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1.
To investigate the CF3 group affecting the coloration and solubility of polyimides (PI), a novel fluorinated diamine 1,1‐bis[4‐(4‐amino‐2‐ trifluoromethylphenoxy)phenyl]‐1‐phenylethane (2) was prepared from 1,1‐ bis(4‐hydrophenyl)‐1‐phenylethan and 2‐chloro‐5‐nitrobenzotrifluoride. A series of light‐colored and soluble PI 5 were synthesized from 2 and various aromatic dianhydrides 3a–f using a standard two‐stage process with thermal 5a– f(H) and chemical 5a–f(C) imidization of poly(amic acid). The 5 series had inherent viscosities ranging from 0.55 to 0.98 dL/g. Most of 5a–f(H) were soluble in amide‐type solvents, such as N‐methyl‐2‐pyrrolidone (NMP), N,N‐ dimethylacetamide (DMAc), and N,N‐dimethylformamide (DMF), and even soluble in less polar solvents, such as m‐Cresol, Py, Dioxane, THF, and CH2Cl2, and the 5(C) series was soluble in all solvents. The GPC data of the 5a–f(C) indicated that the Mn and Mw values were in the range of 5.5–8.7 × 104 and 8.5–10.6 × 104, respectively, and the polydispersity index (PDI) Mw /Mn values were 1.2–1.5. The PI 5 series had excellent mechanical properties. The glass transition temperatures of the 5 series were in the range of 232–276°C, and the 10% weight loss temperatures were at 505–548 °C in nitrogen and 508–532 °C in air, respectively. They left more than 56% char yield at 800°C in nitrogen. These films had cutoff wavelengths between 356.5–411.5 nm, the b* values ranged from 5.0–71.1, the dielectric constants, were 3.11–3.43 (1MHz) and the moisture absorptions were in the range of 011–0.40%. Comparing 5 containing the analogous PI 6 series based on 1,1‐bis[4‐(4‐aminophenoxy)phenyl]‐1‐ phenylethane (BAPPE), the 5 series with the CF3 group showed lower color intensity, dielectric constants, and better solubility. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2399–2412, 2005 相似文献
2.
Qian Chen Takahiro Soeta Masami Kuriyama Ken‐ichi Yamada Kiyoshi Tomioka 《Advanced Synthesis \u0026amp; Catalysis》2006,348(18):2604-2608
Catalytic asymmetric conjugate arylation of racemic 6‐substituted cyclohexenones with arylboronic acids was catalyzed by 3 mol % of chiral amidophosphane‐[RhCl(C2H4)]2 in a 10:1 mixture of 1,4‐dioxane and water at 70 °C to afford a nearly 1:1 mixture of trans‐ and cis‐5‐aryl‐2‐substituted cyclohexanones in high enantioselectivity, which was subsequently epimerized with sodium ethoxide in ethanol to give thermodynamically stable trans‐5‐aryl‐2‐substituted cyclohexanones with 99–97 % ee in high two‐step yields. 相似文献
3.
Zheng‐Jian Qi Xue‐Mei Wang Bin Wei Feng Kang Lan‐Lan Tang Man‐Xin Hong Yue‐Ming Sun 《应用聚合物科学杂志》2011,120(5):2678-2684
Four novel highly soluble p‐/n‐poly[(2,5‐divinyl‐3,4‐dialkylthiophene)‐alt‐2,6‐pyridine] (PA2TV‐Py) and poly[(2,5‐divinyl‐3,4‐dialkylthiophene)‐alt‐(2,5‐diphenyl‐1,3,4‐oxadiazole)] (PA2TV‐OXD) are prepared by Heck coupling approach to compare their photoelectric properties. Characterizations of the copolymers include FT‐IR, 1H‐NMR, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), UV–vis spectroscopy, photoluminescence (PL), and electroluminescence (EL). Four alt‐copolymers exhibit excellent solubility in common organic solvents (e.g., CHCl3, THF) and good thermal stabilities, losing less than 5% on heating to ~ 250°C. The optical properties depict that the band‐gap energy of PA2TV‐Py and PA2TV‐OXD is similarly, ranging from 2.68 to 2.80 eV in solid film and 2.90–2.97 eV in CHCl3 solution. PA2TV‐Pys can emit bright turquoise light with quantum efficiencies (QE) of 30.6 and 53.9%, which about 10‐18 times higher than that of homopolymer in CHCl3 solution. Furthermore, the QE of two PA2TV‐OXDs (purple fluorescence) are increased to 43.6 and 68.5%, respectively, about 1.3–1.4 times higher than that of PA2TV‐Pys. Electrochemical results indicate that the electron affinity (Ea) of four alt‐copolymers range from 2.79 to 3.09 eV, which are propitious to electrons injecting and transporting from the cathode. As a result, these novel copolymers present expected good electroluminescence(EL) performance in their single layer polymer light‐emitting device (PLED) with configuration of ITO/polymer/Al, which turn‐on voltages are between 4.0 and 5.8 V and emit bright green–yellow (538 nm) and yellow (545–552 nm) EL light. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
4.
High Electric‐Induced Strain and Temperature‐Dependent Piezoelectric Properties of 0.75BF–0.25BZT Lead‐Free Ceramics
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0.75BiFeO3–0.25Ba(ZrxTi1?x) + 0.6 wt% MnO2 (0.75BF–0.25BZT) ceramics with Mn addition were prepared by the solid‐state reaction method. The high‐field strain and high‐temperature piezoelectric properties of 0.75BF–0.25BZT ceramics were studied. Introduction of Zr in the solid solutions decreased the Curie temperature slightly, and improved the dielectric and piezoelectric properties obviously. The piezoelectric properties of 0.75BZT–0.25BT ceramics reached the maximum at Zr content of 10 mol%. The Curie temperature Tc, dielectric constant ε and loss tanδ (1 kHz), piezoelectric constant d33, and planner electromechanical coupling factor kp of 0.75BF–0.25BZT ceramics with 10 mol% Zr were 456°C, 650, 5%, 138 pC/N, and 0.30, respectively. The high‐field bipolar and unipolar strain under an electric field of 100 kV/cm reached up to 0.55% and 0.265%, respectively, which were comparable to those of BiScO3–PbTiO3 and “soft” PZT‐based ceramics. The typical “butterfly”‐shaped bipolar strain and frequency‐dependent peak‐to‐peak strain indicated that the large high‐field‐induced strain may be due to non‐180° domain switching. Rayleigh analysis reflected that the improved piezoelectric properties resulted from the enhanced extrinsic contribution by Zr doping. The unipolar strain of 0.75BF‐0.25BZT ceramics with 10 mol% Zr was almost linear from RT to 200°C. These results indicated that 0.75BF–0.25BZT ceramics were promising candidates for high‐temperature and lead‐free piezoelectric actuators. 相似文献
5.
Samira Agbolaghi 《Polymer International》2019,68(8):1516-1523
Reduced graphene oxide nanosheets modified by conductive polymers including polythiophene (GPTh), polyaniline (GPANI) and polypyrrole (GPPy) were prepared using the graphene oxide as both substrate and chemical oxidant. UV–visible and Raman analyses confirmed that the graphene oxide simultaneously produced the reduced graphene oxide and polymerized the conjugated polymers. The prepared nanostructures were subsequently electrospun in mixing with poly(3‐hexylthiophene) (P3HT)/phenyl‐C71‐butyric acid methyl ester (PC71BM) and poly[bis(triisopropylsilylethynyl)benzodithiophene‐bis(decyltetradecylthien)naphthobisthiadiazole] (PBDT‐TIPS‐DTNT‐DT)/PC71BM components and embedded in the active layers of photovoltaic devices to improve the charge mobility and efficiency. The GPTh/PBDT‐TIPS‐DTNT‐DT/PC71BM devices demonstrated better photovoltaic features (Jsc = 11.72 mA cm?2, FF = 61%, Voc = 0.68 V, PCE = 4.86%, μh = 8.7 × 10?3 cm2 V–1 s?1 and μe = 1.3 × 10?2 cm2 V–1 s?1) than the GPPy/PBDT‐TIPS‐DTNT‐DT/PC71BM (Jsc = 10.30 mA cm?2, FF = 60%, Voc = 0.66 V, PCE = 4.08%, μh = 1.4 × 10?3 cm2 V–1 s?1 and μe = 8.9 × 10?3 cm2 V–1 s?1) and GPANI/PBDT‐TIPS‐DTNT‐DT/PC71BM (Jsc = 10.48 mA cm?2, FF = 59%, Voc = 0.65 V, PCE = 4.02%, μh = 8.6 × 10?4 cm2 V–1 s?1 and μe = 7.8 × 10?3 cm2 V–1 s?1) systems, assigned to the greater compatibility of PTh in the nano‐hybrids and the thiophenic conjugated polymers in the bulk of the nanofibers and active thin films. Furthermore, the PBDT‐TIPS‐DTNT‐DT polymer chains (3.35%–5.04%) acted better than the P3HT chains (2.01%–3.76%) because of more complicated conductive structures. © 2019 Society of Chemical Industry 相似文献
6.
Synthesis and Surface Properties of a Novel Sodium 3‐(3‐Alkyloxy‐3‐oxopropoxy)‐3‐oxopropane‐1‐sulfonate at the Air–Water Interface
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Pandari Phani Kumar Rati Ranjan Nayak Sanjit Kanjilal 《Journal of surfactants and detergents》2015,18(4):689-695
The present paper describes the synthesis and evaluation of surface properties of a novel series of anionic surfactant, namely sodium 3‐(3‐alkyloxy‐3‐oxopropoxy)‐3‐oxopropane‐1‐sulfonate with varying alkyl chain length (C8–C16). Synthesis involves initial formation of the 3‐alkyloxy‐3‐oxopropyl acrylate along with fatty acrylate during the direct esterification of fatty alcohol with acrylic acid in the presence of 0.5 % NaHSO4 at 110 °C followed by sulfonation of the terminal double bond of the 3‐alkyloxy‐3‐oxopropyl acrylate. Synthesized compounds were evaluated for surface and thermodynamic properties such as critical micelle concentration (CMC), surface tension at CMC (γcmc), efficiency of surface adsorption (pC20), surface excess (Γmax), minimum area per molecule at the air–water interface (Amin), free energy of adsorption (?G°ads), free energy of micellization (?G°mic), wetting time, emulsifying properties, foaming power and calcium tolerance. Effect of chain length on CMC follows the classic trend, i.e. decrease in CMC with the increase in alkyl chain length. High pC20 (>3) value indicates higher hydrophobic character of the surfactant. These surfactants showed very poor wetting time and calcium tolerance, but exhibited good emulsion stability and excellent foamability. Foaming power and foam stability of C14‐sulfonate were found to be the best among the studied compounds. Foam stability of C14‐sulfonate was also studied at different concentrations over time and excellent foam stability was obtained at a concentration of 0.075 %. Thus this novel class of surfactant may find applications as foam boosters in combination with other suitable surfactants. 相似文献
7.
A combination of reduced graphene oxide (rGO) nanosheets grafted with regioregular poly(3‐hexylthiophene) (P3HT) (rGO‐g‐P3HT) and P3HT‐b‐polystyrene (PS) block copolymers was utilized to modify the morphology of P3HT:[6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM) active layers in photovoltaic devices. Efficiencies greater than 6% were acquired after a mild thermal annealing. To this end, the assembling of P3HT homopolymers and P3HT‐b‐PS block copolymers onto rGO‐g‐P3HT nanosheets was investigated, showing that the copolymers were assembled from the P3HT side onto the rGO‐g‐P3HT nanosheets. Assembling of P3HT‐b‐PS block copolymers onto the rGO‐g‐P3HT nanosheets developed the net hole and electron highways for charge transport, thereby in addition to photoluminescence quenching the charge mobility (μh and μe) values increased considerably. The best charge mobilities were acquired for the P3HT50000:PC71BM:rGO‐g‐P3HT50000:P3HT7000‐b‐PS1000 system (μh = 1.9 × 10?5 cm2 V–1 s–1 and μe = 0.8 × 10?4 cm2 V–1 s–1). Thermal annealing conducted at 120 °C also further increased the hole and electron mobilities to 9.8 × 10?4 and 2.7 × 10?3 cm2 V–1 s–1, respectively. The thermal annealing acted as a driving force for better assembly of the P3HT‐b‐PS copolymers onto the rGO‐g‐P3HT nanosheets. This phenomenon improved the short circuit current density, fill factor, open circuit voltage and power conversion efficiency parameters from 11.13 mA cm?2, 0.63 V, 62% and 4.35% to 12.98 mA cm?2, 0.69 V, 68% and 6.09%, respectively. © 2019 Society of Chemical Industry 相似文献
8.
The thermal degradation kinetics of poly(3‐hydroxybutyrate) (PHB) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) [poly(HB–HV)] under nitrogen was studied by thermogravimetry (TG). The results show that the thermal degradation temperatures (To, Tp, and Tf) increased with an increasing heating rate (B). Poly(HB–HV) was thermally more stable than PHB because its thermal degradation temperatures, To(0), Tp(0), and Tf(0)—determined by extrapolation to B = 0°C/min—increased by 13°C–15°C over those of PHB. The thermal degradation mechanism of PHB and poly(HB–HV) under nitrogen were investigated with TG–FTIR and Py–GC/MS. The results show that the degradation products of PHB are mainly propene, 2‐butenoic acid, propenyl‐2‐butenoate and butyric‐2‐butenoate; whereas, those of poly(HB–HV) are mainly propene, 2‐butenoic acid, 2‐pentenoic acid, propenyl‐2‐butenoate, propenyl‐2‐pentenoate, butyric‐2‐butenoate, pentanoic‐2‐pentenoate, and CO2. The degradation is probably initiated from the chain scission of the ester linkage. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1530–1536, 2003 相似文献
9.
Katalin Barta Giancarlo Franci Walter Leitner GuyC. Lloyd‐Jones IanR. Shepperson 《Advanced Synthesis \u0026amp; Catalysis》2008,350(13):2013-2023
Palladium‐catalysed monophosphorylation of (R)‐2,2′‐bisperfluoroalkanesulfonates of BINOL (RF=CF3 or C4F9) by a diaryl phosphinate [Ar2P(O)H] followed by phosphine oxide reduction (Cl3SiH) then lithium diisopropylamide‐mediated anionic thia‐Fries rearrangement furnishes enantiomerically‐pure (R)‐2′‐diarylphosphino‐2′‐hydroxy‐3′‐perfluoralkanesulfonyl‐1,1′‐binaphthalenes [(R)‐ 8ab and (R)‐ 8g–j ], which can be further diversified by Grignard reagent (RMgX)‐mediated CF3‐displacement [→(R)‐ 8c–f ]. Coupling of (R)‐ 8a–j with (S)‐1,1′‐binaphthalene‐2,2′‐dioxychlorophosphine (S)‐ 9 generates 3′‐sulfonyl BINAPHOS ligands (R,S)‐ 10a–j in good yields (43–82%). These new ligands are of utlility in the asymmetric hydrophosphonylation of styrene ( 1 ) by 4,4,5,5‐tetramethyl‐1,3,2‐dioxaphospholane 2‐oxide ( 2 ), for which a combination of the chiral ligands with either [Pd(Cp)(allyl)] or [Pd(allyl)(MeCN)2]+/NaCH(CO2Me)2 proves to be a convenient and active pre‐catalyst system. A combination of an electron‐rich phosphine moiety and an electron‐deficient 3′‐sulfone moiety provides the best enantioselectivity to date for this process, affording the branched 2‐phenethenephosphonate, (−)‐iso‐ 3 , in up to 74% ee with ligand (R,S)‐ 10i , where Ar=p‐anisyl and the 3′‐SO2R group is triflone. 相似文献
10.
Bismuth triflate was found to be an efficient catalyst in the Sakurai reaction of allyltrimethylsilanes with N‐alkoxycarbonylamino sulfones. The reaction proceeded smoothly with a low catalyst loading of Bi(OTf)3⋅4 H2O (2–5 mol%) to afford the corresponding protected homoallylic amines in very good yields (up to 96%). A sequential allylation reaction followed by ring‐closing metathesis delivers 6–8 membered 3‐Cbz‐protected cycloalkenylamines. 相似文献
11.
Hui Niu Bohumil Volesky 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2000,75(6):436-442
L ‐Cysteine increased gold‐cyanide biosorption by protonated Bacillus subtilis, Penicillium chrysogenum and Sargassum fluitans biomass. At pH 2, the maximum Au uptakes were 20.5 µmol g−1, 14.2 µmol g−1 and 4.7 µmol g−1 of Au, respectively, approximately 148–250% of the biosorption performance in the absence of cysteine. Au biosorption mainly involved anionic AuCN2− species adsorbed by ionizable functional groups on cysteine‐loaded biomass carrying a positive charge when protonated [(biomass–cysteine–H+)–(AuCN2−)]. Deposited gold could be eluted from Au‐loaded biomass at pH 3–5. The elution efficiencies were higher than 92% at pH 5.0 with the Solid‐to‐Liquid ratio, S/L, = 4. Increasing solution ionic strength (NaNO)3 decreased Au uptake. FTIR analyses indicated that the main functional groups involved in gold biosorption in the presence of L ‐cysteine are probably N‐, S‐ and O‐containing groups. The present results confirm that certain waste microbial biomaterials are capable of effectively removing and concentrating gold from solutions containing residual cyanide if applied under appropriate conditions. © 2000 Society of Chemical Industry 相似文献
12.
Takashi Nishikata Yasunori Yamamoto Norio Miyaura 《Advanced Synthesis \u0026amp; Catalysis》2007,349(10):1759-1764
The enantioselective 1,4‐addition of arylboronic acids to β‐arylenones to give β‐diaryl ketones was carried out at 0–25 °C in the presence of a dicationic palladium(II) catalyst, [Pd(S,S‐chiraphos)(PhCN)2](SbF6)2. Addition of a silver salt such as silver tetrafluoroborate [AgBF4] or silver hexafluoroantimonate [AgSbF6] (5–10 mol %) was effective to achieve high enantioselectivities at low temperatures (92–99 % ee) and to reduce the catalyst loading to 0.05 mol %. The protocol provided a simple access to 4‐aryl‐4H‐chromenes. Optically active chromenes were synthesized with up to 99 % ee via dehydration of the 1,4‐adducts between arylboronic acids and β‐(2‐hydroxyaryl)‐α,β‐unsaturated ketones. 相似文献
13.
A variety of N,N‐diallyl compounds, capable of undergoing cyclopolymerization, are prepared from 1,12‐dodecanediamine. Selective monoformylation followed by allylation of the parent diamine afforded N,N‐diallyl‐N′‐formyl‐1,12‐dodecanediamine which was converted into quaternary ammonium monomers N,N‐diallyl‐N‐benzyl (or p‐methoxybenzyl)‐N′‐formyl‐1,12‐dodecanediamine by reacting with benzyl‐ or p‐methoxybenzyl chloride. The monomers on homo‐ and co‐cyclopolymerization (with SO2) afforded the cationic polyelectrolytes which on acidic hydrolysis of the formyl group gave water‐soluble polyelctrolytes. All the synthesized monomers, polymers, and the starting 1,12‐dodecanediamine were used to study the corrosion inhibition of mild steel by gravimetry and electrochemical methods in acidic and saline media at 60°C. The inhibitor molecules (at a concentration of 400 ppm) exhibited inhibition efficiencies (%IE) in the ranges 62%–99% in 1 M HCl, 95%–99% in 4 M HCl, 13%–91% in 7.7 M HCl, 13%–91% in 0.5 M H2SO4, and 75%–90% in 3.5% NaCl. There is a dramatic increase in the IEs by the monomers and polymers in comparison to the parent diamine. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers 相似文献
14.
Magnetic Fe3O4–poly(aniline‐co‐o‐anthranilic acid) nanoparticles were prepared by a novel and simple method: anthranilic acid assisted polymerization. The synthetic strategy involved two steps. First, Fe3O4 nanoparticles capped by anthranilic acid were obtained by a chemical precipitation method, and then the aniline and oxidant were added to the modified Fe3O4 nanoparticles to prepare well‐dispersed Fe3O4–poly(aniline‐co‐o‐anthranilic acid) nanoparticles. Fe3O4–poly(aniline‐co‐o‐anthranilic acid) nanoparticles exhibited a superparamagnetic behavior (i.e., no hysteresis loop) and high‐saturated magnetization (Ms = 21.5 emu/g). The structure of the composite was characterized by Fourier‐transform infrared spectra, X‐ray powder diffraction patterns, and transmission electron microscopy, which proved that the Fe3O4–poly(aniline‐co‐o‐anthranilic acid) nanoparticles were about 20 nm. Moreover, the thermal properties of the composite were evaluated by thermogravimetric analysis, and it showed excellent thermal stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1666–1671, 2006 相似文献
15.
A new diamine 5,5′‐bis[4‐(4‐aminophenoxy)phenyl]‐hexahydro‐4,7‐methanoindan ( 3 ) was prepared through the nucleophilic displacement of 5,5′‐bis(4‐hydroxylphenyl)‐hexahydro‐4,7‐methanoindan ( 1 ) with p‐halonitrobenzene in the presence of K2CO3 in N,N‐dimethylformamide (DMF), followed by catalytic reduction with hydrazine and Pd/C in ethanol. A series of new polyamides were synthesized by the direct polycondensation of diamine 3 with various aromatic dicarboxylic acids. The polymers were obtained in quantitative yields with inherent viscosities of 0.76–1.02 dl g−1. All the polymers were soluble in aprotic dipolar solvents such as N,N‐dimethylacetamide (DMAc) and N‐methyl‐2‐pyrrolidone (NMP), and could be solution cast into transparent, flexible and tough films. The glass transition temperatures of the polyamides were in the range 245–282 °C; their 10% weight loss temperatures were above 468 °C in nitrogen and above 465 °C in air. © 2000 Society of Chemical Industry 相似文献
16.
Jingtang Chen Karlheinz Sünkel Wolfgang Beck 《Advanced Synthesis \u0026amp; Catalysis》1999,341(8):792-796
The reaction of the Cu(II) bis N,O‐chelate‐complexes of L‐2,4‐diaminobutyric acid, L‐ornithine and L‐lysine {Cu[H2N–CH(COO)(CH2)nNH3]2}2+(Cl–)2 (n = 2–4) with terephthaloyl dichloride or isophthaloyl dichloride gives the polymeric complexes {‐OC–C6H4–CO–NH–(CH2)n–CH(nh2)(COO)Cu(OOC)(NH2)CH–CH2)n–NH‐}x 1 – 5 . From these the metal can be removed by precipitation of Cu(II) with H2S. The liberated ω,ω′‐N,N′‐diterephthaloyl (or iso‐phthaloyl)‐diaminoacids 6 – 10 react with [Ru(cymene)Cl2]2, [Ru(C6Me6)Cl2]2, [Cp*RhCl2]2 or [Cp*IrCl2]2 to the ligand bridged bis‐amino acidate complexes [Ln(Cl)M–(OOC)(NH2)CH–(CH2)nNH–CO]2–C6H4 11 – 14 . 相似文献
17.
Ranjana Bhati Nirupama Mallick 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(4):505-512
BACKGROUND: Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) [P(3HB‐co‐3HV)] co‐polymer has immense potential in the field of environmental and biomedical sciences as biodegradable and biocompatible material. The present study examines a filamentous N2‐fixing cyanobacterium, Nostoc muscorum Agardh as a potent feedstock for P(3HB‐co‐3HV) co‐polymer production and characterization of co‐polymer film for commercial applications. RESULTS: Under photoautotrophic growth conditions, N. muscorum Agardh accumulated the homopolymer of poly‐β‐hydroxybutyrate (PHB), whereas synthesis of P(3HB‐co‐3HV) co‐polymer was detected under propionate‐ and valerate‐supplemented conditions. Exogenous carbons such as acetate, fructose and glucose supplementation with propionate/valerate was found highly stimulatory for the co‐polymer accumulation; the content reached 58–60% of dry cell weight (dcw) under P‐/N‐deficiencies with 0.4% acetate + 0.4% valerate supplementation, the highest value reported so far for P(3HB‐co‐3HV) co‐polymer‐producing cyanobacterial species. The material properties of the films were studied by mechanical tests, surface analysis and differential scanning calorimetry (DSC). CONCLUSION: N. muscorum Agardh, a photoautotrophic N2‐fixing cyanobacterium, emerged as a potent host for production of P(3HB‐co‐3HV) co‐polymer with polymer content 60% of dry cell weight. The material properties of the films were found to be comparable with that of the commercial polymer, thus advocating its potential applications in various fields. Copyright © 2012 Society of Chemical Industry 相似文献
18.
Kinetics of oxidative cracking of n‐hexane to olefins over VOx/Ce‐Al2O3 under gas phase oxygen‐free environment
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AbdAlwadood H. Elbadawi Muhammad Y. Khan Mohammad R. Quddus Shaikh A. Razzak Mohammad M. Hossain 《American Institute of Chemical Engineers》2017,63(1):130-138
The kinetics of oxidative cracking of n‐hexane to olefins using lattice oxygen of VOx/Ce‐Al2O3 is investigated. The TPR/TPO analysis shows a consistent reducibility (79%) of VOx/Ce‐Al2O3 in repeated redox cycles. The total acidity of the sample is found to be 0.54 mmol/g with 22% are strong acid sites that favors olefin selectivity. The oxidative cracking of n‐hexane in a fluidized CREC Riser simulator gives approximately 60% olefin selectivity at 30% n‐hexane conversion. A kinetic model is developed considering (1) cracking, (2) oxidative dehydrogenation (ODH), and (3) catalyst deactivations. The proposed cracking mechanism considers adsorption, C–H and C–C bond fission and desorption as elementary steps and implemented by pseudo steady state hypothesis. A Langmuir‐Hinshelwood mechanism is found to represent the ODH reactions. The developed model fits the experimental data with favorable statistical indicators. The estimated specific reaction rate constants are also found to be consistent with the product selectivity data. © 2016 American Institute of Chemical Engineers AIChE J, 63: 130–138, 2017 相似文献
19.
Chien‐Chi Hsiao Yi‐Kuan Lin Chia‐Ju Liu Tsun‐Cheng Wu Yao‐Ting Wu 《Advanced Synthesis \u0026amp; Catalysis》2010,352(18):3267-3274
In the presence of palladium(II) acetate [Pd(OAc)2] and an N‐heterocyclic carbene (NHC) ligand, fluorene derivatives can be generated in good to excellent yields from 2‐halo‐2′‐methylbiaryls through the benzylic C H bond activation (14 examples; 81–97% yields). The scope and limitations of this protocol have been examined. A wide range of functional groups, such as alkyl, alkoxy, ester, nitrile, and others, is able to tolerate the reaction conditions herein. The cyclization of an isotope‐labelled biphenyl gave the corresponding product with a primary kinetic isotope effect (kH/kD=4.8:1), which indicates that the rate‐determining step of this reaction is the activation of the benzylic C H bond. Moreover, indenofluorenes were also accessed in excellent results from terphenyls (3 examples; 91–92% yields). The cascade reaction of 2,6‐dichloro‐2′‐methylbiphenyl with diphenylacetylene produced 8,9‐diphenyl‐4H‐cyclopenta[def]phenanthrene in 60% yield through the activation of an aryl and a benzylic C H bond. 相似文献
20.
The oxidative polycondensation reaction conditions of 4‐[(pyridine‐3‐yl‐methylene) amino]phenol (4‐PMAP) were studied using H2O2, atmospheric O2, and NaOCl oxidants in an aqueous alkaline medium between 30°C and 90°C. Synthesized oligo‐4‐[(pyridine‐3‐yl‐methylene) amino] phenol (O‐4‐PMAP) was characterized by 1H‐, 13C NMR, FTIR, UV–vis, size exclusion chromatography (SEC), and elemental analysis techniques. The yield of O‐4‐PMAP was found to be 32% (for H2O2 oxidant), 68% (for atmospheric O2 oxidant), and 82% (for NaOCl oxidant). According to the SEC analysis, the number–average molecular weight, weight–average molecular weight, and polydispersity index values of O‐4‐PMAP was found to be 5767, 6646 g mol?1, and 1.152, respectively, using H2O2, and 4540, 5139 g mol?1, and 1.132, respectively, using atmospheric O2, and 9037, 9235 g mol?1, and 1.022, using NaOCl, respectively. According to TG and DSC analyses, O‐4‐PMAP was more stable than 4‐PMAP against thermal decomposition. The weight loss of O‐4‐PMAP was found to be 94.80% at 1000°C. Also, antimicrobial activities of the oligomer were tested against B. cereus, L. monocytogenes, B. megaterium, B. subtilis, E. coli, Str. thermophilus, M. smegmatis, B. brevis, E. aeroginesa, P. vulgaris, M. luteus, S. aureus, and B. jeoreseens. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3327–3333, 2006 相似文献