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Pharmaceuticals
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
The starting material, p-aminophenol (4-aminophenol), is produced from phenol by nitration followed by reduction with iron. Alternatively, the partial hydrogenation of nitrobenzene affords phenylhydroxylamine which rearranges primarily to 4-aminophenol: C6H5NO2+2H2→C6H5NHOH+H2OC6H5NHOH→HOC6H4NH2
Catalytic Application of Magnetic Nanocomposites
Published in Sam Zhang, Dongliang Zhao, Advances in Magnetic Materials, 2017
Poly(N,N′-methylenebis(acrylamide)-co-poly(2-dimethylaminoethylmethacry late)- functionalized, magnetic nanoparticle-supported Au-NPs, named Au-NPs/Fe3O4@SiO2@PHEMA-co-PDMAEMA, were reported with a small and narrow-distributed Au-NPs (∼3.7 nm) [106]. The catalyst catalyzed reduction reaction of 4-nitrophenol to 4-aminophenol quantitatively within 15 min at room temperature. The catalyst was reused six times with sustained activity [106]. However, metal nanoparticle leaching may cause a decrease in catalyst performance due to the loss of active centers. Meanwhile, the leaching metals may also contaminate the products. To maintain the high activity, Yao et al. reported a catalyst comprising of mesoporous SiO2-coated, magnetic nanoparticle-supported Pd-NPs (Pd-NPs/FexOy)@SiO2 [107]. The coating layer of mesoporous SiO2 was slightly larger than the magnetic core, and thus the layer was movable to enhance the interaction between Pd active centers and substrates. The catalyst is highly active in reduction of 4-nitrophenol to 4- aminophenol with NaBH4 and recyclable at least 10 times with sustained activity (100% conversion). The hybrid was found highly stable even at ultrasonic treatment [107]. Interestingly, pristine Fe3O4 magnetic nanoparticles produced in situ by reducing an iron complex such as Fe(acac)3, FeAc2, FeCl3 ⋅ 6H2O, and FeCl2 ⋅ 4H2O with hydrazine in excess also showed high activity in the hydrogenation of nitroaromaticles under microwave irradiation [108,109]. With the catalysts, various functionalized aniline products were obtained in 95%–99% yields from corresponding nitroarenes using hydrazine hydrate as the reductant within 2–8 min [108,109]. The in situ- prepared, Fe3O4 nanoparticle-based catalysts were also recyclable with sustained activity. However, both commercially available Fe3O4 and Fe0 powders were not active in this type of reaction [108,109]. Fe25Co75 nanoparticles were prepared and deposited onto the surface of grapheme oxide; the supported MNPs exhibited high activity for the reduction of 4-nitrophenol with NaBH4 in a TOF value of 2.9 × 1016 s−1 [110,111]. Other active and magnetic recyclable catalysts, including Fe3O4-NPs/GOs [112] and Ni-NPs/GOs [113], were also reported using NaBH4 as the reducing agent. It was found that the activity of these magnetic nanoparticles-based catalysts could be significantly improved by near-infrared irradiation [114]. Ma and others prepared Pt-NPs (∼5 nm) catalyst supported on a carbon-coated MNPs, Pt-NPs/Fe3O4@C [115]. The catalyst was highly effective for substituted nitrobenzene, R-C6H4-NO2 (R = H, 4-Cl, 4-Br, 4-Me, 2-NH2, 3-NH2, 4-NH2, 2-OH, 4-OH, 4-CHO, 4-CH2OH, 4-COMe, and 2-NO2), to the corresponding anilines in 95%–99% yields with H2 as the reductant at room temperature [115].
Anionic hydrogel fabricated with metal nanoparticles: highly efficient and easily recyclable catalysts
Published in Soft Materials, 2021
Hina Naeem, Muhammad Ajmal, Saba Zamurad Khan, Muhammad Naeem Ashiq, Muhammad Siddiq
Catalytic performance of prepared p(MAAc)-M composite hydrogels were explored by studying the degradation of some nitroaromatic compounds like 4-NP, 2-NP, 2-NA along with some organic dyes such as Eosin Y (EY) methyl orange (MO). Also, the simultaneous degradation of the nitro compound and dye solution was studied to explain the importance of prepared composite materials on an industrial level. Nitro compounds were selected for the catalytic test due to their extensive usage in industries like agrochemicals, pesticides,[22] herbicides,[24] textile industries,[25] and in pharmaceuticals, etc. Furthermore, the release of various azo dyes into the environment is alarming because of coloration, toxicity, and carcinogenicity associated with the dyes and their biodegradation products. So, it is important to degrade such type of aromatic/organic contaminants to less toxic and industrially important compounds like aminophenols.[25] Aminophenols are considered as very valuable reagents in the pharmaceutical industry due to their involvement in the formation of antipyretic, analgesic pharmaceutical products.
A novel green synthesis of gold nanoparticles using seaweed Lobophora variegata and its potential application in the reduction of nitrophenols
Published in Particulate Science and Technology, 2020
Princy Kaithavelikkakath Francis, Sreeja Sivadasan, Anna Avarachan, Anu Gopinath
Nitrophenols (NP) are anthropogenic organic pollutants in wastewater produced from industrial plants for the manufacture of pesticides, insecticides, herbicides, explosives, and synthetic dyes (Higson 1992). Because of the carcinogenic and mutagenic properties, these are very harmful to human beings and aquatic organisms. They are enrolled as a toxin by the United States Environment Protection Agency (Arora, Srivastava, and Singh 2014; Pandey and Mishra 2014). Conversely, its reduction product aminophenols (AP) have a wide range of applications such as precursors for the manufacture of several analgesic and antipyretic drugs, as photographic developer, as anticorrosion agent in paints, and in dye industries (Vaidya, Kulkarni, and Chaudhari 2003; Nemanashi and Meijboom 2013). One of the prominent methods to convert toxic nitrophenols to beneficial aminophenols is to carry out their reduction using NaBH4. However, this reaction is insignificantly slow in the absence of a catalyst. In recent times, nanocatalysis has emerged as a rapidly developing area of research in which metal nanoparticles are used as catalysts for wide range of chemical reactions. Small size, high surface area to volume fraction, and size relative activity have made metal nanoparticle an efficient catalyst. The potential catalytic ability of noble metal nanoparticles in the reduction of NP have been reported recently (Sen, Maity, and Islam 2013; Zhao et al. 2015).
Hexabranched dendrimers encapsulated metallic copper nanoparticles and their catalytic evaluation for the conversion of para-nitrophenol to para-aminophenol
Published in Inorganic and Nano-Metal Chemistry, 2023
Negin Mousavi, Parastoo Keshtiara, Marzieh Daryanavard
There is an immense interest in the use of dendrimers as catalysts for removing organic pollutants from wastewater. Nitrophenols are one of the organic pollutants that are generated from industrial and agricultural sources such as pharmaceutical, coal conversion, petrochemicals, paper, steel, food, textile, and pesticide industries.[30] Since they are bioaccumulative, highly toxic, and persistent, it is vital to develop the methods to remove or reduce their concentration in wastewaters.[29] The reduction of nitrophenols to aminophenols is a favorable reaction because aminophenols can be utilized for the production of various high-value chemicals and products.[31–33]