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Name Reactions
Published in Benny K.G. Theng, Clay Mineral Catalysis of Organic Reactions, 2018
Shimizu et al. (2002, 2004) used [Pd(NH3)4]2+-exchanged sepiolite as the catalyst for the Suzuki reaction of 4-bromophenol (1) with either phenylboronic acid (2) or sodium tetraphenylborate in water (or dimethylformamide), and K/Na carbonate as the base, to yield 4-hydroxybiphenyl (3), also known as 4-phenylphenol, according to Scheme 5.27. Strong electrostatic interactions between the [Pd(NH3)4]2+ complex and sepiolite surface inhibited Pd metal precipitation, giving rise to a stable catalyst and high turnover numbers. Na+-sepiolite impregnated with PdCl2 was similarly efficient in promoting the cross-coupling reaction of halobenzenes with phenylboronic acid to yield the corresponding biphenyl compounds (Corma et al. 2004). Similarly, Scheuermann et al. (2009) have obtained a biphenyl by reacting 4-nitro bromobenzene with phenylboronic acid in the presence of an organophilic Pd0-montmorillonite catalyst. In this context, we might mention the facile conversion of arylboronic acids to phenols by aqueous H2O2 in the presence of K10 montmorillonite (Sudhakar et al. 2013).
Sensing Effects and Sensitive Polymers
Published in Gábor Harsányi, Polymer Films in Sensor Applications, 2017
Microelectrodes with “membranes” of only several microns diameter but more than 100-μm thickness are particularly affected. The specific resistance of the membrane can be decreased by lipophilic salts, which dissociate substantially in the membrane medium. The lipophilic salt may dissociate into two lipophilic ions, as in the case of tetraalkylammonium tetraphenylborates, or into one lipophilic and one hydrophilic ion (e.g., potassium tetraphenylborate), where the hydrophilic ion is the ion being sensed. In the latter case, the molar concentration of the lipophilic salt should not exceed that of the neutral carrier (1:1 complexation between the carrier and the hydrophilic ion being assumed).
Liquid Plasma
Published in Ming-Fa Lin, Wen-Dung Hsu, Jow-Lay Huang, Lithium-Ion Batteries and Solar Cells, 2021
Masahiro Yoshimura, Jaganathan Senthilnathan, Anupama Surenjan
Functionalized graphene has been considered to be one of the most emergent materials; however, as described in Chapter 8 of this book, it is not well established to date. Senthilnathan et al. demonstrated the nitrogen functionalization of graphene in the liquid plasma process at ambient conditions [53]. In this study, a high potential was applied across the electrodes (graphite and platinum electrodes) in acetonitrile and radicalized graphene and punctured graphene sheets were exfoliated from the graphite electrode. The radicalized acetylene monomer •CH2C≡N present in the acetonitrile readily reacts with punctured graphene and forms nitrogen-functionalized graphene [10,53]. A schematic representation of micro-plasma discharge, graphene, and acetonitrile radical reaction, and the formation of nitrogen-functionalized graphene are given in Figure 9.3. Similarly, the liquid plasma process was used to prepare the nitrogen and boron co-doped graphene with acetonitrile containing sodium tetraphenylborate solution [54]. The HR-TEM images show that the amorphous-like nanocarbons were produced with 5 mM concentration of boron (Figure 9.4a–c), whereas a sponge-like graphene network was observed when the boron concentration was reduced from 5 to 0.1 mM (Figure 9.4d–f). Further, graphene nanosheets (few-layered) were obtained when the 1 and 0.1 mM boron were used, and the presence of N, B, and C has been monitored by EDX mapping analysis (Figure 9.4g–i). Hyun and Saito successfully demonstrated the formation of nitrogen–carbon nanosheets from 2-pyrrolidone, 1-methylpyrrolidine, pyrrolidine, pyrrole, cyclopentanone, and cyclohexanone in a liquid plasma condition [55].
Electroanalytical sensors-based biogenic synthesized metal oxide nanoparticles for potentiometric assay of pantoprazole sodium
Published in Green Chemistry Letters and Reviews, 2023
Eman M. Alshehri, Nawal A. Alarfaj, Salma A. Al-Tamimi, Maha F. El-Tohamy
PNZ was detected in its pharmaceutical form (Pantozol®40 mg/tablet) to determine the analytical applicability of the proposed sensors. The recorded data were compared with different PNZ sample concentrations and the relative percent recovery was evaluated. The results for the aforementioned sensors were 99.30 ± 0.4, 99.72 ± 0.2, and 99.82 ± 0.2, respectively. It was found that the PNZ-PT-Fe2O3NPs sensor was more sensitive than the PNZ-PT -NiONPs sensor for the determination of PNZ. The higher conductivity of PNZ-PT-Fe2O3NPs than PNZ-PT-NiONPs can be explained by the higher dielectric constant of Fe2O3NPs compared to NiO. The obtained data were statistically analyzed using Student's t-test and F-test [68]. The results were compared with those obtained by the potentiometric method [69], which is based on the preparation of a PNZ sensor with sodium tetraphenylborate. The results demonstrate the high sensitivity of the recommended sensors for the detection of PNZ in pharmaceutical form.
Crystal structure, magnetic properties, and structural prediction for an oxidovanadium(IV) complex [VO(dmf)5][PF6]2
Published in Journal of Coordination Chemistry, 2021
Shohei Yamamoto, Ryoji Mitsuhashi, Masahiro Mikuriya, Masayuki Koikawa, Hiroshi Sakiyama
Pentakis(dimethylformamide-κO)oxidovanadium(IV) was first reported as a perchlorate salt, [VO(dmf)5][ClO4]2, more than half a century ago [10]. At that time, the compound was prepared under anaerobic conditions, and the crystal structure has not been reported despite the simple structure of the [VO(dmf)5]2+ cation. On the other hand, dimethylsulfoxide (dmso) derivatives, [VO(dmso)5][ClO4]2 [11] and [VO(dmso)5][BPh4]2 [12], are more common and easier to prepare. For example, [VO(dmso)5][BPh4]2 can be readily synthesized in air and precipitates easily when NaBPh4 solution is added [12]. On the contrary, however, if a dmf derivative is synthesized in the similar way, tetraphenylborate anion is oxidized to form a tetracoordinate organoboron coordination compound, dimethylformamide-triphenylborane (dmf-BPh3) [13]. In this study, a hexafluoridophosphate ([PF6]–) salt of pentakis-dmf oxidovanadium(IV), [VO(dmf)5][PF6]2, was prepared under aerobic conditions, and its crystal structure was determined.
Research Trends on Separation and Extraction of Rare Alkali Metal from Salt Lake Brine: Rubidium and Cesium
Published in Solvent Extraction and Ion Exchange, 2020
Li Gao, Guihua Ma, Youxiong Zheng, Yan Tang, Guanshun Xie, Jianwei Yu, Bingxin Liu, Junyuan Duan
In precipitation, large anions (polyoxometalates,[20,21] acid complex salt, polyhalides, vitriol, and certain organic reagents) are combined with Rb+ and Cs+ in a solution to form insoluble compounds or crystal precipitates, thus removing Rb+ and Cs+ from the solution.[14,18] The most extensively studied precipitating agents include sodium tetraphenylborate (NaTPB),[22] silicotungstic acid (STA),[21] and potassium iodobismuthate.[20] Soliman et al[22] used sodium NaTPB as precipitant to remove 137Cs from radioactive waste liquid, and proposed that precipitated CsTPB particles can be floated from the solution by coating iron oxide. In addition, there were many studies on the separation and extraction of Rb+ and Cs+ from solution by using phosphotungstic acid (PWA). The reaction formula was