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1.
A new type of optically active N-(L-menthylcarboxylatomethyl)maleimide (MGMI) was synthesized from maleic anhydride, glycine, and L-menthol. Radical homopolymerization of MGMI was performed at 50°C for 24 h to give optically active polymer having [α] D = -57°. Radical copolymerizations of MGMI ( M 1) were performed with styrene (ST, M 2), methyl methacrylate (MMA, M 2) in benzene at 50°C. From the results, the monomer reactivity ratios ( r 1, r 2) and the Alfrey-Price Q, e values were determined as follows: r 1 = 0.16, r 2 = 0.006 for the MGMI-ST system; r 1 = 0.15, r 2 = 1.65 for the MGMI-MMA system, and Q 1 = 0.72, e 1 = 1.59 calculated from the MGMI-MMA system. Anionic homopolymerizations of MGMI were also carried out. Chiroptical properties of the polymers were investigated. 相似文献
2.
Copolymers of p-vinylphenol were prepared in bulk with heptafluorobutyl and pentadecafluorooctyl acrylates and trifluoroethyl, hexafluoroisopropyl, heptafluorobutyl, octafluoropentyl and pentadecafluorooctyl methacrylates using azobisisobutyronitrile as the initiator in sealed tubes. Intrinsic viscosities of the copolymers ranged from 0.44 to 1.85. Monomer reactivity ratios for copolymers of trifluoroethyl methacrylate ( M1) were: with hydroxyethyl methacrylate ( M2), r1 = 0.47, r2 = 1.0; with methyl methacrylate ( M2), r1 = 0.82, r2 = 0.50; with styrene ( M2), r1 = 0.29, r2, = 0.20; and with p-vinylphenol ( M2), r1 = 0.096, r2 = 1.5. Q and e values of trifluoroethyl methacrylate were 1.30 and 0.92, respectively. Monomer reactivity ratios of octafluoropentyl methacrylate ( M1) were: with styrene ( M2), r1 = 0.26, r2 = 0.20; and with p-vinylphenol, r1 = 0.21, r2 = 1.5. Q and e values for octafluoropentyl methacrylate were 1.27 and 0.92, respectively. Critical surface tensions of the homopolymers ranged from 17.9 to 14.8 dyn/cm. A copolymer of hexafluoro- i-propyl methacrylate and p-vinylphenol exhibited a critical surface tension of 16.5 dyn/cm. 相似文献
3.
CoFe 2O 4 and Co x Fe y were anchored into activated carbon (AC) to synthesize CoFe 2O 4/Co x Fe y /AC composites using the sol–gel method for Cd(II) adsorption from wastewater. The results indicated that CoFe 2O 4 and Co x Fe y nanoparticles existed in the pores of AC. The magnetic properties of CoFe 2O 4/Co x Fe y /AC indicated it could be separated and retrieved easily using an external magnet after Cd(II) adsorption. The effects of solution pH, temperature and initial Cd(II) concentration on the Cd(II) adsorption of AC and CoFe 2O 4/Co x Fe y /AC were investigated. The standard free energy, enthalpy change and entropy change were evaluated. The kinetic parameters of Langmuir and Freundlich isothermal equation were analyzed, and the Freundlich kinetic model was feasible for describing the Cd(II) adsorption process of CoFe 2O 4/Co x Fe y /AC composites. 相似文献
4.
The behavior of lattice oxygen species of the ferroelectric material during methane oxidation was investigated using a nonthermal plasma reactor packed with BaTiO
3
pellets. Lattice oxygen species in BaTiO
3
play an important role in the formation of N
2
O and the oxidation of CH
4
. The oxidation products such as CO and CO
2
were formed from independent reaction pathways. Lattice oxygen species were able to preferentially oxidize the carbon species deposited on the pellet surface into CO. Also, N
2
O and NO
x
were independently formed in the N
2– O
2
reaction, suggesting that different oxygen species give N
2
O and NO
x. N
2
O was produced by the oxidation of molecular nitrogen with lattice oxygen species. 相似文献
5.
采用并流共沉淀法制备了不同Zr/Cd原子比(n Zr/n Cd)的ZrCdO x金属氧化物,并与水热法制备的不同硅铝比(n SiO_(2)/n Al_(2O 3))的片状SAPO-18分子筛物理混合制得ZrCdO x/SAPO-18双功能催化剂,研究了其催化CO 2加氢直接合成低碳烯烃性能。采用透射电子显微镜(TEM)、X射线衍射(XRD)、N2吸附-脱附、CO 2程序升温脱附(CO 2-TPD)、NH3程序升温脱附(NH3-TPD)和X射线光电子能谱(XPS)对催化剂进行了分析。与单一ZrO2相比,引入CdO使得ZrCdO x比表面积下降,当n Zr/n Cd=8时制备的Zr8Cd1氧化物呈现出无定形小颗粒状,Zr与Cd之间较强的协同作用使得Zr Cd Ox氧化物产生了更多的氧空位,有利于CO 2的吸附活化。通过对Zr8Cd1金属氧化物与SAPO-18(硅铝比0.1)的质量比、工艺反应温度、压力和空速对催化性能影响的考察,获得了最佳反应条件。研究还发现,当SAPO-18的硅铝比从0.1降为0.01时,Br?nsted酸含量降低,产物中烯烃/烷烃物质的量之比从18.6提高至37.2,但副产物CO含量迅速增加,低碳烯烃时空收率明显下降。 相似文献
6.
Poly(silylenemethylene)s of the types [SiMeRCH 2] n and [SiHRCH 2] n were prepared by the ring-opening polymerization (ROP) of 1,3-disilacyclobutanes (DSCBs) containing n-alkyl substituents, such as C 2H 5, n-C 3H 7, n-C 4H 9, n-C 5H 11, and n-C 6H 13, or a phenyl group on the Si. These new polymers include a monosilicon analog of poly(styrene), [SiHPhCH 2] n. Improved synthesis routes to the DSCB monomers were developed which proceed through Grignard ring closure reactions on alkoxy-substituted chlorocarbosilanes. All of these asymmetrically substituted polymers were obtained in high molecular weight form, except for [SiHPhCH 2] n. The configurations of all of the polymers were found to be atactic. The aryl-substituted polymers have higher glass transition temperatures ( Tgs) and thermal stability than those of the alkyl-substituted poly(silylenemethylene)s. Unlike the polyolefins of the type [C(H)(R)CH 2] n, where Tg drops continuously from R = Me to n-Hex, the Tgs of the n-C nH 2n+1 ( n = 2–6)-substituted [SiMeRCH 2] n PSM's appear to reach a maximum (at −61°C) for the R = n-Pr-substituted polymer. Moreover, where it was possible to make direct comparisons among similarly substituted atactic polymers, all of the poly(silylenemethylene)s were found to have lower Tgs than their all-carbon analogs. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3193–3205, 1997 相似文献
7.
The radiation degradation behavior of methyl α-chloroacrylate (MCA) and methacrylonitrile (MCN) copolymers has been investigated as part of a program to develop high-sensitivity polymeric resists for integrated circuit manufacture. High-molecular-weight copolymers were prepared by emulsion techniques. Several different copolymer compositions were prepared varying from 19 to 68 mole % MCA. These copolymers were fractionated and then subjected to γ irradiation from a 60Co Source. The Gs - Gs, Gs - 4 Gs values were determined from M?; F> nk?1 and Gu?1 versus dose plots, and the Gfs and Gs Values were then calculated. Molecular weights of both unirradiated and irradiated polymers were analyzed by membrane osmometry and gel permeation chromatography. All copolymers exhibited higher degradation susceptibilities than that of poly(methyl methacrylate) (PPMA), which has Gx = 1.3. The individual Gx and Gx values of the copolymers were found to fall between those of the two homopolymers, poly(methyl α-chloroacrylate) ( Gx = 6.0) and polymethacrylonitrile ( Gx ~ 3.1). The dependence of Gx and Gx values on molecular weight was minor. The crosslinking susceptibility of the poly(methyl α-chloroacrylate) ( Gx ~ 0.8), was greatly decreased by copolymerization with MCN. Relatively small amounts of MCN caused a large drop in Gx, i.e., Gx ~ 0.15 at 32% MCN and Gx ~ 0.03 at 51% MCN. The observation could be attributed to the decreasing probability that crosslinking sites, in the MCA monomer units on adjacent chains, would lie in close proximity. 相似文献
8.
The tetrachlorocuprate(II) ethylenediammonium and tetrachlorocadmate(II) ethylenediammonium were synthesized. Chemical analysis, elemental analysis, and X‐ray crystallography were applied to characterize the compositions and crystal structures of the two complexes. The lattice potential energies and the radiuses of the anions of two complexes were calculated to be UPOT[(C 2H 10N 2)CuCl 4]=1810.19 kJ·mol ?1, UPOT[(C 2H 10N 2)CdCl 4]=1784.39 kJ·mol ?1, r[(CuCl 4) 2?]=0.308 nm, and r[(CdCl 4) 2?]=0.321 nm from the data of the crystal structure, respectively. Low‐temperature heat capacities of the two complexes were measured by a precision automatic adiabatic calorimeter with the small sample over the temperature range from 78 to 400 K, respectively. Two polynomial equations of heat capacities against the temperatures were fitted by least square method: Cp, m[(C 2H 10N 2)CuCl 4, s] =213.553+118.578 X?5.816 X2+4.392 X3+0.276 X4 and Cp, m[(C 2H 10N 2)CdCl 4, s] =190.927+98.501 X?7.931 X2+0.657 X3+3.834 X4, in which X= ( T?239)/161. Based on the fitted polynomial equations, the smoothed heat capacities and thermodynamic functions of the two complexes relative to the standard reference temperature 298.15 K were calculated at intervals of 5 K. 相似文献
9.
The retention factors in pure water for a homologous series of s-triazines were calculated by a numerical method basing on Ościk's equation and were correlated with log k
w
values obtained by linear and parabolic extrapolation. Chromatographic data (log k
w
) were compared with the software-calculated partition coefficients in the n-octanol/water system (Alog P, IAlog P, clog P, log P
Kowin
, xlog P, log P
ACD
and log P
Chem.Off.) as alternative hydrophobicity indices. The effect of organic modifier (methanol and acetonitrile) and its concentration in the mobile phase used for log k
w
evaluation were investigated. Very good linear correlations were found between log k
w
values calculated by the numerical method and log P
ACD
, log P
Chem.Off
. and clog P values, independent of organic modifier type. 相似文献
10.
A number of configurations of NLi
n
Na 2 ( n = 1–4) species were optimized using the B3LYP–density functional theory method; the 6-31G * basis set was used in this calculation. In order to study all possible dissociation energies, some related species such as
NLi 2Na, NLi
n
( n = 1–4), Li
n
( n = 1, 2) and Na
n
( n = 1, 2) were also considered. Optimizations of these species were followed by fundamental frequency calculations at the same
level. Global minima of these species were shown to adopt C
2
v
(NLi 4Na 2, NLi 2Na 2), D
3
h
(NLi 3Na 2) and C
s
(NLiNa 2 and NLi 2Na) configurations. All possible dissociation energies were obtained.
Received: 30 November 1998 / Accepted: 15 October 1999 / Published online: 14 March 2000 相似文献
11.
Three new monomers of p-phenylacrylamide derivatives were prepared by either the reaction of p-methyl-, p-nitro-, and p-chloroaniline with acryloyl chloride or with acrylic acid in the presence of dicyclohexyl carbodiimide (DCCI). The prepared monomers were copolymerized with each of tri- n-butyltinacrylate and tri- n-butyltinmethacrylate. Copolymerization reactions were carried out in dioxane at 70°C using 1 mol % azobisisobutyronitrile as a free radical initiator. The structure of the new monomers and the prepared copolymers were investigated by IR and 1H-NMR spectroscopy. The monomer reactivity ratios for the copolymerization of p-chlorophenylacrylamide (M 1) with each of tri- n-butyltinacrylate (TBTA) and tri- n-butyltinmethacrylate (TBTMA) (M 2) were found to be r1 = 2.6; r2 = 0.83 and r1 = 1.3; r2 = 1.71, respectively. In case of p-tolyacrylamide (M 1) with TBTA and TBTMA (M 2) r1 = 0.35, r2 = 1.03 and r1 = 1.38, r2 = 0.366 respectively. The Q and e values for the prepared p-tolyl- and p-chlorophenylacrylamide were calculated © 1993 John Wiley & Sons, Inc. 相似文献
12.
Abstract— The energies of the lowest excited singlet, E s, and triplet, E t, states, and singlet-triplet splitting energies, Δ Es,t, were determined on 18 carcinogenic and 31 noncarcinogenic polycyclic aromatics. A highly significant correlation was found between carcinogenic activity and the energy of the excited singlet state. Compounds with an Es < 312 kJ/mol were 4.8 times more likely to be carcinogens than those compounds with Es 312 kJ/mol ( P= 0.015). Compounds whose singlet energies fell within the narrow range of 297 ≤ Es≤ 310 kJ/mol were 22.8 times more likely to be carcinogens than those compounds which fell outside this range ( P= 0.00006). A significant correlation between carcinogenic activity and Et energies was not found, while the correlation involving Δ Es,t energies was intermediate between the Es and Et correlations. The phosphorescence lifetimes, τ p, of the 18 carcinogenic aromatics and 27 of the noncarcinogenic aromatip were determined, and were shown not to be correlated with carcinogenic activity. When either the Et or Δ Es,t energies were plotted as a function of Es it was found that the carcinogens tended to form in an elliptical cluster. Compounds whose Es and Et energies placed them within the ellipse were 9.7 times more likely to be carcinogens than those compounds which fell outside the ellipse ( P= 0.002), while with the Es, Δ Es,t ellipse, compounds which fell inside were 20.6 times more likely to be carcinogens than those which fell outside ( P= 0.0004). Es, Et, Δ Es,t and τ p values were also determined on 12 carcinogenic and 4 noncarcinogenic alkyl substituted benz[a]anthracenes. There was no significant difference between the carcinogens and noncarcinogens and the “elliptical” correlation predicted both the carcinogens and noncarcinogens to be carcinogenic. The results suggest that either some property(ies) of the lowest excited singlet state, but not its energy, or some molecular property(ies) which runs parallel to singlet state energies may be important in determining carcinogenic activity in polycyclic aromatics. 相似文献
13.
Thermogravimetric
analyses of thermal decomposition (pyrolysis, thermal dissociation and combustion)
of 9 different samples were carried out in dynamic conditions at different
heating rates. The kinetic parameters ( E, A and km)
of thermal decomposition were determined and interrelations between the parameters
and heating rate q were analyzed. There
were also relations between Arrhenius and Eyring equations analyzed for thermal
decomposition of solid phase. It was concluded that Eyring theory is an element,
which interconnects used thermokinetic equations containing Arrhenius law
and suggests considering kinetic quantities in way relative to 3 kinetic constants
( E, A
and km). Analysis
of quantities other than km (i.e. E, A, Δ +H, Δ +S) in relation to heating rate is an incomplete method
and does not lead to unambiguous conclusions. It was ascertained that in ideal
case, assuming constant values of kinetic parameters ( E
and A) towards heating rate and satisfying
both Kissinger equations, reaction rate constant km
should take on values intermediate between constants ( km) 1
and ( km) 2
determined from these equations. Whereas behavior of parameters E and A towards q were not subjected to any rule, then plotting relation km vs. q in the background of ( km) 1
and ( km) 2
made possible classification of differences between thermal decomposition
processes taking place in oxidizing and oxygen-free atmosphere. 相似文献
14.
Seven new cyclohexadepsipeptides, beauvenniatins F, G 1, G 2, G 3, H 1, H 2, and H 3 ( 1 – 7 , resp.), were isolated from cultures of the fungus Acremonium sp. BCC 2629. Their structures were elucidated by extensive spectroscopic analyses. The absolute configurations were addressed by HPLC analyses of their acid hydrolysates. Their biological activities were evaluated against Mycobacterium tuberculosis H37Ra and Plasmodium falciparum K1; the respective MIC and IC50 values were in the micromolar range. 相似文献
15.
Unique hollow‐caged (MN 4) nC 6(10 ? n) (M = Zn, Mg, Fe, n = 1?6) complexes designed by introduction of n porphyrinoid fragments in C 60 fullerene structure were proposed and the atomic and electronic structures were calculated using LC‐DFT MPWB95 and M06 potentials and 6‐311G(d)/6‐31G(d) basis sets. The complexes were optimized using various symmetric configurations from the highest Oh to the lowest C1 point groups in different spin states from S = 0 (singlet) to S = 7 (quindectet) for M = Fe to define energetically preferable atomic and electronic structures. Several metastable complexes were determined and the key role of the metal ions in stabilization of the atomic structure of the complexes was revealed. For Fe 6N 24C 24, the minimum energy was reported for C2h, D2h, and D4h symmetry of pentet state S = 2, so the complex can be regarded as unique molecular magnet. It was found that the metal partial density of states determine the nature of HOMO and LUMO levels making the clusters promising catalysts. © 2014 Wiley Periodicals, Inc. 相似文献
16.
Aluminum oxynitride films were deposited by ion beam sputtering technique at room temperature. The optical properties and morphologies of the aluminum oxynitride films were studied and reported previously. It was found that the optical properties are closely related to the O contents in the films. In this study, the structures of the films were investigated by X‐ray diffractometer and XPS. Three oxidation states of N 1s in oxynitride films, N +, N 2+ and N 3+, were clearly deduced from N 1s spectra in the amorphous films fabricated under various oxygen partial pressures ( PO2). To our knowledge, three oxidation states of N 1s have not been simultaneously observed and reported in the aluminum oxynitride films previously. Corresponding bonding variations in Al 2p and O 1s spectra indicated more oxygen in oxynitride in the film as PO2 increases. Three aluminum oxynitride networks, AlO 2N, AlO 2.5N and AlO 3N were deduced. Optical properties of aluminum oxynitride films resemble those of AlN and Al 2O 3 films when PO2 is low and high during the deposition. The refractive indices and extinction coefficients of the aluminum oxynitride films can be adjusted by using proper PO2 during the film depositions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
17.
Herein Ce 1?xFe xO 2?δ nanocomposites were investigated for dilute magnetic semiconductor (DMS) properties. Ce 1?xFe xO 2?δ nanospheres and porous nanostructures with high surface areas have been successfully prepared by electrochemical deposition at room temperature and atmospheric pressure. The structures and morphologies of Ce 1?xFe xO 2?δ deposits were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N 2 adsorption–desorption techniques. The magnetic properties of the prepared Ce 1?xFe xO 2?δ nanospheres and porous nanostructures were studied, and they showed room‐temperature ferromagnetism and giant magnetic moments. In addition, the effects of morphologies and compositions on the magnetic properties of Ce 1?xFe xO 2?δ deposits were studied. 相似文献
18.
The title compounds were synthesized by reacting the elements in sealed tantalum tubes in a high‐frequency furnace. They crystallize with the Mo 2FeB 2 structure, a ternary ordered variant of the U 3Si 2 type, space group P4/ mbm. All compounds were characterized through Guinier powder patterns and the lattice parameters were obtained from least‐squares fits. Four structures were refined from single crystal X‐ray data: a = 740.5(1) pm, c = 372.5(1) pm, w R2 = 0.0430, 247 F values, 13 variables for Y 2Ni 1.90Mg, a = 764.5(1) pm, c = 394.39(9) pm, w R2 = 0.0371, 310 F values, 12 variables for La 2Ni 2Mg, a = 754.4(1) pm, c = 385.20(9) pm, w R2 = 0.0460, 295 F values, 12 variables for Pr 2Ni 2Mg, and a = 752.53(8) pm, c = 382.33(5) pm, w R2 = 0.0183, 291 F values, and 12 variables for Nd 2Ni 2Mg. A refinement of the occupancy parameters indicated small defects on the nickel site of the yttrium compound, resulting in the composition Y 2Ni 1.90Mg for the investigated single crystal. The compounds with cerium, samarium, and gadolinium to thulium as rare earth component were characterized through their Guinier powder patterns. The cell colume of Ce 2Ni 2Mg is smaller than that of Pr 2Ni 2Mg, indicating intermediate‐valent cerium. The structures can be considered as an intergrowth of distored AlB 2 and CsCl related slabs of compositions LnNi2 and LnMg. Chemical bonding in La 2Ni 2Mg and isotypic La 2Ni 2In is compared on the basis of extended Hückel calculations. 相似文献
19.
Optically active N-bornylmaleimide (NBMI) was copolymerized with styrene, methyl methacrylate, and vinylidene chloride with a free-radical catalyst to obtain optically active copolymers. The monomer reactivity ratios for the radical copolymerization of NBMI (M 2) with styrene, methyl methacrylate, and vinylidene chloride were: ST-NBMI, r1 = 0.13, r2 = 0.05; MMA-NBMI, r1 = 2.02, r2 = 0.16; VCl 2-NBMI, r1 = 1.15, r2 = 0.47. The Q-e values for NBMI were Q2 = 0.48 and e2 = +1.47. The specific rotation and optical rotatory dispersion of these copolymers were measured. The correlation between the specific rotation and composition of these copolymers was not linear. The value of λ c for each copolymer was independent of the copolymer composition and the comonomer, being 260 mμ for the St-NBMI system, 262 mμ for the MMA-system, and 260 mμ for the VCl 2-NBMI system. The effects of solvents and temperature on the specific rotation of these copolymers were investigated. 相似文献
20.
H 2[M II(HNTA) 2]· xH 2O complexes of eleven divalent metals were prepared. These complexes were characterized via elemental analysis, IR spectra, TGA, DTA and 1H NMR. p Ka 1 and p Ka 2 of these acids were determined together with their log? β 1 and log? β 2 as metal complexes. 相似文献
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