaction intermediates. Optimizations revealed that this effect was particularly significant in samples with a low concentration of H2O2, however, a larger excess of H2O2 was essential to complete the destruction in most experiments. The absence of heterogeneous catalysts was in no doubt an additional advantage of the technique applied.
47 citations
TL;DR: In this paper, the catalytic effect of a heteropolyacid, H4SiW12O40, on nitrobenzene (20 and 30μM) oxidation in supercritical water was investigated.
Abstract: The catalytic effect of a heteropolyacid, H4SiW12O40, on nitrobenzene (20 and 30 μM) oxidation in supercritical water was investigated. A capillary flow-through reactor was operated at varying temperatures (T=400–500 °C; P=30.7 MPa) and H4SiW12O40 concentrations (3.5–34.8 μM) in an attempt to establish global power-law rate expressions for homogenous H4SiW12O40-catalyzed and uncatalyzed supercritical water oxidation. Oxidation pathways and reaction mechanisms were further examined via primary oxidation product identification and the addition of various hydroxyl radical scavengers (2-propanol, acetone, acetone-d6, bromide and iodide) to the reaction medium. Under our experimental conditions, nitrobenzene degradation rates were significantly enhanced in the presence of H4SiW12O40. The major differences in temperature dependence observed between catalyzed and uncatalyzed nitrobenzene oxidation kinetics strongly suggest that the reaction path of H4SiW12O40-catalyzed supercritical water oxidation (average activation Ea=218 kJ/mol; k=0.015–0.806 s−1 energy for T=440–500 °C; Ea=134 kJ/mol for the temperature range T=470–490 °C) apparently differs from that of uncatalyzed supercritical water oxidation (Ea=212 kJ/mol; k=0.37–6.6 μM s−1). Similar primary oxidation products (i.e. phenol and 2-, 3-, and 4-nitrophenol) were identified for both treatment systems. H4SiW12O40-catalyzed homogenous nitrobenzene oxidation kinetics was not sensitive to the presence of OH scavengers.
47 citations