Reduction Of Nitrobenzene Derivatives Research Articles

One-pot tandem reduction and site-selective halogenation of nitroarenes.

Halogenated aryl amines are a widely used chemical feedstock in the pharmaceutical and agrochemical industries. Achieving a single regioselective product from the para-selective halogenation of the aryl ring is significantly challenging because of the presence of several C-H bonds with similar reactivities. In this study, single para-halogenated aniline derivatives were prepared by the cascade para-selective halogenation (Cl, Br) and reduction of nitrobenzene derivatives using a mixture of SnCl2/SnCl4 salts. The mechanistic study confirmed that the noncovalent interactions between the chalcogen bond and Sn salt were pivotal for achieving regioselectivity. This synthetic method was applied for the development of potent and highly selective positron emission tomography molecular probes for serotonin transporters.

SYNTHESIS AND CHARACTERIZATION OF SOME NEW NITRONES DERIVATIVES AND SCREENING THEIR BIOLOGICAL ACTIVITIES

Synthetic approached towards the synthesis of some novel nitrones derivatives have been started with reduction of nitrobenzene derivatives as starting material bearing electron withdrawing and electron donating groups to corresponding phenylhydroxylamine in presence of zinc dust as reducing agent in aqueous solution of ammonium chloride (NH4Cl). The prepared phenylhydroxylamine derivatives were reacted with different substituted benzaldehydes to give the target derivatives of nitrone. The structures of the synthesized nitrones were characterized by spectroscopic methods FT-IR, 1H-NMR and 13C NMR. Finally, the newly synthesized compounds were screened for their microorganism activities at different concentration, and inhibited growth of Escherichia coli (E. coli) Gram negative, Staphylococcus aureus (S. aureus) Gram positive, and fungi (candida albicans).

Synthesis and Characterization of Some New Nitrones Derivatives and Screening their Biological Activities

Synthetic approached towards the synthesis of some novel nitrones derivatives have been started with reduction of nitrobenzene derivatives as starting material bearing electron withdrawing and electron donating groups to corresponding phenylhydroxylamine in presence of zinc dust as reducing agent in aqueous solution of ammonium chloride (NH4Cl). The prepared phenylhydroxylamine derivatives were reacted with different substituted benzaldehydes to give the target derivatives of nitrone. The structures of the synthesized nitrones were characterized by spectroscopic methods FT-IR, 1H-NMR and 13C NMR. Finally the newly synthesized compounds were screened for their microorganism activities at different concentration, and inhibited growth of Escherichia coli (E. coli) Gram negative, Staphylococcus aureus (S. aureus) Gram positive, and fungi (candida albicans).

Dendritic Fibrous Colloidal Silica Internally Cross-linked by Bivalent Organic Cations: An Efficient Support for Dye Removal and the Reduction of Nitrobenzene Derivatives.

We designed a new unique amphoteric monodisperse colloid with a large complex internal structure, in which silica surfaces are bridged with an organic cross-linker. The rationale was that such colloids would be excellent adsorbents for cationic and anionic dyes and, when doped with noble metal nanoparticles, would be an excellent catalyst for the reduction of a variety of organic compounds. In the first step, the organo-silica bridging agent (bivalent organic cross-linkers) DABCO-S (silanated DABCO) was prepared through a simple nucleophilic substitution reaction between (3-chloropropyl)triethoxysilane and bivalent 1,4-diazabicyclo[2.2.2]octane (DABCO) (a strong base). In the second step, a DABCO-S bridge was introduced into dendritic fibrous nanostructured colloidal silica (DFNS) under open-vessel reflux conditions. We refer to the product obtained by incorporating DABCO-S in DFNS as DDS. The unique characteristics of DFNS are completely preserved in this new type of periodic mesoporous organo-silica-DFNS. The produced nanocomposite has a high surface area of about 807 m2 g-1, a large pore volume of 1.9 cm3 g-1, and a bimodal pore size distribution, with small 2.5 nm pores and large 30 nm pores. As such, DDS is an efficient adsorbent for dye removal from wastewater. The results show that DDS can adsorb positive and negative dyes such as methylene blue, orange II sodium salt (OR), and procion red mx-58 (PR) with a capacity of 678, 3192, and 3190 mg dye/g adsorbent. Introducing silver nanoparticles in situ into DDS leads to a composite with excellent accessibility of reactants to the Ag surface, resulting in an efficient catalytic reduction of nitro aromatic compounds (NACs) in aqueous media.

Platinum nanoparticles confined in imidazolium-based ionic polymer for assembling a microfluidic reactor with enhanced catalytic activity

A synthetic strategy is developed to grow Pt nanoparticles supported by imidazolium-based ionic polymers (Pt/ImIP-2BrB) on the inner surface of fused-silica capillary. The imidazolium-based ionic polymers ImIP-2BrB are prepared from condensation of tetrakis[4-(1-imidazolyl)phenyl]methane and 1,4-bis-bromomethyl-benzene and are employed to support Pt nanoparticles. The capillary coated with Pt/ImIP-2BrB is further assembled to achieve a catalytic microfluidic reactor. The catalytic activity is probed in either the reduction of nitrobenzene derivatives or the hydrosilylation of phenylacetylene with triethylsilane by flowing through the microfluidic reactor. The catalytic microfluidic reactor demonstrates significantly enhanced activity about 2–8 times in comparison with the corresponding reactions under batch conditions. The reactor greatly reduces the amount of Pt upon achieving similar yields. It also shows good recyclability without significant decrease of the activity.

Magnetically Separable and Sustainable Nanostructured Catalysts for Heterogeneous Reduction of Nitroaromatics

This review is focused on the strategies and designs of magnetic nanostructured catalysts showing the enhanced and sustainable catalytic performances for the heterogeneous reduction of nitoaromatics. Magnetic catalysts have the benefits of easy recovery and reuse after the completion of the reactions and green chemical processes. Magnetic separation, among the various procedures for removing catalysts, not only obviates the requirement of catalyst filtration or centrifugation after the completion of reactions, but also provides a practical technique for recycling the magnetized nanostructured catalysts. Consequently, discussions will address the methodologies and exemplars for the reusable magnetic composite catalysts. Because the synthesis of ideal magnetic nanostructured catalysts is of primary importance in the development of high-quality sustainable processes, the designs, preparation methods and recyclability of various recoverable magnetic nanostructured catalysts are emphasized. The representative methods and strategies for the synthesis of durable and reusable magnetic nanostructured catalysts are highlighted. The advantages, disadvantages, recyclability and the efficiency of the introduced heterogeneous systems have been explored in the reduction of nitrobenzene derivatives.

Electrochemically Controlled Hydrogen Bonding. Nitrobenzenes as Simple Redox-Dependent Receptors for Arylureas

Reduction of nitrobenzene derivatives in the presence of arylureas in aprotic solvents results in large positive shifts in potential of the nitrobenzene(0/)(-) cyclic voltammetry wave with little change in wave shape. This behavior is indicative of reversible hydrogen bonding between nitrobenzene radical anions and arylureas. Computer fitting of the cyclic voltammetry of 4-nitroaniline, NA, plus 1,3-diphenylurea in DMF shows essentially no binding between urea and NA in the oxidized state (K(ox) < 1 M(-)(1)), but very strong binding in the reduced state (K(red) = 8 x 10(4) M(-)(1)), along with very rapid rates of hydrogen bond formation (k(f)'s approximately 10(8)-10(10) M(-)(1) s(-)(1)), making this system a fast on/off redox switch.