19618-17-8Relevant articles and documents
Synthesis and characterization of highly transparent and hydrophobic fluorinated polyimides derived from perfluorodecylthio substituted diamine monomers
Tapaswi, Pradip Kumar,Choi, Myeon-Cheon,Nagappan, Saravanan,Ha, Chang-Sik
, p. 479 - 488 (2015)
Two new perfluorodecylthio substituted aromatic diamines, namely 2,4-diamino-1-(1H,1H,2H,2H-perfluorodecathio) benzene (DAPFB) and 2,2′-Bis((1H,1H,2H,2H-perfluorodecyl) thio)[1,1′-biphenyl]4,4′-diamine (BPFBD) were synthesized and polycondensed with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) to produce two new perfluorinated polyimides (PI2 and PI4). The chemical structures of these polyimides were confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Two other polyimides (PI1 and PI3) were also synthesized from 6FDA and analogous perfluorodecylthio unsubstituted diamines to investigate the incorporation effect of perfluorodecylthio group on various physical and chemical properties of the synthesized PIs. Compared with PI1 and PI3, PI2 and PI4 exhibited improved solubility, optical transparency, and hydrophobicity, lower moisture absorption, dielectric constant, and thermo-mechanical stabilities owing to the presence of the perfluorodecylthio side group in the polymer chain. Even though thermo-mechanical properties of PI2 and PI4 (Td5: 413 and 404 °C, Tg: 220 and 209 °C, tensile strength of 101 and 76 MPa, tensile modulus of 1.7 and 1.5 GPa and elongation at break of 8 and 10%, respectively) were reduced in comparison to PI1 and PI3 but still were good enough for most of the practical applications. Most importantly, the presence of the perfluorodecylthio side group in BPFBD considerably reduced the dielectric constant of PI4 to 2.71 which was quite low as aromatic polyimide.
Modulating the catalytic behavior of non-noble metal nanoparticles by inter-particle interaction for chemoselective hydrogenation of nitroarenes into corresponding azoxy or azo compounds
Liu, Lichen,Concepción, Patricia,Corma, Avelino
, p. 312 - 323 (2018/12/11)
Aromatic azoxy compounds have wide applications and they can be prepared by stoichiometric or catalytic reactions with H2O2 or N2H4 starting from anilines or nitroarenes. In this work, we will present the direct chemoselective hydrogenation of nitroarenes with H2 to give aromatic azoxy compounds under base-free mild conditions, with a bifunctional catalytic system formed by Ni nanoparticles covered by a few layers of carbon (Ni@C NPs) and CeO2 nanoparticles. The catalytic performance of Ni@C-CeO2 catalyst surpasses the state-of-art Au/CeO2 catalyst for the direct production of azoxybenzene from nitrobenzene. By means of kinetic and spectroscopic results, a bifunctional mechanism is proposed in which, the hydrogenation of nitrobenzene can be stopped at the formation of azoxybenzene with >95% conversion and >93% selectivity, or can be further driven to the formation of azobenzene with >85% selectivity. By making a bifunctional catalyst with a non-noble metal, one can achieve chemoselective hydrogenation of nitroarenes not only to anilines, but also to corresponding azoxy and azo compounds.
Novel diamine having perfluorodecylthio group, preparation method thereof and fluorinated polyimid film prepared therefrom
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Paragraph 0128; 0130; 0131, (2017/08/26)
The present invention relates to a novel diamine having a perfluorodecylthio group for preparing a novel fluorinated polyimide film, a method for preparing the same, and a novel fluorinated polyimide film having a perfluorodecylthio group obtained from the diamine. The polyimide film obtained from the novel diamine having a perfluorodecylthio group according to the present invention comprises a perfluorodecylthio side group, and thus reduces a CTC effect between polymer chains and improves optical transparency through a steric hindrance effect and an induction effect of the perfluorodecyl side group (electron-donating effect of the diamine), improves solubility, provides increased hydrophobicity and shows improved physical properties, including low water absorbability and a low dielectric constant. Thus, the film according to the present invention can be used advisably instead of the existing polyimide films.COPYRIGHT KIPO 2017
Reduction of nitroarenes to azoxybenzenes by NaOH-PEG 400
Liu, Yufang,Liu, Bo,Guo, Ailing,Dong, Zhenming,Jin, Shuo,Lu, Yun
experimental part, p. 2201 - 2206 (2012/06/16)
The reduction of nitroarenes to azoxybenzenes by NaOH-PEG 400 in benzene is described. The protocol is facile, economical, and effective.
Reduction of nitroarenes to azoxybenzenes by potassium borohydride in water
Liu, Yufang,Liu, Bo,Guo, Ailing,Dong, Zhenming,Jin, Shuo,Lu, Yun
experimental part, p. 3563 - 3568 (2011/06/26)
The synthesis of the azoxybenzenes by the reduction of nitroarenes with reducing agent potassium borohydride in water was reported for the first time. PEG-400 was used as a phase transfer catalyst and could effectively catalyze the reduction. The electronic effects of substituent groups play an important role in determining the reduction efficiencies. Electron-withdrawing substituents promote the formation of the azoxybenzene products, while electron-releasing groups retard the reductions to various degrees depending on the extent of their electron-donating ability.
Competition between Radical and Nonradical Reactions of Halonitrobenzenes in Alkaline Alcoholic Solutions
Arca, Vittorio,Paradisi, Cristina,Scorrano, Gianfranco
, p. 3617 - 3621 (2007/10/02)
The study of the reactivity of monohalonitrobenzenes in 2-propanol solutions of potassium 2-propoxide has led to the identification of three distinct reaction paths: (a) hydro dehalogenation to nitrobenzene, (b) alkoxy dehalogenation via the SNAr mechanism, and (c) nitro reduction to azoxy and anilino derivatives via nitroso intermediates.With the exception of 2- and 4-fluoronitrobenzene, radical processes c or a are faster than the SNAr reaction.The radical processes proceed via a common intermediate, the radical anion *-, which can undergo unimolecular fragmentation to nitroaryl radical and X- (path a, favored for X = 2-I, 2-Br), or reduction to the dianion 2-, the direct precursor of the nitroso intermediate XC6H4NO (path c).In the presence of oxyen, an effective oxidant of the radical-anion intermediate, the SNAr reaction prevails for the activated ortho and para substrates.Cation-anion interactions are also major consequence in determining the course of reaction.Ion pairing favors nitro reduction, whereas it slows both the SNAr and the hydro dehalogenation reactions.
REACTION OF AROMATIC COMPOUNDS WITH NUCLEOPHILIC REAGENTS IN LIQUID AMMONIA. VII. DIRECTION OF HYDROXYLATION OF 3-SUBSTITUTED (Cl, Br, I, NO2) NITROBENZENES WITH POTASSIUM HYDROXIDE
Malykhin, E. V.,Kolesnichenko, G. A.,Shteingarts, V. D.
, p. 720 - 726 (2007/10/02)
The reaction of 3-chloro-, 3-bromo-, and 3-iodonitrobenzenes with potassium hydroxide and oxygen in liquid ammonia (-33 deg C) leads to the formation of nitrohalogenophenols, corresponding to substitution of the hydrogen atom at the orto and para positions of the ring in relation to the nitro group by a hydroxy group.In the case of the last two substrates it also leads to the corresponding 2-halogeno-3',4'-dinitrodiphenylamines.In view of the fact that substitued diphenylamines are formed under the same conditions as a result of the reaction of 3-nitroaniline with 3-halogenonitrobenzenes it is suggested that 3-bromo- and 3-iodonitrobenzenes are partly converted into 3-nitroaniline through the intermediate formation of 3-nitrodehydrobenzene.During dehydroxylation in the absence of oxygen the proportion of the phenols corresponding to substitution of the hydrogen atom at the para position to the nitro group by the hydroxy group increases, and the degree of transformation of the inital compounds decreases. 2,4-Dinitrophenol is formed with a low yield during the reaction of 1,3-nitrobenzene and potassium hydroxide in the presence of oxygen or in an atmosphere of argon.
